[Show abstract][Hide abstract] ABSTRACT: By registering pre-supernova (pre-SN) and post-supernova (post-SN)
images, usually taken at high resolution, roughly three dozen
core-collapse supernovae have now had the properties of their progenitor
stars either directly measured or (more commonly) constrained by
establishing upper limits on their luminosities. Here we reexamine the
particularly vexing case of supernova SN 2006my, a classic nearby Type
II-Plateau supernova (SN II-P) whose explosion site had been
fortuitously imaged by the Hubble Space Telescope (HST) twelve years
prior to the explosion, enabling three independent investigations to be
carried out. In the first, Li et. al. (2007) reported spatial
coincidence between SN 2006my and a (possibly extended) source with
properties deemed consistent with those of a red supergiant (i.e., the
type of progenitor expected for an SN II-P). Subsequent analyses by
Leonard et al. (2008) and Crockett et al. (2010), however, refuted the
Li et al. detection claim, but recognized that existing data did not
permit a definitive resolution of the issue, since the SN 2006my
localizations still placed it on *part* of the putative progenitor's
point-spread-function in the pre-SN frames, just no longer at its
center. To definitively establish the association/non-association of SN
2006my with the source identified in the pre-SN images, we have acquired
new HST images of the site of SN 2006my (long after SN 2006my has faded
beyond detection), and here report the final results of our study (i.e.,
whether any of the proposed progenitor object's light has now
disappeared). We also report preliminary results from a similarly
carried out investigation into the progenitor of the Type Ib SN 2007fo.
Support for Program numbers HST-GO-12282 and HST-GO-12170 was provided
by NASA through a grant from the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Incorporated, under NASA contract NAS5-26555.
[Show abstract][Hide abstract] ABSTRACT: The Palomar Transient Factory (PTF) is an optical wide-field variability
survey carried out using a camera with a 7.8 square degree field of view
mounted on the 48-in Oschin Schmidt telescope at Palomar Observatory. One of
the key goals of this survey is to conduct high-cadence monitoring of the sky
in order to detect optical transient sources shortly after they occur. Here, we
describe the real-time capabilities of the PTF and our related rapid
multiwavelength follow-up programs, extending from the radio to the gamma-ray
bands. We present as a case study observations of the optical transient
PTF10vdl (SN 2010id), revealed to be a very young core-collapse (Type II-P)
supernova having a remarkably low luminosity. Our results demonstrate that the
PTF now provides for optical transients the real-time discovery and
rapid-response follow-up capabilities previously reserved only for high-energy
transients like gamma-ray bursts.
Full-text · Article · Jun 2011 · The Astrophysical Journal
[Show abstract][Hide abstract] ABSTRACT: 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 PTF 10fqs, 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 M_r = −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 Hα
(≈930 km s^(−1)) and narrow calcium emission lines. The explosion signature (the light curve and spectra) is overall
similar to that of M85 OT2006-1, SN 2008S, and NGC 300 OT. The origin of these events is shrouded in mystery
and controversy (and in some cases, in dust). PTF 10fqs shows some evidence of a broad feature (around 8600 Å)
that may suggest very large velocities (≈10,000 km s^(−1)) 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.
Full-text · Article · Mar 2011 · The Astrophysical Journal
[Show abstract][Hide abstract] ABSTRACT: We present the discovery and characterisation of PTF10iya, a short-lived (dt
~ 10 d, with an optical decay rate of ~ 0.3 mag per d), luminous (M_g ~ -21
mag) transient source found by the Palomar Transient Factory. The
ultraviolet/optical spectral energy distribution is reasonably well fit by a
blackbody with T ~ 1-2 x 10^4 K and peak bolometric luminosity L_BB ~ 1-5 x
10^44 erg per s (depending on the details of the extinction correction). A
comparable amount of energy is radiated in the X-ray band that appears to
result from a distinct physical process. The location of PTF10iya is consistent
with the nucleus of a star-forming galaxy (z = 0.22405 +/- 0.00006) to within
350 mas (99.7 per cent confidence radius), or a projected distance of less than
1.2 kpc. At first glance, these properties appear reminiscent of the
characteristic "big blue bump" seen in the near-ultraviolet spectra of many
active galactic nuclei (AGNs). However, emission-line diagnostics of the host
galaxy, along with a historical light curve extending back to 2007, show no
evidence for AGN-like activity. We therefore consider whether the tidal
disruption of a star by an otherwise quiescent supermassive black hole may
account for our observations. Though with limited temporal information,
PTF10iya appears broadly consistent with the predictions for the early
"super-Eddington" phase of a solar-type star disrupted by a ~ 10^7 M_sun black
hole. Regardless of the precise physical origin of the accreting material, the
large luminosity and short duration suggest that otherwise quiescent galaxies
can transition extremely rapidly to radiate near the Eddington limit; many such
outbursts may have been missed by previous surveys lacking sufficient cadence.
Full-text · Article · Mar 2011 · Monthly Notices of the Royal Astronomical Society
[Show abstract][Hide abstract] ABSTRACT: We present the discovery and follow-up observations of a broad-line type-Ic
supernova (SN), PTF 10bzf (SN 2010ah), detected by the Palomar Transient
Factory (PTF) on 2010 February 23. The SN distance is \cong 218 Mpc, greater
than GRB 980425 / SN 1998bw and GRB 060218 / SN 2006aj, but smaller than the
other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a
multi-wavelength follow-up campaign with Palomar-48 inch, Palomar 60-inch,
Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, CARMA, WSRT, and EVLA.
Here we compare the properties of PTF 10bzf with those of SN 1998bw and other
broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf
suggest that this SN is intermediate, in kinetic energy and amount of 56Ni,
between non GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe
like 1998bw. No X-ray or radio counterpart to PTF 10bzf was detected. X-ray
upper-limits allow us to exclude the presence of an underlying X-ray afterglow
as luminous as that of other SN-associated GRBs like GRB 030329 or GRB 031203.
Early-time radio upper-limits do not show evidence for mildly-relativistic
ejecta. Late-time radio upper-limits rule out the presence of an underlying
off-axis GRB, with energy and wind density similar to the SN-associated GRB
030329 and GRB 031203. Finally, by performing a search for a GRB in the time
window and at the position of PTF 10bzf, we find that no GRB in the IPN catalog
could be associated with this SN.
Full-text · Article · Jan 2011 · The Astrophysical Journal
[Show abstract][Hide abstract] ABSTRACT: The PTF (ATEL #1964; http://www.astro.caltech.edu/ptf/) reports the discovery of a new supernova, PTF10abyy. The supernova was discovered by Oarical, an autonomous software framework of the PTF collaboration, on December 8 UT at RA(J2000) = 05:16:40.52 and DEC(J2000) = +06:47:53.8 at a magnitude of 18.7 in R-band (calibrated with respect to the USNOB1 catalog). The supernova was not detected down to mag 21 in previous PTF images taken during Dec.
[Show abstract][Hide abstract] ABSTRACT: We report the discovery and spectroscopic classification of 17 new supernovae from the Palomar Transient Factory (PTF; http://www.astro.caltech.edu/ptf ). The supernovae were discovered and classified by Oarical, an autonomous software framework of the PTF collaboration, based on observations made with the Palomar 48-inch Oschin Schmidt telescope. Spectroscopy was undertaken with the R-C spectrograph mounted at the Cassegrain focus of the Mayall 4-m telescope at Kitt Peak Observatory on UT 2010 October 8-10 by Ben- Ami, Badenes, Kulkarni, and Matheson.
[Show abstract][Hide abstract] ABSTRACT: On UT 2010 Sep 15.243, the Palomar Transient Factory discovered an optical transient, PTF10vdl at RA(J2000) = 23:05:49.001 and DEC(J2000)=03:31:20.50 near NGC 7483. We obtained Target Of Opportunity spectra with Gemini-S/GMOS (PI Kasliwal) on Sep 16.29. The spectrum was extremely blue (f_nu proportional to nu^4.5) and nearly featureless. We further obtained a spectrum with the TNG/DOLORES (PI Walker) on Sep 17.40 and P-Cygni profiles of four Balmer lines were clearly visible, consistent with the redshift of NGC 7483, suggesting this is a Type II supernova.
[Show abstract][Hide abstract] ABSTRACT: The PTF (ATEL #1964; http://www.astro.caltech.edu/ptf) reports the discovery of a new supernova, PTF10myz. The supernova was discovered on July 1 UT at RA(J2000) = 14:58:13.71 and DEC(J2000) = +48:11:28.2 at a magnitude of 19.2 in R-band (calibrated with respect to the USNO catalog) in the galaxy KUG 1456+483 (z=0.0282). The supernova was not detected down to mag 21.5 in previous PTF images taken during 2009/2010 (3-sigma).
[Show abstract][Hide abstract] ABSTRACT: The PTF (ATEL #1964; http://www.astro.caltech.edu/ptf/) reports the discovery of a new supernova, PTF10htz. The supernova was discovered on April 03 UT at RA(J2000) = 13:08:37.52 and DEC(J2000) = +79:47:13.2 at a magnitude of 20.5 in R-band (calibrated with respect to the USNO catalog) in the galaxy CGCG 352-058 (z=0.035). The supernova was not detected down to mag 21 in previous PTF images taken during 2009 (3-sigma).