A (CO)-O-18 STUDY OF THE ORIGIN OF THE POWER-LAW NATURE IN THE INITIAL MASS FUNCTION

作者：Ikeda Norio^*; Kitamura Yoshimi

来源：Astrophysical Journal Letters, 2009, 705(1): L95-L98.

DOI：10.1088/0004-637X/705/1/L95

• ISM: clouds
• ISM: individual (Orion A)
• stars: formation

We have performed (CO)-O-18 (J = 1-0) mapping observations of a 20' x 20' area of the OMC-1 region in the Orion A cloud. We identified 65 (CO)-O-18 cores, which have a mean radius, a velocity width in FWHM, and an LTE mass of 0.18 +/- 0.03 pc, 0.40 +/- 0.15 km s(-1), and 7.2 +/- 4.5 M-circle dot, respectively. All the cores are most likely to be gravitationally bound by considering the uncertainty in the (CO)-O-18 abundance. We derived a (CO)-O-18 core mass function, which shows a power-law-like behavior above 5 M-circle dot. The best-fit power-law index of -2.3 +/- 0.3 is consistent with those of the dense core mass functions and the stellar initial mass IMF) previously derived in the OMC-1 region. This agreement strongly suggests that the power-law form of the IMF has been already determined at the density of similar to 10(3) cm(-3), traced by the (CO)-O-18 (J = 1-0) line. Consequently, we propose that the origin of the IMF should be searched in tenuous cloud structures with densities of less than 10(3) cm(-3).

• 出版日期2009-11-1