Midterm colloquium by Eva Bøgelund – Niels Bohr Institute - University of Copenhagen

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Midterm colloquium by Eva Bøgelund

The Luminosities of protostars and the star forming regions in Chamaeleon

When studying star formation one of the challenges is to construct sufficiently large and unbiased samples of young stellar objects. This is for example important when trying to answer questions such as how efficient the process of star formation is? How much material from the molecular cloud ends up in the newly formed stars? And what factors regulate whether the stars are formed in isolation or end up in groups or clusters? In the recent years the Spitzer Space Telescope has surveyed many of the nearby star forming regions to establish such unbiased samples of sources.

In this colloquium I will discuss how basic properties such as bolometric temperatures and luminosities can be used to determine evolutionary stages of young stars. One of the key findings in recent years is that low-mass protostars are underluminous compared to theoretical expectations. To study this so-called "luminosity problem" Dunham et al. (2013) identify 230 protostars in 18 molecular clouds observed by Spitzer and compile complete SEDs from which to calculate bolometric temperatures and luminosities. By studying the luminosity distributions and comparing to models, we can learn more of the accretion processes of forming stars. Dunham et al. also investigate the extent to which lacking photometry influence the calculations of bolometric luminosities and discuss how future surveys with ALMA and Herschel can benefit further work in the field. 

The aim of my thesis work is to use Spitzer mid-infrared observations of the Chamaeleon molecular clouds to characterize the populations of young stellar objects there, their numbers and distribution and to place them in the context of star formation in a more global sense.

Supervisor: Jes K. Jørgensen