Research

 
 

Star formation scaling relations in NGC 300

Nearby galaxies provide the perfect laboratory in which to study star formation by virtue of providing a more complete sample of molecular clouds all at a single distance. I am working with Charles Lada and Jan Forbrich to measure star formation rates (SFRs, via Spitzer mid-IR, GALEX UV, and narrow-band photometry) and gas (via CO J=2-1 and other tracers) in the star-forming regions of the local (d=1.9 Mpc) galaxy NGC 300. Broadly, we hope to better understand the Schmidt-Kennicutt (SFR vs. gas mass) relation on the full range of scales from individual clouds to cloud complexes to entire galaxies.


The Role of Pressure in Molecular Clouds and Cores

It is commonly assumed that pressure gradients are negligible in molecular clouds, and thus that knowing the kinetic and potential energies provides a complete description of the virialization state of these clouds.  I am working on a project with Alyssa Goodman to test this assumption by estimating the pressure observationally as a function of position in several clouds such as Perseus using data from the COMPLETE survey, and comparing the results to simulations of star-forming regions.


Variability in Young Stars

Young stellar objects (YSOs) are often variable in the mid-infrared, yet little is known of the physical mechanisms that drive these changes.  I worked with Kevin Covey and the YSOVAR collaboration to explore this question through a spectral variability study of several stars in the rho-Ophiuchus star forming region.  We found that although mass accretion rates can vary greatly over short (days to weeks) timescales in active YSOs, there is no direct correlation between such behavior and the mid-infrared photometric variability we observe with Spitzer. Our paper is now accepted, is on the arXiv (http://arxiv.org/abs/1209.5749), and will appear in PASP, November 2012.

primary collaborators


star formation

stellar and chemical evolution

rho Ophiuchus (photo credit: Michael Stecker)

NGC 300 (photo credit: ESO archive)

Cloudshine in Perseus (Foster & Goodman 2006)

Spitzer Space Telescope (credit: NASA/IPAC)

It is difficult to conceive of a terrestrial physical process involving a change in density of over 20 orders of magnitude, and yet this is precisely what occurs regularly in the Universe as diffuse gas cools and eventually forms stars.  Although we believe we understand the basic inner workings of stars throughout their lifetimes - and even their deaths - a theory that comprehensively explains how stars form remains elusive.  What are the key parameters governing the star formation process?  How can local, resolved studies inform galaxy-scale star formation, and vice-versa? What conditions in protostellar disks are favorable for the formation of planets?  I am addressing these (and other) questions through several projects: