Molecular Cloud-scale Star Formation in NGC 300

Autor(en)

Christopher M. Faesi, Charles J. Lada, Jan Forbrich, Karl M. Menten, Hervé Bouy

Abstrakt

We present the results of a galaxy-wide study of molecular gas and star

formation in a sample of 76 H II regions in the nearby spiral galaxy NGC

300. We have measured the molecular gas at 250 pc scales using pointed

CO(J = 2-1) observations with the Atacama Pathfinder Experiment

telescope. We detect CO in 42 of our targets, deriving molecular gas

masses ranging from our sensitivity limit of ~105 M

☉ to 7 × 105 M ☉. We

find a clear decline in the CO detection rate with galactocentric

distance, which we attribute primarily to the decreasing radial

metallicity gradient in NGC 300. We combine Galaxy Evolution Explorer

far-ultraviolet, Spitzer 24 μm, and Hα narrowband imaging to

measure the star formation activity in our sample. We have developed a

new direct modeling approach for computing star formation rates (SFRs)

that utilizes these data and population synthesis models to derive the

masses and ages of the young stellar clusters associated with each of

our H II region targets. We find a characteristic gas depletion time of

230 Myr at 250 pc scales in NGC 300, more similar to the results

obtained for Milky Way giant molecular clouds than the longer (>2

Gyr) global depletion times derived for entire galaxies and

kiloparsec-sized regions within them. This difference is partially due

to the fact that our study accounts for only the gas and stars within

the youngest star-forming regions. We also note a large scatter in the

NGC 300 SFR-molecular gas mass scaling relation that is furthermore

consistent with the Milky Way cloud results. This scatter likely

represents real differences in giant molecular cloud physical properties

such as the dense gas fraction.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Harvard-Smithsonian Center for Astrophysics, National Science Foundation, Max-Planck-Institut für Radioastronomie, Spanish National Research Council (CSIC)

Journal

The Astrophysical Journal

Band

789

Seiten

23

Anzahl der Seiten

23

ISSN

0004-637X

DOI

https://doi.org/10.1088/0004-637X/789/1/81

Publikationsdatum

07-2014

Peer-reviewed

Ja

ÖFOS 2012

103004 Astrophysik, 103003 Astronomie

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/molecular-cloudscale-star-formation-in-ngc300(c1eb7b3d-e1fe-4263-af70-2cca080085c0).html