Site Map
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

M dwarfs in the b201 tile of the VVV survey
Colour-based selection, spectral types and light curves

B. Rojas-Ayala, D. Iglesias, D. Minniti, R. K. Saito, F. Surot

Context. The intrinsically faint M dwarfs are the most numerous stars in the Galaxy, have main-sequence lifetimes longer than the Hubble time, and host some of the most interesting planetary systems known to date. Their identification and classification throughout the Galaxy is crucial to unraveling the processes involved in the formation of planets, stars, and the Milky Way. The ESO Public Survey VVV is a deep near-IR survey mapping the Galactic bulge and southern plane. The VVV b201 tile, located in the border area of the bulge, was specifically selected for the characterisation of M dwarfs.
We used VISTA photometry to identify M dwarfs in the VVV b201 tile, to estimate their subtypes, and to search for transit-like light curves from the first 26 epochs of the survey.
UKIDSS photometry from SDSS spectroscopically identified M dwarfs was used to calculate their expected colours in the YJHKs VISTA system. A colour-based spectral subtype calibration was computed. Possible giants were identified by a (JKs,HJ) reduced proper motion diagram. The light curves of 12.8 <Ks< 15.8 colour-selected M dwarfs were inspected for signals consistent with transiting objects.
We identified 23 345 objects in VVV b201 with colours consistent with M dwarfs. We provided their spectral types and photometric distances, up to ~300 pc for M9s and ~1.2 kpc for M4s, from photometry. In the range 12 <Ks< 16, we identified 753 stars as possible giants out of 9232 M dwarf candidates. While only the first 26 epochs of VVV were available, and 1 epoch was excluded, we were already able to identify transit-like signals in the light curves of 95 M dwarfs and of 12 possible giants.
Thanks to its deeper photometry (~4 mag deeper than 2MASS), the VVV survey will be a major contributor to the discovery and study of M dwarfs and possible companions towards the centre of the Milky Way.

surveys – stars: fundamental parameters – stars: low-mass – Galaxy: bulge

Astronomy and Astrophysics
Volume 571, Page A36_1
November 2014

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website