Robyn Ellyn Sanderson's Home Page A photo of Robyn

Welcome! You've reached Robyn Sanderson's home page.

I am an NSF Astronomy and Astrophysics Postdoctoral Fellow based at the Columbia University Department of Astronomy in New York. I work primarily with Kathryn Johnston's group at Columbia and with David Hogg's group in the Center for Cosmology and Particle Physics at NYU.

From 2011 to 2014 I was a postdoctoral researcher in the group of Amina Helmi at the Kapteyn Astronomical Institute in Groningen, the Netherlands.


If you're looking for the Gaia Challenge dataset, there it is.


Many people find it useful to know how to make a movie out of image files with FFMPEG.

Research Information

I seek to understand how dark matter is distributed in our Galaxy and other nearby ones by measuring the orbits of stars. In particular, I am interested in the orbits of stars in tidal streams, beautiful structures formed when a smaller ("dwarf") galaxy merges with a bigger galaxy (like ours). Not only do these streams provide striking confirmation of one of the basic predictions of the current best model for the Universe's history, they can also tell us about the shape and size of the dark matter halos that are thought to surround every galaxy---another important prediction.

Tidal streams are useful for weighing and measuring dark matter halos because the stars in a given stream all came from the same place originally---a small galaxy that was torn up by merging with a larger one. The way a stream looks depends, among other things, on the way mass is distributed in the large galaxy that is doing the disrupting, and most of that mass is in the dark matter halo. Measuring the orbits of the stars in the stream can rule out mass distributions by looking for consistency in the speeds and positions of the stars; effectively "running time backward" to re-assemble the stream into a galaxy. Though this concept is simple, its application in real life is more complicated, thanks in part to all the other things the final shape of a stream can depend on, and thanks also to the fact that measuring even a single star's orbit completely is so difficult. So my research looks for ways to simplify the process and maximize the measuring power of the streams.


Personal Information

I maintain an ADS library with a list of my scientific publications. My ORCID is 0000-0003-3939-3297.

You can find my resume on LinkedIn.

You may also download my full academic CV.


An archived version of my previous home page (from my graduate-student days) can be found here.