Title

IPHAS discoveries of young stars towards Cyg OB2 and its southern periphery

Authors

Authors

J. S. Vink; J. E. Drew; D. Steeghs; N. J. Wright; E. L. Martin; B. T. Gasicke; R. Greimel;J. Drake

Comments

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Abbreviated Journal Title

Mon. Not. Roy. Astron. Soc.

Keywords

stars : early-type; stars : emission line, Be; stars : formation; stars; : individual : T Tauri; stars : pre-main-sequence; LUMINOUS BLUE VARIABLES; CYGNUS-X REGION; MAIN-SEQUENCE EVOLUTION; T-TAURI STARS; MASSIVE STARS; CIRCUMSTELLAR DISKS; EMISSION-LINE; CLUSTER; OB2; NEBULA; Astronomy & Astrophysics

Abstract

We report on the discovery of over 50 strong H alpha emitting objects towards the large OB association Cyg OB2 and the H II region DR 15 on its southern periphery. This was achieved using the INT Photometric H alpha Survey of the Northern Galactic Plane (IPHAS), combined with follow-up spectroscopy using the MMT multi-object spectrometer HectoSpec. We present optical spectra, supplemented with optical r', i' and H alpha photometry from IPHAS, and near-infrared J, H and K photometry from Two Micron All Sky Survey. The position of the objects in the (J - H) versus (H - K) diagram strongly suggests most of them are young. Many show Ca II infrared triplet emission indicating that they are in a pre-main-sequence phase of evolution of T Tauri and Herbig Ae nature. Among these, we have uncovered pronounced clustering of T Tauri stars roughly a degree south of the centre of Cyg OB2, in an arc close to the H II region DR 15, and the radio ring nebula G79.29+0.46, for which we discuss its candidacy as a luminous blue variable. The emission-line objects towards Cyg OB2 itself could be the brightest most prominent component of a population of lower mass pre-main-sequence stars that has yet to be uncovered. Finally, we discuss the nature of the ongoing star formation in Cyg OB2 and the possibility that the central OB stars have triggered star formation in the periphery.

Journal Title

Monthly Notices of the Royal Astronomical Society

Volume

387

Issue/Number

1

Publication Date

1-1-2008

Document Type

Article

Language

English

First Page

308

Last Page

318

WOS Identifier

WOS:000256378700029

ISSN

0035-8711

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