@inproceedings{e6318cbf13e845f1addf277b6824747f,
title = "Starspots and spin-orbit alignment in the WASP-4 exoplanetary system",
abstract = "We present the photometric analysis of 4 transits of the exoplanet WASP-4b, obtained with the Baade 6.5m telescope, one of the two Magellan telescopes at Las Campanas. The light curves have a photometric precision of 0.5 mmag and a time sampling of 30s. This high precision has allowed us to detect several {"}spot anomalies{"}: temporary brightenings due to the occultation of a starspot on the transit chord. By analyzing these anomalies we find the sky-projected stellar obliquity to be λ = 1°+12°-14°. The small value suggests that the planet migration mechanism preserved the initially low obliquity, or that tidal evolution has realigned the system.",
keywords = "Planetary systems, Stars: spots, Techniques: photometric",
author = "Roberto Sanchis-Ojeda and Winn, {Joshua N.} and Holman, {Matthew J.} and Carter, {Joshua A.} and Osip, {David J.} and Fuentes, {Cesar I.}",
year = "2010",
month = oct,
doi = "10.1017/S1743921311021016",
language = "English (US)",
isbn = "9780521196529",
series = "Proceedings of the International Astronomical Union",
number = "S276",
pages = "511--512",
editor = "Alessandro Sozzetti and Mario Lattanzi and Alan Boss",
booktitle = "The Astrophysics of Planetary Systems",
edition = "S276",
}