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office
Pupin 1327

email
marcel at astro.columbia.edu

phone
+1 212 854 6814

fax
+1 212 854 8121

mail
MC 5246
550 W120th St
NY NY 10027

CU astronomy »


I am an observational astronomer who is interested in using new datasets and technologies to address classic questions in stellar astrophysics. One example is my work using Palomar Transient Factory (PTF) data to obtain stellar rotational periods. This is part of an open cluster survey I am leading to calibrate the relationship between stellar age, rotation, and magnetic activity. The existence of such a relationship was established over 40 years ago in solar-mass stars, but its exact form and theoretical underpinnings remain unknown, especially in stars less massive than the Sun. This has implications for stellar evolution and for observationally determining the ages of field stars, an exercise that currently is surprisingly frustrating. In addition to PTF, I also use Columbia's very own (well, co-own) MDM Observatory to obtain spectra for stars in these clusters, and use these to investigate their magnetic activity.

I also study white dwarfs and neutron stars, two of the possible endpoints of stellar evolution. In these stars fusion has ended and degeneracy pressure is preventing gravitational collapse. White dwarfs are typically the size of the Earth but two-thirds as massive as the Sun, while neutron stars, city-sized but roughly one and a half times the mass of the Sun, are even more compact. In particular, I am interested in observationally constraining the mass-radius relationship for neutron stars, and in uncovering the expected (but unseen) companions to recently discovered low-mass white dwarfs (which have masses less than one-fifth that of the Sun). Here I rely heavily on data from the Sloan Digital Sky Survey, and occasionally on access to the 3.5 m at Apache Point Observatory.

My work to date has required observations at wavelengths ranging from X-rays to the infrared and the use of large-scale survey data, both photometric and spectroscopic. (You can check my ADS publications for more details.) Using these data has unexpected consequences, like getting an asteroid named after me... an honor I did very little to deserve!