Dr. Warren R. Brown
wbrown @ cfa.harvard.edu
(617) 496-7905
60 Garden St, Mail Stop 20, Cambridge, MA 02138

I am an astronomer at the Smithsonian. I am best known for my Hypervelocity Star discoveries, stars ejected from our galaxy by the Milky Way's central massive black hole. With Mukremin Kilic, I am leading a targeted survey for merging pairs of white dwarfs that may one day explode as supernovae and that are currently the strongest known sources of gravitational waves at mHz frequencies.

I chair the CfA OIR Time Allocation Committee that oversees our use of MMT, Magellan, and FLWO telescopes. I direct the Smithsonian's Telescope Data Center, a group that archives, processes, and distributes data from our telescopes on a nightly basis. I also build new instruments for our ground-based telescopes. I am PI of the SAO Widefield InfraRed Camera (SWIRC), a near-infrared imager for the MMT telescope that I took from proposal to commissioning in 13 months, and PI of the the MMT Cam optical imager.

Hypervelocity Stars!

I discovered the first hypervelocity star, a star whose extreme 1.5 million mph speed can be explained only by a slingshot from the Galaxy's central black hole. The hypervelocity star is an outcast, exiled to drift in the empty depths of space. I have since discovered 16 unbound stars in a targeted survey, first announced here.

The two most fascinating aspects of hypervelocity stars are their link to the central black hole, and the fact that they have traveled out over 200,000 light years allowing us measure the dark matter that surrounds the Milky Way. To hear the big picture, listen to the New Scientist podcast or the American Physical Society podcast.

I have been awarded Harvard's Bok Prize "for outstanding work in the discovery of hypervelocity stars, a new class of objects in the Milky Way," and the Smithsonian Secretary's Research Prize for my "successful targeted survey for hypervelocity stars." This Astronomy Beat column published by the Astronomical Society of the Pacific describes my hypervelocity star research to a general public audience.

More recently we have how measured proper motions and trajectories for some of the hypervelocity stars with the Hubble Space Telescope, and have measured the age and flight times of other hypervelocity stars, as described in Scientific American.

In 2015 I published an invited review article on Hypervelocity Stars in the Annual Review of Astronomy and Astrophysics. I am pleased to be able to provide complimentary one-time access to the PDF file of my Annual Review article for personal use. This 2016 Physics Today article gives the highlights.

Merging White Dwarfs!

The Hypervelocity Star Survey has also discovered under-weight white dwarfs in compact pairs: they are among the strongest known sources of gravitational waves that will detected by the future LISA gravitational wave observatory.

We discovered a record-breaking detached pair of white dwarfs with a 12.75 minute orbital period. This system is a gravitational wave source 10,000 times stronger than the Hulse-Taylor pulsar and will merge in less than 1 million years. It's rapid change in orbital period will provide a fundamental test of general relativity as described by National Geographic.

Selected Scientific Publications:

Hypervelocity Stars

  • Gaia and the Galactic Center Origin of Hypervelocity Stars .pdf
  • Proper Motions and Trajectories for 16 Extreme Runaway and Hypervelocity Stars .pdf
  • MMT Hypervelocity Star Survey III: The Complete Survey .pdf
  • The Origin of HVS17, an Unbound Main Sequence B Star at 50 kpc .pdf
  • The Nature of Hypervelocity Stars and the Time Between Their Formation and Ejection .pdf
  • MMT Hypervelocity Star Survey. II. Five New Unbound Stars .pdf
  • Binary Disruption by Massive Black Holes: Hypervelocity Stars, S Stars, and Tidal Disruption Events .pdf
  • A Galactic Center Origin for HE 0437-5439, the Hypervelocity Star near the Large Magellanic Cloud .pdf
  • Runaway Stars, Hypervelocity Stars, and Radial Velocity Surveys .pdf
  • The Anisotropic Spatial Distribution of Hypervelocity Stars .pdf
  • MMT Hypervelocity Star Survey .pdf
  • HVS 7: a chemically peculiar hypervelocity star .pdf
  • Hypervelocity Stars: From the Galactic Center to the Halo .pdf
  • Hypervelocity Stars. III. The Space Density and Ejection History of Main Sequence Stars from the Galactic Center .pdf
  • Hypervelocity Stars. II. The Bound Population .pdf
  • Hypervelocity Stars. I. The Spectroscopic Survey .pdf
  • Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities .pdf
  • A Successful Targeted Search for Hypervelocity Stars .pdf
  • Merging White Dwarfs

  • The Discovery of Two LISA Sources within 0.5 kpc
  • A 1201 s Orbital Period Detached Binary: The First Double Helium Core White Dwarf LISA Verification Binary
  • The ELM Survey. VIII. Ninety-eight Double White Dwarf Binaries
  • Discovery of a Detached, Eclipsing 40 Minute Period Double White Dwarf Binary and a Friend: Implications for He+CO White Dwarf Mergers
  • The Physical Nature of Subdwarf A Stars: White Dwarf Impostors
  • Most Double Degenerate Low Mass White Dwarf Binaries Merge
  • The ELM Survey. VII. Orbital Properties of Low-Mass White Dwarf Binaries
  • The ELM Survey. VI. Eleven New Double Degenerates
  • A new gravitational wave verification source
  • Radius Constraints from High-speed Photometry of 20 Low-mass White Dwarf Binaries
  • SDSS J0745: Discovery of a Metal-Rich and Tidally Distorted Extremely Low Mass White Dwarf
  • The ELM Survey. V. Merging Massive White Dwarf Binaries
  • Rapid Orbital Decay in the 12.75-minute WD+WD Binary J0651+2844
  • The ELM Survey. IV. 24 White Dwarf Merger Systems
  • Two New Tidally Distorted White Dwarfs
  • The ELM Survey. III. A Successful Targeted Survey for Extremely Low Mass White Dwarfs
  • The Shortest Period Detached Binary White Dwarf System
  • The Binary Fraction of Low-mass White Dwarfs
  • The Merger Rate of Extremely Low Mass White Dwarf Binaries: Links to the Formation of AM CVn Stars and Underluminous Supernovae
  • The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
  • The ELM Survey. I. A Complete Sample of Extremely Low-mass White Dwarfs
  • The Discovery of Binary White Dwarfs that will Merge within 500 Myr
  • The Runaway White Dwarf LP40022 has a Companion
  • The Discovery of a Companion to the Lowest Mass White Dwarf
  • The Lowest Mass White Dwarf
  • Century Survey Galactic Halo Project

  • Stellar Velocity Dispersion and Anisotropy of the Milky Way Inner Halo
  • The Most Distant Stars in the Milky Way
  • Identifying Star Streams in the Milky Way Halo
  • The Mass Profile of the Galaxy to 80 kpc .pdf
  • Velocity Dispersion Profile of the Milky Way Halo .pdf
  • The Century Survey Galactic Halo Project III: A Complete 4300 sq. deg. Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo .pdf
  • The Century Survey Galactic Halo Project II: Global Properties and the Luminosity Function of Field Blue Horizontal Branch Stars .pdf
  • Mapping the Inner Halo of the Galaxy with 2MASS-Selected Horizontal Branch Candidates .pdf
  • The Century Survey Galactic Halo Project I: Stellar Spectral Analysis .pdf

  • Galaxies

  • MMT Extremely Metal Poor Galaxy Survey I. An Efficient Technique to Identify Metal Poor Galaxies
  • Stellar Velocity Dispersion of the Leo A Dwarf Galaxy
  • SDSS 0809+1729: Connections Between Extremely Metal-Poor Galaxies and Gamma-Ray Burst Hosts
  • V and R-band Galaxy Luminosity Functions and Low Surface Brightness Galaxies in the Century Survey
  • UV Excess Galaxies: Wolf-Rayet Galaxies

  • Instrumentation

  • MMT and Magellan Infrared Spectrograph
  • Smithsonian Widefield Infrared Camera .pdf
  • The Cryogenic Refractive Indices of S-FTM16, a Unique Optical Glass for Near-Infrared Instruments .pdf
  • A Detailed Thermal Analysis of the Binospec Spectrograph
  • SPIE paper on my design recommendations for Binospec

  • Here is a link to my ancient cheat sheet, "Grad Student Time-Saving Tools", that summarizes computer tips for astronomers.
    Before Grad School