University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, October 3rd 2014
Speaker: Dr. Nino Pangia, STSci
Subject: Star Formation as Seen by Low Mass Stars

We have undertaken a systematic study of pre-main-sequence (PMS) stars spanning
a wide range of masses (0.5 - 4 Msun), metallicities (0.1 - 1 Zsun) and ages
(0.5 - 30 Myr). We have used the Hubble Space Telescope to identify and
characterise a large sample of PMS objects in several star forming regions in
the Magellanic Clouds, namely 30 Dor, the SN1987A field and NGC1850 in the LMC
and NGC 346 and NGC 602 in the SMC, and have compared them to PMS stars in
similar regions in the Milky Way, such as NGC 3603 and Trumpler 14.

Thanks to a novel method that we have developed to combine broad-band (V,I)
photometry with narrow-band Halpha imaging, we have determined the physical
parameters (temperature, luminosity, age, mass and mass accretion rate) of more
than 3000 bona-fide PMS stars still undergoing active mass accretion. This is
presently the largest and most homogeneous sample of PMS objects with known
physical properties, and includes not only very young objects but also PMS
stars older than 10-20 Myr that are approaching the main sequence.

I will present the current results of our project, including the fact that the
mass accretion rates are systematically higher in the Magellanic Clouds than in
the Milky Way for stars of the same mass and age, scaling roughly with the
inverse of the cube root of the metallicity. These results are bound to have
important implications for, and constraints on our understanding of the star
formation process in the Universe.

The weekly calendar is also available via subscription to the physics-announce mailing list, and by RSS feed.