Survey of OH Masers at 1665 and 1667 MHz. I. Galactic Longitudes 326° to 40°

Caswell, J. L.; Haynes, R. F.; Goss, W. M.

doi:10.1071/ph800639

Cited by 58 publications

(103 citation statements)

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“…We discovered this H 2 0 source in the direction of a new OH maser (Caswell et al 1980); the H 2 0 profile shows a main feature at -84 km S-l and a weaker feature at -78 km s -1.…”

Section: Resultsmentioning

confidence: 95%

“…This source was discovered in 1975 December (CaswelLet al 1976) at the position of an unusual OH source (Caswell et al 1980). The strongest feature of 1975 December was 540Jy at V = -43·5kms-1 but was not detectable « 15 Jy) in 1976 August, while a secondary feature at V = -39·5 kms-1 had decayed from -50 to -30 Jy.…”

mentioning

confidence: 99%

“…This source was discovered in 1976 August near anew OH maser (Caswell et al 1980); the intensity in 1977 May had increased by a factor of 2. A weaker feature ( -20 Jy) is present at -50 km S -1.…”

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confidence: 99%

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Galactic Plane H2O Masers: A Southern Survey

Batchelor¹,

Caswell²,

Goss³

et al. 1980

Aust. J. Phys.

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An extensive 22 GHz survey of H 2 0 masers has been made with the Parkes 64 m radio telescope. We present data here for 68 sources, of which almost one-half were discovered in the present series of observations. The telescope beamsize, 100' arc to half-power, has enabled us to improve the position measurements of most of the known sources and in a few cases has allowed us to resolve a 'source' into several spatially separated components. The wide velocity coverage of our observations (> 200 km s -1) has led to the discovery of several interesting new high-velocity features. In addition to details for each source, the general properties of the sample are discussed. In the typical interval of 8 months between successive observations, the peak intensity of many sources varied only slightly (by less than a factor of 2); a few sources, however, showed more dramatic variations.

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“…We discovered this H 2 0 source in the direction of a new OH maser (Caswell et al 1980); the H 2 0 profile shows a main feature at -84 km S-l and a weaker feature at -78 km s -1.…”

Section: Resultsmentioning

confidence: 95%

mentioning

confidence: 99%

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Galactic Plane H2O Masers: A Southern Survey

Batchelor¹,

Caswell²,

Goss³

et al. 1980

Aust. J. Phys.

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“…Evidence of active star formation in the G331.5-0.1 GMC is further provided by the detection of OH and methanol maser emission Caswell et al 1980;Caswell 1997Caswell , 1998Pestalozzi et al 2005), as well as H 2 O maser emission (J. L. Caswell 2013, private communication). Hydroxyl masers are known to be excellent indicators of UCHII regions, whereas methanol maser emission is a common phenomenon in regions of massive star formation (Menten et al 1986) and H 2 O maser emission is thought to be a probe of the earliest stages of massive star formation (Furuya 2003).…”

Section: Introductionmentioning

confidence: 99%

Physical Characteristics of G331.5-0.1: The Luminous Central Region of a Giant Molecular Cloud

Merello

Bronfman

Garay

et al. 2013

ApJ

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We report molecular line and dust continuum observations toward the high-mass star-forming region G331.5-0.1, one of the most luminous regions of massive star formation in the Milky Way, located at the tangent region of the Norma spiral arm, at a distance of 7.5 kpc. Molecular emission was mapped toward the G331.5-0.1 GMC in the CO(J = 1 → 0) and C 18 O(J = 1 → 0) lines with NANTEN, while its central region was mapped in CS(J = 2 → 1 and J = 5 → 4) with SEST, and in CS(J = 7 → 6) and 13 CO(J = 3 → 2) with ASTE. Continuum emission mapped at 1.2 mm with SIMBA and at 0.87 mm with LABOCA reveal the presence of six compact and luminous dust clumps, making this source one of the most densely populated central regions of a GMC in the Galaxy. The dust clumps are associated with molecular gas and they have the following average properties: size of 1.6 pc, mass of 3.2 × 10 3 M , molecular hydrogen density of 3.7 × 10 4 cm −3 , dust temperature of 32 K, and integrated luminosity of 5.7 × 10 5 L , consistent with values found toward other massive star-forming dust clumps. The CS and 13 CO spectra show the presence of two velocity components: a high-velocity component at ∼−89 km s −1 , seen toward four of the clumps, and a low-velocity component at ∼−101 km s −1 seen toward the other two clumps. Radio continuum emission is present toward four of the molecular clumps, with spectral index estimated for two of them of 0.8 ± 0.2 and 1.2 ± 0.2. A high-velocity molecular outflow is found at the center of the brightest clump, with a line width of 26 km s −1 (FWHM) in CS(J = 7 → 6). Observations of SiO(J = 7 → 6 and J = 8 → 7), and SO(J K = 8 8 → 7 7 and J K = 8 7 → 7 6 ) lines provide estimates of the gas rotational temperature toward this outflow >120 K and >75 K, respectively.

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“…8). The OH maser was first detected by Caswell et al (1977); an H 2 0 maser has. not been detected at this position (CBFW 87).…”

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confidence: 99%

Survey of OH Masers at 1665 MHz. III. Galactic Longitudes 233° to 326°

Caswell

Haynes

1987

Aust. J. Phys.

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Aust. J. Phys., 1987, 40, 215-38 We have searched the galactic plane from longitude 233° to 326° for OH emission on the 1665 MHz transition. Between longitudes 270° and 326°, where the survey zone was a uniformly sampled grid, we detected 35 OH maser sources, including 24 new ones; most are of the Type I variety that delineates sites of current star formation, and many of the sites are young, with no well-developed HII regions in the vicinity. By combining the present results with those of earlier surveys Oongitudes 326° -+ 360° -+ 2°: Parts I and II) we have improved on previous estimates of the galactic distribution of these masers.All sources were studied in both circular polarisations on the 1665 and 1667 MHz transitions of the OH ground state; measurements of the 1612 and 1720 MHz transitions will be needed to single out any masers of different varieties, such as those associated with late-type stars rather than regions of star formation.Three individually interesting discoveries are: OH301·14-0·23, which shows weak 'highvelocity' emission displaced more than 20 km s -1 from the main features, similar to the displacements seen in the associated H 2 0 maser; OH310·06-3.02, which is probably an unusual variety of late-type star; and OH 311·64 -0· 38, whose systemic velocity of + 34 kms -1 .indicates a location outside the solar circle, in a previously uncharted extension of the Carina spiral arm, 16· 3 kpc from the Sun.

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Survey of OH Masers at 1665 and 1667 MHz. I. Galactic Longitudes 326° to 40°

Cited by 58 publications

References 3 publications

Galactic Plane H2O Masers: A Southern Survey

Galactic Plane H2O Masers: A Southern Survey

Physical Characteristics of G331.5-0.1: The Luminous Central Region of a Giant Molecular Cloud

Survey of OH Masers at 1665 MHz. III. Galactic Longitudes 233° to 326°

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