Large Magellanic Cloud Extreme Star Formation in a Low-Metallicity Environment
Embargo until
Date
2018-04-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Johns Hopkins University
Abstract
Young stellar objects (YSOs) with high masses (> 8 M_sun) interact with the interstellar medium (ISM) via accretion and feedback processes on both local and galaxy-wide scales. Massive stars are rare and evolve very quickly, making them difficult to observe. My thesis aims to answer the question: How do massive stars form?
We study the molecular gas observed with ALMA in 30 Doradus, N159, and N79 using dendrograms, a new method that deconstructs the nested hierarchy inherent to the ISM. We find additional YSO candidates missed by initial studies by individually inspecting the spectral energy distribution of the point sources in the ALMA footprints of the three extreme regions. Feedback from turbulence regulates star formation: the energy injected into the ISM can trigger further formation of stars or quench the star formation process. We have measured the contribution of this feedback by comparing size-linewidth relations in 30 Doradus and N159. The size-linewidth relation in 30 Doradus is shifted to higher linewidths for a given clump size in comparison to N159 because of the turbulent feedback and increased star formation activity from the nearly super star cluster (SSC). By looking at where the stars are forming in relation to the molecular gas, we find the gas density necessary to form massive stars in the LMC is at least 500 M_sun/pc^2, x5 higher than the gas density necessary to form low-mass stars in the Milky Way.
ALMA observations of H72.97-69.39 in the N79 region of the LMC reveal filaments, outflows, and the first extragalactic detection of a rotating toroid around a cluster. The luminosity of this source is over 2,000,000 L_sun, making this one of the most luminous compact source ever discovered. What is this very luminous source? My thesis shows that this object is a embedded early-stage SSC.
This thesis present insights on high-mass star formation in a low-metallicity environment by studying the individual protostars and proto-clusters at high resolution with ALMA.
Description
Keywords
Large Magellanic Cloud, Massive Star Formation