Institute of Astronomy

Novae and Supernovae: Intimate Connections

SpeakerTalk DateTalk Series
Michael Shara (American Museum of Natural History in New York/IoA, Cambridge)16 March 2017Institute of Astronomy Colloquia

Abstract

Classical novae and supernovae were long thought to be completely separate
astrophysical phenomena.
This is no longer true; most type Ia supernovae (SNIa), the "standardizable
candles" that led to the discovery of the dark energy,
are now understood to have had symbiotic nova progenitors. Symbiotic novae
consist of a red giant and a rapidly accreting, frequently erupting white
dwarf.
Some of the offspring of these binaries are close double white dwarfs, which
are equally viable SNIa progenitors. Understanding the evolution of these
binaries over a Hubble time is essential to a robust calibration of the
crucial standard candles that they produce.

I'll review the current state of knowledge of the short and long-term
temporal evolution of the white dwarfs in novae, and predictions about how
these can lead to SNIa. A test of a key prediction of the theory is
underway. In 2017 the Hubble Space Telescope is imaging the giant elliptical
galaxy M87 53 times - every 5 days over 9 months - in a search for recurring
"ultraviolet flashers" in M87. These are the symbiotic novae predicted to
produce SNIa. I'll present early results from this program, which should
finally quantify the fractions of SNIa progenitors containing one and two
white dwarfs at redshift zero. This will be a strong constraint on all
evolutionary models of the binaries which produce SNIa.

Presentation

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