The largest molecular cloud complexes in the first galactic quadrant
T. M. Dame, B. G. Elmegreen, R. S. Cohen, P. Thaddeus;
ApJ, 1986, 305, 892
ABSTRACT:The Columbia CO survey of the first Galactic quadrant was used to determine the locations and
physical properties of the largest molecular complexes in the inner
Galaxy.
Within the range of the survey (l = 12-60 deg), 26 complexes were detected with
masses greater than 5 x 10 to the 5th solar masses, and roughly several hundred
such complexes are deduced to exist throughout the Galaxy within the solar
circle.
These complexes are the parent objects of much of the Population I in the
Galaxy.
Distances to most of the complexes were determined kinematically, the distance
ambiguity being resolved with the aid of associated H II regions, OB
associations, masers, and other early Population I objects.
The largest complexes
are good tracers of spiral structure, the Sagittarius arm in particular
being delineated with unprecedented clarity.
A total of 17 large complexes
are distributed rather uniformly along a 15 kpc stretch of the arm with a
spacing comparable to that of the strings of regularly spaced H Ii regions
observed in external galaxies.
Power-law relations exist between the line
widths and sizes of the complexes and between their densities and sizes.
The
forms of these relations are in good agreement with those found previously
and are extended by roughly an order of magnitude in cloud mass.
KEYWORDS: galactic structure, milky way galaxy, molecular clouds, carbon monoxide, h ii regions, least squares method, noise reduction, quadrants, statistical tests
PERSOKEY:co, milky way, h2, ,
CODE: dame86