No detectable H 3 + emission from the atmospheres of hot jupiters

Evgenya Shkolnik, Eric Gaidos, Nick Moskovitz

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

H 3 + emission is the dominant cooling mechanism in Jupiter's thermosphere and a useful probe of temperature and ion densities. The H 3 + ion is predicted to form in the thermospheres of close-in "hot Jupiters," where its emission would be a significant factor in the thermal energy budget, affecting temperature and the rate of hydrogen escape from the exosphere. Hot Jupiters are predicted to have up to 105 times Jupiter's H 3 + emission because they experience extreme stellar irradiation and enhanced interactions may occur between the planetary magnetosphere and the stellar wind. Direct (but unresolved) detection of an extrasolar planet, or the establishment of useful upper limits, may be possible because a small but significant fraction of the total energy received by the planet is reradiated in a few narrow lines of H 3 + within which the flux from the star is limited. We present the observing strategy and results of our search for emission from the Q(1,0) transition of H 3 + (3.953 μm) from extrasolar planets orbiting six late-type dwarfs using CSHELL, the high-resolution echelle spectrograph on NASA's Infrared Telescope Facility. We exploited the timedependent Doppler shift of the planet, which can be as large as 150 km s -1 by differencing spectra between nights, thereby removing the stellar photospheric signal and telluric lines. We set limits on the H 3 + emission from each of these systems and compare them with models in the literature. Ideal candidates for future searches are intrinsically faint stars, such as M dwarfs, at very close distances.

Original languageEnglish (US)
Pages (from-to)1267-1274
Number of pages8
JournalAstronomical Journal
Volume132
Issue number3
DOIs
StatePublished - Sep 1 2006
Externally publishedYes

Keywords

  • Planetary systems
  • Stars: individual (v Andromedae, HD 46375, 55 Cancri, GJ 436, τ Bootis, HD 217101)
  • Stars: late-type

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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