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San Diego, CA 92182-1221
This is a schematic diagram of the 20 dynamically confirmed black hole binaries. Seventeen have low mass companions (i.e. stars with masses less than about 3 solar masses), and the three on the top have high mass companions. The color scale for the 17 objects with low mass companions represents the temperature of the star (Cyg X-1, LMC X-1, and LMC X-3 all have companions which are considerably hotter, and it is difficult to make a good color scale that includes all objects). Click here for a PostScript version of this image (it is a bit clearer when printed out on a high resolution color printer).
Click here for a GIF version with variable star names, and (here for a PostScript version).
This is a compilation of the mass ranges for the 17 black holes pictured above. The arrows for the black holes point to the mass function, which is a firm lower limit for the mass of the black hole. In most cases the mass function is quite well known. In a few cases like GRS 1915+105, XTE J1550-564, and XTE J1859+226, the error on the mass function is still relatively large. Some of the limits shown are 95% confidence limits (e.g. GRO J1655-40), some are 1 sigma (e.g. GRS 1915+105), and some limits are educated guesses of the inclination based on reports of the light curve morphology and reasonable estimates for the secondary star's mass (e.g. XTE J1859+226). In the near future I hope to analyze most or all of the systems in a uniform way so that it becomes easier to compare the observed mass distribution with theory. Click here for a PostScript version of this image.
ASTR 450, Astrophysics
of Star Systems: Spring 2003, Spring 2005.
ASTR 510, Exoplanets: Fall 2013.
ASTR 610, Binary Stars: Fall 2002, Fall 2004, Fall 2006,
Fall 2010, Fall 2012.
ASTR 620, Galactic
Structure: Spring 2004, Spring 2006, Spring 2008, Spring 2010,
Spring 2012, Spring 2014.
ASTR 101, Principles of
Astronomy: Fall 2014, section 2 (T TH 9:30-10:45).
Fall 2014, section 1 (T TH 15:30-16:45).
I was a graduate student in the Yale University Department of Astronomy where I did a thesis called "Optical Observations of Black Hole X-ray Novae" (click here for a brief summary).
I have recently moved here to San Diego. Previously I was at the Sterrenkundig Instituut of the Universiteit Utrecht supported by Marten van Kerkwijk and Frank Verbunt, and before that at the Department of Astronomy and Astrophysics at The Pennsylvania State University. I was working with Richard. A. Wade on models of the UV spectra of selected cataclysmic variable stars in order to better understand the spectral line formation in the hot inner regions of the accretion disks found in these systems.
I continue to collaborate with Charles Bailyn (Yale University), Jeffrey McClintock (Harvard-Smithsonian Center for Astrophysics), and Ronald Remillard (Center for Space Research at the Massachusetts Institute of Technology) on optical and X-ray observations of black hole binaries.
Click here for recent results on M33 X-7.
Click here for a finding chart of 4U 1700-377.
Here is a ''Clear Sky Clock'' for Mount Laguna Observatory generated by Attilla Danko. Click on the image for more information.
Last updated 2010 February 28