Tracey Hill (University of Exeter)

Spectral energy distribution analysis and Parkes ammonia observations of massive star formation regions - Tracey Hill Colloquium

ATNF Marsfield Lecture Theatre

Abstract

The formation and evolution of a massive star is a fundamental astrophysical process that is still largely unclear, especially the
earliest phases of their evolution. Massive stars form and evolve
rapidly, in clustered environments, deeply embedded in their natal
molecular cloud. The rarity of candidates means that the field has also been lacking a large sample of objects at the earliest evolutionary phases. We have, through two large-scale (sub)millimetre continuum surveys (SIMBA/SEST and SCUBA/JCMT), identified a new class of object - the 'mm-only' core which may represent the earliest phases of massive star formation.

The millimetre continuum (SIMBA/SEST) survey (Hill et al., 2005)
detected 405 sources, the majority of which (255) were previously
unknown and unstudied cores devoid of any indications of high-mass star formation. Subsequent submillimetre (SCUBA/JCMT) observations (Hill et al., 2006) and spectral energy distribution modelling (Hill et al., 2009) indicate these mm-only cores to be excellent candidates for early stage protostars. That is, the mm-only core may represent the very earliest stages of high-mass star formation, satisfying the much-sought young massive star candidates. We have recently undertaken a complementary ammonia spectral line survey, in the lowest two inversion transitions, of a large sample of the SIMBA sources using the new K-Band receiver on the Parkes telescope. The purpose of this work was to obtain accurate temperatures in order to constrain further SED fitting and facilitate accurate determinations of the source mass.

I present here, the results of our SED fitting and analysis as well as
data and preliminary results from our Parkes ammonia study.