Tommi T Koskinen

Interests

Teaching

Astrophysics, planetary atmospheres, exoplanet atmospheres, evolution of the atmosphere, plasma physics, viscous and comprehensible fluid dynamics, gaskinetic theory

Research

Planetary science, planetary atmospheres, extrasolar planets, plasma physics, planetary ionospheres, global circulation models, radiative transfer applications, numerical methods, stellar high energy emissions

Courses

Scholarly Contributions

Chapters

• Cho, J., Thrastarson, H., Koskinen, T. T., Read, P., Tobias, S., Moon, W., & Skinner, J. (2019). Exoplanets and the Sun. In Zonal Jets: Phenomenology, Genesis, and Physics(pp 104-116). Cambridge University Press. doi:https://doi.org/10.1017/9781107358225.005
• Strobel, D., Koskinen, T. T., & Mueller-Wodarg, I. (2019). Saturn's variable thermosphere. In Saturn in the 21st century(pp 224-250). Cambridge University Press. doi:10.1017/9781316227220
• Garc{\'{\i}a, M. A., Koskinen, T., & Lavvas, P. (2018). Upper Atmospheres and Ionospheres of Planets and Satellites. In Handbook of Exoplanets(p. 52).

Journals/Publications

• Cubillos, P., Fossati, L., Koskinen, T., Huang, C., Sreejith, A., France, K., Wilson Cauley, P., & Haswell, C. (2023). The Hubble/STIS near-ultraviolet transmission spectrum of HD 189733 b. Astron. Astrophys., 671, A170.
• Fossati, L., Biassoni, F., Cappello, G., Borsa, F., Shulyak, D., Bonomo, A., Gandolfi, D., Haardt, F., Koskinen, T., Lanza, A., Nascimbeni, V., Sicilia, D., Young, M., Aresu, G., Bignamini, A., Brogi, M., Carleo, I., Claudi, R., Cosentino, R., , Guilluy, G., et al. (2023). The GAPS programme at TNG. XLV. HI Balmer lines transmission spectroscopy and NLTE atmospheric modelling of the ultra-hot Jupiter KELT-20b/MASCARA-2b. Astron. Astrophys., 676, A99.
• France, K., Fleming, B., Egan, A., Desert, J., Fossati, L., Koskinen, T. T., Nell, N., Petit, P., Vidotto, A. A., Beasley, M., DeCicco, N., Sreejith, A. G., Suresh, A., Baumert, J., Cauley, P. W., Villarreal, D. C., Hoadley, K., Kane, R., Kohnert, R., , Lambert, J., et al. (2023). The Colorado Ultraviolet Transit Experiment Mission Overview. Astron. J., 165(2), 63.
• Huang, C., Koskinen, T., Lavvas, P., & Fossati, L. (2023). A Hydrodynamic Study of the Escape of Metal Species and Excited Hydrogen from the Atmosphere of the Hot Jupiter WASP-121b. Astrophys. J., 951(2), 123.
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  LPL postdoc first author
• Moses, J. I., Brown, Z. L., Koskinen, T. T., Fletcher, L. N., Serigano, J., Guerlet, S., Moore, L., Waite, J. H., Ben-Jaffel, L., Galand, M., Chadney, J. M., H{\"orst}, S. M., Sinclair, J. A., Vuitton, V., & M{\"uller-Wodarg}, I. (2023). Saturn's atmospheric response to the large influx of ring material inferred from Cassini INMS measurements. Icarus, 391, 115328.
• Sreejith, A., France, K., Fossati, L., Koskinen, T. T., Egan, A., Cauley, P. W., Cubillos, P. E., Ambily, S., Huang, C., Lavvas, P., Fleming, B. T., Desert, J., Nell, N., Petit, P., & Vidotto, A. (2023). CUTE Reveals Escaping Metals in the Upper Atmosphere of the Ultrahot Jupiter WASP-189b. Astrophys. J. Lett., 954(1), L23.
• Steinrueck, M. E., Koskinen, T., Lavvas, P., Parmentier, V., Zieba, S., Tan, X., Zhang, X. i., & Kreidberg, L. (2023). Photochemical Hazes Dramatically Alter Temperature Structure and Atmospheric Circulation in 3D Simulations of Hot Jupiters. Astrophys. J., 951(2), 117.
• Tamburo, P., Withers, P., Dalba, P. A., Moore, L., & Koskinen, T. (2023).

  Cassini Radio Occultation Observations of Saturn's Ionosphere: Electron Density Profiles From 2005 to 2013

  . Journal of Geophysical Research: Space Physics, 128(4). doi:10.1029/2023ja031310
• Tamburo, P., Withers, P., Dalba, P., Moore, L., & Koskinen, T. (2023). Cassini Radio Occultation Observations of Saturn's Ionosphere: Electron Density Profiles From 2005 to 2013. Journal of Geophysical Research (Space Physics), 128(4), e2023JA031310.
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  Boston University student first author
• Amerstorfer, U. V., Barstow, M., Bourrier, V., Champey, P., Drake, J. J., Fleming, B., Fossati, L., France, K., Froning, C. S., Green, J. C., Grisé, F., Gronoff, G., Hellickson, T., Jin, M., Koskinen, T. T., Kowalski, A. F., Kruczek, N., Linsky, J. L., Lipscy, S. J., , Mason, J., et al. (2022).

  Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution mission: motivation and overview

  . Journal of Astronomical Telescopes, Instruments, and Systems, 8(01). doi:10.1117/1.jatis.8.1.014006
• Bergsten, G. J., Pascucci, I., Mulders, G. D., Fernandes, R. B., & Koskinen, T. T. (2022). The Demographics of Kepler's Earths and Super-Earths into the Habitable Zone. Astron. J., 164(5), 190.
• Brown, Z. L., Medvedev, A. S., Starichenko, E. D., Koskinen, T. T., & M{\"uller-Wodarg}, I. C. (2022). Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation. Geophys. Res. Lett., 49(8), e97219.
• Chadney, J., Koskinen, T., Hu, X., Galand, M., Lavvas, P., Unruh, Y., Serigano, J., H{\"orst}, S., & Yelle, R. (2022). Energy deposition in Saturn's equatorial upper atmosphere. Icarus, 372, 114724.
• Fernandes, R. B., Mulders, G. D., Pascucci, I., Bergsten, G. J., Koskinen, T. T., Hardegree-Ullman, K. K., Pearson, K. A., Giacalone, S., Zink, J., Ciardi, D. R., & O'Brien, P. (2022). pterodactyls: A Tool to Uniformly Search and Vet for Young Transiting Planets in TESS Primary Mission Photometry. Astron. J., 164(3), 78.
• France, K., Fleming, B., Youngblood, A., Mason, J., Drake, J. J., Amerstorfer, U. V., Barstow, M., Bourrier, V., Champey, P., Fossati, L., Froning, C. S., Green, J. C., Gris{\'e}, F., Gronoff, G., Hellickson, T., Jin, M., Koskinen, T. T., Kowalski, A. F., Kruczek, N., , Linsky, J. L., et al. (2022). Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution mission: motivation and overview. Journal of Astronomical Telescopes, Instruments, and Systems, 8, 014006.
• Koskinen, T. T., Brown, Z. L., Medvedev, A. S., Starichenko, E. D., & Müller‐Wodarg, I. C. (2022). Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation. Geophysical Research Letters, 49(8). doi:10.1029/2021gl097219
• Koskinen, T. T., Lavvas, P., Huang, C., Bergsten, G., Fernandes, R. B., & Young, M. E. (2022). Mass Loss by Atmospheric Escape from Extremely Close-in Planets. Astrophys. J., 929(1), 52.
• Koskinen, T. T., Serigano, J., Hörst, S. M., He, C., Gautier, T., Yelle, R. V., Trainer, M. G., & Radke, M. J. (2022). Compositional Measurements of Saturn's Upper Atmosphere and Rings From Cassini INMS: An Extended Analysis of Measurements From Cassini's Grand Finale Orbits. Journal of Geophysical Research: Planets, 127(6). doi:10.1029/2022je007238
• Morgan, A., Cauley, P. W., France, K., Youngblood, A., & Koskinen, T. T. (2022). Detection Feasibility of H$_2$ in Ultra-hot Jupiter Atmospheres. Research Notes of the American Astronomical Society, 6(7), 141.
• Rodriguez, S., Vinatier, S., Cordier, D., Tobie, G., Achterberg, R. K., Anderson, C. M., Badman, S. V., Barnes, J. W., Barth, E. L., B{\'ezard}, B., Carrasco, N., Charnay, B., Clark, R. N., Coll, P., Cornet, T., Coustenis, A., Couturier-Tamburelli, I., Dobrijevic, M., Flasar, F. M., , Kok, R., et al. (2022). Science goals and new mission concepts for future exploration of Titan's atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON). Experimental Astronomy, 54(2-3), 911-973.
• Serigano, J., H{\"orst}, S., He, C., Gautier, T., Yelle, R., Koskinen, T., Trainer, M., & Radke, M. (2022). Compositional Measurements of Saturn's Upper Atmosphere and Rings From Cassini INMS: An Extended Analysis of Measurements From Cassini's Grand Finale Orbits. Journal of Geophysical Research (Planets), 127(6), e07238.
• Atkinson, D. H., Brooks, S. M., Cao, H., Cuzzi, J. N., Estrada, P. R., Fuller, J., Hedman, M. M., Hendrix, A. R., Ingersoll, A. P., Johnson, R. E., Koskinen, T., Kurth, W. S., Lunine, J. I., Miller, K. E., Nicholson, P. D., Parisi, M., Paty, C. S., Schindhelm, R., Showalter, M. R., , Spilker, L. J., et al. (2021).

  The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn’s rings, atmosphere, interior and inner magnetosphere

  . Bulletin of the AAS, 53(4). doi:10.3847/25c2cfeb.82f6e9ff
• Borsa, F., Fossati, L., Koskinen, T., Young, M. E., & Shulyak, D. (2021). High-resolution detection of neutral oxygen and non-LTE effects in the atmosphere of KELT-9b. Nature Astronomy.
• Fossati, L., Young, M., Shulyak, D., Koskinen, T., Huang, C., Cubillos, P., France, K., & Sreejith, A. (2021). Non-local thermodynamic equilibrium effects determine the upper atmospheric temperature structure of the ultra-hot Jupiter KELT-9b. Astron. Astrophys., 653, A52.
• Koskinen, T., Strobel, D., & Brown, Z. (2021). An empirical model of the Saturn thermosphere. Icarus, 362, 114396.
• Steinrueck, M. E., Showman, A. P., Lavvas, P., Koskinen, T., Tan, X., & Zhang, X. i. (2021). 3D simulations of photochemical hazes in the atmosphere of hot Jupiter HD 189733b. MNRAS, 504(2), 2783-2799.
• Tribbett, P. D., Robinson, T. D., & Koskinen, T. T. (2021). Titan in Transit: Ultraviolet Stellar Occultation Observations Reveal a Complex Atmospheric Structure. Plan. Sci. J., 2(3), 109.
• Yelle, R. V., Koskinen, T., & Palmer, M. (2021). Titan occultations of Orion's belt observed with Cassini/UVIS. Icarus, 368, 114587.
• Brown, Z., Koskinen, T., M{\"uller-Wodarg}, I., West, R., Jouchoux, A., & Esposito, L. (2020). A pole-to-pole pressure-temperature map of Saturn's thermosphere from Cassini Grand Finale data. Nature Astronomy, 4, 872-879.
• Cubillos, P. E., Fossati, L., Koskinen, T., Young, M. E., Salz, M., France, K., Sreejith, A., & Haswell, C. A. (2020). Near-ultraviolet Transmission Spectroscopy of HD 209458b: Evidence of Ionized Iron Beyond the Planetary Roche Lobe. AJ, 159(3), 111.
• Fletcher, L., Sromovsky, L., Hue, V., Moses, J., Guerlet, S., West, R., & Koskinen, T. (2020). Saturn's Seasonal Atmosphere at Northern Summer Solstice. arXiv e-prints, arXiv:2012.09288.
• Fossati, L., Shulyak, D., Sreejith, A., Koskinen, T., Young, M., Cubillos, P., Lara, L., France, K., Rengel, M., Cauley, P., Turner, J., Wyttenbach, A., & Yan, F. (2020). A data-driven approach to constraining the atmospheric temperature structure of the ultra-hot Jupiter KELT-9b. A&A, 643, A131.
• France, K., Duvvuri, G., Egan, H., Koskinen, T., Wilson, D. J., Youngblood, A., Froning, C. S., Brown, A., Alvarado-G{\'omez}, J. D., Berta-Thompson, Z. K., Drake, J. J., Garraffo, C., Kaltenegger, L., Kowalski, A. F., Linsky, J. L., Loyd, R. P., Mauas, P. J., Miguel, Y., Pineda, J. S., , Rugheimer, S., et al. (2020). The High-energy Radiation Environment around a 10 Gyr M Dwarf: Habitable at Last?. AJ, 160(5), 237.
• Hendrix, A. R., Becker, T. M., Bodewits, D., Bradley, E. T., Brooks, S., Byron, B., Cahill, J., Clarke, J., Feaga, L., Feldman, P., Gladstone, G. R., Hansen, C. J., Hibbitts, C., Koskinen, T. T., Magana, L., Molyneux, P., Nikzad, S., Noonan, J., Pryor, W., , Raut, U., et al. (2020). Ultraviolet-Based Science in the Solar System: Advances and Next Steps. arXiv e-prints, arXiv:2007.14993.
• Koskinen, T., Sandel, B., Yelle, R., Holsclaw, G., & Quemerais, E. (2020). Corrigendum to ``Saturn in Lyman alpha: A comparison of Cassini and Voyager observations'' [Icarus 339 (2020) 113594]. Icarus, 351, 113919.
• Koskinen, T., Sandel, B., Yelle, R., Holsclaw, G., & Quemerais, E. (2020). Saturn in Lyman alpha: A comparison of Cassini and Voyager observations. Icarus, 339, 113594.
• Serigano, J., Horst, S., He, C., Gautier, T., Yelle, R., Koskinen, T., & Trainer, M. (2020). Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS. Journal of Geophysical Research (Planets), 125(8), e06427.
• Steinrueck, M. E., Showman, A. P., Lavvas, P., Koskinen, T., Tan, X., & Zhang, X. i. (2020). 3D simulations of photochemical hazes in the atmosphere of hot Jupiter HD 189733b. arXiv e-prints, arXiv:2011.14022.
• Tiscareno, M. S., Vaquero, M., Hedman, M. M., Cao, H., Estrada, P. R., Ingersoll, A. P., Miller, K. E., Parisi, M., Atkinson, D. H., Brooks, S. M., Cuzzi, J. N., Fuller, J., Hendrix, A. R., Johnson, R. E., Koskinen, T., Kurth, W. S., Lunine, J. I., Nicholson, P. D., Paty, C. S., , Schindhelm, R., et al. (2020). The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn's rings, atmosphere, interior, and inner magnetosphere. arXiv e-prints, arXiv:2007.15767.
• Tribbett, P. D., Robinson, T. D., & Koskinen, T. T. (2020). Titan in Transit: Ultraviolet Occultation Observations Reveal a Complex Atmospheric Structure. arXiv e-prints, arXiv:2006.14670.
• Turner, J. D., Mooij, E. J., Jayawardhana, R., Young, M. E., Fossati, L., Koskinen, T., Lothringer, J. D., Karjalainen, R., & Karjalainen, M. (2020). Detection of Ionized Calcium in the Atmosphere of the Ultra-hot Jupiter KELT-9b. ApJL, 888(1), L13.
• Villarreal, D. C., Vidotto, A., Esquivel, A., Sgr{\'o}, M., Koskinen, T., & Fossati, L. (2020). Star-planet interaction through spectral lines. IAU Symposium, 354, 280-285.
• Vriesema, J., Koskinen, T., & Yelle, R. (2020). Electrodynamics in Saturn's thermosphere at low and middle latitudes. Icarus, 344, 113390.
• Y-K., C. J., Thrastarson, H. T., Koskinen, T., Read, P., Tobias, S., Moon, W., & Skinner, J. (2020). Exoplanets and the Sun. arXiv e-prints, arXiv:2010.09878.
• Young, M., Fossati, L., Koskinen, T., Salz, M., Cubillos, P., & France, K. (2020). Non-local thermodynamic equilibrium transmission spectrum modelling of HD 209458b. A&A, 641, A47.
• Koskinen, T. T., Sreejith, A. G., Fossati, L., Fleming, B. T., France, K. C., Egan, A., Rüdisser, H. T., & Steller, M. (2019). Colorado Ultraviolet Transit Experiment data simulator. Journal of Astronomical Telescopes, Instruments, and Systems, 5(01), 1. doi:10.1117/1.jatis.5.1.018004
• Koskinen, T., Pryor, W. R., Esposito, L. W., Jouchoux, A., West, R. A., Grodent, D., Gérard, J., Radioti, A., & Lamy, L. (2019). Cassini UVIS Detection of Saturn's North Polar Hexagon in the Grand Finale Orbits. Journal of Geophysical Research: Planets, 124(7), 1979-1988. doi:10.1029/2019je005922
• Lavvas, P., Koskinen, T., Steinrueck, M. E., Garc{\'\ia, M. A., & Showman, A. P. (2019). Photochemical Hazes in Sub-Neptunian Atmospheres with a Focus on GJ 1214b. ApJ, 878(2), 118.
• Mueller-Wodarg, I., Koskinen, T. T., Moore, L., Serigano, J., Yelle, R. V., Horst, S., Waite, J. H., & Mendillo, M. (2019). Atmospheric waves and their effect on the thermal structure of Saturn's thermosphere. GRL.
• Pearson, K. A., Griffith, C. A., Zellem, R. T., Koskinen, T. T., & Roudier, G. M. (2019). Ground-based Spectroscopy of the Exoplanet XO-2b Using a Systematic Wavelength Calibration. AJ, 157(1), 21.
• Pearson, K., Griffith, C., Zellem, R., Koskinen, T., & Roudier, G. (2019). VizieR Online Data Catalog: Ground-based spectroscopy of the exoplanet XO-2b (Pearson+, 2019). VizieR Online Data Catalog, J/AJ/157/21.
• Pryor, W., Esposito, L., Jouchoux, A., West, R., Grodent, D., G{\'erard}, J. -., Radioti, A., Lamy, L., & Koskinen, T. (2019). Cassini UVIS Detection of Saturn's North Polar Hexagon in the Grand Finale Orbits. Journal of Geophysical Research (Planets), 124(7), 1979-1988.
• Sreejith, A. G., Fossati, L., Fleming, B. T., France, K., Koskinen, T., Egan, A., R{\"udisser}, H. T., & Steller, M. (2019). Colorado Ultraviolet Transit Experiment data simulator. Journal of Astronomical Telescopes, Instruments, and Systems, 5, 018004.
• Youngblood, A., Drake, J., Mason, J., Osten, R., Jin, M., Kowalski, A., France, K., Fleming, B., Allred, J., Amerstorfer, U., Berta-Thompson, Z., Bourrier, V., Fossati, L., Froning, C., Garraffo, C., Gronoff, G., Koskinen, T., & Lichtenegger, H. (2019). EUV observations of cool dwarf stars. BAAS, 51(3), 300.
• Youngblood, A., France, K., Koskinen, T., Fossati, L., Amerstorfer, U., Lichtenegger, H., Drake, J., Mason, J., Fleming, B., Allred, J., Berta-Thompson, Z., Bourrier, V., Froning, C., Garraffo, C., Gronoff, G., Jin, M., Kowalski, A., & Osten, R. (2019). EUV influences on exoplanet atmospheric stability and evolution. BAAS, 51(3), 320.
• Cui, J., Zhao, L., Yelle, R. V., Stone, S., Jiang, F., Cao, Y., Yao, M., Koskinen, T. T., & Wei, Y. (2018). The impact of crustal magnetic fields on the thermal structure of the Martian upper atmosphere. ApJL, 853, L33.
• Fleming, B., France, K., Nell, N., Kohnert, R., Pool, K., Egan, A., Fossati, L., Koskinen, T., Vidotto, A., Hoadley, K., Desert, J., Beasley, M., & Petit, P. (2018). Colorado Ultraviolet Transit Experiment: a dedicated CubeSat mission to study exoplanetary mass loss and magnetic fields. Journal of Astronomical Telescopes, Instruments, and Systems, 4(1), 014004.
• Fossati, L., Koskinen, T. T., France, K., Cubillos, P. E., Haswell, C. A., Lanza, A. F., & Pillitteri, I. (2018). Suppressed Far-UV stellar activity and low planetary mass loss in the WASP-18 system. ApJ, 155, 113.
• Fossati, L., Koskinen, T., Lothringer, J., France, K., Young, M., & Sreejith, A. (2018). Extreme-ultraviolet Radiation from A-stars: Implications for Ultra-hot Jupiters. ApJL, 868, L30.
• Gr{\"oller}, H., Montmessin, F., Yelle, R., Lef{\`evre}, F., Forget, F., Schneider, N., Koskinen, T., Deighan, J., & Jain, S. (2018). MAVEN/IUVS Stellar Occultation Measurements of Mars Atmospheric Structure and Composition. Journal of Geophysical Research (Planets), 123, 1449-1483.
• Koskinen, T. T., & Guerlet, S. (2018). Atmospheric structure and helium abundance on Saturn from Cassini/UVIS and CIRS observations. Icarus, 307, 161-171.
• Lothringer, J., Barman, T., & Koskinen, T. (2018). Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H$^‑$ Opacity, and Thermal Dissociation of Molecules. ApJ, 866, 27.
• Tinetti, G., Drossart, P., Eccleston, P., Hartogh, P., Heske, A., Leconte, J., Micela, G., Ollivier, M., Pilbratt, G., Puig, L., & al., e. (2018). A chemical survey of exoplanets with ARIEL. Experimental Astronomy, 46, 135-209.
• Yelle, R., Serigano, J., Koskinen, T., H{\"orst}, S., Perry, M., Perryman, R., & Waite, J. (2018). Thermal Structure and Composition of Saturn's Upper Atmosphere From Cassini/Ion Neutral Mass Spectrometer Measurements. GRL, 45, 10.
• Zellem, R. T., Roudier, G. M., Pearson, K. A., Koskinen, T. T., & Griffith, C. A. (2018). Ground-based Spectroscopy of the Exoplanet XO-2b Using a Systematic Wavelength Calibration. The Astronomical Journal, 157(1), 21. doi:10.3847/1538-3881/aaf1ae
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  Exoplanets orbiting close to their host star are expected to support a large ionosphere, which extends to larger pressures than witnessed in our Solar System. These ionospheres can be investigated with ground-based transit observations of the optical signatures of alkali metals, which are the source of the ions. Here, we present new observations and analyses of optical transit spectra that cover the Na doublet in the atmosphere of the exoplanet XO-2 b. To assess the consistency of our results, observations were obtained from two separate platforms: Gemini/GMOS and Mayall/KOSMOS. To mitigate the systematic errors, we chose XO-2, because it has a binary companion of the same brightness and stellar type, which provides an ideal reference star to model Earth's atmospheric effects. We find that interpretation of the data is highly sensitive to time-varying translations along the detector, which change according to wavelength and differ between the target and reference star. It was necessary to employ a time-dependent cross-correlation to align our wavelength bins and correct for atmospheric differential refraction. This approach allows us to resolve the wings of the Na line across 5 wavelength bins at a resolution of $\sim$1.6nm and limit the abundance of Na. We obtain consistent results from each telescope with a Na amplitude of 521$\pm$161 ppm and 403$\pm$186 ppm for GMOS and KOSMOS respectively. The results are analyzed with a radiative transfer model that includes the effects of ionization. The data are consistent with a clear atmosphere between $\sim$1--100 mbar which establish a lower limit on Na at 0.4$^{+2}_{-0.3}$ ppm ([Na/H]=-0.64$^{+0.78}_{-0.6}$), consistent with solar. However, we can not rule out the presence of clouds at $\sim$10 mbar which allow for higher Na abundances which would be consistent with stellar metallicity measured for the host star ([Na/H]=0.485$\pm$0.043).
• Chadney, J., Koskinen, T., Galand, M., Unruh, Y., & Sanz-Forcada, J. .. (2017). Effect of stellar flares on the upper atmospheres of HD 189733b and HD 209458b. A&A, 608, A75.
• Fossati, L., Marcelja, S., Staab, D., Cubillos, P., France, K., Haswell, C., Ingrassia, S., Jenkins, J., Koskinen, T., Lanza, A., Redfield, S., Youngblood, A., & Pelzmann, G. (2017). The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies. A&A, 601, A104.
• Lavvas, P., & Koskinen, T. (2017). Aerosol Properties of the Atmospheres of Extrasolar Giant Planets. ApJ, 847, 32.
• Parke, L. R., Koskinen, T., France, K., Schneider, C., & Redfield, S. (2017). Ultraviolet C II and Si III Transit Spectroscopy and Modeling of the Evaporating Atmosphere of GJ436b. ApJL, 834, L17.
• Capalbo, F., B{\'enilan}, Y., Fray, N., Schwell, M., Champion, N., Es-sebbar, E., Koskinen, T., Lehocki, I., & Yelle, R. (2016). New benzene absorption cross sections in the VUV, relevance for Titan's upper atmosphere. Icarus, 265, 95-109.
• Chadney, J., Galand, M., Koskinen, T., Miller, S., Sanz-Forcada, J. .., Unruh, Y., & Yelle, R. (2016). EUV-driven ionospheres and electron transport on extrasolar giant planets orbiting active stars. A&A, 587, A87.
• Cui, J., Cao, Y., Lavvas, P., & Koskinen, T. (2016). The Variability of HCN in Titan's Upper Atmosphere as Implied by the Cassini Ion-Neutral Mass Spectrometer Measurements. ApJL, 826, L5.
• Koskinen, T. T., Moses, J. I., West, R. A., Guerlet, S., & Jouchoux, A. (2016). The detection of benzene in Saturn's upper atmosphere: C₆H₆ ON SATURN. Geophysical Research Letters, 43(15), 7895-7901. doi:10.1002/2016gl070000
• Koskinen, T., Moses, J., West, R., Guerlet, S., & Jouchoux, A. (2016). The detection of benzene in Saturn's upper atmosphere. GRL, 43, 7895-7901.
• Capalbo, F., B{\'enilan}, Y., Yelle, R., & Koskinen, T. (2015). Titan's Upper Atmosphere from Cassini/UVIS Solar Occultations. ApJ, 814, 86.
• Chadney, J., Galand, M., Unruh, Y., Koskinen, T., & Sanz-Forcada, J. .. (2015). XUV-driven mass loss from extrasolar giant planets orbiting active stars. Icarus, 250, 357-367.
• Fossati, L., France, K., Koskinen, T., Juvan, I., Haswell, C., & Lendl, M. (2015). Far-UV Spectroscopy of the Planet-hosting Star WASP-13: High-energy Irradiance, Distance, Age, Planetary Mass-loss Rate, and Circumstellar Environment. ApJ, 815, 118.
• Gr{\"oller}, H., Yelle, R., Koskinen, T., Montmessin, F., Lacombe, G., Schneider, N., Deighan, J., Stewart, A., Jain, S., Chaffin, M., Crismani, M., Stiepen, A., Lef{\`evre}, F., McClintock, W., Clarke, J., Holsclaw, G., Mahaffy, P., Bougher, S., & Jakosky, B. (2015). Probing the Martian atmosphere with MAVEN/IUVS stellar occultations. GRL, 42, 9064-9070.
• Koskinen, T., Erwin, J., & Yelle, R. (2015). On the escape of CH4 from Pluto's atmosphere. GRL, 42, 7200-7205.
• Koskinen, T., Sandel, B., Yelle, R., Strobel, D., M{\"uller-Wodarg}, I., & Erwin, J. (2015). Saturn's variable thermosphere from Cassini/UVIS occultations. Icarus, 260, 174-189.
• Koskinen, T., Yelle, R. V., Schwell, M., Lehocki, I., Koskinen, T., Fray, N., Es-sebbar, E., Champion, N., Capalbo, F. J., & Benilan, Y. (2015). New benzene absorption cross sections in the VUV, relevance for Titan’s. Icarus, 265.
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  Benzene is an important molecule in Titan’s atmosphere because it is a potential link between the gas phase and the organic solid phase. We measured photoabsorption in the ultraviolet by benzene gas at temperatures covering the range from room temperature to 215 K. We derived benzene absorption cross sections and analyzed them in terms of the transitions observed. No significant variation with measurement temperature was observed. We discuss the implications of our measurements for the derivation of benzene abundance profiles in Titan’s thermosphere, by the Cassini/Ultraviolet Imaging Spectrograph (UVIS). The use of absorption cross sections at low temperature is recommended to avoid small systematic uncertainties in the profiles. We used our measurements, together with absorption cross sections from other molecules, to analyze four stellar occultations by Titan, measured by UVIS during flybys T21, T41, T41_II, and T53. We derived and compared benzene abundance profiles in Titan’s thermosphere between approximately 530 and 1000 km, for different dates and geographical locations. The comparisons of our benzene profiles with each other, and with profiles from models of the upper atmosphere, point to a complex behavior that is not explained by current photochemical models. 2015 Elsevier Inc. All rights reserved.
• Sandel, B., Gr{\"oller}, H., Yelle, R., Koskinen, T., Lewis, N., Bertaux, J., Montmessin, F., & Qu{\'emerais}, E. (2015). Altitude profiles of O2 on Mars from SPICAM stellar occultations. Icarus, 252, 154-160.
• Tinetti, G., Drossart, P., Eccleston, P., Hartogh, P., Isaak, K., Linder, M., Lovis, C., Micela, G., Ollivier, M., Puig, L., & al., e. (2015). The EChO science case. Experimental Astronomy, 40, 329-391.
• Koskinen, T., Lavvas, P., Harris, M., & Yelle, R. (2014). Thermal escape from extrasolar giant planets. Philosophical Transactions of the Royal Society of London Series A, 372, 20130089-20130089.
• Koskinen, T., Yelle, R., Lavvas, P., & Y-K.~Cho, J. (2014). Electrodynamics on Extrasolar Giant Planets. ApJ, 796, 16.
• Lavvas, P., Koskinen, T., & Yelle, R. (2014). Electron Densities and Alkali Atoms in Exoplanet Atmospheres. ApJ, 796, 15.
• Yelle, R. V., Koskinen, T. T., Lavvas, P., & Harris, M. J. (2014). Thermal escape from extrasolar giant planets. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 372(2014), 20130089. doi:10.1098/rsta.2013.0089
• Yelle, R. V., Lavvas, P., Koskinen, T. T., & Cho, J. Y. (2014). ELECTRODYNAMICS ON EXTRASOLAR GIANT PLANETS. The Astrophysical Journal, 796(1), 16. doi:10.1088/0004-637x/796/1/16
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  Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter themore » energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially be used to constrain electrodynamics in the future.« less
• Capalbo, F., B{\'enilan}, Y., Yelle, R., Koskinen, T., Sandel, B., Holsclaw, G., & McClintock, W. (2013). Solar Occultation by Titan Measured by Cassini/UVIS. ApJL, 766, L16.
• Koskinen, T., Harris, M., Yelle, R., & Lavvas, P. (2013). The escape of heavy atoms from the ionosphere of HD209458b. I. A photochemical-dynamical model of the thermosphere. Icarus, 226, 1678-1694.
• Koskinen, T., Sandel, B., Yelle, R., Capalbo, F., Holsclaw, G., McClintock, W., & Edgington, S. (2013). The density and temperature structure near the exobase of Saturn from Cassini UVIS solar occultations. Icarus, 226, 1318-1330.
• Koskinen, T., Yelle, R., Harris, M., & Lavvas, P. (2013). The escape of heavy atoms from the ionosphere of HD209458b. II. Interpretation of the observations. Icarus, 226, 1695-1708.
• Lavvas, P., Yelle, R. V., Koskinen, T. T., Bazin, A., Vuitton, V., Vigren, E., Galand, M., Wellbrock, A., Coates, A. J., Wahlund, J., Crary, F. J., & Snowden, D. (2013). Aerosol growth in Titan's ionosphere. PNAS, 110(8), 2729-2734. doi:https://doi.org/10.1073/pnas.1217059110
• Menager, H., Barth{\'elemy}, M., Koskinen, T., Lilensten, J., Ehrenreich, D., & Parkinson, C. (2013). Calculation of the H Lyman alpha emission of the hot Jupiters HD 209458b and HD 189733b. Icarus, 226, 1709-1718.
• Yelle, R. V., Sandel, B. R., Mcclintock, W. E., Koskinen, T. T., Holsclaw, G. M., Capalbo, F. J., & Benilan, Y. (2013). SOLAR OCCULTATION BY TITAN MEASURED BY CASSINI/UVIS. The Astrophysical Journal, 766(2), L16. doi:10.1088/2041-8205/766/2/l16
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  We present the first published analysis of a solar occultation by Titan's atmosphere measured by the Ultraviolet Imaging Spectrograph on board Cassini. The data were measured during flyby T53 in 2009 April and correspond to latitudes between 21 Degree-Sign and 28 Degree-Sign south. The analysis utilizes the absorption of two solar emission lines (584 A and 630 A) in the ionization continuum of the N{sub 2} absorption cross section and solar emission lines around 1085 A where absorption is due to CH{sub 4}. The measured transmission at these wavelengths provides a direct estimate of the N{sub 2} and CH{sub 4} column densities along the line of sight from the spacecraft to the Sun, which we inverted to obtain the number densities. The high signal-to-noise ratio of the data allowed us to retrieve density profiles in the altitude range 1120-1400 km for nitrogen and 850-1300 km for methane. We find an N{sub 2} scale height of {approx}76 km and a temperature of {approx}153 K. Our results are in general agreement with those from previous work, although there are some differences. Particularly, our profiles agree, considering uncertainties, with the density profiles derived from the Voyager 1 Ultraviolet Spectrograph data, and with inmore » situ measurements by the Ion Neutral Mass Spectrometer with revised calibration.« less
• Encrenaz, T., Mueller-wodarg, I., Demangeon, O., Deroo, P., Focardi, M., Fouque, P., Maggio, A., Sicardy, B., Smith, A., Viti, S., Achilleos, N., Ade, P. A., Adriani, A., Afonso, C., Agnor, C. B., Aylward, A. D., Bakos, G. A., Barber, R. J., Barbera, A. L., , Barlow, M. J., et al. (2012).

  EChO - Exoplanet Characterisation Observatory

  . Experimental Astronomy, 34(2), 311-353. doi:10.1007/s10686-012-9303-4
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  A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. EChO -the Exoplanet Characterisation Observatory- is a mission concept specifically geared for this purpose. EChO will provide simultaneous, multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures. EChO will build on observations by Hubble, Spitzer and groundbased telescopes, which discovered the first molecules and atoms in exoplanetary atmospheres. EChO will simultaneously observe a broad enough spectral region -from the visible to the mid-IR- to constrain from one single spectrum the temperature structure of the atmosphere and the abundances of the major molecular species. The spectral range and resolution are tailored to separate bands belonging to up to 30 molecules to retrieve the composition and temperature structure of planetary atmospheres. The target list for EChO includes planets ranging from Jupiter-sized with equilibrium temperatures Teq up to 2000 K, to those of a few Earth masses, with Teq ~300 K. We have baselined a dispersive spectrograph design covering continuously the 0.4-16 micron spectral range in 6 channels (1 in the VIS, 5 in the IR), which allows the spectral resolution to be adapted from several tens to several hundreds, depending on the target brightness. The instrument will be mounted behind a 1.5 m class telescope, passively cooled to 50 K, with the instrument structure and optics passively cooled to ~45 K. EChO will be placed in a grand halo orbit around L2. We have also undertaken a first-order cost and development plan analysis and find that EChO is easily compatible with the ESA M-class mission framework.
• Yelle, R. V., Strobel, D. F., Snowden, D. S., Muller-wodarg, I. C., Koskinen, T. T., Galand, M., & Cui, J. (2012). The CH4 structure in Titan's upper atmosphere revisited. Journal of Geophysical Research, 117(11), n/a-n/a. doi:10.1029/2012je004222
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  [1] In this study, we reanalyze the CH4 structure in Titan's upper atmosphere combining the Cassini Ion Neutral Mass Spectrometer (INMS) data from 32 flybys and incorporating several updates in the data reduction algorithms. We argue that based on our current knowledge of eddy mixing and neutral temperature, strong CH4 escape must occur on Titan. Ignoring ionospheric chemistry, the optimal CH4 loss rate is ∼3 × 1027 s−1 or 80 kg s−1 in a globally averaged sense, consistent with the early result of Yelle et al. (2008). The considerable variability in CH4 structure among different flybys implies that CH4 escape on Titan is more likely a sporadic rather than a steady process, with the CH4 profiles from about half of the flybys showing evidence for strong escape and most of the other flybys consistent with diffusive equilibrium. CH4 inflow is also occasionally required to interpret the data. Our analysis further reveals that strong CH4escape preferentially occurs on the nightside of Titan, in conflict with the expectations of any solar-driven model. In addition, there is an apparent tendency of elevated CH4 escape with enhanced electron precipitation from the ambient plasma, but this is likely to be a coincidence as the time response of the CH4 structure may not be fast enough to leave an observable effect during a Titan encounter.
• Yelle, R. V., West, R. A., Snowden, D. S., Sandel, B. R., Lavvas, P., Koskinen, T. T., Capalbo, F. J., & Benilan, Y. (2011). The mesosphere and lower thermosphere of Titan revealed by Cassini/UVIS stellar occultations. Icarus, 216(2), 507-534. doi:10.1016/j.icarus.2011.09.022
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  Abstract Stellar occultations observed by the Cassini/UVIS instrument provide unique data that probe the mesosphere and lower thermosphere of Titan at altitudes between 400 and 1400 km. This region is a site of complex photochemistry that forms hydrocarbon and nitrile species, and plays a crucial role in the formation of the organic hazes observed in the stratosphere, but has yet to be adequately characterized. We analyzed publicly available data obtained between flybys Tb in December 2004 and T58 in July 2009, with an emphasis on two stable occultations obtained during flybys T41 and T53. We derived detailed density profiles for CH 4 , C 2 H 2 , C 2 H 4 , C 4 H 2 , HCN, HC 3 N and C 6 H 6 between ∼400 and 1200 km and extinction coefficients for aerosols between 400 and 900 km. Our analysis reveals the presence of extinction layers in the occultation data that are associated with large perturbations in the density profiles of the gaseous species and extinction profiles of the aerosols. These relatively stable features vary in appearance with location and change slowly over time. In particular, we identify a sharp extinction layer between 450 and 550 km that coincides with the detached haze layer. In line with recent images obtained by Cassini/ISS, the altitude of this layer changes rapidly around the equinox in 2009. Our results point to unexpected complexity that may have significant consequences for the dynamics and physical processes taking place in the upper atmosphere of Titan.
• Achilleos, N., Ade, P. A., Adriani, A., Afonso, C., Agnor, C. B., Aylward, A. D., Bakos, G. A., Barber, R. J., Barbera, A. L., Barlow, M. J., Beaulieu, J., Bernath, P. F., Bezard, B., Boekel, R. V., Borde, P., Bouwman, J., Brown, L. R., Cassan, A., Cavarroc, C., , Cho, J. Y., et al. (2010).

  The science of EChO

  . Proceedings of the International Astronomical Union, 276(S276), 359-370. doi:10.1017/s1743921311020448
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  The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are? In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life. The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole. EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.
• Koskinen, T. T., Cho, J. Y., Aylward, A. D., & Achilleos, N. (2010). Ionization of extrasolar giant planet atmospheres. The Astrophysical Journal, 722(1), 178-187. doi:10.1088/0004-637x/722/1/178
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  Many extrasolar planets orbit close in and are subject to intense ionizing radiation from their host stars. Therefore, we expect them to have strong, and extended, ionospheres. Ionospheres are important because they modulate escape in the upper atmosphere and can modify circulation, as well as leave their signatures, in the lower atmosphere. In this paper, we evaluate the vertical location and extent of the EUV ionization peak layer. We find that -10 nbar—for a wide range of orbital distances (a = 0.047-1 AU) from the host star—and , where Hp is the pressure scale height. At , the plasma frequency is ~80-450 MHz, depending on a. We also study global ion transport, and its dependence on a, using a three-dimensional thermosphere-ionosphere model. On tidally synchronized planets with weak intrinsic magnetic fields, our model shows only a small, but discernible, difference in electron density from the dayside to the nightside (~9 × 1013 m–3 to ~2 × 1012 m–3, respectively) at . On asynchronous planets, the distribution is essentially uniform. These results have consequences for hydrodynamic modeling of the atmospheres of close-in extrasolar giant planets.
• Yelle, R. V., Lewis, N. K., Lavvas, P., & Koskinen, T. T. (2010). Characterizing the Thermosphere of HD209458b with UV Transit Observations. The Astrophysical Journal, 723(1), 116-128. doi:10.1088/0004-637x/723/1/116
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  Transmission spectroscopy at UV wavelengths is a rich and largely unexplored source of information about the upper atmospheres of extrasolar planets. So far, UV transit observations have led to the detection of atomic hydrogen, oxygen, and ionized carbon in the upper atmosphere of HD209458b. The interpretation of these observations is controversial—it is not clear if the absorption arises from an escaping atmosphere interacting with the stellar radiation and stellar wind, or from the thermosphere inside the Roche lobe. In this paper, we introduce an empirical model that can be used to analyze UV transit depths of extrasolar planets. We use this model to interpret the transits of HD209458b in the H I 1216 and the O I 1304 triplet emission lines. The results indicate that the mean temperature of the thermosphere is T = 8000-11,000 K and that the H2/H dissociation front is located at pressures between p = 0.1 and 1 μbar, which correspond to a distance r 1.1 Rp from the center of the planet. The upper boundary of the model thermosphere is located at r = 2.7-3 Rp , above which the atmosphere is mostly ionized. We find that the H I transit depth in the wings of the H Lyα line reflects the optical depth of the thermosphere, but that the atmosphere also overflows the Roche lobe. By assuming a solar mixing ratio of oxygen, we obtain an O I transit depth that is statistically consistent with the observations. An O I transit depth comparable to the H I transit depth is possible if the atmosphere is undergoing fast hydrodynamic escape, the O/H ratio is supersolar, or if a significant quantity of neutral oxygen is found outside the Roche lobe. We find that the observations can be explained solely by absorption in the upper atmosphere and extended clouds of energetic neutral atoms or atoms strongly perturbed by radiation pressure are not required. Due to the large uncertainty in the data, repeated observations are necessary to better constrain the O I transit depths and thus the composition of the thermosphere.
• Aylward, A. D., Koskinen, T. T., & Miller, S. (2009).

  THE UPPER ATMOSPHERE OF HD17156b

  . The Astrophysical Journal, 693(1), 868-885. doi:10.1088/0004-637x/693/1/868
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  HD17156b is a newly found transiting extrasolar giant planet that orbits its G-type host star in a highly eccentric orbit (e ~ 0.67) with an orbital semimajor axis of 0.16 AU. Its period, 21.2 Earth days, is the longest among the known transiting planets. The atmosphere of the planet undergoes a 27-fold variation in stellar irradiation during each orbit, making it an interesting subject for atmospheric modeling. We have used a three-dimensional model of the upper atmosphere and ionosphere for extrasolar gas giants in order to simulate the progress of HD17156b along its eccentric orbit. Here we present the results of these simulations and discuss the stability, circulation, and composition of its upper atmosphere. Contrary to the well-known transiting planet HD209458b, we find that the atmosphere of HD17156b is unlikely to undergo fast hydrodynamic escape at any point along the orbit, even if the upper atmosphere is almost entirely composed of atomic hydrogen and H+, and infrared cooling by H+ 3 ions is negligible. The nature of the upper atmosphere is sensitive to the composition of the thermosphere, and in particular to the mixing ratio of H2, as the availability of H2 regulates radiative cooling. In light of different simulations we make specific predictions about the thermosphere-ionosphere system of HD17156b that can potentially be verified by observations.
• Miller, S., Koskinen, T. T., & Aylward, A. D. (2007). A stability limit for the atmospheres of giant extrasolar planets.. Nature, 450(7171), 845-8. doi:10.1038/nature06378
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  Recent observations of the planet HD209458b indicate that it is surrounded by an expanded atmosphere of atomic hydrogen that is escaping hydrodynamically. Theoretically, it has been shown that such escape is possible at least inside an orbit of 0.1 au (refs 4 and 5), and also that H3+ ions play a crucial role in cooling the upper atmosphere. Jupiter's atmosphere is stable, so somewhere between 5 and 0.1 au there must be a crossover between stability and instability. Here we show that there is a sharp breakdown in atmospheric stability between 0.14 and 0.16 au for a Jupiter-like planet orbiting a solar-type star. These results are in contrast to earlier modelling that implied much higher thermospheric temperatures and more significant evaporation farther from the star. (We use a three-dimensional, time-dependent coupled thermosphere-ionosphere model and properly include cooling by H3+ ions, allowing us to model globally the redistribution of heat and changes in molecular composition.) Between 0.2 and 0.16 au cooling by H3+ ions balances heating by the star, but inside 0.16 au molecular hydrogen dissociates thermally, suppressing the formation of H3+ and effectively shutting down that mode of cooling.
• Smith, C. G., Miller, S., Koskinen, T. T., & Aylward, A. D. (2007). A thermospheric circulation model for extrasolar giant planets. The Astrophysical Journal, 661(1), 515-526. doi:10.1086/513594
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  Several models of extrasolar giant planet (EGP) atmospheres have been developed recently. Many of them are one-dimensional or concentrate on the lower or middle atmosphere. Three-dimensional hydrodynamic models are needed to study the horizontal variations in temperature and composition of EGP atmospheres. Circulation models for the upper atmosphere are particularly important as they can be used to study the thermal structure due to stellar irradiation, radiative cooling, and atmospheric circulation in the thermospheres of close-in EGPs and hence the rate of evaporation of their atmospheres. We present a generic gas giant model that is capable of generating three-dimensional, self-consistent global simulations of stable EGP thermospheres at different orbital distances. Calculations performed by this model indicate that IR emissions from H ions may play a significant role in cooling the thermospheres of EGPs at least in the range of 0.2-1 AU from a solar-type host star. In this range thermal dissociation of H2 is negligible and ion densities are small compared to the overall neutral density. Inside 0.2 AU thermal dissociation and dissociative photoionization of H2 may prevent the effective formation of H. In the absence of radiative cooling from H the upper atmospheres reach temperatures well above 10,000 K within ~0.5 AU. In this case the upper thermospheres are entirely converted into atomic hydrogen and the temperatures are high enough for significant atmospheric loss to take place. Our model is capable of calculating the IR signal strengths for various vibrational transitions of H based on the thermal state and the composition of the atmosphere. Potential detection of such signals would thus provide a validation of some of our results.

Proceedings Publications

• Aickara, G. S., France, K., Fossati, L., Suresh, A., Cubillos, P., Egan, A., Cauley, P., Nell, N., Desert, J., Koskinen, T., Petit, P., & Vidotto, A. (2023, January). Near ultraviolet observations of WASP-189b with CUTE telescope. In American Astronomical Society Meeting Abstracts, 55.
• Bergsten, G., Pascucci, I., Mulders, G., Fernandes, R., & Koskinen, T. (2023, January). Demographics of Kepler's Small Planets into the Habitable Zone. In American Astronomical Society Meeting Abstracts, 55.
• Brown, Z., Koskinen, T., Guerlet, S., Medvedev, A., Moses, J., Mueller-Wodarg, I., & Starichenko, E. (2023, October). Saturn's Upper Atmosphere Revealed by Cassini Stellar Occultations. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
• Fernandes, R., Mulders, G., Pascucci, I., Bergsten, G., Koskinen, T., & Hardegree-Ullman, K. (2023, January). Preliminary Estimates of the Occurrence of close in (sub-)Neptunes in Young Clusters. In American Astronomical Society Meeting Abstracts, 55.
• Huang, C., Koskinen, T., Lavvas, P., & Fossati, L. (2023, October). A hydrodynamic study of the atmospheric escape of the hot Jupiter WASP-121b. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
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  LPL former postdoc first author
• Koskinen, T. T., Brown, Z. L., Moses, J. I., Mueller-Wodarg, I. C., Sandel, B. R., Hamden, E. T., Harris, W. M., Yelle, R. V., Ballester, G. E., & Marley, M. S. (2023, July). Giant planet middle and upper atmospheres and the case for ultraviolet observations by the Uranus Orbiter. In Uranus Flagship 2023: Investigations and instruments for cross-discipline science.
• Koskinen, T., Huang, C., Aickara, G. S., France, K., Fossati, L., & Lavvas, P. (2023, October). Atmospheric escape and near-UV signatures of ultra-hot Jupiters. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
• Koskinen, T., Huang, C., Lavvas, P., Fossati, L., Sreejith, A., & France, K. (2023, September). Modeling the near-UV signatures of escaping ultra-hot Jupiter atmospheres. In American Astronomical Society Meeting Abstracts, 55.
• Lavvas, P., & Koskinen, T. T. (2023, June). Titan's upper atmosphere from Cassini UVIS: Atmospheric composition and haze. In Titan Through Time VI.
• Moses, J., Brown, Z., Koskinen, T., Fletcher, L., Guerlet, S., Serigano, J., Moore, L., Waite, J. H., Ben-Jaffel, L., Galand, M., Chadney, J., Horst, S., Sinclair, J., Vuitton, V., & Mueller-Wodarg, I. (2023, October). Implications of the Cassini Grand Finale INMS measurements for atmospheric chemistry on Saturn (and vice versa). In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
• Mueller-Wodarg, I., Inurrigarro, P., Moore, L., Medvedev, A., & Koskinen, T. (2023, October). Towards a new global Jupiter Thermosphere Ionosphere Model (JTIM). In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
• Stephenson, P., Koskinen, T., Brown, Z., Quemerais, E., Lavvas, P., Moses, J., Sandel, B., & Yelle, R. (2023, October). Seasonal variation of Saturn's Lyman alpha airglow and upper atmospheric hydrogen. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
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  LPL postdoc first author
• Bergsten, G., Pascucci, I., Mulders, G., Fernandes, R., & Koskinen, T. (2022, jun). The Population of Earths and super-Earths into the Habitable Zone. In Bulletin of the American Astronomical Society, 54.
• Bergsten, G., Pascucci, I., Mulders, G., Fernandes, R., & Koskinen, T. (2022, nov). The Demographics of Kepler's Earths and Super-Earths into the Habitable Zone. In Exoplanets in Our Backyard 2, 2687.
• Brown, Z., Koskinen, T., Moses, J., & Guerlet, S. (2022, dec). Investigating Photochemical Products in Saturn's Mesosphere. In AAS/Division for Planetary Sciences Meeting Abstracts, 54.
• Fernandes, R., Mulders, G., Pascucci, I., Bergsten, G., & Koskinen, T. (2022, jun). Understanding the Demographics of Young Transiting Planets in TESS Photometry using Pterodactyls. In Bulletin of the American Astronomical Society, 54.
• Garraffo, C., Jeremy, D., Wargelin, B., Cheimets, P., Cadwell, D., Monsch, K., Testa, P., Alvarado, G., Cohen, O., France, K., Kashyap, V., Youngblood, A., Norton, T., Fleming, B., Gladstone, R., Mason, J., Wolk, S., Barstow, M., Siegmund, O., , Gronoff, G., et al. (2022, jul). NExtUP: The Normal-incidence Extreme Ultraviolet Photometer. In 44th COSPAR Scientific Assembly. Held 16-24 July, 44.
• Huang, C., Koskinen, T., Lavvas, P., & Fossati, L. (2022, jun). A hydrodynamic study of the escape of metal species and excited hydrogen in the atmosphere of the hot Jupiter WASP-121b. In Bulletin of the American Astronomical Society, 54.
• Koskinen, T., Huang, C., Lavvas, P., Cubillos, P., Fossati, L., France, K., & Cauley, P. W. (2022, dec). The rapidly escaping atmosphere of WASP-121b. In AAS/Division for Planetary Sciences Meeting Abstracts, 54.
• Lavvas, P., & Koskinen, T. (2022, sep). Titan's atmospheric structure from Cassini/UVIS airglow observations. In European Planetary Science Congress.
• Steinrueck, M. E., Koskinen, T., Parmentier, V., Lavvas, P., Tan, X., & Zhang, X. i. (2022, jun). Radiative Feedback of Photochemical Hazes in 3D Simulations of Hot Jupiters. In Bulletin of the American Astronomical Society, 54.
• Steinrueck, M., Koskinen, T., Parmentier, V., Lavvas, P., Tan, X., & Zhang, X. i. (2022, sep). Photochemical hazes dramatically alter temperature structure and atmospheric circulation in 3D simulations of hot Jupiters. In European Planetary Science Congress.
• Bergsten, G., Pascucci, I., Mulders, G., Fernandes, R., & Koskinen, T. (2021, jul). Demographics of Small Kepler Planets and their Dependence on Stellar Mass. In Posters from the TESS Science Conference II (TSC2).
• Brown, Z., Koskinen, T., Guerlet, S., & Moses, J. (2021, oct). A Snapshot of Photochemical Products in Saturn's Mesosphere. In AAS/Division for Planetary Sciences Meeting Abstracts, 53.
• Drake, J. J., Cheimets, P., Garraffo, C., Wargelin, B., Youngblood, A., Kashyap, V. L., Testa, P., Caldwell, D., Mason, J., Fleming, B., France, K., Wolk, S., Siegmund, O., Koskinen, T., Alvarado-Gomez, J., Lopez-Morales, M. M., Gronoff, G., Bookbinder, J., Barstow, M., , Windt, D., et al. (2021, aug). NExtUP: the Normal-incidence Extreme Ultraviolet Photometer. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11821.
• Drake, J., Garraffo, C., Youngblood, A., Kashyap, V., Wargelin, B., Fleming, B., France, K., Cheimets, P., Caldwell, D., Siegmund, O., Mason, J., Bookbinder, J., Alvarado-G{\'omez}, J., Barstow, M., Gronoff, G., Gladstone, R., Koskinen, T., Lopez-Morales, M. .., Moschou, S., & Wolk, S. (2021, mar). The Normal-incidence Extreme Ultraviolet Photometer (NExtUP). In Bulletin of the American Astronomical Society, 53.
• France, K., Fleming, B., Youngblood, A., Mason, J., Drake, J. J., Amerstorfer, U., Barstow, M., Bourrier, V., Champey, P., Fossati, L., Froning, C., Green, J. C., Gris{\'e}, F., Gronoff, G., Hellickson, T., Jin, M., Koskinen, T. T., Kowalski, A. F., Kruczek, N., , Linsky, J. L., et al. (2021, aug). The ESCAPE mission overview: exploring the stellar drivers of exoplanet habitability. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11821.
• Hendrix, A., Becker, T., Bodewits, D., Bradley, T., Brooks, S., Byron, B., Cahill, J., Clarke, J., Feaga, L., Feldman, P., Gladstone, R., Hansen, C., Hibbitts, C., Koskinen, T., Magana, L., Molyneux, P., Nikzad, S., Noonan, J., Pryor, W., , Raut, U., et al. (2021, may). Ultraviolet-Based Science in the Solar System: Advances and Next Steps. In Bulletin of the American Astronomical Society, 53.
• Huang, C., & Koskinen, T. (2021, jan). A hydrodynamic study of radiative cooling and escape of metal species in hot Jupiter atmospheres. In American Astronomical Society Meeting Abstracts, 53.
• Moses, J., Brown, Z., Koskinen, T., Guerlet, S., Fletcher, L., Ben-Jaffel, L., Serigano, J., Moore, L., Vuitton, V., Greathouse, T., & Galand, M. (2021, oct). Seasonal variation of hydrocarbon abundances on Saturn: Comparisons of coupled ion-neutral photochemical models with Cassini UVIS, CIRS, and INMS data. In AAS/Division for Planetary Sciences Meeting Abstracts, 53.
• Steinrueck, M., Koskinen, T., Lavvas, P., Tan, X., & Zhang, X. i. (2021, oct). Simulating radiative feedback of photochemical hazes in general circulation models of hot Jupiters. In AAS/Division for Planetary Sciences Meeting Abstracts, 53.
• Steinrueck, M., Koskinen, T., Lavvas, P., Zhang, X. i., & Tan, X. (2021, sep). Simulating haze radiative feedback in general circulation models of hot Jupiters. In European Planetary Science Congress.
• Tiscareno, M., Vaquero, M., Hedman, M. M., Cao, H., Estrada, P. R., Ingersoll, A. P., Miller, K. E., Parisi, M., Atkinson, D. H., Brooks, S. M., Cuzzi, J. N., Fuller, J., Hendrix, A. R., Johnson, R. E., Koskinen, T., Kurth, W. S., Lunine, J. I., Nicholson, P. D., Paty, C. S., , Schindhelm, R., et al. (2021, may). The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn's rings, atmosphere, interior and inner magnetosphere. In Bulletin of the American Astronomical Society, 53.
• Wong, M. H., Luszcz-Cook, S., Sayanagi, K., Moore, L., Koskinen, T., Moses, J. I., Pater, I., Aslam, S., Atreya, S. K., Baines, K. H., Bjoraker, G., Kleer, K. R., Edgington, S. G., Fortney, J., Greathouse, T. K., Hammel, H. B., Li, C., Mahaffy, P. R., Sinclair, J., & Sromovsky, L. A. (2021, may). Gas Giant and Ice Giant Atmospheres: Focused Questions for 2023-2032. In Bulletin of the American Astronomical Society, 53.
• Brown, Z., & Koskinen, T. (2020, oct). The distribution of hydrocarbons in Saturn's mesosphere from Cassini's Grand Finale. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
• Huang, C., & Koskinen, T. (2020, jun). A hydrodynamic study of radiative cooling and escape of metal species in hot Jupiter atmospheres. In American Astronomical Society Meeting Abstracts \#236, 236.
• Parkinson, C., Koskinen, T., Yoshi, J., Shemansky, D., Yung, Y., & Esposito, L. (2020, oct). Cassini UVIS Observations of He 584A Airglow at Saturn. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
• Serigano, J., Horst, S., He, C., Gautier, T., Yelle, R., & Koskinen, T. (2020, feb). Investigating the Interactions Between Saturn's Upper Atmosphere and Rings from Cassini INMS Measurements. In Exoplanets in Our Backyard: Solar System and Exoplanet Synergies on Planetary Formation, Evolution, and Habitability, 2195.
• Serigano, J., Horst, S., He, C., Gautier, T., Yelle, R., Koskinen, T., & Trainer, M. (2020, oct). Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
• Steinrueck, M., Showman, A., Lavvas, P., Koskinen, T., Zhang, X. i., & Tan, X. (2020, sep). Three-dimensional Simulations of Photochemical Hazes in the Atmosphere of Hot Jupiter HD 189733b. In European Planetary Science Congress.
• Steinrueck, M., Showman, A., Lavvas, P., Koskinen, T., Zhang, X., & Tan, X. (2020, oct). Three-dimensional Simulations of Photochemical Hazes in the Atmosphere of Hot Jupiter HD 189733b. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
• Tiscareno, M., Hedman, M., Vaquero, M., Cao, H., Estrada, P., Fuller, J., Ingersoll, A., Miller, K., Parisi, M., Paty, C., Cuzzi, J., Hendrix, A., Johnson, R., Koskinen, T., Kurth, W., Lunine, J., Nicholson, P., Schindhelm, R., Showalter, M., , Spilker, L., et al. (2020, mar). Saturn Ring Skimmer Mission Concept. In Lunar and Planetary Science Conference.
• Tiscareno, M., Vaquero, M., Hedman, M., Cao, H., Estrada, P., Ingersoll, A., Miller, K., Parisi, M., Brooks, S., Cuzzi, J., Fuller, J., Hendrix, A., Johnson, R., Koskinen, T., Kurth, W., Lunine, J., Nicholson, P., Paty, C., Schindhelm, R., , Showalter, M., et al. (2020, feb). Saturn Ring Skimmer Mission Concept. In Outer Planets Assessment Group (OPAG) Meeting, 2194.
• Brown, Z., Koskinen, T., Mueller-Wodarg, I., West, R., Jouchoux, A., & Esposito, L. (2019, Sep). Thermospheric Circulation and Pole-to-Pole Temperatures from Cassini Grand Finale Occultations. In EPSC-DPS Joint Meeting 2019, 2019.
• Cubillos, P. E., Fossati, L., Koskinen, T., Young, M. E., Salz, M., France, K., Sreejith, A. G., & Haswell, C. A. (2019, Sep). Signs of Ionized Iron Beyond the Roche Lobe of HD 209458b from NUV Observations. In EPSC-DPS Joint Meeting 2019, 2019.
• Cubillos, P., Fossati, L., Koskinen, T., Young, M., France, K., Salz, M., Sreejith, A., & Haswell, C. (2019, Aug). Revisiting the NUV Transmission Spectrum of HD 209458b: Signs of Ionized Iron Beyond the Roche Lobe. In AAS/Division for Extreme Solar Systems Abstracts, 51.
• Fossati, L., France, K., Fleming, B., Desert, J., Koskinen, T., Petit, P., Vidotto, A., Egan, A., Aickara, G. S., Villarreal, D. C., & Beasley, M. (2019, Sep). The CUTE Small Satellite Mission. In EPSC-DPS Joint Meeting 2019, 2019.
• France, K., Fleming, B. T., Drake, J. J., Mason, J. P., Youngblood, A., Bourrier, V., Fossati, L., Froning, C. S., Koskinen, T., Kruczek, N., Lipscy, S., McEntaffer, R., Romaine, S., Siegmund, O. H., & Wilkinson, E. (2019, Sep). The extreme-ultraviolet stellar characterization for atmospheric physics and evolution (ESCAPE) mission concept. In Proc. SPIE, 11118.
• Lavvas, P., Koskinen, T., Steinrueck, M., Garcia, M. A., & Showman, A. (2019, Sep). Photochemical hazes in sub-Neptunian atmospheres with focus on GJ 1214 b. In EPSC-DPS Joint Meeting 2019, 2019.
• Palmer, M., Yelle, R., & Koskinen, T. (2019, Sep). Latitudinal variations in Titan's atmosphere: UVIS observations of three simultaneous stellar occultations. In EPSC-DPS Joint Meeting 2019, 2019.
• Parkinson, C., Koskinen, T., & Esposito, L. (2019, Sep). Monitoring Saturn's Upper Atmosphere Density Variations and He Mixing Ratio Using Cassini Helium 584 \r{A} Airglow Observations. In EPSC-DPS Joint Meeting 2019, 2019.
• Pearson, K., Griffith, C., Zellem, R. T., Koskinen, T., & Roudier, G. (2019, Jan). Constraints on the Na abundance of XO-2 b using ground-based mutli-object spectroscopy. In American Astronomical Society Meeting Abstracts \#233, 233.
• Serigano, J., Horst, S., Yelle, R., Koskinen, T., & He, C. (2019, Sep). Investigating the Interactions between Saturn's Upper Atmosphere and Rings from Cassini INMS Measurements. In EPSC-DPS Joint Meeting 2019, 2019.
• Steinrueck, M. E., Showman, A., Koskinen, T., & Lavvas, P. (2019, Aug). Three-Dimensonal Mixing of Photochemical Hazes in the Atmospheres of Hot Jupiters. In AAS/Division for Extreme Solar Systems Abstracts, 51.
• Steinrueck, M., Showman, A., Koskinen, T., & Lavvas, P. (2019, Sep). Three-dimensonal Mixing of Photochemical Hazes in the Atmospheres of Hot Jupiters. In EPSC-DPS Joint Meeting 2019, 2019.
• Vriesema, J., Koskinen, T., Yelle, R., & M{\"uller-Wodarg}, I. (2019, Sep). Results from an Improved Model of Electrodynamics in Saturn's Upper Atmosphere. In EPSC-DPS Joint Meeting 2019, 2019.
• Fossati, L., Cubillos, P., Koskinen, T., France, K., Lendl, M., & Aickara Gopinathan, S. (2018, sep). The near-UV transmission spectrum of the prototypical hot Jupiter HD209458b. In European Planetary Science Congress, 12, EPSC2018-424.
• Fossati, L., France, K., Flaming, B., Aickara Gopinathan, S., Egan, A., Desert, J., Koskinen, T., Petit, P., & Vidotto, A. (2018, sep). CUTE: A Small NUV Satellite Mission to Study Exoplanet Atmospheres. In European Planetary Science Congress, 12, EPSC2018-419.
• Koskinen, T., Brown, Z., West, R., Jouchoux, A., & Esposito, L. (2018, sep). Saturn's upper atmosphere from the Cassini/UVIS Grand Finale stellar occultations. In European Planetary Science Congress, 12, EPSC2018-571.
• Koskinen, T., Strobel, D., & Brown, Z. (2018, sep). An empirical model of Saturn's thermosphere based on Cassini/UVIS occultations. In European Planetary Science Congress, 12, EPSC2018-573.
• Moses, J., Koskinen, T., Guerlet, S., Galand, M., Fox, J., Kim, S., Lavvas, P., Moore, L., Mueller-Wodarg, I. .., & Vuitton, V. (2018, oct). The formation of benzene and complex hydrocarbons in the auroral and non-auroral regions of Saturn. In AAS/Division for Planetary Sciences Meeting Abstracts \#50, 50.
• M{\"uller-Wodarg}, I., Koskinen, T., Moore, L., & Mendillo, M. (2018, sep). Energy balance in Saturn's upper atmosphere. In European Planetary Science Congress, 12, EPSC2018-919.
• Parkinson, C., Koskinen, T., & Esposito, L. (2018, oct). Monitoring Saturn's Upper Atmosphere Density Variations and Determination of the Saturnian He Mixing Ratio Using Helium 584 \AA Airglow. In AAS/Division for Planetary Sciences Meeting Abstracts \#50, 50.
• Serigano}, J., Horst, S., Yelle, R., Koskinen, T., He, C., Perry, M., Cravens, T., Perryman, R., Waite, J., & Team, {. I. (2018, oct). The Composition and Thermal Structure of Saturn's Upper Atmosphere from Cassini/INMS Measurements. In AAS/Division for Planetary Sciences Meeting Abstracts \#50, 50.
• Erwin, J., Yelle, R., & Koskinen, T. (2017, apr). Escape of Hydrogen from HD209458b. In EGU General Assembly Conference Abstracts, 19.
• Fleming, B., France, K., Nell, N., Kohnert, R., Pool, K., Egan, A., Fossati, L., Koskinen, T., Vidotto, A., Hoadley, K., Desert, J., Beasley, M., & Petit, P. (2017, aug). The Colorado Ultraviolet Transit Experiment (CUTE): a dedicated cubesat mission for the study of exoplanetary mass loss and magnetic fields. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 10397.
• Fossati, L., France, K., Fleming, B., Koskinen, T., Vidotto, A., Beasley, M., Desert, J., Hoadley, K., Kohnert, R., Nell, N., & Petit, P. (2017, sep). CUTE: The Colorado Ultraviolet Transit Experiment. In Second BRITE-Constellation Science Conference: Small satellites science, Proceedings of the Polish Astronomical Society volume 5, held 22-26 August, 2016 in Innsbruck, Austria. Other: Polish Astronomical Society, Bartycka 18, 00-716 Warsaw, Poland, pp.73-75.
• Gr{\"oller}, H., Yelle, R., Koskinen, T., Montmessin, F., Lacombe, G., Jain, S., Deighan, J., Schneider, N., Nakagawa, H., & Medvedev, A. (2017, jan). Temperature Profiles and Wave Structures Observed with IUVS/MAVEN Stellar Occultations. In The Mars Atmosphere: Modelling and observation.
• Guerlet, S., & Koskinen, T. (2017, sep). Stratospheric benzene and hydrocarbon aerosols observed in Saturn's upper atmosphere. In European Planetary Science Congress, 11, EPSC2017-621.
• Koskinen, T., & Guerlet, S. (2017, oct). Constraints on atmospheric structure and helium abundance of Saturn from Cassini/UVIS and CIRS. In AAS/Division for Planetary Sciences Meeting Abstracts \#49, 49.
• Lavvas, P., & Koskinen, T. (2017, sep). Aerosols and clouds in the atmosphere of HD 189733 b. In European Planetary Science Congress, 11, EPSC2017-351.
• Vriesema, J., Koskinen, T., & Yelle, R. (2017, oct). Resistive Heating and Ion Drag in Saturn's Thermosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#49, 49.
• Yelle, R., Gr{\"oller}, H., Koskinen, T., Montmessin, F., Lacombe, G., Lef{\`evre}, F., Jain, S., Deighan, J., & Schneider, N. (2017, jan). Atmospheric Abundances Retrieved from IUVS/MAVEN Stellar Occultations. In The Mars Atmosphere: Modelling and observation.
• Yelle, R., Koskinen, T., & Lavvas, P. (2017, oct). Non-LTE Models for the Thermal Structure of Hot Jupiters. In AAS/Division for Planetary Sciences Meeting Abstracts \#49, 49.
• Yelle, R., Koskinen, T., & Lavvas, P. (2017, sep). Thermal Structure of Pluto's Lower Atmosphere. In European Planetary Science Congress.
• Gr{\"oller}, H., Yelle, R., Koskinen, T., Montmessin, F., Lacombe, G., Kass, D., Kleinb{\"ohl}, A., Schofield, T., McCleese, D., Schneider, N., Deighan, J., Jain, S., & Jakosky, B. (2016, mar). Martian Temperature Profiles Measured by MAVEN and MRO from 20 to 160 km. In Lunar and Planetary Science Conference, 47.
• Koskinen, T., Moses, J., West, R., Guerlet, S., & Jouchoux, A. (2016, oct). New observational constraints on hydrocarbon chemistry in Saturn's upper atmosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#48, 48.
• Lavvas, P., Koskinen, T., Royer, E., Rannou, P., & West, R. (2016, jun). Aerosol properties in Titan's upper atmosphere. In Titan Aeronomy and Climate.
• Vriesema, J., Koskinen, T., & Yelle, R. (2016, oct). Resistive Heating in Saturn's Thermosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#48, 48.
• Yelle, R., Koskinen, T., Withers, P., Schinder, P., Moses, J., & Mueller-Wodarg, I. .. (2016, oct). The Effect of Diurnal Variations on Ionospheric Radio Occultations. In AAS/Division for Planetary Sciences Meeting Abstracts \#48, 48.
• Chadney, J., Galand, M., Unruh, Y., Koskinen, T., & Sanz-Forcada, J. .. (2015, oct). Modelling the ionosphere of gas-giant exoplanets irradiated by low-mass stars. In European Planetary Science Congress, 10, EPSC2015-307.
• Erwin, J., Koskinen, T., & Yelle, R. (2015, nov). Radiative equilibrium and escape of Pluto's atmosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#47, 47.
• Gr{\"oller}, H., Yelle, R., Koskinen, T., Montmessin, F., Lacombe, G., Schneider, N., Deighan, J., Stewart, I., Jain, S., Chaffin, M., Crismani, M., Stiepen, A., Lef{\`evre}, F., McClintock, B., Clarke, J., Holsclaw, G., Mahaffy, P., Bougher, S., & Jakosky, B. (2015, dec). Probing the Martian Atmosphere with MAVEN/IUVS Stellar Occultations. In AGU Fall Meeting Abstracts, P21A-2066.
• Koskinen, T., Erwin, J., & Yelle, R. (2015, nov). Predictions for the escape of CH4 from Pluto. In AAS/Division for Planetary Sciences Meeting Abstracts \#47, 47.
• Koskinen, T., Strobel, D., West, R., & Yelle, R. (2015, oct). Variability in Saturn's upper atmosphere from Cassini/UVIS occultations. In European Planetary Science Congress, 10, EPSC2015-294.
• Lavvas, P., & Koskinen, T. (2015, oct). Implications of hazes in observations of exoplanet atmospheres. In European Planetary Science Congress, 10, EPSC2015-507.
• Lavvas, P., Koskinen, T., Royer, E., Rannou, P., & West, R. (2015, nov). Aerosol properties in Titan's upper atmosphere from UVIS airglow observations. In AAS/Division for Planetary Sciences Meeting Abstracts \#47, 47.
• Parkinson, C., Koskinen, T., Gronoff, G., Yung, Y., & Esposito, L. (2015, nov). Analysis of Cassini UVIS Extreme and Far Ultraviolet Observations of Saturn's Atmosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#47, 47.
• Chadney, J., Galand, M., Unruh, Y., Koskinen, T., & Sanz-Forcada, J. .. (2014, apr). Modelling of Hot Jupiter thermospheres and ionospheres under irradiation from active stars. In European Planetary Science Congress, 9, EPSC2014-579.
• Erwin, J., Yelle, R., & Koskinen, T. (2014, apr). Escape of Hydrogen from HD209458b. In European Planetary Science Congress, 9, EPSC2014-594.
• Erwin, J., Yelle, R., & Koskinen, T. (2014, nov). Escaping hydrogen from HD209458b. In AAS/Division for Planetary Sciences Meeting Abstracts \#46, 46.
• Gr{\"oller}, H., Sandel, B., Yelle, R., Koskinen, T., Lewis, N., Bertaux, J., Montmessin, F., & Quemerais, E. (2014, apr). O2 abundance on Mars observed by Mars Express / SPICAM. In European Planetary Science Congress, 9, EPSC2014-536.
• Gr{\"oller}, H., Sandel, B., Yelle, R., Koskinen, T., Lewis, N., Bertaux, J., Montmessin, F., & Qu{\'emerais}, E. (2014, nov). O2 abundance on Mars observed by Mars Express / SPICAM. In AAS/Division for Planetary Sciences Meeting Abstracts \#46, 46.
• Koskinen, T., Sandel, B., & Yelle, R. (2014, nov). The variability of Saturn's thermosphere from Cassini/UVIS occultations. In AAS/Division for Planetary Sciences Meeting Abstracts \#46, 46.
• Koskinen, T., Yelle, R., Lavvas, P., & Cho, J. (2014, dec). Electrodynamics in Giant Planet Atmospheres. In AGU Fall Meeting Abstracts, P51G-03.
• Lavvas, P., Koskinen, T., & Yelle, R. (2014, nov). Electron densities and alkali atoms in exoplanet atmospheres. In AAS/Division for Planetary Sciences Meeting Abstracts \#46, 46.
• Lavvas, P., Yelle, R., & Koskinen, T. (2014, apr). Na, K, and electrons in exoplanet atmospheres. In European Planetary Science Congress, 9, EPSC2014-132.
• Stevens, M., Koskinen, T., Evans, S., & West, R. (2014, nov). N2 and CH4 Densities Retrieved from Dayglow and Occultation Observations of Titan's Upper Atmosphere. In AAS/Division for Planetary Sciences Meeting Abstracts \#46, 46.
• Chadney, J., Galand, M., Unruh, Y., Koskinen, T., & Sanz-Forcada, J. .. (2013, sep). Hot-Jupiter ionospheres irradiated by low-mass stars. In European Planetary Science Congress, 8, EPSC2013-800.
• Cho, J., & Koskinen, T. (2013, sep). Dynamics of Ionized Giant Planet Atmospheres. In European Planetary Science Congress, 8, EPSC2013-970.
• Koskinen, T., Sandel, B., Yelle, R., Capalbo, F., Holsclaw, G., McClintock, B., & Edgington, S. (2013, oct). The thermosphere of Saturn from Cassini UVIS occultations. In AAS/Division for Planetary Sciences Meeting Abstracts \#45, 45.
• Lavvas, P., Koskinen, T., & Yelle, R. (2013, sep). Aerosol properties in exoplanet atmospheres. In European Planetary Science Congress, 8, EPSC2013-288.

Presentations

• Brown, Z. L., Koskinen, T. T., West, R. A., Jouchoux, A., & Esposito, L. W. (2018, August). Polar temperature profiles from Grand Finale UVIS stellar occultations. Cassini Science Symposium. Boulder, Colorado: University of Colorado.
• Koskinen, T. T., Yelle, R. V., Holsclaw, G. M., & Sandel, B. R. (2018, August). Saturn in Lyman a: A comparison of Cassini and Voyager observations. Cassini Science Symposium. Boulder, Colorado: University of Colorado.
• Koskinen, T. T., Yelle, R. V., Serigano, J., Horst, S., & Waite, J. H. (2018, March). Densities in Saturn's thermosphere: A multi-instrument perspective. Cassini Project Science Group Meeting 74. Rome, Italy: NASA/JPL.
• Serigano, J., Yelle, R. V., Koskinen, T. T., & Horst, S. (2018, August). The composition of Saturn's upper atmosphere from Cassini/INMS measurements. Cassini Science Symposium. Boulder, Colorado: University of Colorado.
• Vriesema, J., Koskinen, T. T., & Yelle, R. V. (2018, August). Exploring low-latitude electrodynamics in Saturn's thermosphere. Cassini Science Symposium. Boulder, Colorado: University of Colorado.
• West, R. A., Hu, J., & Koskinen, T. T. (2018, August). Cassini UV reflection spectra of Saturn: Acetylene and haze. Cassini Science Symposium. Boulder, Colorado: University of Colorado.
• Koskinen, T. T. (2017, March). Thermal escape from hot extrasolar planets. Colloquium. Department of Physics and Astronomy, George Mason University, Fairfax County, VA.
• Koskinen, T. T. (2017, May). Cool giants and hot exoplanets: Adventures in upper atmospheres. Colloquium. Jet Propulsion Laboratory, Pasadena, CA.
• Koskinen, T. T., & Guerlet, S. (2017, February). UVIS/CIRS constraints on Saturn's He abundance. Cassini Project Science Group meeting 71. Pasadena, CA: NASA/JPL.
• Koskinen, T. T., Moses, J., West, R., Guerlet, S., & Jouchoux, A. (2016, June). The detection of benzene in Saturn's upper atmosphere. Cassini Project Science Group meeting 69. Noordwijk, Netherlands: NASA/JPL.
• Koskinen, T. T., Strobel, D. F., Sandel, B. R., Yelle, R. V., & Mueller-Wodarg, I. (2015, January). The expansion and contraction of Saturn's thermosphere. Cassini Project Science Group meeting 65. Rome, Italy: NASA/JPL.
• Koskinen, T. T. (2014, March). Sunsets on Saturn - A new perspective on the upper atmosphere from Cassini/UVIS occultations. Colloquium. Center for Space Physics, Boston University.
• Koskinen, T. T., Sandel, B. R., Yelle, R. V., Mueller-Wodarg, I., & Strobel, D. F. (2014, June). Saturn's upper atmosphere from Cassini/UVIS occultations. Cassini Project Science Group meeting 63. Noordwijk, Netherlands: NASA/JPL.
• Koskinen, T. T., Strobel, D. F., & Mueller-Wodarg, I. (2014, Summer). Saturn's variable thermosphere. Part 1: The view from UV occultations. Saturn Science Conference: Saturn in the 21st century. Madison, WI.
• Koskinen, T. T. (2013, Spring). Giants playing with fire - The story of thermal atmospheric escape. Characterizing stellar and exoplanetary environments. Bern, Switzerland (invited via Skype): International Space Science Institute (ISSI).
• Koskinen, T. T. (2013, Spring). Thermal escape from extrasolar giant planets. Royal Society Discussion Meeting: Characterizing exoplanets, detection, formation, interiors, atmospheres and habitability. London, UK: Royal Society, London, UK.

Poster Presentations

• Koskinen, T. T., Brown, Z. L., West, R. A., Jouchoux, A., Esposito, L. W., & Muller-Wodarg, I. (2018, July). Saturn's thermosphere from Cassini/UVIS Grand Finale stellar occultations. Magnetospheres of the Outer Planets (MOP). Boulder, Colorado: University of Colorado.
• Vriesema, J., Koskinen, T. T., & Yelle, R. (2018, July). Exploring low-latitude electrodynamics in Saturn’s thermosphere. Magnetospheres of the Outer Solar System (MOP). Boulder, Colorado: University of Colorado.