Title

An IPHAS-based search for accreting very low-mass objects using VO tools

Authors

Authors

L. Valdivielso; E. L. Martin; H. Bouy; E. Solano; J. E. Drew; R. Greimel; R. Gutierrez; Y. C. Unruh;J. S. Vink

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

Astron. Astrophys.

Keywords

stars: low-mass, brown dwarfs; stars: formation; stars: planetary; systems: protoplanetary disks; stars: pre-main sequence; infrared: stars; YOUNG BROWN DWARFS; NORTHERN GALACTIC PLANE; H-ALPHA EMISSION; T-TAURI; STARS; SIGMA-ORIONIS; SPECTRAL SEQUENCE; SKY SURVEY; SPECTROSCOPY; CLUSTER; DISCOVERY; Astronomy & Astrophysics

Abstract

Context. The main goal of this paper is to prove that accreting very low-mass stars and brown dwarfs can be identified in IPHAS, an Ha emission survey of the northern Milky Way. Full exploitation of the IPHAS database and a future extension of it in the southern hemisphere will be useful in identifying very low-mass accreting objects near to and far from well-known star-forming regions. Aims. We have used Virtual Observatory tools to cross-match the IPHAS catalogue with the 2MASS catalogue. We defined photometric criteria to identify Ha emission sources with near-infrared colours similar to those of known young very low-mass stars and brown dwarfs. 4000 candidates were identified that met our criteria over an area of 1600 square degrees. We present low-resolution optical spectra of 113 candidates. Spectral types have been derived for the 33 candidates that have spectroscopically confirmed Ha emission, negligible reddening and spectral class M. We have also measured Ha emission and investigated the NaI doublet (818.3 nm, 819.5 nm) in these 33 objects. Methods. We confirm that 33 IPHAS candidates have strong Ha emission indicative of disc accretion for their spectral type. Twenty-three of them have spectral class M4 or later, of which ten have classes in the range M5.5-M7.0 and could thus be very young brown dwarfs. Many objects also have a weak NaI doublet, an indication of low surface gravity. Results. IPHAS provides a very valuable database for identifying accreting very low-mass stars and brown dwarfs. Virtual Observatory tools provide an efficient method for identifying these objects over large areas of the sky. Based on our success rate of 23 Ha emission objects with spectral type in the range M4-M7 out of 113 candidates with spectroscopic follow-up, we estimate that there could be hundreds of such objects in the full IPHAS survey.

Journal Title

Astronomy & Astrophysics

Volume

497

Issue/Number

3

Publication Date

1-1-2009

Document Type

Article

Language

English

First Page

973

Last Page

981

WOS Identifier

WOS:000265280500029

ISSN

0004-6361

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