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Title: Herschel observations of star-forming regions from the HOBYS programme
Author: Rayner, Thomas
ISNI:       0000 0004 5371 0268
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2015
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This thesis presents three higher-mass star forming regions (Mon R1, Mon R2 and NGC 2264) as observed by Herschel, and also the JCMT (SCUBA-2), and the IRAM 30-m telescope, with additional data from the Spitzer and WISE archives. The Herschel observations, using the SPIRE and PACS instruments over a range of 70 m{500 m, were taken as part of the HOBYS Key Programme, and the data were reduced using the HIPE mapmaking environment with sources identified and characterised by the 'get-sources' routine. The Herschel observations cover the peaks of cold dust SEDs, allowing robust estimates of mass and temperature to be made. Comparisons of the Herschel observations of the three regions suggest a picture of star formation in which the densest parts of certain molecular clouds can accrete matter via filaments from the surrounding regions, fuelling far more star formation than occurs in the outer regions. My study of these regions has led to the potential classification of two separate regimes of star formation. The first occurs in filamentary regions (generally observed with a column density of 3 10²¹ cm⁻²-1.5 10²²cm⁻²), and is associated with gravitational accretion. The second occcurs in dense ridges and filamentary hubs (>1.5 10²² cm⁻²), in which intense star formation is fed by material flowing inward, with feedback from newly-formed stars interacting with the infalling material. The identification of these distinct populations is backed up by characterisation of the probability density functions (PDFs) and by determination of local core formation efficiency (CFE), both of which show a regime change at 1.5 10²²cm⁻². Comparisons of source mass, FWHM, and luminosity also indicate a separate population of cores forming in such regions.
Supervisor: Not available Sponsor: Science and Technology Facilities Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QB Astronomy ; QC Physics