226 research outputs found
The Rate of Type Ia Supernovae at z~0.2 from SDSS-I Overlapping Fields
In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of
the surveyed area was observed more than once due to field tiling overlap,
usually at different epochs. We utilize some of these data to perform a
supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~ 5%
of the SDSS-I overlap area, produces 29 SN candidates clearly associated with
host galaxies. Using the Bayesian photometric classification algorithm of
Poznanski et al., and correcting for classification bias, we find 17 of the 29
candidates are likely Type Ia SNe. Accounting for the detection efficiency of
the survey and for host extinction, this implies a Type Ia SN rate of
R=14.0+(2.5,1.4}-(2.5,1.1}+/-2.5 10^-14 h(70)^2 yr^-1 L_sun^-1, where the
errors are Poisson error, systematic detection efficiency error, and systematic
classification error, respectively. The volumetric rate is
R=1.89+(0.42,0.18)-(0.34,0.15)+/-0.42 10^-5 yr^-1 h(70)^3 Mpc^-3. Our
measurement is consistent with other rate measurements at low redshift. An
order of magnitude increase in the number of SNe is possible by analyzing the
full SDSS-I database.Comment: 11 pages, 7 figures, Accepted by MNRA
The Progenitor of the Type II-P SN 2004dj in NGC 2403
The Type II-P supernova 2004dj in the nearby galaxy NGC 2403 occurred at a
position coincident with object 96 in the list of luminous stars and clusters
in this galaxy published by Sandage in 1984. The coincidence is established
definitively through astrometric registration of our ground-based archival
images of NGC 2403 with our recent images showing the SN. The archival images
show that Sandage 96 is slightly resolved from the ground. Pre-outburst blue
spectrograms obtained by Humphreys and Aaronson reveal that Sandage 96 has a
composite spectrum, dominated in the blue region by A- and B-type stars, while
infrared photometry shows that Sandage 96 also contains red supergiants. These
results demonstrate that Sandage 96 is a young compact cluster. We have studied
the stellar population of Sandage 96, using published photometric measurements
combined with a chi-square-fitting code. We derive a cluster age of 13.6 Ma, a
reddening of E(4405-5495)=0.172, and a total stellar mass of 24 000 M_Sun. For
this cluster age, the SN progenitor had a main-sequence mass of 15 M_Sun.
Post-outburst photometry of Sandage 96 may establish whether the progenitor was
a red or blue supergiant.Comment: Accepted for publication in ApJL. Replaces previous version not
revised by the referee.13 pages, 3 figure
The Palomar Transient Factory photometric catalog 1.0
We construct a photometrically calibrated catalog of non-variable sources
from the Palomar Transient Factory (PTF) observations. The first version of
this catalog presented here, the PTF photometric catalog 1.0, contains
calibrated R_PTF-filter magnitudes for about 21 million sources brighter than
magnitude 19, over an area of about 11233 deg^2. The magnitudes are provided in
the PTF photometric system, and the color of a source is required in order to
convert these magnitudes into other magnitude systems. We estimate that the
magnitudes in this catalog have typical accuracy of about 0.02 mag with respect
to magnitudes from the Sloan Digital Sky Survey. The median repeatability of
our catalog's magnitudes for stars between 15 and 16 mag, is about 0.01 mag,
and it is better than 0.03 mag for 95% of the sources in this magnitude range.
The main goal of this catalog is to provide reference magnitudes for
photometric calibration of visible light observations. Subsequent versions of
this catalog, which will be published incrementally online, will be extended to
a larger sky area and will also include g_PTF-filter magnitudes, as well as
variability and proper motion information.Comment: 6 pages, 6 figures, PASP in pres
The counterphobic defense in children
The clinical data for this study were derived from the case histories of five children who consistently used the counterphobic defense either alone or in combination with phobic attitudes. The children's manifestations of this defense appeared in both verbal and nonverbal behavioral patterns. The choice of defensive style was found related to at least three factors: an early history of trauma, especially separation, parental encouragement of âtoughness,â and essentially a counterphobic family style.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43947/1/10578_2005_Article_BF01433642.pd
SN2010jp (PTF10aaxi): A Jet-Driven Type II Supernova
We present photometry and spectroscopy of the peculiar TypeII supernova (SN)
2010jp, also named PTF10aaxi. The light curve exhibits a linear decline with a
relatively low peak absolute magnitude of only -15.9, and a low radioactive
decay luminosity at late times that suggests a nickel mass below 0.003
. Spectra of SN2010jp display an unprecedented triple-peaked
H line profile, showing: (1) a narrow (800 km/s) central component that
suggests shock interaction with dense CSM; (2) high-velocity blue and red
emission features centered at -12600 and +15400 km/s; and (3) broad wings
extending from -22000 to +25000 km/s. These features persist during 100 days
after explosion. We propose that this line profile indicates a bipolar
jet-driven explosion, with the central component produced by normal SN ejecta
and CSM interaction at mid latitudes, while the high-velocity bumps and broad
line wings arise in a nonrelativistic bipolar jet. Two variations of the jet
interpretation seem plausible: (1) A fast jet mixes 56Ni to high velocities in
polar zones of the H-rich envelope, or (2) the reverse shock in the jet
produces blue and red bumps in Balmer lines when a jet interacts with dense
CSM. Jet-driven SNeII are predicted for collapsars resulting from a wide range
of initial masses above 25 at sub-solar metallicity. This seems
consistent with the SN host environment, which is either an extremely
low-luminosity dwarf galaxy or very remote parts of an interacting pair of
star-forming galaxies. It also seems consistent with the low 56Ni mass that may
accompany black hole formation. We speculate that the jet survives to produce
observable signatures because the star's H envelope was mostly stripped away by
previous eruptive mass loss.Comment: 11 pages, 9 figures, submitted to MNRA
Evidence for a Compact Wolf-Rayet Progenitor for the Type Ic Supernova PTF 10vgv
We present the discovery of PTF 10vgv, a Type Ic supernova (SN) detected by the Palomar Transient Factory, using the Palomar 48 inch telescope (P48). R-band observations of the PTF 10vgv field with P48 probe the SN emission from its very early phases (about two weeks before R-band maximum) and set limits on its flux in the week prior to the discovery. Our sensitive upper limits and early detections constrain the post-shock-breakout luminosity of this event. Via comparison to numerical (analytical) models, we derive an upper-limit of R âž 4.5 R_â (R âž 1 R_â) on the radius of the progenitor star, a direct indication in favor of a compact Wolf-Rayet star. Applying a similar analysis to the historical observations of SN 1994I yields R âž 1/4 R_â for the progenitor radius of this SN
PTF11kx: A Type-Ia Supernova with a Symbiotic Nova Progenitor
There is a consensus that Type-Ia supernovae (SNe Ia) arise from the
thermonuclear explosion of white dwarf stars that accrete matter from a binary
companion. However, direct observation of SN Ia progenitors is lacking, and the
precise nature of the binary companion remains uncertain. A temporal series of
high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex
circumstellar environment that provides an unprecedentedly detailed view of the
progenitor system. Multiple shells of circumsteller are detected and the SN
ejecta are seen to interact with circumstellar material (CSM) starting 59 days
after the explosion. These features are best described by a symbiotic nova
progenitor, similar to RS Ophiuchi.Comment: 27 pages, 5 figures. In pres
Early Radio and X-Ray Observations of the Youngest Nearby Type Ia Supernova PTF 11kly (SN 2011fe)
On 2011 August 24 (UT) the Palomar Transient Factory (PTF) discovered PTF11kly (SN 2011fe), the youngest
and most nearby Type Ia supernova (SN Ia) in decades. We followed this event up in the radio (centimeter and
millimeter bands) and X-ray bands, starting about a day after the estimated explosion time.We present our analysis
of the radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate
from the progenitor system of this supernova. We find a robust limit of áš âž 10^(â8)(w/100 km s^(â1))M_â yr^(â1) from
sensitive X-ray non-detections, as well as a similar limit from radio data, which depends, however, on assumptions
about microphysical parameters. We discuss our results in the context of single-degenerate models for SNe Ia and
find that our observations modestly disfavor symbiotic progenitor models involving a red giant donor, but cannot
constrain systems accreting from main-sequence or sub-giant stars, including the popular supersoft channel. In
view of the proximity of PTF11kly and the sensitivity of our prompt observations, we would have to wait for a long
time (a decade or longer) in order to more meaningfully probe the circumstellar matter of SNe Ia
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