The sub-stellar birth rate from UKIDSS
Day-Jones, A. C.
Zhang, Z. H.
Ruiz, M. T.
Jenkins, J. S.
Folkes, S. L.
Clarke, J. R. A.
We present a new sample of mid-L to mid-T dwarfs with effective temperatures of 11001700 K selected from the UKIDSS Large Area Survey (LAS) and confirmed with infrared spectra from X-shooter/Very Large Telescope. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our programme, covering 495 square degrees of sky, complete to J = 18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of masses 0.10-0.03 M-circle dot and ages 1-10 Gyr. We find that the more extreme birth rates (e. g. a halo type form) can likely be excluded as the true form of the birth rate. In addition, we find that although there is substantial scatter we find a preference for a mass function, with a power-law index a in the range -1 <alpha <0 that is consistent (within the errors) with the studies of late T dwarfs.
Published inMonthly Notices of the Royal Astronomical Society
RelationsSchool of Physics, Astronomy and Mathematics
MetadataShow full item record
Showing items related by title, author, creator and subject.
Discovery of the first white dwarf + T dwarf binary system and the use of white dwarfs as age calibrators Day-Jones, Avril; Pinfield, D.J.; Ruiz, M.; Beaumont, H.; Gallardo, J.; Gianninas, A.; Bergeron, P.; Napiwotzki, Ralf; Jenkins, J.S.; Burningham, B.; Zhang, Z.H.; Jones, H.R.A.; Murray, D.; Catalan, Silvia; Ines Gomes, Joana (American Institute of Physics, 2010)We present the discovery of the first white dwarf + T dwarf binary system. Systems containing a white dwarf and a brown dwarf are rare but can be used to place constraints on the age of the binary, making them valuable ...
The Prospects for Finding Brown Dwarfs in Eclipsing Binary Systems and Measuring Brown Dwarf Properties Pinfield, D.J.; Jones, H.R.A.; Steele, I.A. (2005)
Smart, R. L.; Marocco, F.; Caballero, J. A.; Jones, H. R. A.; Barrado, David; Beamin, J.C.; Pinfield, D. J.; Sarro, L. M. (2017-07-01)We identify and investigate known ultracool stars and brown dwarfs that are being observed or indirectly constrained by the Gaia mission. These objects will be the core of the Gaia ultracool dwarf sample composed of all ...