Infall motions in massive star-forming regions: results from years 1 and 2 of the MALT90 survey

He, Yuxin; Zhou, Jianjun; Esimbek, Jarken; Ji, Wei; Wu, Gang; Tang, Xindi; Yuan, Yé; Li, Da-Lei; Baan, Willem A.

doi:10.1093/mnras/stv732

Cited by 57 publications

(83 citation statements)

References 54 publications

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“…The infall velocity, V inf and the mass infall rate are estimated to be 1.8 km s −1 and 9.9×10 −3 M yr −1 , respectively. The mass infall rate estimate is higher compared to the value of 6.4 × 10 −3 M yr −1 derived by He et al (2015). As discussed in Section 3.3.4, our clump mass and radius estimates are higher.…”

Section: Infall Activitycontrasting

confidence: 63%

“…The clump enclosing G12.42+0.50, C1 is the largest and most massive clump having a radius 0.8 pc, column density 3.3×10 22 cm −2 and mass 1375 M . He et al (2015) derives the radius, column density and mass of the clump associated with G12.42+0.50 to be 0.57 pc, 1.3×10 23 cm −2 and 724 M , respectively. Apart from a larger size estimated by us, the other factors contributing to this difference in the estimated values of mass and column density are the different opacity and dust temperature values adopted by He et al (2015).…”

Section: Properties Of Cold Dust Clumpsmentioning

confidence: 99%

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Initial phases of high-mass star formation: a multiwavelength study towards the extended green object G12.42+0.50

Issac

Tej

Varricatt

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a multiwavelength study of the extended green object, G12.42+0.50 in this paper. The associated ionized, dust, and molecular components of this source are studied in detail employing various observations at near-, mid-and far-infrared, submillimeter and radio wavelengths. Radio continuum emission mapped at 610 and 1390 MHz, using the Giant Meterwave Radio Telescope, India, advocates for a scenario of coexistence of an UC H II region and an ionized thermal jet possibly powered by the massive young stellar object, IRAS 18079-1756 with an estimated spectral type of B1 − B0.5. Shock-excited lines of H 2 and [FeII], as seen in the near-infrared spectra obtained with UKIRT-UIST, lend support to this picture. Cold dust emission shows a massive clump of mass 1375 M enveloping G12.42+0.50. Study of the molecular gas kinematics using the MALT90 and JCMT archival data unravels the presence of both infall activity and large-scale outflow suggesting an early stage of massive star formation in G12.42+0.50. A network of filamentary features are also revealed merging with the massive clump mimicking a hub-filament layout. Velocity structure along these indicate bulk inflow motion.

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Section: Infall Activitycontrasting

confidence: 63%

Section: Properties Of Cold Dust Clumpsmentioning

confidence: 99%

Initial phases of high-mass star formation: a multiwavelength study towards the extended green object G12.42+0.50

Issac

Tej

Varricatt

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Contreras et al (2013), we found eight dense clumps involved in this region. Half of these (AGAL341.217-00.212, AGAL341.219-00.259, AGAL341.236-00.271, and AGAL341.266-00.302) show infall motions (He et al 2015), indicating star formation activities are ongoing actively in this filamentary cloud. We consider the mass-size relationship of these clumps to find out whether they have sufficient mass to form massive stars.…”

Section: Fragmentationmentioning

confidence: 98%

A multiwavelength study of filamentary cloud G341.244-00.265

Wang

2019

A&A

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We present a multiwavelength study toward the filamentary molecular cloud G341.244-00.265, to investigate the physical and chemical properties, as well as star formation activities taking place therein. Our radio continuum and molecular line data were obtained from the Sydney University Molonglo Sky Survey (SUMSS), Atacama Pathfinder Experiment Telescope Large Area Survey of the Galaxy (ATLASGAL), Structure, excitation, and dynamics of the inner Galactic interstellar medium (SEDIGISM) and Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90). The infrared archival data come from Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE), Wide-field Infrared Survey Explorer (WISE), and Herschel InfraRed Galactic Plane Survey (Hi-GAL). G341.244-00.265 displays an elongated filamentary structure both in far-infrared and molecular line emissions; the “head” and “tail” of this molecular cloud are associated with known infrared bubbles S21, S22, and S24. We made H2 column density and dust temperature maps of this region by the spectral energy distribution (SED) method. G341.244-00.265 has a linear mass density of about 1654 M⊙ pc−1 and has a projected length of 11.1 pc. The cloud is prone to collapse based on the virial analysis. Even though the interactions between this filamentary cloud and its surrounding bubbles are evident, we found these bubbles are too young to trigger the next generation of star formation in G341.244-00.265. From the ATLASGAL catalog, we found eight dense massive clumps associated with this filamentary cloud. All of these clumps have sufficient mass to form massive stars. Using data from the GLIMPSE and WISE survey, we search the young stellar objects (YSOs) in G341.244-00.265. We found an age gradient of star formation in this filamentary cloud: most of the YSOs distributed in the center are Class I sources, while most Class II candidates are located in the head and tail of G341.244-00.265, indicating star formation at the two ends of this filament is prior to the center. The abundance ratio of N(N2H+)/N(C18O) is higher in the center than that in the two ends, also indicating that the gas in the center is less evolved. Taking into account the distributions of YSOs and the N(N2H+)/N(C18O) ratio map, our study is in agreement with the prediction of the so-called “end-dominated collapse” star formation scenario.

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“…We assumed a cloud size of ∼1 pc (e.g. Dunham et al 2010Dunham et al , 2011Rosolowsky et al 2010;Urquhart et al 2014;He et al 2015;Wienen et al 2015;König et al 2017;Yuan et al 2017), a velocity gradient dv/dr = 1 km s…”

Section: Non-thermal Velocity Dispersion-temperature Relationmentioning

confidence: 99%

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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Infall motions in massive star-forming regions: results from years 1 and 2 of the MALT90 survey

Cited by 57 publications

References 54 publications

Initial phases of high-mass star formation: a multiwavelength study towards the extended green object G12.42+0.50

Initial phases of high-mass star formation: a multiwavelength study towards the extended green object G12.42+0.50

A multiwavelength study of filamentary cloud G341.244-00.265

ATLASGAL-selected massive clumps in the inner Galaxy

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