The spin-orbit angles of the transiting exoplanets WASP-1b, WASP-24b, WASP-38b and HAT-P-8b from Rossiter-McLaughlin observations
2011 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 414, no 4, 3023-3035 p.Article in journal (Refereed) Published
We present observations of the Rossiter-McLaughlin effect for the transiting exoplanets WASP-1b, WASP-24b, WASP-38b and HAT-P-8b, and deduce the orientations of the planetary orbits with respect to the host stars' rotation axes. The planets WASP-24b, WASP-38b and HAT-P-8b appear to move in prograde orbits and be well aligned, having sky-projected spin-orbit angles consistent with zero: lambda = -4 degrees.7 +/- 4 degrees.0, 15 degrees(+43)(-33) and -9 degrees.7(-7.7)(+9.0), respectively. The host stars have T(eff) < 6250K and conform with the trend of cooler stars having low obliquities. WASP-38b is a massive planet on a moderately long period, eccentric orbit so may be expected to have a misaligned orbit given the high obliquities measured in similar systems. However, we find no evidence for a large spin-orbit angle. By contrast, WASP-1b joins the growing number of misaligned systems and has an almost polar orbit, lambda = -79 degrees.0(-4.3)(+4.5). It is neither very massive, eccentric nor orbiting a hot host star, and therefore does not share the properties of many other misaligned systems.
Place, publisher, year, edition, pages
2011. Vol. 414, no 4, 3023-3035 p.
techniques, radial velocities, stars, WASP-1, WASP-24, WASP-38, HAT-P-8, planetary systems
IdentifiersURN: urn:nbn:se:uu:diva-157046DOI: 10.1111/j.1365-2966.2011.18603.xISI: 000293178600018OAI: oai:DiVA.org:uu-157046DiVA: diva2:434394