* Astronomy

Blobrana · L

RE: WASP-3b

Blobrana · L

Title: The Doppler Shadow of WASP-3b: A tomographic analysis of Rossiter-McLaughlin observations
Authors: G. R. M. Miller, A. Collier Cameron, E. K. Simpson, D. Pollacco, B. Enoch, N.P. Gibson, D. Queloz, A.H.M.J. Triaud, G. Hébrard, I. Boisse, C. Moutou, I. Skillen

Hot-Jupiter planets must form at large separations from their host stars where the temperatures are cool enough for their cores to condense. They then migrate inwards to their current observed orbital separations. Different theories of how this migration occurs lead to varying distributions of orbital eccentricity and the alignment between the rotation axis of the star and the orbital axis of the planet. The spin-orbit alignment of a transiting system is revealed via the Rossiter-McLaughlin effect, which is the anomaly present in the radial velocity measurements of the rotating star during transit due to the planet blocking some of the starlight. In this paper we aim to measure the spin-orbit alignment of the WASP-3 system via a new way of analysing the Rossiter-McLaughlin observations. We apply a new tomographic method for analysing the time variable asymmetry of stellar line profiles caused by the Rossiter-McLaughlin effect. This new method eliminates the systematic error inherent in previous methods used to analyse the effect. We find a value for the projected stellar spin rate of v sin i = 13.9 \pm 0.03 km/s which is in agreement with previous measurements but has a much higher precision. The system is found to be well aligned which favours an evolutionary history for WASP-3b involving migration through tidal interactions with a protoplanetary disc. Using gyrochronology we estimate the age of the star to be ~300 Myr with an upper limit of 2 Gyr from comparison with isochrones.

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Blobrana · L

Title: Transit timing variation in exoplanet WASP-3b
Authors: G.Maciejewski, D.Dimitrov, R.Neuhaeuser, A.Niedzielski, St.Raetz, Ch.Ginski, Ch.Adam, C.Marka, M.Moualla, M.Mugrauer

Photometric follow-ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. We present photometric observations gathered in 2009 and 2010 for exoplanet WASP-3b during the dedicated transit-timing-variation campaign. The observed transit timing cannot be explained by a constant period but by a periodic variation in the observations minus calculations diagram. Simplified models assuming the existence of a perturbing planet in the system and reproducing the observed variations of timing residuals were identified by three-body simulations. We found that the configuration with the hypothetical second planet of the mass of about 15 Earth masses, located close to the outer 2:1 mean motion resonance is the most likely scenario reproducing observed transit timing. We emphasise, however, that more observations are required to constrain better the parameters of the hypothetical second planet in WASP-3 system. For final interpretation not only transit timing but also photometric observations of the transit of the predicted second planet and the high precision radial-velocity data are needed.

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Blobrana · L

WASP-3b is an extrasolar planet orbiting the star WASP-3 located over 727 light-years away in the constellation Lyra. It was discovered via the transit method by SuperWASP, and follow up radial velocity observations confirmed that WASP-3b is a planet.
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Blobrana · L

Title: WASP-3b: a strongly-irradiated transiting gas-giant planet
Authors: D. Pollacco, I. Skillen, A. Collier Cameron, B. Loeillet, H.C. Stempels, F. Bouchy, N.P. Gibson, L. Hebb, G. Hebrard, Y.C. Joshi, I. McDonald, B. Smalley, A.M.S. Smith, R.A. Street, S. Udry, R.G. West, D.M. Wilson, P.J. Wheatley, S. Aigrain, C.R. Benn, V.A. Bruce, D.J. Christian, W.I. Clarkson, B. Enoch, A. Evans, A.Fitzsimmons, C.A. Haswell, C. Hellier, S. Hickey, S.T. Hodgkin, K. Horne, M. Hrudkova, J. Irwin, S.R. Kane, F.P. Keenan, T.A. Lister, P. Maxted, M. Mayor, C. Moutou, A.J. Norton, J. P. Osborne, N. Parley, F. Pont, D. Queloz, R. Ryans, E. Simpson

We report the discovery of WASP-3b, the third transiting exoplanet to be discovered by the WASP and SOPHIE collaboration. WASP-3b transits its host star USNO-B1.0 1256-0285133 every 1.846834 ±0.000002 days. Our high precision radial-velocity measurements present a variation with amplitude characteristic of a planetary-mass companion and in-phase with the light-curve. Adaptive optics imaging shows no evidence for nearby stellar companions, and line-bisector analysis excludes faint, unresolved binarity and stellar activity as the cause of the radial-velocity variations. We make a preliminary spectroscopic analysis of the host star finding it to have Teff = 6400 ±100 K and log g = 4.25 ±0.05 which suggests it is most likely an unevolved main sequence star of spectral type F7-8V. Our simultaneous modelling of the transit photometry and reflex motion of the host leads us to derive a mass of 1.76 +0.08 -0.14 M_J and radius 1.31 +0.07-0.14 R_J for WASP-3b. The proximity and relative temperature of the host star suggests that WASP-3b is one of the hottest exoplanets known, and thus has the potential to place stringent constraints on exoplanet atmospheric models.

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