A distance-limited sample of massive star-forming cores from the RMS survey

Maud, L. T.; Lumsden, S. L.; Moore, T. J. T.; Mottram, J. C.; Urquhart, J. S.; Cicchini, A.

doi:10.1093/mnras/stv1334

Cited by 35 publications

(28 citation statements)

References 79 publications

(129 reference statements)

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“…Previous observations of NH 3 (Wouterloot et al 1988;Myers et al 1991;Harju et al 1993;Ladd et al 1994;Molinari et al 1996;Jijina et al 1999;Wu et al 2006;Urquhart et al 2011Urquhart et al , 2015, C 18 O (Saito et al 2001;Ridge et al 2003;Maud et al 2015), and 13 CO (Wang et al 2009;Lundquist et al 2015) suggest that the line width is correlated with luminosity, which indicates the presence of a link between formed stars and velocity dispersion. We investigate the line width-luminosity relation in the case of the dense gas tracer H 2 CO. We plot the line width-luminosity relation in Figure 9.…”

Section: Line Width-luminosity Relationmentioning

confidence: 89%

ATLASGAL-selected massive clumps in the inner Galaxy

Tang

Henkel

Wyrowski

et al. 2018

A&A

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Context. Formaldehyde (H 2 CO) is a reliable tracer to accurately measure the physical parameters of dense gas in star-forming regions. Aims. We aim to determine directly the kinetic temperature and spatial density with formaldehyde for the ∼100 brightest ATLASGALselected clumps (the TOP100 sample) at 870 µm representing various evolutionary stages of high-mass star formation. Methods. Ten transitions (J = 3-2 and 4-3) of ortho-and para-H 2 CO near 211, 218, 225, and 291 GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12 m telescope. Results. Using non-LTE models with RADEX, we derived the gas kinetic temperature and spatial density with the measured para-H 2 CO 3 21 -2 20 /3 03 -2 02 , 4 22 -3 21 /4 04 -3 03 , and 4 04 -3 03 /3 03 -2 02 ratios. The gas kinetic temperatures derived from the para-H 2 CO 3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 line ratios are high, ranging from 43 to >300 K with an unweighted average of 91 ± 4 K. Deduced T kin values from the J = 3-2 and 4-3 transitions are similar. Spatial densities of the gas derived from the para-H 2 CO 4 04 -3 03 /3 03 -2 02 line ratios yield 0.6-8.3 × 10 6 cm −3 with an unweighted average of 1.5 (±0.1) × 10 6 cm −3 . A comparison of kinetic temperatures derived from para-H 2 CO, NH 3 , and dust emission indicates that para-H 2 CO traces a distinctly higher temperature than the NH 3 (2,2)/(1,1) transitions and the dust, tracing heated gas more directly associated with the star formation process. The H 2 CO line widths are found to be correlated with bolometric luminosity and increase with the evolutionary stage of the clumps, which suggests that higher luminosities tend to be associated with a more turbulent molecular medium. It seems that the spatial densities measured with H 2 CO do not vary significantly with the evolutionary stage of the clumps. However, averaged gas kinetic temperatures derived from H 2 CO increase with time through the evolution of the clumps. The high temperature of the gas traced by H 2 CO may be mainly caused by radiation from embedded young massive stars and the interaction of outflows with the ambient medium. For L bol /M clump 10 L ⊙ /M ⊙ , we find a rough correlation between gas kinetic temperature and this ratio, which is indicative of the evolutionary stage of the individual clumps. The strong relationship between H 2 CO line luminosities and clump masses is apparently linear during the late evolutionary stages of the clumps, indicating that L H 2 CO does reliably trace the mass of warm dense molecular gas. In our massive clumps H 2 CO line luminosities are approximately linearly correlated with bolometric luminosities over about four orders of magnitude in L bol , which suggests that the mass of dense molecular gas traced by the H 2 CO line luminosity is well correlated with star formation.

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Section: Line Width-luminosity Relationmentioning

confidence: 89%

ATLASGAL-selected massive clumps in the inner Galaxy

Tang

Henkel

Wyrowski

et al. 2018

A&A

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“…Finally, we note that a priori the mass estimate can be affected by significant errors (a factor of ∼2; see Maud et al 2015a), mostly due to the uncertainties on κ dust and T dust . However, the latter is unlikely to vary more than T c [160−70], namely ∼40%, while the former should not change much from source to source because the selected sample is relatively homogeneous.…”

Section: Target Selection and Characterizationmentioning

confidence: 98%

Chasing discs around O-type (proto)stars: Evidence from ALMA observations

Cesaroni

Sánchez-Monge

Beltrán

et al. 2017

A&A

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Context. Circumstellar discs around massive stars could mediate the accretion onto the star from the infalling envelope, and could minimize the effects of radiation pressure. Despite such a crucial role, only a few convincing candidates have been provided for discs around deeply embedded O-type (proto)stars. Aims. In order to establish whether disc-mediated accretion is the formation mechanism for the most massive stars, we have searched for circumstellar, rotating discs around a limited sample of six luminous (>10 5 L ) young stellar objects. These objects were selected on the basis of their IR and radio properties in order to maximize the likelihood of association with disc+jet systems. Methods. We used ALMA with ∼0 . 2 resolution to observe a large number of molecular lines typical of hot molecular cores. In this paper we limit our analysis to two disc tracers (methyl cyanide, CH 3 CN, and its isotopologue, 13 CH 3 CN), and an outflow tracer (silicon monoxide, SiO). Results. We reveal many cores, although their number depends dramatically on the target. We focus on the cores that present prominent molecular line emission. In six of these a velocity gradient is seen across the core, three of which show evidence of Keplerian-like rotation. The SiO data reveal clear but poorly collimated bipolar outflow signatures towards two objects only. This can be explained if real jets are rare (perhaps short-lived) in very massive objects and/or if stellar multiplicity significantly affects the outflow structure. For all cores with velocity gradients, the velocity field is analysed through position-velocity plots to establish whether the gas is undergoing rotation with rot ∝ R −α , as expected for Keplerian-like discs. Conclusions. Our results suggest that in three objects we are observing rotation in circumstellar discs, with three more tentative cases, and one core where no evidence for rotation is found. In all cases but one, we find that the gas mass is less than the mass of any embedded O-type star, consistent with the (putative) discs undergoing Keplerian-like rotation. With the caveat of low number statistics, we conclude that the disc detection rate could be sensitive to the evolutionary stage of the young stellar object. In young, deeply embedded sources, the evidence for discs could be weak because of confusion with the surrounding envelope, while in the most evolved sources the molecular component of the disc could have already been dispersed. Only in those objects that are at an intermediate stage of the evolution would the molecular disc be sufficiently prominent and relatively less embedded to be detectable by mm/submm observations.

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“…Compared with their results, the AGAL337.9 outflow have properties typical to the previously known massive outflows in the Milky Way; the M flow of the AGAL337.9 outflow can be plotted in the middle of the scatter of the sample distribution (see the left-top panel of Figure 5 in Maud et al 2015b), while P flow and E flow are seen around the upper ends of the scatters in the same source luminosity, although they are still within the scatters (see the right-top and left-center panels). Maud et al (2015a) also built a correlation between M core and M flow (see their Figure 9), and the AGAL337.9-S outflow can be plotted within their scatter and appears to follow its linear scaling.…”

Section: Comparisons With Other Massive Molecular Outflows and Massivmentioning

confidence: 99%

“…The driving source, AGAL337.9-S, has a total far-infrared luminosity of 0.5 × 10 4 L ⊙ . Recently, Maud et al (2015a) and Maud et al (2015b) conducted statistical studies of massive YSOs and massive outflows based on the CO J=3-2 observations of a relatively unbiased mid-infrared bright sample covering total source luminosities L src from 10 3 L ⊙ to ∼10 5 L ⊙ . As shown in Figure 5 in Maud et al (2015b), the authors found linear correlations between the outflow parameters and L src , which can be scaled to those of the low-mass sources.…”

Section: Comparisons With Other Massive Molecular Outflows and Massivmentioning

confidence: 99%

A Massive Molecular Outflow in the Dense Dust Core AGAL G337.916-00.477

Torii

Hattori

Hasegawa

et al. 2017

ApJ

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Massive molecular outflows erupting from high-mass young stellar objects provide important clues to understanding the mechanism of high-mass star formation. Based on new CO J=3-2 and J=1-0 observations using the Atacama Submillimeter Telescope Experiment (ASTE) and Mopra telescope facilities, we discovered a massive bipolar outflow associated with the dense dust core AGAL G337.916-00.477 (AGAL337.9-S), located 3.48 kpc from the Sun. The outflow lobes have extensions of less than 1 pc-and thus were not fully resolved in the angular resolutions of ASTE and Mopra-and masses of 35 -40 M ⊙ . The maximum velocities of the outflow lobes are as high as 35 -40 km s −1 . Our analysis of the infrared and sub-mm data indicates that AGAL337.9-S is in an early evolutionary stage of the high-mass star formation, having the total far-infrared luminosity of ∼ 5 × 10 4 L ⊙ . We also found that another dust core AGAL G337.922-00.456 (AGAL337.9-N) located 2 ′ north of AGAL337.9-S is a high-mass young stellar object in an earlier evolutional stage than AGAL337.9-S, although it is less bright in the mid-infrared than AGAL337.9-S.

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A distance-limited sample of massive star-forming cores from the RMS survey

Cited by 35 publications

References 79 publications

ATLASGAL-selected massive clumps in the inner Galaxy

ATLASGAL-selected massive clumps in the inner Galaxy

Chasing discs around O-type (proto)stars: Evidence from ALMA observations

A Massive Molecular Outflow in the Dense Dust Core AGAL G337.916-00.477

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