A high stellar obliquity in the WASP-7 exoplanetary system

Albrecht, Simon and Winn, Joshua N. and Butler, R. Paul and Crane, Jeffrey D. and Shectman, Stephen A. and Thompson, Ian B. and Hirano, Teruyuki and Wittenmyer, Robert A. (2012) A high stellar obliquity in the WASP-7 exoplanetary system. The Astrophysical Journal, 744 (2). ISSN 0004-637X

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Abstract

We measure a tilt of 86° ± 6° between the sky projections of the rotation axis of the WASP-7 star and the orbital axis of its close-in giant planet. This measurement is based on observations of the Rossiter-McLaughlin (RM) effect with the Planet Finder Spectrograph on the Magellan II telescope. The result conforms with the previously noted pattern among hot-Jupiter hosts, namely, that the hosts lacking thick convective envelopes have high obliquities. Because the planet's trajectory crosses a wide range of stellar latitudes, observations of the RM effect can in principle reveal the stellar differential rotation profile; however, with the present data the signal of differential rotation could not be detected. The host star is found to exhibit radial-velocity noise ('stellar jitter') with an amplitude of ≈ 30 m s-1 over a timescale of days.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version due to publisher copyright policy.
Faculty / Department / School: No Faculty
Date Deposited: 12 May 2017 06:44
Last Modified: 02 Nov 2017 04:42
Uncontrolled Keywords: planetary systems; planets and satellites; formation; planetstar interactions; individual stars (WASP-7); stars; rotation; spectroscopic techniques
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1088/0004-637X/744/2/189
URI: http://eprints.usq.edu.au/id/eprint/31775

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