Stellar clusterings around "Isolated" Massive YSOs in the LMC

Abstract

Observations suggest that there is a significant fraction of O-stars in the field of the Milky Way that appear to have formed in isolation or in low mass clusters ($<$100 $M_{\odot }$). The existence of these high-mass stars that apparently formed in the field challenges the generally accepted paradigm, which requires star formation to occur in clustered environments. In order to understand the physical conditions for the formation of these stars, it is necessary to observe isolated high-mass stars while they are still forming. With the $Hubble$ $Space$ $Telescope$, we observe the seven most isolated massive ($>$8 $M_{\odot }$) young stellar objects (MYSOs) in the Large Magellanic Cloud (LMC). The observations show that while these MYSOs are remote from other MYSOs, OB associations, and even from known giant molecular clouds, they are actually not isolated at all. Imaging reveals $\sim$100 to several hundred pre--main-sequence (PMS) stars in the vicinity of each MYSO. These previously undetected PMS stars form prominent compact clusters around the MYSOs, and in most cases they are also distributed sparsely across the observed regions. Contrary to what previous high-mass field star studies show, these observations suggest that high-mass stars may not be able to form in clusters with masses less than 100 $M_{\odot }$. If these MYSOs are indeed the best candidates for isolated high-mass star formation, then the lack of isolation is at odds with random sampling of the IMF. Moreover, while isolated MYSOs may not exist, we find evidence that isolated clusters containing O-stars can exist, which in itself is rare.

Accepted to ApJ

References in corpus (7)

• Improving PARSEC models for very low mass stars
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• Do O-stars form in isolation?
• Dependency of dynamical ejections of O stars on the masses of very young star clusters
• The Evolution of Massive YSOs in the LMC: Part I. Identification and Spectral Classification
• A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population
• Low-mass pre--main-sequence stars in the Magellanic Clouds

Cited by in corpus (13)

• The optimally-sampled galaxy-wide stellar initial mass function - Observational tests and the publicly available GalIMF code
• Catalogue of new Herbig Ae/Be and classical Be stars. A machine learning approach to Gaia DR2
• Zooming in on Individual Star Formation: Low- and High-mass Stars
• Do star clusters form in a completely mass-segregated way?
• Do the majority of stars form as gravitationally unbound?
• The origin of discrete multiple stellar populations in globular clusters
• Formation of stellar clusters
• How many explosions does one need? -- Quantifying supernovae in globular clusters from iron abundance spreads
• Formation of High-Mass stars in an isolated environment in the Large Magellanic Cloud
• On the origin of very massive stars around NGC 3603
• The initial mass function of stars and the star-formation rates of galaxies
• A clustered origin for isolated massive stars
• The mmax-Mecl relation in the LEGUS clusters