Detection of thermal emission from an extrasolar planet

David Charbonneau, Lori E. Allen, S. Thomas Megeath, Guillermo Torres, Roi Alonso, Timothy M. Brown, Ronald Lynn Gilliland, David W. Latham, Georgi Mandushev, Francis T. O'Donovan, Alessandro Sozzetti

Research output: Contribution to journalArticle

461 Citations (Scopus)

Abstract

We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e., the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066±0.00013 at 4.5 μu and 0.00225±0.00036 at 8.0 μm. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of Tp = 1060±50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31±0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We also compare our data to a previously published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. This model adequately reproduces the observed planet-to-star flux ratio at 8.0 μm; however, it significantly overpredicts the ratio at 4.5 μm. We also present an estimate of the timing of the secondary eclipse, which we use to place a strong constraint on the expression e cos ω, where e is the orbital eccentricity and ω is the longitude of periastron. The resulting upper limit on e is sufficiently small that we conclude that tidal dissipation is unlikely to provide a significant source of energy interior to the planet.

Original languageEnglish (US)
Pages (from-to)523-529
Number of pages7
JournalAstrophysical Journal
Volume626
Issue number1 I
DOIs
StatePublished - Jun 10 2005

Fingerprint

extrasolar planets
thermal emission
planets
planet
eclipses
stars
estimates
time measurement
stellar radiation
Space Infrared Telescope Facility
atmospheric models
longitude
detection
albedo
Jupiter (planet)
eccentricity
carbon monoxide
Jupiter
dissipation
orbitals

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

Charbonneau, D., Allen, L. E., Megeath, S. T., Torres, G., Alonso, R., Brown, T. M., ... Sozzetti, A. (2005). Detection of thermal emission from an extrasolar planet. Astrophysical Journal, 626(1 I), 523-529. https://doi.org/10.1086/429991
Charbonneau, David ; Allen, Lori E. ; Megeath, S. Thomas ; Torres, Guillermo ; Alonso, Roi ; Brown, Timothy M. ; Gilliland, Ronald Lynn ; Latham, David W. ; Mandushev, Georgi ; O'Donovan, Francis T. ; Sozzetti, Alessandro. / Detection of thermal emission from an extrasolar planet. In: Astrophysical Journal. 2005 ; Vol. 626, No. 1 I. pp. 523-529.
@article{addc930e3008476a8b556d91fcaf591c,
title = "Detection of thermal emission from an extrasolar planet",
abstract = "We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e., the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066±0.00013 at 4.5 μu and 0.00225±0.00036 at 8.0 μm. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of Tp = 1060±50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31±0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We also compare our data to a previously published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. This model adequately reproduces the observed planet-to-star flux ratio at 8.0 μm; however, it significantly overpredicts the ratio at 4.5 μm. We also present an estimate of the timing of the secondary eclipse, which we use to place a strong constraint on the expression e cos ω, where e is the orbital eccentricity and ω is the longitude of periastron. The resulting upper limit on e is sufficiently small that we conclude that tidal dissipation is unlikely to provide a significant source of energy interior to the planet.",
author = "David Charbonneau and Allen, {Lori E.} and Megeath, {S. Thomas} and Guillermo Torres and Roi Alonso and Brown, {Timothy M.} and Gilliland, {Ronald Lynn} and Latham, {David W.} and Georgi Mandushev and O'Donovan, {Francis T.} and Alessandro Sozzetti",
year = "2005",
month = "6",
day = "10",
doi = "10.1086/429991",
language = "English (US)",
volume = "626",
pages = "523--529",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 I",

}

Charbonneau, D, Allen, LE, Megeath, ST, Torres, G, Alonso, R, Brown, TM, Gilliland, RL, Latham, DW, Mandushev, G, O'Donovan, FT & Sozzetti, A 2005, 'Detection of thermal emission from an extrasolar planet', Astrophysical Journal, vol. 626, no. 1 I, pp. 523-529. https://doi.org/10.1086/429991

Detection of thermal emission from an extrasolar planet. / Charbonneau, David; Allen, Lori E.; Megeath, S. Thomas; Torres, Guillermo; Alonso, Roi; Brown, Timothy M.; Gilliland, Ronald Lynn; Latham, David W.; Mandushev, Georgi; O'Donovan, Francis T.; Sozzetti, Alessandro.

In: Astrophysical Journal, Vol. 626, No. 1 I, 10.06.2005, p. 523-529.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Detection of thermal emission from an extrasolar planet

AU - Charbonneau, David

AU - Allen, Lori E.

AU - Megeath, S. Thomas

AU - Torres, Guillermo

AU - Alonso, Roi

AU - Brown, Timothy M.

AU - Gilliland, Ronald Lynn

AU - Latham, David W.

AU - Mandushev, Georgi

AU - O'Donovan, Francis T.

AU - Sozzetti, Alessandro

PY - 2005/6/10

Y1 - 2005/6/10

N2 - We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e., the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066±0.00013 at 4.5 μu and 0.00225±0.00036 at 8.0 μm. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of Tp = 1060±50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31±0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We also compare our data to a previously published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. This model adequately reproduces the observed planet-to-star flux ratio at 8.0 μm; however, it significantly overpredicts the ratio at 4.5 μm. We also present an estimate of the timing of the secondary eclipse, which we use to place a strong constraint on the expression e cos ω, where e is the orbital eccentricity and ω is the longitude of periastron. The resulting upper limit on e is sufficiently small that we conclude that tidal dissipation is unlikely to provide a significant source of energy interior to the planet.

AB - We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e., the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066±0.00013 at 4.5 μu and 0.00225±0.00036 at 8.0 μm. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of Tp = 1060±50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31±0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We also compare our data to a previously published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. This model adequately reproduces the observed planet-to-star flux ratio at 8.0 μm; however, it significantly overpredicts the ratio at 4.5 μm. We also present an estimate of the timing of the secondary eclipse, which we use to place a strong constraint on the expression e cos ω, where e is the orbital eccentricity and ω is the longitude of periastron. The resulting upper limit on e is sufficiently small that we conclude that tidal dissipation is unlikely to provide a significant source of energy interior to the planet.

UR - http://www.scopus.com/inward/record.url?scp=22544479438&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=22544479438&partnerID=8YFLogxK

U2 - 10.1086/429991

DO - 10.1086/429991

M3 - Article

VL - 626

SP - 523

EP - 529

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 I

ER -

Charbonneau D, Allen LE, Megeath ST, Torres G, Alonso R, Brown TM et al. Detection of thermal emission from an extrasolar planet. Astrophysical Journal. 2005 Jun 10;626(1 I):523-529. https://doi.org/10.1086/429991