TESS Full Orbital Phase Curve of the WASP-18b System

Avi Shporer, Ian Wong, Chelsea X. Huang, Michael Line, Keivan G. Stassun, Tara Fetherolf, Stephen R. Kane, Luke G. Bouma, Tansu Daylan, Maximilian N. Güenther, George R. Ricker, David W. Latham, Roland Vanderspek, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Ana Glidden, Zach Berta-Thompson, Eric B. Ting, Jie Li & 1 others Kari Haworth

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We present a visible-light full orbital phase curve of the transiting planet WASP-18b measured by the TESS mission. The phase curve includes the transit, secondary eclipse, and sinusoidal modulations across the orbital phase shaped by the planet's atmospheric characteristics and the star-planet gravitational interaction. We measure the beaming (Doppler boosting) and tidal ellipsoidal distortion phase modulations and show that the amplitudes of both agree with theoretical expectations. We find that the light from the planet's dayside hemisphere occulted during secondary eclipse, with a relative brightness of 341-18 +17 ppm, is dominated by thermal emission, leading to an upper limit on the geometric albedo in the TESS band of 0.048 (2σ). We also detect the phase modulation due to the planet's atmosphere longitudinal brightness distribution. We find that its maximum is well aligned with the substellar point to within 2.°9 (2σ). We do not detect light from the planet's nightside hemisphere, with an upper limit of 43 ppm (2σ), which is 13% of the dayside brightness. The low albedo, lack of atmospheric phase shift, and inefficient heat distribution from the day to night hemispheres that we deduce from our analysis are consistent with theoretical expectations and similar findings for other strongly irradiated gas giant planets. This work demonstrates the potential of TESS data for studying the full orbital phase curves of transiting systems. Finally, we complement our study by looking for transit timing variations (TTVs) in the TESS data combined with previously published transit times, although we do not find a statistically significant TTV signal.

Original languageEnglish (US)
Article number178
JournalAstronomical Journal
Volume157
Issue number5
DOIs
StatePublished - May 1 2019
Externally publishedYes

Fingerprint

planets
planet
orbitals
curves
transit
hemispheres
eclipses
albedo
phase modulation
brightness
time measurement
gas giant planets
brightness distribution
transit time
thermal emission
night
complement
phase shift
modulation
atmospheres

Keywords

  • planetary systems
  • planets and satellites: atmospheres
  • stars: individual (WASP-18, TIC 100100827, TOI 185)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Shporer, A., Wong, I., Huang, C. X., Line, M., Stassun, K. G., Fetherolf, T., ... Haworth, K. (2019). TESS Full Orbital Phase Curve of the WASP-18b System. Astronomical Journal, 157(5), [178]. https://doi.org/10.3847/1538-3881/ab0f96

TESS Full Orbital Phase Curve of the WASP-18b System. / Shporer, Avi; Wong, Ian; Huang, Chelsea X.; Line, Michael; Stassun, Keivan G.; Fetherolf, Tara; Kane, Stephen R.; Bouma, Luke G.; Daylan, Tansu; Güenther, Maximilian N.; Ricker, George R.; Latham, David W.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Glidden, Ana; Berta-Thompson, Zach; Ting, Eric B.; Li, Jie; Haworth, Kari.

In: Astronomical Journal, Vol. 157, No. 5, 178, 01.05.2019.

Research output: Contribution to journalArticle

Shporer, A, Wong, I, Huang, CX, Line, M, Stassun, KG, Fetherolf, T, Kane, SR, Bouma, LG, Daylan, T, Güenther, MN, Ricker, GR, Latham, DW, Vanderspek, R, Seager, S, Winn, JN, Jenkins, JM, Glidden, A, Berta-Thompson, Z, Ting, EB, Li, J & Haworth, K 2019, 'TESS Full Orbital Phase Curve of the WASP-18b System', Astronomical Journal, vol. 157, no. 5, 178. https://doi.org/10.3847/1538-3881/ab0f96
Shporer A, Wong I, Huang CX, Line M, Stassun KG, Fetherolf T et al. TESS Full Orbital Phase Curve of the WASP-18b System. Astronomical Journal. 2019 May 1;157(5). 178. https://doi.org/10.3847/1538-3881/ab0f96
Shporer, Avi ; Wong, Ian ; Huang, Chelsea X. ; Line, Michael ; Stassun, Keivan G. ; Fetherolf, Tara ; Kane, Stephen R. ; Bouma, Luke G. ; Daylan, Tansu ; Güenther, Maximilian N. ; Ricker, George R. ; Latham, David W. ; Vanderspek, Roland ; Seager, Sara ; Winn, Joshua N. ; Jenkins, Jon M. ; Glidden, Ana ; Berta-Thompson, Zach ; Ting, Eric B. ; Li, Jie ; Haworth, Kari. / TESS Full Orbital Phase Curve of the WASP-18b System. In: Astronomical Journal. 2019 ; Vol. 157, No. 5.
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AU - Stassun, Keivan G.

AU - Fetherolf, Tara

AU - Kane, Stephen R.

AU - Bouma, Luke G.

AU - Daylan, Tansu

AU - Güenther, Maximilian N.

AU - Ricker, George R.

AU - Latham, David W.

AU - Vanderspek, Roland

AU - Seager, Sara

AU - Winn, Joshua N.

AU - Jenkins, Jon M.

AU - Glidden, Ana

AU - Berta-Thompson, Zach

AU - Ting, Eric B.

AU - Li, Jie

AU - Haworth, Kari

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N2 - We present a visible-light full orbital phase curve of the transiting planet WASP-18b measured by the TESS mission. The phase curve includes the transit, secondary eclipse, and sinusoidal modulations across the orbital phase shaped by the planet's atmospheric characteristics and the star-planet gravitational interaction. We measure the beaming (Doppler boosting) and tidal ellipsoidal distortion phase modulations and show that the amplitudes of both agree with theoretical expectations. We find that the light from the planet's dayside hemisphere occulted during secondary eclipse, with a relative brightness of 341-18 +17 ppm, is dominated by thermal emission, leading to an upper limit on the geometric albedo in the TESS band of 0.048 (2σ). We also detect the phase modulation due to the planet's atmosphere longitudinal brightness distribution. We find that its maximum is well aligned with the substellar point to within 2.°9 (2σ). We do not detect light from the planet's nightside hemisphere, with an upper limit of 43 ppm (2σ), which is 13% of the dayside brightness. The low albedo, lack of atmospheric phase shift, and inefficient heat distribution from the day to night hemispheres that we deduce from our analysis are consistent with theoretical expectations and similar findings for other strongly irradiated gas giant planets. This work demonstrates the potential of TESS data for studying the full orbital phase curves of transiting systems. Finally, we complement our study by looking for transit timing variations (TTVs) in the TESS data combined with previously published transit times, although we do not find a statistically significant TTV signal.

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