Speaker
Ricardo Retes
(INAOE)
Description
We study the star formation (SF) law in 12 Galactic molecular clouds with ongoing
high-mass star formation (HMSF) activity, as traced by the presence of a bright IRAS
source and other HMSF tracers.
We define the molecular cloud (MC) associated to each IRAS source using 13^CO line
emission, and count the young stellar objects (YSOs) within these clouds using
GLIMPSE and MIPSGAL Spitzer databases. The masses for high luminosity YSOs
(L_bol>10Lo) are determined individually using Pre Main Sequence evolutionary tracks
and the evolutionary stages of the sources, whereas a mean mass of 0.5Mo was adopted
to determine the masses in the low luminosity YSO population. The star formation rate
surface density (SD) corresponding to a gas surface density is obtained by counting
the number of the YSOs within successive contours of 13^CO line emission. We find a
break in the relation between SFR SD and gas SD, with the relation being power-law
(SFR-SD propto GAS-SD^N) with the index N varying between 1.3 and 3.6 above the
break. The GAS SD at the break is between 100-224 Mo/pc^2 for the sample clouds,
which compares well with the threshold gas density found in recent studies of
Galactic SF regions. Below this threshold, we find SFR SD remaining almost constant
independent of the gas SD. We also studied the star formation law for the clouds as a
whole, and find that our clouds lie between the Kennicutt (1998) relation and the
linear relation for Galactic and extragalactic dense SF regions. The global values of
star formation rate (SFR) and star formation efficiency (SFE) in our clouds ranges
between 12-756 and 0.5%-3.8, respectively, comparable to the
values in Orion A/B and other Galactic high-mass SF regions. We find a tendency for
the high-mass YSOs to be found preferentially in dense regions at densities larger
than 600 Mo/pc^2.
Primary author
Ricardo Retes
(INAOE)
