Simultaneous low- and high-mass star formation in massive protoclusters: ALMA results
U St Andrews, St Andrews, GB
Most stars form in clusters, yet basic aspects of how this occurs
remain unknown, including the relative birth order of high and low
mass stars. In clump-scale "competitive accretion"-type models,
massive stars and their surrounding cluster of lower mass stars form
simultaneously. Thus a key, testable prediction of these models is
that centrally condensed low-mass cores should exist within the
accretion reservoir of a forming massive star.
I will present results from an ALMA Cycle 2 program to search for low-mass cores within the accretion reservoir of a high-mass (proto)cluster. Our ALMA mosaic achieves a dynamic range of ~1000 at a linear resolution of ~1700 AU and reveals a rich population of low-mass cores surrounding the central, massive (proto)cluster members (see figure). Of these low-mass sources, the most centrally-condensed and "core-like" are located in the outer reaches of the accretion reservoir (as traced by single-dish dust emission), ~0.2-0.3 pc from the central massive (proto)star. The central, massive (proto)star is accreting, as indicated by its active outflow activity. At least three of the low-mass cores are also driving outflows (traced by collimated 12CO emission, observed with the SMA, and/or H2CO and CH3OH emission, observed with ALMA), suggesting that both high- and low-mass stars are forming (accreting) simultaneously within this (proto)cluster.
C. Brogan, NRAO, US
T. Hunter, NRAO, US
R. Smith, Manchester, GB
D. Kruijssen, ZAH/MPIA, DE
I. Bonnell, U St Andrews, GB