Radio spectrum of the compact source at the galactic center

Journal Article · Fri Dec 01 00:00:00 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), Vol. 83:12
• Country of Publication: United States
• Language: English

Related Subjects

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