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Nathan E. Sanders

Harvard–Smithsonian Center for Astrophysics

Primary research: Core-collapse supernova progenitors

Core-collapse supernovae, the end-of-life explosions of stars much more massive than the sun, are one of the primary drivers responsible for enriching our solar system and others with all elements heavier than hydrogen and helium. To understand this process of chemical enrichment in the universe, it is critical to understand the diversity of stellar explosions that produce these elements and how they relate to the populations of stars in galaxies.

Roughly one out of four of these exploding stars undergo radical mass loss during their lives, losing their entire outer hydrogen and helium layers before explosion (Type Ibc supernovae). In 2012, I completed a campaign to characterize the host galaxies of 60 of these stripped-envelope core-collapse supernovae. Through modeling of the optical spectra of these host environments, we showed that the level of stripping on the progenitor star (Type Ib or Ic) does not depend measurably on its chemical composition (metallicity; see plot at right). This result limits the role that chemical composition, and metal line-driven stellar winds, can play in the stripping of these massive stars.

Gamma-ray bursts (GRBs) are the most energetic transient events observed in the universe and, because they can be seen at great distances, may become invaluable tracers of star formation in the early universe. A clear association exists between some nearby long GRBs and broad-lined Type Ic supernovae. However, it is not yet understood what causes only a special few of this class of supernovae to produce visible GRBs. We investigate the properties of these supernovae, and especially the environments in which they occur, to look for clues that would explain the physical processes that produce them.

We perform multi-wavelength follow-up observations of new SNe discovered by the high-cadence, multi-band medium-deep survey of the Pan-STARRS1 telescope. You can read more about our study of SN 2010ay here


Selected peer-reviewed publications

Full publication listing: NASA ADS link

Unsupervised Transient Light Curve Analysis Via Hierarchical Bayesian Inference.
Sanders, N.; M. Betancourt; Soderberg, A., The Astrophysical Journal 800, 36. arXiv:1404.3619
Towards Characterization of the Type IIP Supernova Progenitor Population:
a Statistical Sample of Light Curves from Pan-STARRS1.
Sanders, N.; Soderberg, A.; S. Gezari; M. Betancourt et al. The Astrophysical Journal 799, 208. arXiv:1404.2004
A New Approach to Developing Interactive Software Modules through Graduate Education.
Sanders, N.; Faesi, C.; Goodman, A.. The Journal of Science Education and Technology.
More information here. arXiv:1308.1908
PS1-12sk is a Peculiar Supernova From a He-rich Progenitor System in a Brightest Cluster Galaxy Environment.
Sanders, N.; Soderberg, A.; et al. The Astrophysical Journal, 769, 39.
More information here. arXiv:1303.1818
Using Colors to Improve Photometric Metallicity Estimates for Galaxies.
Sanders, N.; Levesque, E.; and Soderberg, A.. The Astrophysical Journal, 775, 125.
More information here. arXiv:1210.5520
A Spectroscopic Study of Type Ibc Supernova Host Galaxies from Untargeted Surveys.
Sanders, N.; Soderberg, A.; Levesque, E.; et al. The Astrophysical Journal, 758, 132.
More information here. arXiv:1206.2643
The metallicity profile of M31 from spectroscopy of hundreds of HII regions and PNe.
Sanders, N.; Caldwell, N.; McDowell, J. et al. The Astrophysical Journal, 758, 133.
More information here. arXiv:1209.2251
Preparing Undergraduates for Research Careers: Using Astrobites in the Classroom.
Sanders, N.; Kohler, S.; Newton, E.; and the Astrobites collaboration. Astronomy Education Review. arXiv:1208.4791
SN 2010ay Is a Luminous and Broad-Lined Type Ic Supernova Within a Low-Metallicity Host Galaxy.
Sanders, N.; Soderberg, A.; Valenti, S.; Chomiuk, L. et al. The Astrophysical Journal, 756, 184.
More information here. arXiv:1110.2363.
The size distributions of nanoscale Fe-Ni-S droplets in Stardust melted grains from comet 81P/Wild 2.
Sanders, N.; Velbel, M.. Meteoritics and Planetary Science, 47, 4, 594-612.

Selected Past Conference Presentations

12. Sanders, N.; Soderberg, A. (January 2014). Type IIP supernova progenitor properties from Pan-STARRS1 light curves. AAS 223: 2014 Winter Meeting; Washington D.C.. Talk
11. Sanders, N.; the Astrobites crew (February 2013). Astrobites: An Online Research Digest for Undergraduates. AAAS 2013; Boston. Download poster
10. Sanders, N. (11 September 2012). Type Ibc Supernova Host Environments in the Era of Untargeted Transient Searches. Supernovae Illuminating the Universe: from Individuals to Populations; Garching, Germany. Talk
9. Sanders, N.; Soderberg, A., Levesque, E. (20 June 2011). Probing the GRB Connection With an Unbiased Statistical Survey of Ibc Host Abundances. Supernovae and their Host Galaxies; Sydney, Australia. Talk
8. Sanders, N.; the Astrobites crew (2011). Astrobites: The Astro-ph Reader's Digest For Undergraduates. AAS 218; Boston; Boston. Download poster
7. Sanders, N.; Soderberg, A., Levesque, E. (2011). The First Unbiased Statistical Survey of Ibc Host Abundances. AAS 218; Boston; Boston. Talk
6. Sanders, N.; Soderberg, A., Levesque, E. (2011). Probing the GRB Connection With an Unbiased Statistical Survey of Ibc Host Abundances. GRBs as Probes; Como, Italy. Talk
5. Sanders, N.; Velbel, M. (2010). The Size Distribution of Stardust Metal Sulfide Droplets. 41st Lunar and Planetary Science Conference, 1533. 2010LPI....41.1175S. Download poster
4. Sanders, N.; Caldwell, N.; and McDowell, J. (2010). The Abundance Distribution In M31 From Optical Spectroscopy Of HII Regions And Planetary Nebulae. AAS Meeting #215, #415.33. 2010AAS...21541533S. Download poster
3. Kundu, A.; Sanders, N.; Martinez, W.; Zepf, S. E.; Geisler, D. (2010). A Multiwavelength Study of Extragalactic Globular Clusters. AAS Meeting #215, #478.02. 2010AAS...21547802K.
2. Jones, T.; Morey, S.; Sanders, N.; DeCamp, S. (2010). Astronomical Outreach Through Visual and Interactive Demonstrations. AAS Meeting #215, #445.06. 2010AAS...21544506J. Download poster
1. Hintz, E.; Schoonmaker, J.; Jibson, D.; Smith, H.; Sanders, N.; Giddings, R. (2010). An Examination of the Binary Nature of the delta Scuti Variable AN Lyncis. AAS Meeting #215, #417.18. 2010AAS...21541718H.

  • Nathan E. Sanders
  • nsanders /at\ cfa.harvard.edu
  • Rm. P-306, CfA