title: Imaging the surface of Altair.
abstract: Spatially resolving the surfaces of nearby stars promises to advance our knowledge of stellar physics. Using optical long-baseline interferometry, we constructed a near-infrared image of the rapidly rotating hot star Altair with a resolution of <1 milliarcsecond. The image clearly reveals the strong effect of gravity darkening on the highly distorted stellar photosphere. Standard models for a uniformly rotating star cannot explain our findings, which appear to result from differential rotation, alternative gravity-darkening laws, or both.
authors.affiliation: Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA. monnier@umich.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Monnier
authors.forename: M
authors.initials: M
authors.lastname: Zhao
authors.forename: E
authors.initials: E
authors.lastname: Pedretti
authors.forename: N
authors.initials: N
authors.lastname: Thureau
authors.forename: M
authors.initials: M
authors.lastname: Ireland
authors.forename: P
authors.initials: P
authors.lastname: Muirhead
authors.forename: J-P
authors.initials: JP
authors.lastname: Berger
authors.forename: R
authors.initials: R
authors.lastname: Millan-Gabet
authors.forename: G
authors.initials: G
authors.lastname: Van Belle
authors.forename: T
authors.initials: T
authors.lastname: Ten Brummelaar
authors.forename: H
authors.initials: H
authors.lastname: McAlister
authors.forename: S
authors.initials: S
authors.lastname: Ridgway
authors.forename: N
authors.initials: N
authors.lastname: Turner
authors.forename: L
authors.initials: L
authors.lastname: Sturmann
authors.forename: J
authors.initials: J
authors.lastname: Sturmann
authors.forename: D
authors.initials: D
authors.lastname: Berger