Friday, 17th November at 2.00pm @ Gemini¹

ABSTRACT: We have obtained measurements that affect our understanding of several fundamental aspects of molecular cloud evolution. I will introduce two main results in this talk.

• We have obtained a lower limit of formation time for molecular clouds (> 5-10 Myr) through studies of HI narrow self-absorption (HINSA). This result limits the applicability of simulations and/or of theories which propose "fast star formation".
• Our submillimeter survey of quiescent cores in Orion reveals a core mass function (CMF) significantly flatter than the Salpeter initial mass function (IMF). Our analysis also raises doubts about some of the previous studies that find a turning point in the CMF. A CMF that differs from the IMF suggests environmental effects in the formation of the IMF.

Related papers:
Li et al., 2006, "Massive Quiescent Cores in Orion. - II. Core Mass Function", astro-ph/0610634
Goldsmith and Li, 2005, "HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation", astro-ph/0412427

¹This seminar will be hosted at the Gemini North headquarters, next to the JAC on N. A'ohoku Place, in Hilo. Our thanks to Gemini (particularly Scott and Andy) for their help.