ATLASGAL – properties of compact H ii regions and their natal clumps★

Urquhart, J. S.; Thompson, M. A.; Moore, T. J. T.; Purcell, Cormac; Hoare, M. G.; Schüller, F.; Wyrowski, F.; Csengeri, T.; Menten, K. M.; Lumsden, S. L.; Kurtz, S.; Walmsley, C. M.; Bronfman, L.; Morgan, L. K.; Eden, David; Russeil, D.

doi:10.1093/mnras/stt1310

Cited by 127 publications

(99 citation statements)

References 135 publications

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“…The distribution of the whole sample ( Fig. 3a) peaks close to b = 0 and this is consistent with the fact that the faster-evolving higher-mass MYSOs (and OB stars) have a small scale height above the Plane (∼20-30 pc in the inner Galaxy: Reed 2000; Urquhart et al 2013, which is 0.2-0.3 degrees at a median distance of ∼6 kpc). The pattern inside | | < 40 • (Fig.…”

Section: Global Trends In Milky Way Star Formationsupporting

confidence: 79%

The role of spiral arms in Milky Way star formation

Ragan

Moore

Eden

et al. 2018

Monthly Notices of the Royal Astronomical Society

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What role does Galactic structure play in star formation? We have used the Herschel Hi-GAL compact-clump catalogue to examine trends in evolutionary stage over large spatial scales in the inner Galaxy. We examine the relationship between the fraction of clumps with embedded star formation (the star-forming fraction, or SFF) and other measures of star-formation activity. Based on a positive correlation between SFF and evolutionary indicators such as the luminosity-to-mass ratio, we assert that the SFF principally traces the average evolutionary state of a sample and must depend on the local fraction of rapidly-evolving, high-mass young stellar objects. The spiralarm tangent point longitudes show small excesses in the SFF, though these can be accounted for by a small number of the most massive clusters, just 7.6% of the total number of clumps in the catalogue. This suggests that while the arms tend to be home to the Galaxy's massive clusters, the remaining 92.4% of Hi-GAL clumps in our catalogue do not show an enhancement of star formation within arms. Globally, the SFF is highest at the Galactic midplane and inner longitudes. We find no significant trend in evolutionary stage as a function of position across spiral arms at the tangentpoint longitudes. This indicates that the angular offset observed between gas and stars, if coordinated by a density wave, is not evident at the clump phase; alternatively, the onset of star formation is not triggered by the spiral density wave.

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Section: Global Trends In Milky Way Star Formationsupporting

confidence: 79%

The role of spiral arms in Milky Way star formation

Ragan

Moore

Eden

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The sources are closely confined to the Galactic plane, as expected for very young massive star forming regions. Using the CORNISH survey, Urquhart et al (2013) fit a scale-height of 20.7 ± 1.7 pc for compact and ultra-compact H II regions. The majority of the ultra-compact H II regions have angular sizes below 5 , with the histogram peaking towards unresolved sources.…”

Section: Radio Properties Of the Cornish Uchiismentioning

confidence: 99%

The coordinated radio and infrared survey for high-mass star formation

Kalcheva

Hoare

Urquhart

et al. 2018

A&A

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A catalogue of 239 ultra-compact H II regions (UCHIIs) found in the CORNISH survey at 5 GHz and 1.5 resolution in the region 10 • < l < 65 • , |b| < 1 • is presented. This is the largest complete and well-selected sample of UCHIIs to date and provides the opportunity to explore the global and individual properties of this key state in massive star formation at multiple wavelengths. The nature of the candidates was validated, based on observational properties and calculated spectral indices, and the analysis is presented in this work. The physical sizes, luminosities and other physical properties were computed by utilising literature distances or calculating the distances whenever a value was not available. The near-and mid-infrared extended source fluxes were measured and the extinctions towards the UCHIIs were computed. The new results were combined with available data at longer wavelengths and the spectral energy distributions (SEDs) were reconstructed for 177 UCHIIs. The bolometric luminosities obtained from SED fitting are presented. By comparing the radio flux densities to previous observational epochs, we find about 5% of the sources appear to be time variable. This first high-resolution area survey of the Galactic plane shows that the total number of UCHIIs in the Galaxy is ∼ 750 -a factor of 3-4 fewer than found in previous large area radio surveys. It will form the basis for future tests of models of massive star formation.

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“…Two of the earliest stages in the formation of OB stars are massive young stellar objects (MYSOs) (Lumsden et al 2013) and the compact HII regions (Wood & Churchwell 1989;Kurtz et al 1994;Urquhart et al 2013b). During the MYSO stage the newly-formed protostar begins to heat up its envelope and becomes detectable at mid-infrared wavelengths.…”

Section: Introductionmentioning

confidence: 99%

The RMS survey: Ammonia mapping of the environment of young massive stellar objects – II★

Billington

Urquhart

Figura

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present the results from NH 3 mapping observations towards 34 regions identified by the Red MSX Source (RMS) survey. We have used the Australia Telescope Compact Array to map ammonia (1,1) and (2,2) inversion emission spectra at a resolution of 10 with velocity channel resolution of 0.4 km s −1 towards the positions of embedded massive star formation. Complementary data have been used from the ATLASGAL and GLIMPSE Legacy Surveys in order to improve the understanding of the regions and to estimate physical parameters for the environments. The fields have typical masses of ∼1000 M , radii of ∼0.15 pc and distances of ∼3.5 kpc. Luminosities range between ∼10 3 to ∼10 6 L and kinetic temperatures between 10 and 40 K. We classify each field into one of two subsets in order to construct an evolutionary system for massive star formation in these regions based on the morphology and relative positions of the NH 3 emission, RMS sources and ATLASGAL thermal dust emission. Differences in morphology between NH 3 emission and ATLASGAL clumps are shown to correspond to evolutionary stages of ongoing massive star formation in these regions. The study has been further refined by including the positions of known methanol and water masers in the regions to gain insight into possible protostellar regions and triggered star formation.

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ATLASGAL – properties of compact H ii regions and their natal clumps★

Cited by 127 publications

References 135 publications

The role of spiral arms in Milky Way star formation

The role of spiral arms in Milky Way star formation

The coordinated radio and infrared survey for high-mass star formation

The RMS survey: Ammonia mapping of the environment of young massive stellar objects – II★

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