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

    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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