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Title: The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets

Abstract

We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar types. We validate our model against altitude-dependent transmission spectra of the Earth from ATMOS and against lunar eclipse spectra from Pallé et al. We perform detectability studies to show the potential effects of refraction on hypothetical observations of Earth analogs with the James Webb Space Telescope NIRSPEC. Due to refraction, there will be a maximum tangent pressure level that can be probed during transit for each given planet-star system. We show that because of refraction, for an Earth-analog planet orbiting in the habitable zone of a Sun-like star only the top 0.3 bars of the atmosphere can be probed, leading to a decrease in the signal-to-noise ratio (S/N) of absorption features by 60%, while for an Earth-analog planet orbiting in the habitable zone of an M5V star it is possible to probe almost the entire atmosphere with minimal decreases in S/N. We also show that refraction can result in temporal variations in the transit transmission spectrum which may provide a way to obtain altitude-dependent spectra of exoplanetmore » atmospheres. Additionally, the variations prior to ingress and subsequent to egress provide a way to probe pressures greater than the maximum tangent pressure that can be probed during transit. Therefore, probing the maximum range of atmospheric altitudes, and in particular the near-surface environment of an Earth-analog exoplanet, will require looking at out-of-transit refracted light in addition to the in-transit spectrum.« less

Authors:
;  [1];  [2]
  1. Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States)
  2. NAI Virtual Planetary Laboratory, Seattle, WA (United States)
Publication Date:
OSTI Identifier:
22365195
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ALTITUDE; ECLIPSE; PLANETS; RADIANT HEAT TRANSFER; REFRACTION; SATELLITE ATMOSPHERES; SIGNAL-TO-NOISE RATIO; SPACE; SPECTRA; SPECTROSCOPY; SUN; TELESCOPES; TRANSMISSION; VARIATIONS; VISIBLE RADIATION

Citation Formats

Misra, Amit, Meadows, Victoria, and Crisp, Dave, E-mail: amit0@astro.washington.edu. The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets. United States: N. p., 2014. Web. doi:10.1088/0004-637X/792/1/61.
Misra, Amit, Meadows, Victoria, & Crisp, Dave, E-mail: amit0@astro.washington.edu. The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets. United States. doi:10.1088/0004-637X/792/1/61.
Misra, Amit, Meadows, Victoria, and Crisp, Dave, E-mail: amit0@astro.washington.edu. Mon . "The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets". United States. doi:10.1088/0004-637X/792/1/61.
@article{osti_22365195,
title = {The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets},
author = {Misra, Amit and Meadows, Victoria and Crisp, Dave, E-mail: amit0@astro.washington.edu},
abstractNote = {We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar types. We validate our model against altitude-dependent transmission spectra of the Earth from ATMOS and against lunar eclipse spectra from Pallé et al. We perform detectability studies to show the potential effects of refraction on hypothetical observations of Earth analogs with the James Webb Space Telescope NIRSPEC. Due to refraction, there will be a maximum tangent pressure level that can be probed during transit for each given planet-star system. We show that because of refraction, for an Earth-analog planet orbiting in the habitable zone of a Sun-like star only the top 0.3 bars of the atmosphere can be probed, leading to a decrease in the signal-to-noise ratio (S/N) of absorption features by 60%, while for an Earth-analog planet orbiting in the habitable zone of an M5V star it is possible to probe almost the entire atmosphere with minimal decreases in S/N. We also show that refraction can result in temporal variations in the transit transmission spectrum which may provide a way to obtain altitude-dependent spectra of exoplanet atmospheres. Additionally, the variations prior to ingress and subsequent to egress provide a way to probe pressures greater than the maximum tangent pressure that can be probed during transit. Therefore, probing the maximum range of atmospheric altitudes, and in particular the near-surface environment of an Earth-analog exoplanet, will require looking at out-of-transit refracted light in addition to the in-transit spectrum.},
doi = {10.1088/0004-637X/792/1/61},
journal = {Astrophysical Journal},
number = 1,
volume = 792,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}