Simultaneous low- and high-mass star formation in a massive protocluster : ALMA observations of G11.92-0.61
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We present 1.05 mm ALMA observations of the deeply embedded high-mass protocluster G11.92−0.61, designed to search for low-mass cores within the accretion reservoir of the massive protostars. Our ALMA mosaic, which covers an extent of ∼0.7 pc at sub-arcsecond (∼1400 au) resolution, reveals a rich population of 16 new millimetre continuum sources surrounding the three previously-known millimetre cores. Most ofthe new sources are located in the outer reaches of the accretion reservoir: the median projected separation from the central, massive (proto)star MM1 is ∼0.17 pc. The derived physical properties of the new millimetre continuum sources are consistent with those of low-mass prestellar and protostellar cores in nearby star-forming regions:the median mass, radius, and density of the new sources are 1.3 M⊙, 1600 au, and nH2 ∼107 cm−3. At least three of the low-mass cores in G11.92−0.61 drive molecular outflows, traced by high-velocity 12CO(3-2) (observed with the SMA) and/or by H2CO and CH3OH emission (observed with ALMA). This finding, combined with the known outflow/accretion activity of MM1, indicates that high- and low-mass stars are forming (accreting) simultaneously within this protocluster. Our ALMA results are consistent with the predictions of competitive-accretion-type models in which high-mass stars form along with their surrounding clusters.
Cyganowski , C J , Brogan , C L , Hunter , T R , Smith , R , Kruijssen , J M D , Bonnell , I A & Zhang , Q 2017 , ' Simultaneous low- and high-mass star formation in a massive protocluster : ALMA observations of G11.92-0.61 ' Monthly Notices of the Royal Astronomical Society , vol 468 , no. 3 , pp. 3694-3708 . DOI: 10.1093/mnras/stx043
Monthly Notices of the Royal Astronomical Society
© 2017, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at academic.oup.com/mnras / http://doi.org/10.1093/mnras/stx043
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