THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA

Caroline V. Morley, Jonathan J. Fortney, Mark S. Marley, Kevin Zahnle, Michael Line, Eliza Kempton, Nikole Lewis, Kerri Cahoy

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000 solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (∼400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (∼200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.

Original languageEnglish (US)
Article number110
JournalAstrophysical Journal
Volume815
Issue number2
DOIs
StatePublished - Dec 20 2015
Externally publishedYes

Fingerprint

haze
planets
thermal emission
planet
emission spectra
albedo
metallicity
James Webb Space Telescope
Neptune (planet)
coronagraphs
solar atmosphere
high altitude
spectral resolution
inversion layer
sulfides
Neptune
atmosphere
inversions
galaxies
salts

Keywords

  • planets and satellites: atmospheres
  • planets and satellites: individual (GJ 1214b)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Morley, C. V., Fortney, J. J., Marley, M. S., Zahnle, K., Line, M., Kempton, E., ... Cahoy, K. (2015). THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA. Astrophysical Journal, 815(2), [110]. https://doi.org/10.1088/0004-637X/815/2/110

THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA. / Morley, Caroline V.; Fortney, Jonathan J.; Marley, Mark S.; Zahnle, Kevin; Line, Michael; Kempton, Eliza; Lewis, Nikole; Cahoy, Kerri.

In: Astrophysical Journal, Vol. 815, No. 2, 110, 20.12.2015.

Research output: Contribution to journalArticle

Morley, CV, Fortney, JJ, Marley, MS, Zahnle, K, Line, M, Kempton, E, Lewis, N & Cahoy, K 2015, 'THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA', Astrophysical Journal, vol. 815, no. 2, 110. https://doi.org/10.1088/0004-637X/815/2/110
Morley, Caroline V. ; Fortney, Jonathan J. ; Marley, Mark S. ; Zahnle, Kevin ; Line, Michael ; Kempton, Eliza ; Lewis, Nikole ; Cahoy, Kerri. / THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA. In: Astrophysical Journal. 2015 ; Vol. 815, No. 2.
@article{4ed461d38a5649bc8ab167d5b543cc29,
title = "THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA",
abstract = "Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000 solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (∼400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (∼200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.",
keywords = "planets and satellites: atmospheres, planets and satellites: individual (GJ 1214b)",
author = "Morley, {Caroline V.} and Fortney, {Jonathan J.} and Marley, {Mark S.} and Kevin Zahnle and Michael Line and Eliza Kempton and Nikole Lewis and Kerri Cahoy",
year = "2015",
month = "12",
day = "20",
doi = "10.1088/0004-637X/815/2/110",
language = "English (US)",
volume = "815",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - THERMAL EMISSION and REFLECTED LIGHT SPECTRA of SUPER EARTHS with FLAT TRANSMISSION SPECTRA

AU - Morley, Caroline V.

AU - Fortney, Jonathan J.

AU - Marley, Mark S.

AU - Zahnle, Kevin

AU - Line, Michael

AU - Kempton, Eliza

AU - Lewis, Nikole

AU - Cahoy, Kerri

PY - 2015/12/20

Y1 - 2015/12/20

N2 - Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000 solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (∼400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (∼200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.

AB - Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000 solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (∼400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (∼200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.

KW - planets and satellites: atmospheres

KW - planets and satellites: individual (GJ 1214b)

UR - http://www.scopus.com/inward/record.url?scp=84951821034&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84951821034&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/815/2/110

DO - 10.1088/0004-637X/815/2/110

M3 - Article

AN - SCOPUS:84951821034

VL - 815

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 110

ER -