The RMS survey

Urquhart, J. S.; Hoare, M. G.; Purcell, Cormac; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Busfield, A. L.; Mottram, J. C.; Davies, Ben

doi:10.1051/0004-6361/200912108

Cited by 157 publications

(188 citation statements)

References 31 publications

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“…Leaf 16 is a confirmed HII region (Urquhart et al 2009), and its associated v lsr of 31.3 km s −1 is consistent with that measured in the IRDC. In R12, this diffuse source did not meet our PSFfitting criteria, thus its SED was not fit.…”

Section: Individual Sourcessupporting

confidence: 77%

“…Interestingly, the prominent absorption feature to the northeast, which strongly emits in NH 3 (1,1) and (2,2) (known tracers of cold, dense gas, Ragan et al 2011) is not recovered in SABOCA emission. Leaf 16 is a confirmed HII region (Urquhart et al 2009), and its associated v lsr of 31.3 km s −1 is consistent with that measured in the IRDC. In R12, this diffuse source did not meet our PSFfitting criteria, thus its SED was not fit.…”

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confidence: 77%

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APEX/SABOCA observations of small-scale structure of infrared-dark clouds

Ragan

Henning

Beuther

2013

A&A

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Infrared-dark clouds (IRDCs) harbor the early phases of cluster and high-mass star formation and are comprised of cold (∼20 K), dense (n > 10 4 cm −3 ) gas. The spectral energy distribution (SED) of IRDCs is dominated by the far-infrared and millimeter wavelength regime, and our initial Herschel study examined IRDCs at the peak of the SED with high angular resolution. Here we present a follow-up study using the SABOCA instrument on APEX which delivers 7.8 angular resolution at 350 µm, matching the resolution we achieved with Herschel/PACS, and allowing us to characterize substructure on ∼0.1 pc scales. Our sample of 11 nearby IRDCs are a mix of filamentary and clumpy morphologies, and the filamentary clouds show significant hierarchical structure, while the clumpy IRDCs exhibit little hierarchical structure. All IRDCs, regardless of morphology, have about 14% of their total mass in small scale core-like structures which roughly follow a trend of constant volume density over all size scales. Out of the 89 protostellar cores we identified in this sample with Herschel, we recover 40 of the brightest and re-fit their SEDs and find their properties agree fairly well with our previous estimates ( T ∼ 19 K). We detect a new population of "cold cores" which have no 70 µm counterpart, but are 100 and 160 µm-bright, with colder temperatures ( T ∼ 16 K). This latter population, along with SABOCA-only detections, are predominantly low-mass objects, but their evolutionary diagnostics are consistent with the earliest starless or prestellar phase of cores in IRDCs.Key words. catalogs -stars: formation -ISM: structure -submillimeter: ISM Background and motivationDespite the importance of high-mass stars to the energy budget of galaxies, their formation remains a major open question in astronomy (Zinnecker & Yorke 2007). A major hindrance to progress is the inherent difficulty in obtaining well-defined initial conditions observationally. Because high-mass stars are rare, they are on average at large distances, thus angular resolution is of paramount importance. With the advent of Spitzer Space Telescope and Herschel Space Observatory (Pilbratt et al. 2010), coupled with extensive ground-based survey efforts, we now can approach this observational task statistically.Ever since their discovery in absorption in mid-infrared Galactic plane surveys, ISO data (Perault et al. 1996) and MSX observations (Egan et al. 1998), infrared-dark clouds (IRDCs) have been subject to intense study because they are the cold (T < 20 K), dense (n > 10 4 cm −3 ) environments believed to be required for the formation of high-mass stars and clusters (cf. Rathborne et al. 2006;Ragan et al. 2009;Battersby et al. 2010). They are located throughout the Galactic plane, concentrated within the spiral arms (Jackson et al. 2008). The formation of IRDCs, their kinematic structure and population of Based on observations carried out with the Atacama Pathfinder Experiment (APEX). APEX is a collaboration between Max Planck Institut für Radioastronomie (MPIf...

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Section: Individual Sourcessupporting

confidence: 77%

supporting

confidence: 77%

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

Ragan

Henning

Beuther

2013

A&A

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“…It was the discovery of a methanol maser source at the centre of CBJC-8 by Pestalozzi et al (2005) that provided firm evidence of its young age and high mass. This was further strengthened by associations with a compact HII region and CO and ammonia clouds that were discovered later (Urquhart et al 2008a(Urquhart et al , 2009). The range of kinematic distances to these line-emitting sources led us to adopt a heliocentric distance of 8 kpc to this young complex, placing it in the Perseus arm.…”

Section: Source Counts and Infrared Colour-colour Diagramsmentioning

confidence: 89%

“…A byproduct of their extinction-mapping method, based on comparing K-band star counts and (H − K) colour-index distributions, was to locate even quite faint embedded clusters in a very efficient way. Among these, CBJC 8 stands out for containing a 6.7 GHz methanol maser close to its centre, found and catalogued as G85.40-0.00 by Pestalozzi et al (2005) and an associated radio HII region, G085.4102+00.0032 (Urquhart et al 2009). The cluster lies in a region of the northern NAPN complex, away from the line of sight of highest obscuration.…”

Section: Introductionmentioning

confidence: 99%

The distant young embedded stellar cluster CBJC 8 associated with G085.40-0.00

Persi

Tapia

Gómez

2010

A&A

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Context. The infrared cluster CBJC 8 is associated with a 6.7 GHz methanol maser and a compact radio-continuum source, G85.40-0.00. It is located at a distance of about 8 kpc.Aims. The aim is to study the characteristics of this distant and compact embedded cluster and derive the properties of its stellar population. Methods. We present new ground-based near-and mid-infrared imaging observations of this region. The calibrated images were analysed together with archive Spitzer IRAC images. Results. Based on the discovery of a considerable fraction of embedded sources with infrared excess emission that are concentrated within a radius around 16 centred near the position of the compact HII region G85.40-0.00, we were able to confirm the presence of a very young embedded cluster. It was found to contain more than 58 members brighter than M K = 2.6, two-thirds of which showing significant near-or mid-IR excess emission. We present spectral energy distributions and extrapolated total luminosities for nine sources with large mid-infrared excesses that were measured in all four IRAC bands. For the brightest of these, G8540A, which is associated with a methanol maser and a compact HII region, we fitted a model of an infalling envelope plus disc plus central star to its observed 1.6 to 850 μm fluxes to get an idea of its physical properties. We also report a single 2.12 μm molecular hydrogen line emission knot near the centre of the cluster, which support the idea about an outflow activity.

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“…We have used arcsecond resolution mid-infrared imaging from the Spitzer GLIMPSE survey (Benjamin et al 2003) or our own ground-based imaging (e.g., Mottram et al 2007) to reveal multiple and/or extended sources within the MSX beam, as well as MYSOs in close proximity to existing HII regions. We have obtained arcsecond resolution radio continuum data with ATCA and the VLA (Urquhart et al 2007a(Urquhart et al , 2009) to identify UCHII regions and PNe, whilst observations of 13 CO transitions (Urquhart et al 2007b(Urquhart et al , 2008a) deliver kinematic velocities. Finally we have obtained near-infrared spectroscopy (e.g., Clarke et al 2006) which allows us to identify the more pathological evolved stars.…”

Section: Introductionmentioning

confidence: 99%

The RMS survey

Urquhart

Hoare

Lumsden

et al. 2009

A&A

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Context. The red MSX source (RMS) survey has identified a large sample of candidate massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ∼2000 MSX and 2MASS colour selected sources. Aims. To search for H 2 O masers towards a large sample of young high mass stars and to investigate the statistical correlation of H 2 O masers with the earliest stages of massive star formation. Methods. We have used the Mopra Radio telescope to make position-switched observations towards ∼500 UCHII regions and MYSOs candidates identified from the RMS survey and located between 190 • < l < 30 • . These observations have a 4σ sensitivity of ∼1 Jy and a velocity resolution of ∼0.4 km s −1 . Results. We have detected 161 H 2 O masers, approximately 75% of which were previously unknown. Comparing the maser velocities with the velocities of the RMS sources, determined from 13 CO observations, we have identified 135 RMS-H 2 O maser associations, which corresponds to a detection rate of ∼27%. Taking into account the differences in sensitivity and source selection we find our detection rate is in general agreement with previously reported surveys. Conclusions. We find similar detection rates for UCHII regions and MYSOs candidates, suggesting that the conditions needed for maser activity are equally likely in these two stages of the star formation process. Looking at the detection rate as a function of distance from the Galactic centre we find it significantly enhanced within the solar circle, peaking at ∼37% between 6-7 kpc, which is consistent with previous surveys of UC HII regions, possibly indicating the presence of a high proportion of more luminous YSOs and HII regions.

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The RMS survey

Cited by 157 publications

References 31 publications

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

The distant young embedded stellar cluster CBJC 8 associated with G085.40-0.00

The RMS survey

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