Abstract:
Supernovae Type Iax
(
SNe Iax
)
are less energetic and less luminous than typical thermonuclear explosions. A
suggested explanation for the observed characteristics of this subclass is a binary progenitor system consisting of a
CO white dwarf primary accreting from a helium star companion. A single-degenerate explosion channel might be
expected to result in a dense circumstellar medium
(
CSM
)
, although no evidence for such a CSM has yet been
observed for this subclass. Here we present recent
Spitzer
observations of the SN Iax 2014dt obtained by the
SPIRITS program nearly one year post-explosion that reveal a strong mid-IR excess over the expected
fl
uxes of
more normal SNe Ia. This excess is consistent with 10
−
5
M
of newly formed dust, which would be the
fi
rst time
that newly formed dust has been observed to form in a Type Ia. The excess, however, is also consistent with a
dusty CSM that was likely formed in pre-explosion mass-loss, thereby suggesting a single degenerate progenitor
system. Compared to other SNe Ia that show signi
fi
cant shock interaction
(
SNe Ia-CSM
)
and interacting core-
collapse events
(
SNe IIn
)
, this dust shell in SN 2014dt is less massive. We consider the implications that such a
pre-existing dust shell has for the progenitor system, including a binary system with a mass donor that is a red
giant, a red supergiant, or an asymptotic giant branch star.
