ACCESS

Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b

Alex Bixel, Benjamin V. Rackham, Daniel Apai, Néstor Espinoza, Mercedes López-Morales, David Osip, Andrés Jordán, Chima McGruder, Ian Weaver

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We present an optical transmission spectrum of the atmosphere of WASP-4b obtained through observations of four transits with Magellan/IMACS, as part of the Arizona-CfA-Católica-Carnegie Exoplanet Spectroscopy Survey (ACCESS). Using a Bayesian approach to atmospheric retrieval, we find no evidence for scattering or absorption features in our transit spectrum. Our models include a component to model the transit light source effect (spectral contamination from unocculted spots on the stellar photosphere), which we show can have a marked impact on the observed transmission spectrum for reasonable spot-covering fractions (<5%); this is the first such analysis for WASP-4b. We are also able to fit for the size and temperature contrast of spots observed during the second and third transits, finding evidence for both small, cool and large, warm spot-like features on the photosphere. Finally, we compare our results to those published by Huitson et al. using Gemini/GMOS and May et al. using IMACS, and we find that our data are in agreement.

Original languageEnglish (US)
Article number68
JournalAstronomical Journal
Volume157
Issue number2
DOIs
StatePublished - Feb 1 2019

Fingerprint

extrasolar planets
transit
Jupiter (planet)
Jupiter
spectroscopy
photosphere
scattering
retrieval
light sources
contamination
coverings
atmosphere
atmospheres
temperature

Keywords

  • planets and satellites: atmospheres
  • planets and satellites: individual (WASP-4b)
  • stars: activity
  • starspots
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Bixel, A., Rackham, B. V., Apai, D., Espinoza, N., López-Morales, M., Osip, D., ... Weaver, I. (2019). ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b. Astronomical Journal, 157(2), [68]. https://doi.org/10.3847/1538-3881/aaf9a3

ACCESS : Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b. / Bixel, Alex; Rackham, Benjamin V.; Apai, Daniel; Espinoza, Néstor; López-Morales, Mercedes; Osip, David; Jordán, Andrés; McGruder, Chima; Weaver, Ian.

In: Astronomical Journal, Vol. 157, No. 2, 68, 01.02.2019.

Research output: Contribution to journalArticle

Bixel, A, Rackham, BV, Apai, D, Espinoza, N, López-Morales, M, Osip, D, Jordán, A, McGruder, C & Weaver, I 2019, 'ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b', Astronomical Journal, vol. 157, no. 2, 68. https://doi.org/10.3847/1538-3881/aaf9a3
Bixel, Alex ; Rackham, Benjamin V. ; Apai, Daniel ; Espinoza, Néstor ; López-Morales, Mercedes ; Osip, David ; Jordán, Andrés ; McGruder, Chima ; Weaver, Ian. / ACCESS : Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b. In: Astronomical Journal. 2019 ; Vol. 157, No. 2.
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