Accurate water maser positions from HOPS

Walsh, A. J.; Purcell, Cormac; Longmore, Steven N.; Breen, S. L.; Green, James; Harvey-Smith, Lisa; Jordan, C.; Macpherson, Christopher

doi:10.1093/mnras/stu989

Cited by 76 publications

(136 citation statements)

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“…6 shows the distributions of integrated flux densities for the 6.7-and 12.2-GHz methanol masers (these values are not available for either the water masers or the excited-state OH masers) and the overall distributions are similar to that of the peak flux densities. The most striking difference in the distributions is the preponderance of 12.2-GHz methanol masers with low integrated flux densities, dominated by a large number of weak, sin- Caswell et al 2010;Green et al 2010;Caswell et al 2011;Green et al 2012;Breen et al 2015), 12.2-GHz methanol (pink; Breen et al 2012aBreen et al ,b, 2014Breen et al , 2016, water (blue; Walsh et al 2014) and excited-state OH masers (orange; Avison et al 2016), and; (bottom) integrated flux density distribution of the 6.7-GHz methanol (magenta; Breen et al 2015) and 12.2-GHz methanol (pink; Breen et al 2012aBreen et al ,b, 2014Breen et al , 2016.…”

Section: Distribution Of Peak and Integrated Flux Densitiesmentioning

confidence: 99%

“…The fact that the water masers show the largest velocity range is expected, particularly because of their tendency to trace high-velocity outflow, but the median velocity of the HOPS sources is significantly lower than either of the Breen et al (2010b) or Titmarsh et al (2014Titmarsh et al ( , 2016 targeted water maser observations which have medians of 15 and 17 km s −1 , respectively. A part of this difference can be accounted for by the fact that the Walsh et al (2014) quoted peak velocities of spots and therefore results in an underestimation of the velocity ranges of sites, but some of the difference is due to the unbiased nature of HOPS. The fact that the velocity range of the excited-state OH masers exceed the 12.2-GHz methanol masers is perhaps surprising given that 12.2-GHz methanol masers generally have much higher peak flux densities, and suggests that the excited-OH emission is arising from a larger volume of gas than the 12.2-GHz maser emission.…”

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

“…Since Walsh et al (2014) published the peak velocity of each detected maser feature, masers consisting of a single spectral feature have a calculated velocity range of zero. It can be seen in Fig.…”

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

“…Breen et al (2010b) found that water masers with single features, and those that have no 6.7-GHz methanol or OH maser counterpart, are more likely to fall below the detection limit of a sensitive, single-epoch search and so it is likely that this population is particularly underrepresented in the HOPS sample. Walsh et al (2014) presented their water masers as a series of water maser spots. One might expect that the number of water maser spots is closely linked to the velocity range of the maser emission and a comparison of Fig.…”

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

“…Two of the most commonly detected masers in our Galaxy arise from the 6.7-GHz methanol and 22-GHz water transitions (e.g. Breen et al 2015;Walsh et al 2014), followed by a host of other transitions that include the 12.2-GHz methanol maser (e.g. Breen et al 2016) and 6035-MHz excited OH masers (e.g.…”

Section: Introductionmentioning

confidence: 99%

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The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

Breen

Contreras

Ellingsen

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We have compared the occurrence of 6.7-GHz and 12.2-GHz methanol masers with 22-GHz water masers and 6035-MHz excited-state OH masers in the 100 square degree region of the southern Galactic plane common to the Methanol Multibeam (MMB) and H 2 O southern Galactic Plane surveys (HOPS). We find the most populous star formation species to be 6.7-GHz methanol, followed by water, then 12.2-GHz and, finally, excited-state OH masers. We present association statistics, flux density (and luminosity where appropriate) and velocity range distributions across the largest, fully surveyed portion of the Galactic plane for four of the most common types of masers found in the vicinity of star formation regions.Comparison of the occurrence of the four maser types with far-infrared dust temperatures shows that sources exhibiting excited-state OH maser emission are warmer than sources showing any of the other three maser types. We further find that sources exhibiting both 6.7-GHz and 12.2-GHz methanol masers are warmer than sources exhibiting just 6.7-GHz methanol maser emission. These findings are consistent with previously made suggestions that both OH and 12.2-GHz methanol masers generally trace a later stage of star formation compared to other common maser types.

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Section: Distribution Of Peak and Integrated Flux Densitiesmentioning

confidence: 99%

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

Section: Basic Properties Of the Different Maser Populationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

Breen

Contreras

Ellingsen

et al. 2017

Monthly Notices of the Royal Astronomical Society

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A sensitive search for water masers associated with star formation regions in the Local Group Galaxy NGC 6822

Flanagan

Ellingsen

Cole

2022

Publ. Astron. Soc. Aust.

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We report the results of a sensitive search for water maser emission in the Local Group Galaxy NGC 6822 with the Karl G. Jansky Very Large Array. The observations provide tentative single-epoch detections of four candidates, associated with two infrared-bright star formation regions (Hubble I/III and Hubble IV). The candidate maser detections are all offset from the velocity range where strong emission from Hi neutral gas is observed towards NGC 6822, with the closest offset by $\sim\!40\, \mathrm{kms}^{-1}$ . Our observations include the location of NL1K, a previous tentative water maser detection in NGC 6822. We do not detect any emission from this location with a sensitivity limit approximately a factor of 5 better than the original Sardina Radio Telescope observations.

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Molecular gas kinematics of the CMZ: Great oaks from little acorns grow

Henshaw

2016

Proc. IAU

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Abstract. The central molecular zone (CMZ) hosts some of the most massive and dense molecular clouds and star clusters in the Galaxy, offering an important window into star formation under extreme conditions. Star formation in this extreme environment may be closely linked to the 3-D distribution and orbital dynamics of the gas. Here I discuss how our new, accurate description of the {l, b, v} structure of the CMZ is helping to constrain its 3-D geometry. I also present the discovery of a highly-regular, corrugated velocity field located just upstream from the dust ridge molecular clouds (which include G0.253+0.016 and Sgr B2). The extremes in this velocity field correlate with a series of massive (∼ 10 4 M ) cloud condensations. The corrugation wavelength (∼ 23 pc) and cloud separation (∼ 8 pc) closely agree with the predicted Toomre (∼ 17 pc) and Jeans (∼ 6 pc) lengths, respectively. I conclude that gravitational instabilities are driving the formation of molecular clouds within the Galactic Centre gas stream. Furthermore, I suggest that these seeds are the historical analogues of the dust ridge molecular clouds -possible progenitors of some of the most massive and dense molecular clouds in the Galaxy. If our current best understanding for the 3-D geometry of this system is confirmed, these clouds may pinpoint the beginning of an evolutionary sequence that can be followed, in time, from cloud condensation to star formation.

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Accurate water maser positions from HOPS

Abstract: The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

Cited by 76 publications

References 52 publications

The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

The 6-GHz Multibeam Maser Survey – III. Comparison between the MMB and HOPS

A sensitive search for water masers associated with star formation regions in the Local Group Galaxy NGC 6822

Molecular gas kinematics of the CMZ: Great oaks from little acorns grow

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