"The Sloan Digital Sky Survey Data Release 7 Spectroscopic M Dwarf Catalog I: Data" West el al (2011) - download
"The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: II. The Field". Bochanski et al (2010) - download
The Bochanski paper gives three equations describing the relationship between SDSS magnitudes and the absolute magnitude of M dwarf stars. Once the absolute magnitude is known the distance in parsec can be calculated. Since the absolute magnitude is based on the star being 10 parsec from the observer then any star closer than this distance must have its apparent magnitude brigher than its absolute magnitude.
Constraints - the image of the candidate must not be saturated. Hence the u,g,r,i and z magnitudes need to be fainter than 14.1, 14.1, 14.1, 13.8 and 12.3 respectively. The crucial magnitude is that in the r band since it is Mr (the absolute magnitude in the r band) that is being calculated. If we are only interested in stars with an apparent magnitude brighter than the absolute magnitude then the lower limit of the absolute magnitude must be c14.2.
The Bochanski equations give an (r-i) value of about 2 for a Mr value of 14 so this served as a constraint in the subsequent SQL query.
A total of 107 red dwarf stars were identified as lying within 10 parsec in at least two of the equations. Curiously the third eqaution generated far more candidates than the other two equations but many of these were not confirmed and have not been included in this paper.
It would appear that all these stars are late (M7 to M9) dwarfs
Full details of the 107 stars found to be within 10 parsecs can be downloaded from here.
Over the last few years I have carried out many astronomical data mining or data analysis projects. Most remain unpublished and this series of papers aims to put them all into the public domain. I welcome constructive feedback from readers and encourage colleagues to take the work forward, perhaps as far as peer reviewed publication. I can be contacted by email. and this address is monitored daily.
Martin Piers Nicholson - Shropshire, United Kingdom.
This page was last updated on July 13th 2011.