Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - IV. Upper Sco

Lodieu, N.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 431, Issue 4, p.3222-3235

Advertised on:
6
2013
Number of authors
1
IAC number of authors
1
Citations
50
Refereed citations
46
Description
We present the results of a proper motion wide-field near-infrared survey of the entire Upper Sco (USco) association (˜160 square degrees) released as part of the United Kingdom Infrared Telescope Infrared Deep Sky (UKIDSS) Galactic Clusters Survey (GCS) Data Release 10 (DR10). We have identified a sample of ˜400 astrometric and photometric member candidates combining proper motions and photometry in five near-infrared passbands and another 286 with HK photometry and 2MASS/GCS proper motions. We also provide revised membership for all previously published USco low-mass stars and substellar members based on our selection and identify new candidates, including in regions affected by extinction. We find negligible variability between the two K-band epochs, below the 0.06 mag rms level. We estimate an upper limit of 2.2 per cent for wide common proper motions with projected physical separations less than ˜15 000 au. We derive a disc frequency for USco low-mass stars and brown dwarfs between 26 and 37 per cent, in agreement with estimates in IC 348 and σ Ori. We derive the mass function of the association and find it consistent with the (system) mass function of the solar neighbourhood and other clusters surveyed by the GCS in the 0.2-0.03 M⊙ mass range. We confirm the possible excess of brown dwarfs in USco.
Related projects
Discovery of a system of super-Earths orbiting the star HD 176986 with about 5.7 and 9.2 Earth masses.
Very Low Mass Stars, Brown Dwarfs and Planets
Our goal is to study the processes that lead to the formation of low mass stars, brown dwarfs and planets and to characterize the physical properties of these objects in various evolutionary stages. Low mass stars and brown dwarfs are likely the most numerous type of objects in our Galaxy but due to their low intrinsic luminosity they are not so
Rafael
Rebolo López