The discovery of low-mass pre main sequence stars in Cepheus OB3b

Abstract

We report the discovery of low-mass PMS stars in the younger subgroup of the Cepheus OB3 association, Cep OB3b, using {\it UBVI} CCD photometry and spectroscopy. The location of a PMS is well defined in a V versus (V-I) colour-magnitude diagram (CMD). Multi-fibre spectroscopy results of optically-selected PMS candidates confirm the T Tauri nature of 10 objects, with equal numbers of classical and weak-line TTS. There are 6 other objects which we classify as possible PMS stars. The newly discovered TTS have masses in the range 0.9 - 3.0 Msun and ages from <1 to nearly 10 Myr, based on the Siess et al.(2000) isochrones. Their location close to the O and B Their location close to the O and B stars of the association demonstrates that low-mass star formation is possible in this hostile environment dominated by early-type stars and that the latter must have been less effective in eroding the circumstellar discs of their lower mass siblings compared to other OB associations (e.g. lambda Ori). We attribute this to the nature of the local environment, speculating that the bulk of molecular material, which shielded low-mass stars from the ionising radiation of their early-type siblings, has only recently been removed (abridged).

arXiv commentAccepted for publication in MNRAS. Contains several very compressed figures. A higher quality version is available from http://www.astro.keele.ac.uk/~rdj/

References in corpus (10)

• Disk Frequencies and Lifetimes in Young Clusters
• X-ray emitting young stars in the Orion Nebula
• Infrared L Band Observations of the Trapezium Cluster: A Census of Circumstellar Disks and Candidate Protostars
• X-ray emission from young stars in Taurus-Auriga-Perseus: Luminosity functions and the rotation-activity-age relation
• Circumstellar Disks in the IC 348 Cluster
• Optimal photometry for colour-magnitude diagrams and its application to NGC 2547
• Chandra X-ray Observation of the Orion Nebula Cluster. I Detection, Identification and Determination of X-ray Luminosities
• A Mid-Infrared Study of the Young Stellar Population in the NGC 2024 Cluster
• The discovery of a low mass, pre-main-sequence stellar association around gamma Velorum
• Observational clues for a role of circumstellar accretion in PMS X-ray activity

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