The missing link in massive star formation: A NIKA2 and ArTeMis study of a new population of massive starless cores

The initial mass function (IMF) of stars is a fundamental global output of the star formation process, and the question of its origin and universality has been a long-standing open issue. While the base of the IMF (0.1 to 1 Msun) may result from Jeans-like fragmentation of interstellar filaments, the problem of how the most extreme stellar objects (brown dwarfs, intermediate- and high-mass stars) build up their masses remains unsettled. The high-sensitivity and fast mapping capability of instruments such as the 1.2/2mm NIKA2 camera on the IRAM 30m offer the unique opportunity to detect large populations of low-brightness sources, and probe star-forming regions as never before.

The student will use NIKA2 data via the GASTON large programme (PI: Peretto). This programme aims at mapping the intertwined populations of interstellar filaments and intermediate to high-mass cores within galactic plane star-forming regions. A preliminary analysis of the GASTON data reveals a new population of intermediate- to high-mass cores that has never been detected before. These sources could represent the missing link in our current understanding of massive star formation. Indeed, when observing nearby star-forming clouds, one finds that the majority of cores (the direct progenitors of individual stars) are starless, while when probing massive-star-forming clouds, cores seem to be mostly protostellar. This could be explained by the difference of cloud properties that are being observed in both types of region, and the different accretion processes that are at work. In nearby star-forming region, it is believed that core-accretion (i.e the feeding of the protostar by the compact surrounding core) is the dominant mechanism by which stars gain their mass, while in massive-star-forming clouds clump-accretion (i.e. the feeding of the protostar by the larger-scale parent clump) is believed to be probe an intermediate regime where both mechanism could be at play.
The main objective of this PhD is to characterise the properties of the new GASTON sources (mass, temperature, chemical composition), determine whether they are truly different to already known sources. The end goal of this PhD will be to analyse high-angular resolution ALMA data of the GASTON sources in order to determine, for the first time, the mass function of prestellar cores up to very large masses. This can only be achieved in a large, unbiased sample of sources, which is exactly what GASTON provides for.

This project will be funded by the STFC.
Applicants should apply to the Doctor of Philosophy in Physics and Astronomy with a start date of 1st October 2020.
https://www.cardiff.ac.uk/study/postgraduate/research/programmes/programme/physics-and-astronomy

In the research proposal section of your application, please specify the project title and supervisors of this project. If you are applying for more than one project, please list the individual titles of the projects in the text box provided. In the funding section, please select ’I will be applying for a scholarship/grant’ and specify that you are applying for advertised funding from the STFC.

Applicants will need to submit the following documents with their application:
- post high school certificates and transcripts to date
- academic CV
- personal statement
- two academic references. Your references can either be uploaded with your application, or emailed by the referee to [Email Address Removed] or [Email Address Removed]