The Wielen dip over the ragne of 6 < M υ < 9 in the luminosity function (LF) for the solar neighborhood stars could be explained by the combination of two different IMFs which yields the age of 13 billion years of the solar neighborhood. This smaller age than the Galactic age, 15 billion years indicates the slow collapse model of the Galaxy, solving the G-dwarf problem. Two different IMFs suggest two different mechanisms for star formation in the solar neighborhood.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. OBSERVED PDMF
Ⅲ. IMF
Ⅳ. THEORETICAL PDMF
Ⅴ. CONCLUSION
REFERENCES

• LEE SEE-WOO(Department of Astronomy, Seoul National University)
• CHUN MOO YOUNG(Department of Astronomy, Seoul National University)