Figure 3.
Light curves of
three of the doublydegenerate SNe
Ia, from the Kepler
satellite (filled points
and error bars),
compared with
models (blue lines).
ties provided key pieces of evidence that
helped the teams classify the supernovae as
SN Ia.
NASA’s Swift satellite triggered the first result. The ultraviolet emission it detected
from the supernova was initially bright but
decayed rapidly, which supports theoretical models of the “single degenerate” origin,
where the companion star survives its collision with ejected material producing this
emission. The Gemini observations were
part of the Large and Long program that
Mansi Kasliwal (also California Institute of
Technology) leads, designed to obtain rapid
spectroscopy using the Gemini Multi-Object
Spectrograph (GMOS).
In contrast, the second paper shows three
examples with no evidence for interaction
with a surviving companion. This supports a
“double degenerate” origin, which leaves no
material for subsequent interaction. NASA’s
Kepler satellite provided the first observations of these supernovae. The groundbased spectra, using GMOS on both Gemini
North and South, showed that the hosts are
passive galaxies at redshifts around 0.1. The
two papers appear in the journal Nature, volume 521, pages 328 and 332.
Nancy A. Levenson is Deputy Director and Head
of Science at Gemini Observatory. Her office is at
Gemini South headquarters in La Serena, Chile.
She can be reached at: [email protected]
10
GeminiFocus
July 2015