Bibcode
Lodieu, N.; Scholz, R.-D.; McCaughrean, M. J.; Ibata, R.; Irwin, M.; Zinnecker, H.
Bibliographical reference
Astronomy and Astrophysics, Volume 440, Issue 3, September IV 2005, pp.1061-1078
Advertised on:
9
2005
Journal
Citations
65
Refereed citations
64
Description
We present the results of spectroscopic follow-up observations for a
sample of 71 red objects with high proper motions in the range 0.08-1.14
arcsec yr-1 as detected using APM and SSS measurements of
multi-epoch photographic Schmidt plates. Red objects were selected by
combining the photographic B_JRI magnitudes with 2MASS near-infrared
JHKs magnitudes. Some 50 of the 71 spectroscopically
classified objects turn out to be late-type (>M6) dwarfs and in more
detail, the sample includes 35 ultracool dwarfs with spectral types
between M8 and L2, some previously reported, as well as five M-type
subdwarfs, including a cool esdM6 object, SSSPM J0500-5406. Distance
estimates based on the spectral types and 2MASS J magnitudes place
almost all of the late-type (>M6) dwarfs within 50 pc, with 25
objects located inside the 25 pc limit of the catalogue of nearby stars.
Most of the early-type M dwarfs are located at larger distances of
100-200 pc, suggesting halo kinematics for some of them. All objects
with Hα equivalent widths larger than 10 Å have relatively
small tangential velocities (<50 km s-1). Finally, some
late-type but blue objects are candidate binaries.