We have analyzed Gray's observed mean line bisectors of FS, G0, G2, and G5 normal dwarf stars and interpreted them by computing theoretical line bisectors based on a two stream model. A set of perturbed models has been derived, and their detailed structures on temperature fluctuations and velocity fields are presented as a function of depth, which account for the observed bisectors. From the present study, it is found that the degree of stellar convective overshootings and temperature fluctuations in the upper atmospheres increases towards earlier spectral types. The convection cell size inferred from these models is found to increase also with the advancing earlier type. We demonstrated the usefulness of line bisector analysis as a diagnostic probe for stellar convection.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. Observational Characteristics of Solar and Stellar Line Bisectors
Ⅲ. THEORETICAL FOUNDATION
Ⅳ. RESULTS AND DISCUSSIONS
Ⅴ. A BRIEF SUMMARY AND CONCLUSIONS
REFERENCES

• PARK YONG SUN(Department of Astronomy, Seoul National University)
• YUN HONG SIK(Department of Astronomy, Seoul National University)