MEASUREMENT OF THE MASS AND STELLAR POPULATION DISTRIBUTION IN M82 WITH THE LBT

Journal Article · Thu Sep 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/757/1/24· OSTI ID:22092297

Greco, Johnny P.; Martini, Paul

We present a K-band spectroscopic study of the stellar and gas kinematics, mass distribution, and stellar populations of the archetypical starburst galaxy M82. Our results are based on a single spectrum at a position angle of 67.{sup 0}5 through the K-band nucleus. We used the {sup 12}CO stellar absorption band head at 2.29 {mu}m (CO{sub 2.29}) to measure the rotation curve out to nearly 4 kpc radius on both the eastern and western sides of the galaxy. Our data show that the rotation curve is flat from 1 to 4 kpc. This stands in sharp contrast to some previous studies, which have interpreted H I and CO emission-line position-velocity diagrams as evidence for a declining rotation curve. The kinematics of the Br{gamma}, H{sub 2}, and He I emission lines are consistent with, although characterized by slightly higher velocities than, the stellar kinematics. We derived M82's mass distribution from our stellar kinematic measurements and estimate that its total dynamical mass is {approx}10{sup 10} M{sub Sun }. We measured the equivalent width of CO{sub 2.29} (W{sub 2.29}) as a function of distance from the center of the galaxy to investigate the spatial extent of the red supergiant (RSG) population. The variation in W{sub 2.29} with radius clearly shows that RSGs dominate the light inside 500 pc radius. M82's superwind is likely launched from this region, where we estimate that the enclosed mass is {approx}<2 Multiplication-Sign 10{sup 9} M{sub Sun }.

• OSTI ID: 22092297
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 757; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTRA
ASTRONOMY
ASTROPHYSICS
BROMINE
CARBON 12
CARBON MONOXIDE
DIAGRAMS
DISTANCE
EMISSION SPECTRA
GALAXIES
HELIUM
HYDROGEN
MASS
MASS DISTRIBUTION
RED GIANT STARS
ROTATION
VARIATIONS