supernovae and stars

Two great talks today, one by David Nidever (Michigan), who is one of the key people in the SDSS-III APOGEE project, and one by Or Graur (AMNH, Tel Aviv), who is a supernova prosepector. Nidever has been crucial in making the APOGEE spectral reductions precise. He has them so precise that he can actually discover exoplanet and brown-dwarf companions to main-sequence and giant stars. He talked about various constraints on or understandings of the accretion history of the Milky Way, including quite a bit about the puzzling Magellanic stream. What's so crazy is that it has no stars in it. Although perhaps not as crazy as I first thought when I started to think about starless HI structures connecting nearby galaxies like M81 and M82.

Graur talked about supernova searches in data sets (like CLASH) that were designed to find supernovae and also data sets (like SDSS-III BOSS) that were not. In the latter, he has made a very sensitive automated search in the spectra of the luminous red galaxies and found 100-ish type-Ia supernovae. This yield is much lower than you might expect (from the duration and rate of supernovae) but makes sense when you include the finite fiber size and signal-to-noise. He made a very strong point that many astronomical surveys can also be SNe surveys at almost no additional cost. That's good for our long-term future discounted free cash flow.

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