The interstellar medium of a starburst galaxy; millimeter interferometric observations of M82
The Hat Creek Interferometer was used to obtain multi-frequency high resolution observations of the nuclear region of the starburst galaxy M82. Emission from the J = 1 yields 0 rotational transitions of CO, HCO(+) and HCN and from wavelength 3.3 mm continuum were studied at angular resolutions of 5 to 11 seconds (75 to 165 pc) and velocity resolutions at 3.3 to 4.3 km/s. The observations provide information on the state of the molecular and ionized components of the interstellar medium. The pressure of both components ranges from approximately 10(exp 6)/cu cm K near the edge of the starburst region to greater than or equal to 10(exp 7)/cu cm K in the center. The density of the molecular gas is high greater than or equal to 10(exp 5)/cu cm, and the volume filling factor of the molecular gas is low, less than .001. In contrast, the volume filling factor of the Hill regions is high, greater than or equal to 0.1. The Lyman continuum flux determined from the wavelength 3.3 mm emission measure is greater than 6 x 10(exp 53)/s. This is equivalent to the flux of 3 x 10(exp 5) O8 stars and, even though emitted from only the 500 pc diameter starburst region of M82, is greater than the estimated flux from the entire Milky Way. The observations provide evidence that the starburst is spreading from the core of the nuclear region into dense molecular clouds which surround the central region of bright far-infrared emission. The brightest supernova remnants, observed at radio wavelengths, are found in dense molecular clouds on the periphery of the starburst region. In addition, mechanically tunable Gunn oscillators were developed for use as local oscillators in heterodyne astronomical receivers. They were installed on the three element Hat Creek Interferometer to expand the frequency coverage to 70 to 116 GHz; the entire 3 mm atmospheric window.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- OSTI ID:
- 6688980
- Resource Relation:
- Other Information: Ph.D. Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
GALAXIES
COSMIC GASES
HYDROCYANIC ACID
INTERSTELLAR GRAINS
CLOUDS
EXPERIMENTAL DATA
INTERFEROMETRY
MICROWAVE RADIATION
SUPERNOVA REMNANTS
COSMIC RADIO SOURCES
CYANIDES
DATA
ELECTROMAGNETIC RADIATION
FLUIDS
GASES
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
NUMERICAL DATA
PARTICLES
RADIATIONS
640105* - Astrophysics & Cosmology- Galaxies