Spectroscopic classification of red high proper motion objects in the Southern Sky

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
Number of authors
6
IAC number of authors
0
Citations
62
Refereed citations
61
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.