Resolving the surfaces of extrasolar planets with secondary eclipse light curves

Peter K G Williams, David Charbonneau, Curtis S. Cooper, Adam Showman, Jonathan J. Fortney

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially isolate its light from that of the central star. We evaluate the feasibility of this technique for the HD 209458 system by simulating observations made with the Spitzer Infrared Array Camera (IRAC). We consider two representations of the planetary thermal emission: a simple model parameterized by a sinusoidal dependence on longitude and latitude, and the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal asymmetry in the dayside planetary emission. To quantify this signal, we define a new parameter, the "uniform time offset," which measures the time lag between the observed secondary eclipse and that predicted by a planet with spatially uniform emission. We compare the predicted amplitude of this parameter for HD 20948 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6μm of a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands and find that a modest improvement in photometric precision should permit a similarly robust detection.

Original languageEnglish (US)
Pages (from-to)1020-1027
Number of pages8
JournalAstrophysical Journal
Volume649
Issue number2 I
DOIs
StatePublished - Oct 1 2006

Fingerprint

eclipses
extrasolar planets
light curve
planet
cameras
planets
thermal emission
planetary atmosphere
planetary atmospheres
surface flux
longitude
signal-to-noise ratio
asymmetry
signal to noise ratios
time lag
spatial variation
probe
stars
probes
simulation

Keywords

  • Binaries: eclipsing
  • Infrared: stars
  • Planetary systems
  • Stars: individual (HD 209458)
  • Techniques: high angular resolution
  • Techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Williams, P. K. G., Charbonneau, D., Cooper, C. S., Showman, A., & Fortney, J. J. (2006). Resolving the surfaces of extrasolar planets with secondary eclipse light curves. Astrophysical Journal, 649(2 I), 1020-1027. https://doi.org/10.1086/506468

Resolving the surfaces of extrasolar planets with secondary eclipse light curves. / Williams, Peter K G; Charbonneau, David; Cooper, Curtis S.; Showman, Adam; Fortney, Jonathan J.

In: Astrophysical Journal, Vol. 649, No. 2 I, 01.10.2006, p. 1020-1027.

Research output: Contribution to journalArticle

Williams, PKG, Charbonneau, D, Cooper, CS, Showman, A & Fortney, JJ 2006, 'Resolving the surfaces of extrasolar planets with secondary eclipse light curves', Astrophysical Journal, vol. 649, no. 2 I, pp. 1020-1027. https://doi.org/10.1086/506468
Williams, Peter K G ; Charbonneau, David ; Cooper, Curtis S. ; Showman, Adam ; Fortney, Jonathan J. / Resolving the surfaces of extrasolar planets with secondary eclipse light curves. In: Astrophysical Journal. 2006 ; Vol. 649, No. 2 I. pp. 1020-1027.
@article{a925cb4a386f4ac199c09c2f667910d2,
title = "Resolving the surfaces of extrasolar planets with secondary eclipse light curves",
abstract = "We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially isolate its light from that of the central star. We evaluate the feasibility of this technique for the HD 209458 system by simulating observations made with the Spitzer Infrared Array Camera (IRAC). We consider two representations of the planetary thermal emission: a simple model parameterized by a sinusoidal dependence on longitude and latitude, and the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal asymmetry in the dayside planetary emission. To quantify this signal, we define a new parameter, the {"}uniform time offset,{"} which measures the time lag between the observed secondary eclipse and that predicted by a planet with spatially uniform emission. We compare the predicted amplitude of this parameter for HD 20948 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6μm of a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands and find that a modest improvement in photometric precision should permit a similarly robust detection.",
keywords = "Binaries: eclipsing, Infrared: stars, Planetary systems, Stars: individual (HD 209458), Techniques: high angular resolution, Techniques: photometric",
author = "Williams, {Peter K G} and David Charbonneau and Cooper, {Curtis S.} and Adam Showman and Fortney, {Jonathan J.}",
year = "2006",
month = "10",
day = "1",
doi = "10.1086/506468",
language = "English (US)",
volume = "649",
pages = "1020--1027",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 I",

}

TY - JOUR

T1 - Resolving the surfaces of extrasolar planets with secondary eclipse light curves

AU - Williams, Peter K G

AU - Charbonneau, David

AU - Cooper, Curtis S.

AU - Showman, Adam

AU - Fortney, Jonathan J.

PY - 2006/10/1

Y1 - 2006/10/1

N2 - We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially isolate its light from that of the central star. We evaluate the feasibility of this technique for the HD 209458 system by simulating observations made with the Spitzer Infrared Array Camera (IRAC). We consider two representations of the planetary thermal emission: a simple model parameterized by a sinusoidal dependence on longitude and latitude, and the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal asymmetry in the dayside planetary emission. To quantify this signal, we define a new parameter, the "uniform time offset," which measures the time lag between the observed secondary eclipse and that predicted by a planet with spatially uniform emission. We compare the predicted amplitude of this parameter for HD 20948 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6μm of a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands and find that a modest improvement in photometric precision should permit a similarly robust detection.

AB - We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially isolate its light from that of the central star. We evaluate the feasibility of this technique for the HD 209458 system by simulating observations made with the Spitzer Infrared Array Camera (IRAC). We consider two representations of the planetary thermal emission: a simple model parameterized by a sinusoidal dependence on longitude and latitude, and the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal asymmetry in the dayside planetary emission. To quantify this signal, we define a new parameter, the "uniform time offset," which measures the time lag between the observed secondary eclipse and that predicted by a planet with spatially uniform emission. We compare the predicted amplitude of this parameter for HD 20948 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6μm of a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands and find that a modest improvement in photometric precision should permit a similarly robust detection.

KW - Binaries: eclipsing

KW - Infrared: stars

KW - Planetary systems

KW - Stars: individual (HD 209458)

KW - Techniques: high angular resolution

KW - Techniques: photometric

UR - http://www.scopus.com/inward/record.url?scp=33845270580&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33845270580&partnerID=8YFLogxK

U2 - 10.1086/506468

DO - 10.1086/506468

M3 - Article

AN - SCOPUS:33845270580

VL - 649

SP - 1020

EP - 1027

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 I

ER -