Accurate Oh Maser Positions From the Splash Pilot Region

Qiao, Hai-Hua; Walsh, A. J.; Green, James; Breen, S. L.; Dawson, J. R.; Ellingsen, S. P.; Gómez, José F.; Jordan, C.; Shen, Zhi-Qiang; Lowe, Vicki; Jones, P. A.

doi:10.3847/1538-4365/227/2/26

Cited by 22 publications

(51 citation statements)

References 56 publications

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“…In addition to the ex-OH masers, the associations between SPLASH ground state OH maser sites and MMB masers performed by Qiao et al (2016) and Qiao et al (2018) are also used to separate the methanol maser sample into those with and without an association. Only the 143 clumps within the two SPLASH regions of 334 • < l < 344 • and −5 • < l < 5 • through the Galactic centre are considered, giving a 31 masers associated with a ground-state OH transition and 112 without.…”

Section: Hydroxyl Masersmentioning

confidence: 99%

The evolutionary status of protostellar clumps hosting class II methanol masers

Jones

Fuller

Breen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7 GHz class II methanol masers. We characterise the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73%) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of a MYSO to host a 6.7 GHz maser. The median far-infrared (FIR) mass and luminosity are 630 M and 2500 L for sources on the near side of Galactic centre and 3200 M and 10000 L for more distant sources. The median luminosity-to-mass ratio is similar for both at ∼4.2 L / M . We identify an apparent minimum 70 µm luminosity required to sustain a methanol maser of a given luminosity (with L 70 ∝ L 6.7 0.6 ). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70 µm flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7 GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources.

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Section: Hydroxyl Masersmentioning

confidence: 99%

The evolutionary status of protostellar clumps hosting class II methanol masers

Jones

Fuller

Breen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Unbiased surveys of the most abundant of these OH masers, the 1612 MHz transition, have been conducted in the southern and northern hemisphere with the Australia Telescope Compact Array (ATCA) and the Very Large Array (VLA) by Sevenster et al (1997aSevenster et al ( ,b, 2001. Furthermore, Dawson et al (2014) and Qiao et al (2016) used the Parkes single-dish telescope to survey all four OH maser transitions in the southern hemisphere. While the VLA and ATCA studies only covered a single maser transition at moderate sensitivity, the Parkes survey covers only parts of the southern hemisphere.…”

Section: Introductionmentioning

confidence: 99%

OH maser emission in the THOR survey of the northern Milky Way

Beuther

Walsh

Wang

et al. 2019

A&A

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Context. OH masers trace diverse physical processes, from the expanding envelopes around evolved stars to star-forming regions or supernovae remnants. Providing a survey of the ground-state OH maser transitions in the northern hemisphere inner Milky Way facilitates the study of a broad range of scientific topics. Aims. We want to identify the ground-state OH masers at ∼18 cm wavelength in the area covered by "The HI/OH/Recombination line survey of the Milky Way (THOR)". We will present a catalogue of all OH maser features and their possible associated environments. Methods. The THOR survey covers longitude and latitude ranges of 14. • 3 < l < 66. • 8 and b < ±1. • 25. All OH ground state lines 2 Π 3/2 (J=3/2) at 1612 (F=1-2), 1665 (F=1-1), 1667 (F=2-2) and 1720 MHz (F=2-1) have been observed, employing the Very Large Array (VLA) in its C configuration. The spatial resolution of the data varies between 12.5 and 19 , the spectral resolution is 1.5 km s −1 , and the rms sensitivity of the data is ∼10 mJy beam −1 per channel. Results. We identify 1585 individual maser spots (corresponding to single spectral features) distributed over 807 maser sites (regions of size ∼ 10 3 − 10 4 AU). Based on different criteria from spectral profiles to literature comparison, we try to associate the maser sites with astrophysical source types. Approximately 51% of the sites exhibit the double-horned 1612 MHz spectra typically emitted from the expanding shells of evolved stars. The separations of the two main velocity features of the expanding shells typically vary between 22 and 38 km s −1 . In addition to this, at least 20% of the maser sites are associated with star-forming regions. While the largest fraction of 1720 MHz maser spots (21 out of 53) is associated with supernova remnants, a significant fraction of the 1720 MHz maser spots (17) are also associated with star-forming regions. We present comparisons to the thermal 13 CO(1-0) emission as well as to other surveys of class II CH 3 OH and H 2 O maser emission. The catalogue attempts to present associations to astrophysical sources where available, and the full catalogue is available in electronic form.Conclusions. This OH maser catalogue presents a unique resource of stellar and interstellar masers in the northern hemisphere. It provides the basis for a diverse range of follow-up studies from envelopes around evolved stars to star-forming regions and Supernova remnants.

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“…As detailed in Qiao et al (2016a), maser spots have been grouped into maser sites based on their separations. The discussion of the size of maser sites is detailed in Section 4.2.…”

Section: Overall Summarymentioning

confidence: 99%

“…A detailed account of the data reduction procedure is given in Qiao et al (2016a). Once fully calibrated image cubes were created, they were searched for maser emission by eye (along with peak intensity images, i.e.…”

mentioning

confidence: 99%

“…As detailed in Qiao et al (2016a), the absolute uncertainty in maser positions depends on several factors including the phase noise during the observations, but relative positional uncertainty is less affected, allowing us to compare the relative positions of maser spots within one field of view. The phase noise is related to the distance between the phase calibrator and the target region, the accuracy of the known locations of the phase calibrators, the locations of the antennas, as well as the atmospheric conditions, thus it is hard to determine precisely.…”

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confidence: 99%

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Accurate OH Maser Positions. II. The Galactic Center Region

Qiao

Walsh

Breen

et al. 2018

ApJS

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We present high spatial resolution observations of ground-state OH masers, achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted towards 171 pointing centres, where OH maser candidates were identified previously in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) towards the Galactic Center region, between Galactic longitudes of 355 • and 5 • and Galactic latitudes of −2 • and +2 • . We detect maser emission towards 162 target fields and suggest that 6 out of 9 non-detections are due to intrinsic variability. Due to the superior spatial resolution of the follow-up ATCA observations, we have identified 356 OH maser sites in the 162 of the target fields with maser detections. Almost half (161 of 356) of these maser sites have been detected for the first time in these observations. After comparing the positions of these 356 maser sites to the literature, we find that 269 (76%) sites are associated with evolved stars (two of which are planetary nebulae), 31 (9%) are associated with star formation, four are associated with supernova remnants and we were unable to determine the origin of the remaining 52 (15%) sites. Unlike the pilot region (Qiao et al. 2016a), the infrared colors of evolved star sites with symmetric maser profiles in the 1612 MHz transition do not show obvious differences compared with those of evolved star sites with asymmetric maser profiles.

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Accurate Oh Maser Positions From the Splash Pilot Region

Cited by 22 publications

References 56 publications

The evolutionary status of protostellar clumps hosting class II methanol masers

The evolutionary status of protostellar clumps hosting class II methanol masers

OH maser emission in the THOR survey of the northern Milky Way

Accurate OH Maser Positions. II. The Galactic Center Region

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