The Radio Characteristics of HII Regions and the Diffuse Thermal Background

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.

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14 years of 6.7 GHz periodic methanol maser observations towards G188.95+0.89

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003543 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 393-394

Author(s):

Martin M. Mutie ◽

Paul Baki ◽

James O. Chibueze ◽

Khadija El Bouchefry

Keyword(s):

Radio Telescope ◽

Exponential Decay ◽

Hii Regions ◽

Monitoring Period ◽

Methanol Maser ◽

Spectral Components ◽

Methanol Masers ◽

Compact Hii Regions

AbstractWe report the results of 14 years of monitoring of G188.95+0.89 periodic 6.7 GHz methanol masers using the Hartebeesthoek 26-m radio telescope. G188.95+0.89 (S252, AFGL5180) is a radio-quiet methanol maser site that is often interpreted as precursors of ultra-compact HII regions or massive protostar sites. At least five bright spectral components were identified. The maser feature at 11.36 km s-1 was found to experience an exponential decay during the monitoring period. The millimetre continuum reveals two cores associated with the source.

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A Thermal Source with Strong 1612 MHz OH Emission

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000011553 ◽

1969 ◽

Vol 1 (5) ◽

pp. 211-212

Author(s):

B. J. Robinson ◽

W. M. Goss ◽

R. N. Manchester

Keyword(s):

Ground State ◽

Hii Regions ◽

Thermal Source ◽

Strong Source ◽

Galactic Longitude

During 1968 we have found at Parkes several types of emission in the lines of the 18 cm quadruplet of the ground-state OH molecule. This note describes a strong source of 1612 MHz emission near galactic longitude 331°.OH emission was originally detected in the vicinity of HII regions, and a search of a large number of HII regions showed that about a third had associated OH emission. This type of emission is usually strongest at 1665 MHz, and is also seen at 1667 MHz and weakly on one of the satellite lines.

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A Search for Very Compact Structure in 17 OH Masers

Symposium - International Astronomical Union ◽

10.1017/s0074180900134618 ◽

1988 ◽

Vol 129 ◽

pp. 255-256

Author(s):

A. J. Kemball ◽

P. J. Diamond ◽

F. Mantovani

Keyword(s):

Galactic Disk ◽

Hii Regions ◽

Scale Structure ◽

Small Scale ◽

Compact Structure ◽

Small Scale Structure ◽

Interstellar Scattering

The apparent spot sizes of OH masers appear to be significantly broadened when seen through the inner galaxy or large extents of the galactic disk (Burke 1968). Bowers et al (1980) found evidence of small-scale structure (≲ 50 mas) in OH sources at distances of less than 5 kpc but this was characteristically absent in very distant sources (≳ 8kpc) at galactic longitudes 1 ≲ 40°. This result is typically explained in terms of interstellar scattering (ISS) by intervening diffuse HII regions.

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Study of the HII regions in the spiral galaxy NGC6384

Astrophysics ◽

10.1007/s10511-007-0040-8 ◽

2007 ◽

Vol 50 (4) ◽

pp. 426-439 ◽

Cited By ~ 2

Author(s):

A. A. Hakobyan ◽

A. R. Petrosian ◽

A. A. Yeghazaryan ◽

J. Boulesteix

Keyword(s):

Spiral Galaxy ◽

Hii Regions

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Radio Continuum Emission from Sculptor Galaxies

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000026977 ◽

1986 ◽

Vol 6 (3) ◽

pp. 325-329 ◽

Cited By ~ 2

Author(s):

J . I. Harnet

Keyword(s):

Radio Emission ◽

Blue Light ◽

Hii Regions ◽

Radio Continuum ◽

Radial Dependence ◽

Continuum Emission ◽

Upper Limits ◽

Peak Flux

AbstractThe five major members of the Sculptor Group of galaxies and NGC 45 have been observed with the Molonglo observatory synthesis telescope. NGC 247 and NGC 300 were not detected and upper limits to their 843 MHz flux densities are given. Radio emission from NGC 7793 is discussed with particular attention to its morphology, radial dependence compared with that of the blue light and possible coincidences between HII regions and 843 MHz peak flux densities.

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