Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

The retrograde orbit of the HAT-P-6b exoplanet

G. Hébrard, D. Ehrenreich, F. Bouchy, X. Delfosse, C. Moutou, L. Arnold, I. Boisse, X. Bonfils, R. F. Díaz, A. Eggenberger, T. Forveille, A.-M. Lagrange, C. Lovis, F. Pepe, C. Perrier, D. Queloz, A. Santerne, N. C. Santos, D. Ségransan, S. Udry

Abstract
We observed the transit of the HAT-P-6b exoplanet across its host star with the SOPHIE spectrograph (OHP, France). The resulting stellar radial velocities display the Rossiter-McLaughlin anomaly and reveal a retrograde orbit: the planetary orbital spin and the stellar rotational spin point in approximately opposite directions. A fit to the anomaly measures a sky-projected angle λ = 166° ± 10° between these two spin axes. All seven known retrograde planets are hot Jupiters with masses Mp < 3 MJup. About two thirds of the planets in this mass range, however, are prograde and aligned (λ ≃ 0°). In contrast, most of the more massive planets (Mp > 4 MJup) are prograde but misaligned. Different mechanisms may therefore be responsible for planetary obliquities above and below ~3.5 MJup.

Keywords
planets and satellites: dynamical evolution and stability - techniques: radial velocities - planetary systems - stars: individual: HAT-P-6

Notes
Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (program 10A.PNP.CONS).
SOPHIE radial velocities are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/527/L11

Astronomy and Astrophysics
Volume 527, Page L11_1
March 2011

>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website