Other
Scientific paper
Jan 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994phdt........29b&link_type=abstract
PhD Dissertation, Minnesota Univ. Duluth, MN United States
Other
1
Brown Dwarf Stars, Infrared Photometry, M Stars, Main Sequence Stars, Stellar Magnitude, Stellar Mass, Color, Kinematics, Color-Magnitude Diagram, Time Measurement
Scientific paper
We have used the Minnesota Automated Plate Scanner to search three epochs of 6 deg x 6 deg plates and generate a list of candidate members of the Hyades cluster which includes stars complete to more than a magnitude fainter than previous work. All 82 final candidates are very faint and red, and have proper motions compatible with cluster membership . Of 30 candidates which have been observed in the infrared, all but two have the expected JHK colors of very low mass Hyades. However, the optical-infrared color-magnitude diagram shows only five of these candidates lying along the extension of the Hyades main sequence. We estimated of the background contamination by assuming that the field star proper motions are distributed symmetrically about the Basic Solar Reflex Motion. This assumption implies approximately 50% of the candidates are true cluster members. The best explanation for these apparently contradictory findings is that the candidate list is strongly contaminated by a low metallicity population with kinematics somewhat different from the disk stars. The low metallicities of these stars affect their JHK photometry in such a way that they mimic the colors of cooler late-M dwarfs, and their distinctive kinematics are responsible for spoiling our attempt to use proper motions to statistically estimate their numbers. The few available spectra also support this interpretation. Four of the five stars which lie on the extension of the Hyades optical-infrared main sequence have the expected late-M dwarf spectra, while five other candidates observed have earlier spectral types, including three with 'marginal sub-dwarf' features. Adopting the most conservative possible value for the number of true Hyads found, we derive the form of the cluster luminosity function down to luminosities corresponding to masses of M approximately equal to 0.1 Solar Mass. Within the statistical uncertainties, we find that this luminosity function matches best to a moderately increasing mass function with a power law index of alpha approximately equal to 1.0--1.5, but is also compatible with a sharply increasing mass function below M approximately 0.15 Solar Mass. Thus, although brown dwarfs are not likely to contribute significantly to the total mass of the cluster, the possibility that they do remains open.
No associations
LandOfFree
The lower end of the Hyades initial mass function does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The lower end of the Hyades initial mass function, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The lower end of the Hyades initial mass function will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1685560