Discovery of a population of compact radio sources in the spiral galaxy NGC 4736

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185268· OSTI ID:6594375

Duric, N; Dittmar, M R

The discovery of 19 compact radio sources in the near-nuclear region of the spiral galaxy NGC 4736 is reported. Nine are found to have thermal bremsstrahlung spectra. Their small sizes of 1-2 arcsec (20-40 pc at a distance of 4 Mpc), combined with typical flux densities of 0.3-1.0 mJy at 20 cm, suggest high gas densities of 60-270/cu cm. It is proposed that these are H II regions associated with recently formed stars. The remaining 10 sources are all unresolved to 1 arcsec (20 pc) and have synchrotron spectra. Equipartition calculations show that the limits on the relativistic particle energies and magnetic field strengths are consistent with values found for Galactic SNRs. Furthermore, the radio luminosities and small sizes of these sources suggest that these are young SNRs. 20 references.

• Research Organization: New Mexico Univ., Albuquerque (USA)
• OSTI ID: 6594375
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 332; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
CONFIGURATION
COSMIC GASES
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
FLUIDS
FLUX DENSITY
GALAXIES
GASES
H2 REGIONS
LUMINOSITY
MAGNETIC FIELDS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SIZE
SPIRAL CONFIGURATION
STAR EVOLUTION
SUPERNOVA REMNANTS
SYNCHROTRON RADIATION