Galactic plane at 30. 9 MHz

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6275144

Kassim, N E.S.

The Galactic plane was mapped with the Clark Lake TPT telescope at a frequency of 30.9 MHz with unprecedented resolution. The synthesized beam is 13.0' x 11.1' at the zenith. Contour maps were produced for the regions 350/sup 0/ less than or equal to 1 less than or equal to 60/sup 0/, 84/sup 0/ less than or equal to 1 less than or equal to 97/sup 0/, and 133/sup 0/ less than or equal to 1 less than or equal to 250/sup 0/, with absolute value b less than or equal to 2/sup 0/ to 3/sup 0/. A source list is presented that contains integrated flux densities and positions for 696 discrete emission features. More than 60 of these are likely to be previously unidentified Galactic supernova remnants (SNRs). Accurate spectra for 36 known Galactic SNRs were constructed and many show low-frequency turnovers due to free-free absorption by intervening ionized gas. Numerous HII regions were detected in absorption against the Galactic nonthermal background. Source counts in the outer Galaxy (1 greater than or equal to 133/sup 0/) indicate 2.1 x 10/sup 3/ sources per steradian with flux densities greater than 4 Jy at 30.9 MHz. This agrees with the extrapolation of extragalactic source counts at 408 MHz. No new sources with steep spectra similar to the millisecond pulsars PSR1937 +214 and PSR1821-248 were detected. This indicates that any other such sources are of significantly lower flux densities.

• Research Organization: Maryland Univ., College Park (USA)
• OSTI ID: 6275144
• Country of Publication: United States
• Language: English

Related Subjects

640102 -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIO SOURCES
DETECTION
FREQUENCY RANGE
GALAXIES
H2 REGIONS
MAPPING
MHZ RANGE
MHZ RANGE 01-100
MILKY WAY
PULSARS
SUPERNOVA REMNANTS