2 research outputs found
Rapidly Decaying Supernova 2010X: A Candidate ".Ia" Explosion
We present the discovery, photometric and spectroscopic follow-up
observations of SN 2010X (PTF 10bhp). This supernova decays exponentially with
tau_d=5 days, and rivals the current recordholder in speed, SN 2002bj. SN 2010X
peaks at M_r=-17mag and has mean velocities of 10,000 km/s. Our light curve
modeling suggests a radioactivity powered event and an ejecta mass of 0.16
Msun. If powered by Nickel, we show that the Nickel mass must be very small
(0.02 Msun) and that the supernova quickly becomes optically thin to
gamma-rays. Our spectral modeling suggests that SN 2010X and SN 2002bj have
similar chemical compositions and that one of Aluminum or Helium is present. If
Aluminum is present, we speculate that this may be an accretion induced
collapse of an O-Ne-Mg white dwarf. If Helium is present, all observables of SN
2010X are consistent with being a thermonuclear Helium shell detonation on a
white dwarf, a ".Ia" explosion. With the 1-day dynamic-cadence experiment on
the Palomar Transient Factory, we expect to annually discover a few such
events.Comment: 6 pages, 5 figures; Minor Changes; Note correction in Fig 4 caption;
published by ApJ
PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
The Palomar Transient Factory (PTF) is systematically charting the optical
transient and variable sky. A primary science driver of PTF is building a
complete inventory of transients in the local Universe (distance less than 200
Mpc). Here, we report the discovery of PTF10fqs, a transient in the luminosity
"gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF
10fqs has a peak luminosity of Mr = -12.3, red color (g-r = 1.0) and is slowly
evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by
intermediate-width H (930 km/s) and narrow calcium emission lines. The
explosion signature (the light curve and spectra) is overall similar to thatof
M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in
mystery and controversy (and in some cases, in dust). PTF10fqs shows some
evidence of a broad feature (around 8600A) that may suggest very large
velocities (10,000 km/s) in this explosion. Ongoing surveys can be expected to
find a few such events per year. Sensitive spectroscopy, infrared monitoring
and statistics (e.g. disk versus bulge) will eventually make it possible for
astronomers to unravel the nature of these mysterious explosions.Comment: 12 pages, 12 figures, Replaced with published versio