The sample of sub dwarfs are selected from LHS catalogue on the bases of the reduced proper motion diagram utilizing Chui criteria, and confirmed with the available photometric and/or kinematic data. Among them, 20 sub dwarfs have trigonometric parallaxes with accuracy better than 20 % . The color­absolute magnitude relation is derived with them. By adopting this color-magnitude relation and V / V m method, we have derived the sub dwarf luminosity function over the absolute magnitude range of M v = 4.5 and 9.5. This halo luminosity function is consistent with that of Eggen(1987). By adopting the available mass-luminosity relations for halo stars, we have found that the halo IMF is steeper than disk IMFs of Scalo(1986) and Salpter(1955) in this small mass region.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. INITIAL MASS FUNCTION OF SUBDWARFS
Ⅲ. COMPARISON WITH DISK INITIAL MASS FUNCTION
Ⅳ. CONCLUSION
ACKNOWLEDGEMENTS
REFERENCES

• LEE SANG-GAK(Department of Astronomy, Seoul National University)