Radio spectrum of the compact source at the galactic center

Journal Article · Fri Dec 01 04:00:00 EST 1978 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/112368· OSTI ID:6651572

Brown, R L; Lo, K Y; Johnston, K J

Observations of the compact radio source at the Galactic center obtained at 11.1 and 3.7 cm with the Green Bank 35-km radio-link interferometer and at 6, 2, and 1.3 cm with the VLA reveal that the flux density of the source increases with increasing frequency for ..nu..< or approx. =25 GHz. This result, taken in conjunction with recent VLBI observations which show Sgr-A to be < or approx. =0''.001 (10 AU), requires either that the magnetic field in the source is very high, B>200 G, or that the true source size is significantly smaller than the VLBI limits, theta< or approx. =2 AU, and hence that the energy density in the source is very large, >15 erg cm/sup -3/. An alternative to this description is provided by the similarity of the radio properties of Sgr-A to those of Galactic radio stars in which the opacity at centimeter wavelengths is provided by free--free absorption. If this latter interpretation is applicable, the compact radio source at the Galactic center is likely associated with one member of a multiple-star system.

• Research Organization: National Radio Astronomy Observatory, Green Bank, West Virginia 24944
• OSTI ID: 6651572
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 83:12; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics &amp; Cosmology-- Quasi-Stellar
Radio
&amp; X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
COSMIC DUST
COSMIC GASES
DUSTS
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
FLUIDS
GALAXIES
GASES
INTERFEROMETERS
INTERSTELLAR GRAINS
MEASURING INSTRUMENTS
MILKY WAY
PARTICLES
RADIATIONS
RADIOWAVE RADIATION
SPECTRA