The shocking transit of WASP-12b: modelling the observed early ingress in the near ultraviolet

Joe Llama; Kenny Wood; Moira Mary Jardine; Aline Vidotto; Christiane Helling; L. Fossati; C. A. Haswell

doi:10.1111/j.1745-3933.2011.01093.x

The shocking transit of WASP-12b: modelling the observed early ingress in the near ultraviolet

Joe Llama, Kenny Wood, Moira Mary Jardine, Aline Vidotto, Christiane Helling, L. Fossati, C. A. Haswell

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetospheric bow shock which forms when the relative velocity of the planetary and stellar material is supersonic. We aim to reproduce this observed early ingress by modelling the stellar wind (or coronal plasma) in order to derive the speed and density of the material at the planetary orbital radius. From this we determine the orientation of the shock and the density of compressed plasma behind it. With this model for the density structure surrounding the planet we perform Monte Carlo radiation transfer simulations of the near UV transits of WASP-12b with and without a bow shock. We find that we can reproduce the transit lightcurves with a wide range of plasma temperatures, shock geometries and optical depths. Our results support the hypothesis that a bow shock could explain the observed early ingress.

Original language	English
Pages (from-to)	41-44
Journal	Monthly Notices of the Royal Astronomical Society: Letters
Volume	416
Issue number	1
Early online date	6 Jul 2011
DOIs	https://doi.org/10.1111/j.1745-3933.2011.01093.x
Publication status	Published - Sept 2011

Keywords

Planets and satellites
Magnetic fields
WASP-12B
Planet-star interactions
Stars
Coronae
Winds
Outflows

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10.1111/j.1745-3933.2011.01093.x

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This is an author version of this article © 2011 The Authors. Published in Monthly Notices of the Royal Astronomical Society © 2011 RAS. The definitive version is available at www.blackwell-synergy.com
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Astrophysics in St Andrews: Astrophysics in St Andrews / SUPA (Continuan of Rolling Grant - XPP089
Bonnell, I. A. (PI), Cameron, A. C. (CoI), Dominik, M. (CoI), Driver, S. P. (CoI), Greaves, J. S. (CoI), Horne, K. D. (CoI), Jardine, M. M. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
Science & Technology Facilities Council
1/04/09 → 31/03/12
Project: Standard
Wide Area Search for Planets: Project support for the Wide Area Search for Planets
Cameron, A. C. (PI)
Science & Technology Facilities Council
1/08/08 → 31/07/11
Project: Standard

Cite this

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title = "The shocking transit of WASP-12b: modelling the observed early ingress in the near ultraviolet",

abstract = "Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetospheric bow shock which forms when the relative velocity of the planetary and stellar material is supersonic. We aim to reproduce this observed early ingress by modelling the stellar wind (or coronal plasma) in order to derive the speed and density of the material at the planetary orbital radius. From this we determine the orientation of the shock and the density of compressed plasma behind it. With this model for the density structure surrounding the planet we perform Monte Carlo radiation transfer simulations of the near UV transits of WASP-12b with and without a bow shock. We find that we can reproduce the transit lightcurves with a wide range of plasma temperatures, shock geometries and optical depths. Our results support the hypothesis that a bow shock could explain the observed early ingress.",

keywords = "Planets and satellites, Magnetic fields, WASP-12B, Planet-star interactions, Stars, Coronae, Winds, Outflows",

author = "Joe Llama and Kenny Wood and Jardine, {Moira Mary} and Aline Vidotto and Christiane Helling and L. Fossati and Haswell, {C. A.}",

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AU - Llama, Joe

AU - Wood, Kenny

AU - Jardine, Moira Mary

AU - Vidotto, Aline

AU - Helling, Christiane

AU - Fossati, L.

AU - Haswell, C. A.

N1 - 4 pages, 2 figures

PY - 2011/9

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N2 - Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetospheric bow shock which forms when the relative velocity of the planetary and stellar material is supersonic. We aim to reproduce this observed early ingress by modelling the stellar wind (or coronal plasma) in order to derive the speed and density of the material at the planetary orbital radius. From this we determine the orientation of the shock and the density of compressed plasma behind it. With this model for the density structure surrounding the planet we perform Monte Carlo radiation transfer simulations of the near UV transits of WASP-12b with and without a bow shock. We find that we can reproduce the transit lightcurves with a wide range of plasma temperatures, shock geometries and optical depths. Our results support the hypothesis that a bow shock could explain the observed early ingress.

AB - Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetospheric bow shock which forms when the relative velocity of the planetary and stellar material is supersonic. We aim to reproduce this observed early ingress by modelling the stellar wind (or coronal plasma) in order to derive the speed and density of the material at the planetary orbital radius. From this we determine the orientation of the shock and the density of compressed plasma behind it. With this model for the density structure surrounding the planet we perform Monte Carlo radiation transfer simulations of the near UV transits of WASP-12b with and without a bow shock. We find that we can reproduce the transit lightcurves with a wide range of plasma temperatures, shock geometries and optical depths. Our results support the hypothesis that a bow shock could explain the observed early ingress.

KW - Planets and satellites

KW - Magnetic fields

KW - WASP-12B

KW - Planet-star interactions

KW - Stars

KW - Coronae

KW - Winds

KW - Outflows

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JO - Monthly Notices of the Royal Astronomical Society: Letters

JF - Monthly Notices of the Royal Astronomical Society: Letters

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ER -

The shocking transit of WASP-12b: modelling the observed early ingress in the near ultraviolet

Abstract

Keywords

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Projects

Astrophysics in St Andrews: Astrophysics in St Andrews / SUPA (Continuan of Rolling Grant - XPP089

Wide Area Search for Planets: Project support for the Wide Area Search for Planets

Cite this