Exoplanet Atmospheres
The chemical composition and loss of mass from an exoplanet's
atmosphere depends on the ultraviolet, extreme-ultraviolet, and
X-radiation from the host star and the interaction between the
stellar wind and gas in the planet's exosphere. The
photochemistry of such important molecules as water, oxygen, ozone,
methane, and carbon dioxide in the atmospheres of exoplanets depends
critically on the UV and extreme-UV radiation of their host
stars. We have observed the UV radiation of K and M dwarf host stars
for which the Lyman-alpha radiation dominates the UV spectrum but is
largely absorbed by the interstellar medium. We show how to
reconstruct the intrinsic Lyman-alpha flux and infer the
unobservable extreme-UV radiation of host stars. The these data
show the quantitative effects of UV and Lyman-alpha radiation on the
chemistry of exoplanets.
Research Objectives:
- Observe and place in the HST archives very high quality UV
spectra of K and M dwarfs host stars of known exoplanets.
- Reconstruct the intrinsic Lyman-alpha line profiles and fluxes of
exoplanet host stars.
- Estimate the extreme-UV radiation of exoplanet host stars.
- Compute photochemistry models of exoplanets of M dwarf host stars
with measured UV fluxes, reconstructed Lyman-alpha fluxes, and
estimated extreme-UV fluxes.
- Develop scaling laws that relate different flux regions of
exoplanet host stars.
Important Results and Discoveries:
- Obtained ultraviolet spectra of stars with exoplanets as a part
of major observing programs (e.g., MUSCLES and Mega-MUSCLES) with
HST.
- Provided empirical results concerning the effect of Lyman-alpha
emission on the chemical composition of exoplanet atmospheres.
- Developed a technique for estimating the unobservable extreme
ultraviolet emission of stars that drives the mass-loss rates from
exoplanet atmospheres.
- Wrote the book "Host Stars and their Effects on Exoplanet
Atmospheres" as a guide to exoplanet atmosphere modelers concerning
the stellar radiation and phenomena that should take into account.
Papers published in refereed journals since 2000:
- Wood, B.E., Muller, H.R., Redfield, S., Linsky, J.L., et al.:
2021, "New Observational Constraints on the Winds of M dwarf Stars",
Asatrophysical Journal, 915, 37
Wilson, D., Froning, C.S., Duvvuri, G.M., France, K., and Linsky,
J.L., et al. 2021, "The Mega-MUSCLES Spectral Energy Distribution of
TRAPPIST-1", Astrophysical Journal, 911, 18
- Carleo, I., Youngblood, A., Redfield, S., Linsky, J.L., et al.: 2021, "A
multiwavelength look at the GJ 9827b system: No evidence of extended
atmospheres in GJ 9828b and d from HST and CARMENES data",
Astronomical Journal, 161, 136C
- Melbourne, K., Youngblood, A., France, K., Linsky, J.L., et al.:
2020 "Estimating the ultraviolet emission of M dwarfs with exoplanets from
Ca II and Halpha", Astronomical Journal, 160, 269M
- Miguel, Y., Kaltenegger, L., Linsky, J.L., and Rugheimer, S.:
2015, "The effect of Lyman-alpha radiation on mini-Neptune
atmospheres around M stars: application to GJ 436b", Monthly Notices
of the Royal Astronomical Society, 446, 345
- Rugheimer, S., Kaltenegger, L., Segura, A., Linsky, J., and
Mohanty, S.: 2015, "Effect of UV radiation on the spectral
fingerprints of Earth-like planets orbiting M dwarfs",
Astrophysical Journal, 809, 57
- Cowan, N.B., Green, T., Angerhausen, D., Linsky, J.L., et al.:
2015, "Characterizing transiting planet atmospheres through 2025",
Publ. Astronomical Society Pacific, 127, 311
- Linsky, J.L.: 2014, "The radiation environment of exoplanet
atmospheres", Challenges, 5, 351
- Kulow, J.R., France, K., Linsky, J.L., and Parke Loyd, R.O.:
2014, "Lyman alpha spectroscopy and the neutral hydrogen tail of the
hot Neptune GJ 436b", Astrophysical Journal, 786, 132
- France, K., Linsky, J.L., and Parke Loyd, R.O.: 2014, "The
ultraviolet radiation environment in the habitable zones around
low-mass exoplanet host stars", Astrophysics and Space Science, 354,
3
- Tian, F., France, K., Linsky, J.L. et al.: 2014, "High stellar
FUV/NUV ration and oxygen contents in the atmospheres of potentially
habitable planets", Earth and Planetary Science Letters, 385, 22
- Lammer, H., Blanc, M., Linsky, J.L. et al.: 2013, "The science of
exoplanets and their systems", Astrobiology, 13, 9
- France, K., Froning, C.S., Linsky, J.L. et al.: 2013, "The
ultraviolet radiation environment around M dwarf exoplanet host
stars", Astrophysical Journal, 763, 149
- Linsky, J.L., Yang, H., France, K. et al.: 2010, "Observations of
mass loss from the transiting exoplanet HD 209458b", Astrophysical
Journal, 717, 1291
- France, K., Stocke, J.T., Yang, H., Linsky, J.L. et al.: 2010,
"Searching for far-ultraviolet auroral/dayglow emission from
HD209458b", Astrophysical Journal, 712, 1277
- Gomez de Castro, A.I., Lecavelier, A., d'Avillez, M., Linsky,
J.L., and Cernicharo, J.: 2006, "The formation of planetary systems
from the ISM to planets", Astrophysics and Space Science, 303, 33
Review papers and conference papers since 2000:
- Herbst, K., Baalmann, L.R., Bykov, A., Linsky, J.L., et al.:
2022, "Astrospheres of planet-hosting cool stars and beyond: when
modeling meets observations", Space Science Reviews, 218, 29H
- Linsky, J.L.: 2019, "Host Stars and their Effects on Exoplanet
Atmospheres", book published by Springer
- Linsky, J.L. and Guedel, M.: 2015, "Exoplanet host star radiation
and plasma environment", in Characterizing Stellar and Exoplanetary
Environments ed. H. Lammer and M. Khodachenko, Astrophysics and
Space Science Library 411, 3
- Fossati, L., Haswell, C.A., Linsky, J.L. and Kislyakova, K. G.:
2015, "Observations of exoplanet atmospheres and surrounding environments",
in Characterizing Stellar and Exoplanetary
Environments ed. H. Lammer and M. Khodachenko, Astrophysics and
Space Science Library 411, 59
- Linsky, J.L., France, K., and Ayres, T.R.:2015, "Predicting the
extreme-UV and Lyman-alpha fluxes received by exoplanets from their
host stars",in 18th Cambridge Workshop on Cool Stars, Stellar
Systems, and the Sun, ed. G. van Belle and H.C. Harris, p. 831
- Linsky, J.L., France, K., and Ayres, T.: 2014, "Reconstructing
the stellar UV and EUV emission that controls the chemistry of
exoplanet atmospheres" in Formation, Detection, and Characterization
of Extrasolar Habitable Planets, Proc. IAU Symposium No. 293/LI>
Return to main page