Master´s thesis defense by Eva Graulund Bøgelund – Niels Bohr Institute - University of Copenhagen

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Master´s thesis defense by Eva Graulund Bøgelund


When studying star formation one of the challenges is to construct sufficiently large and unbiased samples of young stellar objects (YSOs). 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? How rapid this process is? And what factors regulate whether the stars are formed in isolation or end up in groups or clusters? In recent years the Spitzer Space Telescope has surveyed many star forming regions to establish such unbiased samples of sources.

Using colour-magnitude and colour-colour diagrams I have identified 454 YSO candidates towards the Chamaeleon Cloud Complex and Small Magellanic Cloud. I have studied the spatial distribution of candidates and find this to be well-correlated with high-density, high-extinction areas, consistent with star formation theory. I classify the YSO candidates according to evolutionary phase and detect a tendency for objects in the earlier phases to clump together in tighter groups compared to more evolved objects.

I estimate the luminosity of YSO candidates identified towards Chamaeleon I using additional data in the far-infrared when this is available in the literature, and find these to cover the range 0.01 to 4 L☉, consistent with other galactic, low-mass, star-forming regions. I estimate the mass of individual star-forming regions in the Small Magellanic Cloud by integrating a standard two-part initial mass function and find masses in the range ~1200 to 4700 M☉. I derive star formation rates for each of the star-forming regions and find that, on average, each one converts nearly 2000 M☉ into stars per Myr, consistent with star formation rates of similar regions in the Large Magellanic Cloud.