The Monitor project: rotation periods of low-mass stars in M50

• Published in: Monthly notices of the Royal Astronomical Society Vol. 392; no. 4; pp. 1456 - 1466
• Main Authors: Irwin, Jonathan, Aigrain, Suzanne, Bouvier, Jerome, Hebb, Leslie, Hodgkin, Simon, Irwin, Mike, Moraux, Estelle
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2009; Wiley-Blackwell; Oxford University Press; Oxford University Press (OUP): Policy P - Oxford Open Option A
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; open clusters and associations: individual: M50; Sciences of the Universe; stars: pre-main-sequence; stars: rotation; surveys; techniques: photometric; surveys; stars: pre-main-sequence; open clusters and associations: individual: M50; techniques: photometric; stars: rotation; Low-mass stars; Morphology; Time series; Open clusters; Stellar rotation; Star clusters
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2008.14158.x

We report on the results of a time-series photometric survey of M50 (NGC 2323), a ∼130 Myr open cluster, carried out using the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 812 candidate cluster members over the mass range 0.2 ≲M/M⊙≲ 1.1. The rotation period distributions show a clear mass-dependent morphology, statistically indistinguishable from those in NGC 2516 and M35 taken from the literature. Due to the availability of data from three observing runs separated by ∼10 and 1 month time-scales, we are able to demonstrate clear evidence for evolution of the photometric amplitudes, and hence spot patterns, over the 10 month gap. We are not able to constrain the time-scales for these effects in detail due to limitations imposed by the large gaps in our sampling, which also prevent the use of the phase information.