Bradley E. Schaefer, PhD
Bradley E. Schaefer, Ph.D.

Bradley E. Schaefer, PhD
Professor of Physics & Astronomy

Ph.D., 1983 - Massachusetts Institute of Technology

Louisiana State University
Department of Physics & Astronomy
243-A Nicholson Hall, Tower Dr.
Baton Rouge, LA 70803-4001
(225) 578-0015-Office

 

Hipparchus and The Farnese Atlas

SNprogenitor - Origin of Thermonuclear Supernova Discovered

 

Research Interests

Astronomy - Astrophysics

I have a wide range of interests throughout astrophysics, including Gamma-Ray Bursts, supernovae, supernova remnants, supernova progenitors, historical records of supernovae, novae, recurrent novae, superflare stars, low mass X-ray binaries, eclipsing binaries, Nereid, Pluto, Kuiper Belt Objects, sunspot counts, the visibility of objects in the sky (especially lunar crescents and heliacal rises), astronomical effects on history, the accuracy of the press in reporting astronomy, the origin of the Greek and Chinese constellations, archaeoastronomy, astronomical events in history (e.g., the Crucifixion and the Star of Bethlehem), and astronomical events in literature (especially in The Hobbit and in the Sherlock Holmes canon).

A primary thrust of research is to use photometry of exploding objects to get results of interest for cosmology: For supernovae, as part of the Supernova Cosmology Project, a Hubble Diagram was created with high accuracy out to a red shift of ~1.0. This demonstrated that the Cosmological Constant is non-zero and causes our Universe's expansion to accelerate. This is the discovery of what is now called 'Dark Energy'. This work was awarded the 2007 Gruber Prize for Cosmology and the 2011 Nobel Prize in Physics. Further work has been getting answers to the notorious and highly-important Type Ia supernova progenitor problem. For example, in a recent Nature paper, the lack of any possible ex-companion star in the center of SNR 0509-67.5 in the LMC proves that at least this Type Ia supernova must have come from a double-degenerate progenitor.

For Recurrent Novae, the question is whether they are the progenitors of Type Ia supernovae, as the knowledge of the progenitor type is required for any evolution calculation such as is needed for the future precision cosmology with supernovae. To answer the progenitor question, extensive work is being pursued to get Recurrent Novae orbital periods, accretion rates, outburst dates, eruption light curves, and the average magnitudes between outbursts. A centerpiece of this work is the timing of eclipses from four systems (U Sco, T Pyx, T CrB, and CI Aql) since 1855 to measure the orbital period change across the latest eruptions (in 2010, 2011, 1946, and 2000 respectively) to get the first measure of the ejected mass, with the result in all four cases that the white dwarfs are ejecting much more mass than they had acrreted in the previous cycle, so the white dwarfs are losing mass and recurrent novae are not supernova progenitors. The eruption of U Sco was predicted and occurred in 2010, with a large international collaboration (collecting data from 8 satellites and 30 telescopes) making this eruption the all-time best observed nova event. In 2011, the eruption of T Pyx was observed with ~100,000 magnitudes in the light curve.

For Gamma-Ray Bursts, the big advance has been the realization that the bursts are standard candles (like Type Ia Supernovae and Cepheids). With this, GRBs become tools for cosmology that can be seen out to red shifts from ~0.2 to around 20. This allows GRBs to be light sources for the first real detection of the Gunn-Peterson effect, to create a Hubble Diagram from 0.2<z<10, and to measure the star formation rate of our Universe out to z~20.

Current and Selected Publications

  • PRIZE WINNING PUBLICATIONS
    • Nobel Prize in Physics 2011 (Prize went to team leader of the Supernova Cosmology Project, Saul Perlmutter, for this paper reporting discovery of Dark Energy)   AND

      Gruber Prize for Cosmology 2007 ($500,0000 shared by all Supernova Cosmology Project for discovery of Dark Energy).
      “Measurements of Omega and Lambda from 42 High-Redshift Supernovae,” S. Perlmutter et al., Astrophysical Journal 517, 565 (1999) - Electronic Version

    • American Physical Society Top Ten News Stories of 1999
      “Severe Limits on Variations of the Speed of Light with Frequency,” B. E. Schaefer, Physical Review Letters 82, 4964 (1999) - Electronic Version
    • Herbert C. Pollock Award 2003 (history of astronomy)
      “The latitude and epoch for the origin of the astronomical lore of Eudoxus,” B. E. Schaefer, Journal for the History of Astronomy 35, 161 (2004) - Electronic Version
    • Solar Physics Division Popular Writing Award 1998
      “Sunspots that Changed the World,’ B. E. Schaefer, Sky and Telescope 93, 34 (April 1997) - Electronic Version
    • Arthur Beer Prize 1993
      “Astronomy and the Limits of Vision,” B. E. Schaefer, Vistas in Astronomy 36, 311 (1993) - Electronic Version
  • SELECTED PUBLICATIONS
    • Gamma-Ray Bursts:
      “The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts,” B. E. Schaefer, Astrophysical Journal 660, 16 (2007) - Electronic Version
    • Supernovae:
      "Volume Limited Samples of Supernovae," B. E. Schaefer, Astrophysical Journal 464, 404 (1996) - Electronic Version
    • Novae:
      “Catalog of 93 Nova Light Curves: Classification and Properties,” R. J. Strope, B. E. Schaefer, and A. A. Henden, Astronomical Journal 140, 34 (2010) - Electronic Version
    • Recurrent Novae:
      “Comprehensive Photometric Histories of All Known Galactic Recurrent Novae,” B. E. Schaefer, Astrophysical Journal Supplement 187, 275 (2010) - Electronic Version
    • Hubble Constant:
      “Peak Brightnesses of Historical Supernovae and the Hubble Constant," B. E. Schaefer, Astrophysical Journal 459, 55 (1996) - Electronic Version
    • Large Magellanic Cloud
      “A Problem with the Clustering of Recent Measures of the Distance to the Large Magellanic Cloud,”, B. E. Schaefcr, Astronomical Journal 135, 112 (2008) - Electronic Version
    • Superflares:
      "Superflares on Ordinary Solar-Type Stars,” B. E. Schaefer, J. R. King, and C. P. Deliyannis, Astrophysical Journal 529, 1026 (2000) - Electronic Version
    • Kuiper Belt Objects:
      “The Diverse Solar Phase Curves of Distant Icy Bodies II. The Cause of the Opposition Surges and Their Correlations,” B. E. Schaefer, D. L. Rabinowitz, and S. W. Tourtellotte, Astronomical Journal, 137, 129 (2009) - Electronic Version
    • Pluto:
      “Pluto’s Light Curve in 1933-1934,” B. E. Schaefer, M. W. Buie, and L. T. Smith, Icarus 197, 590 (2008) - Electronic Version
    • Nereid:
      “Nereid’s Light Curve for 1999-2006 and a Scenario for its Variation,” B. E. Schaefer, D. L. Rabinowitz, S. W. Tourtellotte, aand M. W. Schaefer, Icarus, 196, 225 (2008) - Electronic Version
    • Celestial Visibility:
      “Lunar Crescent Visibility,” L. Doggett and B. E. Schaefer, Icarus, 107, 388 (1994) - Electronic Version
    • History of Astronomy:
      “The Epoch of the Constellations on the Farnese Atlas and their Origin in Hipparchus’ Lost Catalog,” B. E. Schaefer, Journal for the History of Astronomy 36, 167 (2004) - Electronic Version
    • Archaeoastronomy:
      "Case Studies of Three of the Most Famous Claimed Archaeoastronomical Alignments in North America: Keynote Address", B. E. Schaefer, in Viewing the Sky Through Past and Present Cultures; Selected Papers from the Oxford VII International Conference on Archaeoastronomy, eds T. W. Bostwick and B. Bates (Pheonix, Pueblo Grande Museum), pp. 27-56 (2006). [Keynote Address at the Quadrennial Oxford Conference]
    • Astronomy in Literature:
      "Sherlock Holmes and Some Astronomical Connections", B. E. Schaefer, Journal of the British Astronomical Association 103, 30 (1993). Also reprinted in Mercury 22, 9 (1993); L’Astronomie 109, 61 (1995); New Baker Street Pillbox 15, 16 (1993); and Baker Street Journal 43, 171 (1993) - Electronic Versions[1] - [2] - [3]