The molecular environment of the Galactic star forming region G19.61–0.23

Santangelo, G.; Testi, L.; Leurini, S.; Walmsley, C. M.; Cesaroni, R.; Bronfman, L.; Carey, Sean; Gregorini, L.; Menten, K. M.; Molinari, S.; Noriega-Crespo, A.; Olmi, L.; Schüller, F.

doi:10.1051/0004-6361/201014177

Cited by 3 publications

(3 citation statements)

References 70 publications

(109 reference statements)

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“…In fact, this cloud is the only in our sample that is experiencing a merger/collision at this particular timeframe, where a long filamentary cloud, v /R), as a function of gas surface density Σ for all resolved GMCs extracted from the H 2 densities as circles (grey being inter-arm clouds, and black being arm clouds). The light-green triangles are a compilation of Galactic GMCs, while the dark-green star symbols are GMCs from extragalactic studies (from Rosolowsky et al 2003;Rosolowsky 2007;Bolatto et al 2008;Heyer et al 2009;Rathborne et al 2009;Santangelo et al 2010;Wong et al 2011;Swinbank et al 2011;Ginsburg et al 2012;Wei et al 2012;Giannetti et al 2013;Battersby et al 2014;Colombo et al 2014;Walker et al 2015). The dashed curves show the expected force balance (kinetic, gravitational and external pressure), for different values of external pressure, from P = 1 to 100 M pc −3 km 2 s −2 (which corresponds to P/k ∼ 5 × 10 3 − 5 × 10 5 K cm −3 ).…”

Section: High Velocity Dispersion Cloudsmentioning

confidence: 99%

What can simulated molecular clouds tell us about real molecular clouds?

Duarte-Cabral

Dobbs

2016

Mon. Not. R. Astron. Soc.

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We study the properties of giant molecular clouds (GMCs) from a smoothed particle hydrodynamics simulation of a portion of a spiral galaxy, modelled at high resolution, with robust representations of the physics of the interstellar medium. We examine the global molecular gas content of clouds, and investigate the effect of using CO or H 2 densities to define the GMCs. We find that CO can reliably trace the high-density H 2 gas, but misses less dense H 2 clouds. We also investigate the effect of using 3D CO densities versus CO emission with an observer's perspective, and find that CO-emission clouds trace well the peaks of the actual GMCs in 3D, but can miss the lower density molecular gas between density peaks which is often CO-dark. Thus the CO emission typically traces smaller clouds within larger GMC complexes. We also investigate the effect of the galactic environment (in particular the presence of spiral arms), on the distribution of GMC properties, and we find that the mean properties are similar between arm and inter-arm clouds, but the tails of some distributions are indicative of intrinsic differences in the environment. We find highly filamentary clouds (similar to the giant molecular filaments of our Galaxy) exclusively in the inter-arm region, formed by galactic shear. We also find that the most massive GMC complexes are located in the arm, and that as a consequence of more frequent cloud interactions/mergers in the arm, arm clouds are more sub-structured and have higher velocity dispersions than inter-arm clouds.

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Section: High Velocity Dispersion Cloudsmentioning

confidence: 99%

What can simulated molecular clouds tell us about real molecular clouds?

Duarte-Cabral

Dobbs

2016

Mon. Not. R. Astron. Soc.

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“…G19.61−0.23 is a well-known region of high-mass star formation in the Galaxy, containing OH (Caswell & Haynes 1983) and CH 3 OH masers (Caswell et al 1995;Walsh et al 1998), including the rare 9.9 GHz CH 3 OH maser (Voronkov et al 2010), cold dust continuum emission (Walsh et al 2003;Thompson et al 2006), molecular line emission (Santangelo et al 2010) and multiple ultracompact (UC) H II regions (Garay et al 1998). Kolpak et al (2003) determined a distance to G19.61−0.23 of 12.3 kpc, based on HI observations.…”

Section: Nhmentioning

confidence: 99%

The H2O Southern Galactic Plane Survey (HOPS) - I. Techniques and H2O maser data

Walsh¹,

Breen²,

Britton³

et al. 2011

Monthly Notices of the Royal Astronomical Society

192

208

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We present first results of the H2O Southern Galactic Plane Survey (HOPS), using the Mopra Radio Telescope with a broad‐band backend and a beam size of about 2 arcmin. We have observed 100 deg2 of the southern Galactic plane at 12 mm (19.5–27.5 GHz), including spectral line emission from H2O masers, multiple metastable transitions of ammonia, cyanoacetylene, methanol and radio recombination lines. In this paper, we report on the characteristics of the survey and H2O maser emission. We find 540 H2O masers, of which 334 are new detections. The strongest maser is 3933 Jy and the weakest is 0.7 Jy, with 62 masers over 100 Jy. In 14 maser sites, the spread in the velocity of the H2O maser emission exceeds 100 km s−1. In one region, the H2O maser velocities are separated by 351.3 km s−1. The rms noise levels are typically between 1 and 2 Jy, with 95 per cent of the survey under 2 Jy. We estimate completeness limits of 98 per cent at around 8.4 Jy and 50 per cent at around 5.5 Jy. We estimate that there are between 800 and 1500 H2O masers in the Galaxy that are detectable in a survey with similar completeness limits to HOPS. We report possible masers in NH3 (11,9) and (8,6) emission towards G19.61−0.23 and in the NH3 (3,3) line towards G23.33−0.30.

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“…5.3 for details). For comparison, the density of points in this plot from a compilation of extragalactic cloud samples (from Rosolowsky et al 2003;Rosolowsky 2007;Bolatto et al 2008;Santangelo et al 2010;Wong et al 2011;Wei et al 2012;Colombo et al 2014) and a compilation of Galactic cloud samples (from Heyer et al 2009;Rathborne et al 2009;Wang et al 2009;Ginsburg et al 2012;Giannetti et al 2013;Battersby et al 2014;Walker et al 2015) are shown with blue contours, and with blue colour shading, respectively. The green dotted curves show the expected force balance between kinetic, gravitational and external pressure, for different values of external pressure, from P = 1 to 100 M pc −3 km 2 s −2 (which corresponds to P/k ∼ 5 × 10 3 − 5 × 10 5 K cm −3 ).…”

Section: Propertymentioning

confidence: 99%

SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium

Schüller

Csengeri

Urquhart

et al. 2017

A&A

Self Cite

103

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Context. The origin and life-cycle of molecular clouds are still poorly constrained, despite their importance for understanding the evolution of the interstellar medium. Many large-scale surveys of the Galactic plane have been conducted recently, allowing for rapid progress in this field. Nevertheless, a sub-arcminute resolution global view of the large-scale distribution of molecular gas, from the diffuse medium to dense clouds and clumps, and of their relationship to the spiral structure, is still missing. Aims. We have carried out a systematic, homogeneous, spectroscopic survey of the inner Galactic plane, in order to complement the many continuum Galactic surveys available with crucial distance and gas-kinematic information. Our aim is to combine this data set with recent infrared to sub-millimetre surveys at similar angular resolutions. Methods. The SEDIGISM survey covers 78 deg 2 of the inner Galaxy (−60CO. This isotopologue of CO is less abundant than 12 CO by factors up to 100. Therefore, its emission has low to moderate optical depths, and higher critical density, making it an ideal tracer of the cold, dense interstellar medium. The data have been observed with the SHFI single-pixel instrument at APEX. The observational setup covers the 13 CO(2 -1) and C 18 O(2 -1) lines, plus several transitions from other molecules. Results. The observations have been completed. Data reduction is in progress, and the final data products will be made available in the near future. Here we give a detailed description of the survey and the dedicated data reduction pipeline. To illustrate the scientific potential of this survey, preliminary results based on a science demonstration field covering −20 • ≤ ≤ -18.5 • are presented. Analysis of the 13 CO(2 -1) data in this field reveals compact clumps, diffuse clouds, and filamentary structures at a range of heliocentric distances. By combining our data with data in the (1-0) transition of CO isotopologues from the ThrUMMS survey, we are able to compute a 3D realization of the excitation temperature and optical depth in the interstellar medium. Ultimately, this survey will provide a detailed, global view of the inner Galactic interstellar medium at an unprecedented angular resolution of ∼30 .

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The molecular environment of the Galactic star forming region G19.61–0.23

Cited by 3 publications

References 70 publications

What can simulated molecular clouds tell us about real molecular clouds?

What can simulated molecular clouds tell us about real molecular clouds?

The H2O Southern Galactic Plane Survey (HOPS) - I. Techniques and H2O maser data

SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium

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