Meeting the Cool Neighbors. VIII. A Preliminary 20 Parsec Census from the NLTT Catalogue

July 2004 • 2004AJ....128..463R

Authors • Reid, I. Neill • Cruz, Kelle L. • Allen, Peter • Mungall, F. • Kilkenny, D. • Liebert, James • Hawley, Suzanne L. • Fraser, Oliver J. • Covey, Kevin R. • Lowrance, Patrick • Kirkpatrick, J. Davy • Burgasser, Adam J.

Abstract • Continuing our census of late-type dwarfs in the solar neighborhood, we present BVRI photometry and optical spectroscopy of 800 mid-type M dwarfs drawn from the NLTT proper-motion catalog. The targets are taken both from our own cross-referencing of the NLTT Catalogue and the 2MASS Second Incremental Data Release, and from the revised NLTT compiled recently by Salim & Gould. All are identified as nearby-star candidates based on their location in the (m_r,m_r-K_s) diagram. Three hundred stars discussed here have previous astrometric, photometric, or spectroscopic observations. We present new BVRI photometry for 101 stars, together with low-resolution spectroscopy of a further 400 dwarfs. In total, we find that 241 stars are within 20 pc of the Sun, while a further 70 lie within 1 σ of our distance limit. Combining the present results with previous analyses, we have quantitative observations for 1910 of the 1913 candidates in our NLTT nearby-star samples. Eight hundred fifteen of those stars have distance estimates of 20 pc or less, including 312 additions to the local census. With our NLTT follow-up observations essentially complete, we have searched the literature for K and early-type M dwarfs within the sampling volume covered by the 2MASS second release. Comparing the resultant 20 pc census against predicted numbers, derived from the 8 pc luminosity function, shows an overall deficit of ~20% for stellar systems and ~35% for individual stars. Almost all are likely to be fainter than M_J=7, and at least half are probably as yet undiscovered companions of known nearby stars. Our results suggest that there are relatively few missing systems at the lowest luminosities, M_J>8.5. We discuss possible means of identifying the missing stars.

Links

• PREPRINT http://arxiv.org/abs/astro-ph/0404061
• ELECTR https://doi.org/10.1086%2F421374
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2004AJ....128..463R
• PDF https://stacks.iop.org/1538-3881/128/463/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/128/463
• DATA https://irsa.ipac.caltech.edu/bibdata/2004/R/2004AJ....128..463R.html
• SPIRES http://inspirehep.net/search?p=find+eprint+astro-ph/0404061