9 research outputs found
Multi-color Optical and NIR Light Curves of 64 Stripped-Envelope Core-Collapse Supernovae
We present a densely-sampled, homogeneous set of light curves of 64 low
redshift (z < 0.05) stripped-envelope supernovae (SN of type IIb, Ib, Ic and
Ic-bl). These data were obtained between 2001 and 2009 at the Fred L. Whipple
Observatory (FLWO) on Mt. Hopkins in Arizona, with the optical FLWO 1.2-m and
the near-infrared PAIRITEL 1.3-m telescopes. Our dataset consists of 4543
optical photometric measurements on 61 SN, including a combination of UBVRI,
UBVr'i', and u'BVr'i', and 2142 JHKs near-infrared measurements on 25 SN. This
sample constitutes the most extensive multi-color data set of stripped-envelope
SN to date. Our photometry is based on template-subtracted images to eliminate
any potential host galaxy light contamination. This work presents these
photometric data, compares them with data in the literature, and estimates
basic statistical quantities: date of maximum, color, and photometric
properties. We identify promising color trends that may permit the
identification of stripped-envelope SN subtypes from their photometry alone.
Many of these SN were observed spectroscopically by the CfA SN group, and the
spectra are presented in a companion paper (Modjaz et al. 2014). A thorough
exploration that combines the CfA photometry and spectroscopy of
stripped-envelope core-collapse SN will be presented in a follow-up paper.Comment: 26 pages, 17 figures, 8 tables. Revised version resubmitted to ApJ
Supplements after referee report. Additional online material is available
through http://cosmo.nyu.edu/SNYU
CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae
CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light
curves for Type Ia supernovae (SN Ia) obtained with the 1.3m Peters Automated
InfraRed Imaging TELescope (PAIRITEL). This data set includes 4607 measurements
of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred
Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs
photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia
in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia.
CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More
than half of the light curves begin before the time of maximum and the coverage
typically contains ~13-18 epochs of observation, depending on the filter. We
present extensive tests that verify the fidelity of the CfAIR2 data pipeline,
including comparison to the excellent data of the Carnegie Supernova Project.
CfAIR2 contributes to a firm local anchor for supernova cosmology studies in
the NIR. Because SN Ia are more nearly standard candles in the NIR and are less
vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the
supernova cosmology community develop more precise and accurate extragalactic
distance probes to improve our knowledge of cosmological parameters, including
dark energy and its potential time variation.Comment: 31 pages, 15 figures, 10 tables. Accepted to ApJS. v2 modified to
more closely match journal versio
Type Ia Supernovae are Good Standard Candles in the Near Infrared: Evidence from PAIRITEL
We have obtained 1087 NIR (JHKs) measurements of 21 SNe Ia using PAIRITEL,
nearly doubling the number of well-sampled NIR SN Ia light curves. These data
strengthen the evidence that SNe Ia are excellent standard candles in the NIR,
even without correction for optical light-curve shape. We construct fiducial
NIR templates for normal SNe Ia from our sample, excluding only the three known
peculiar SNe Ia: SN 2005bl, SN 2005hk, and SN 2005ke. The H-band absolute
magnitudes in this sample of 18 SNe Ia have an intrinsic rms of only 0.15 mag
with no correction for light-curve shape. We found a relationship between the
H-band extinction and optical color excess of AH=0.2E(B-V). This variation is
as small as the scatter in distance modulus measurements currently used for
cosmology based on optical light curves after corrections for light-curve
shape. Combining the homogeneous PAIRITEL measurements with 23 SNe Ia from the
literature, these 41 SNe Ia have standard H-band magnitudes with an rms scatter
of 0.16 mag. The good match of our sample with the literature sample suggests
there are few systematic problems with the photometry. We present a nearby NIR
Hubble diagram that shows no correlation of the residuals from the Hubble line
with light-curve properties. Future samples that account for optical and NIR
light-curve shapes, absorption, spectroscopic variation, or host-galaxy
properties may reveal effective ways to improve the use of SNe Ia as distance
indicators. Since systematic errors due to dust absorption in optical bands
remain the leading difficulty in the cosmological use of supernovae, the good
behavior of SN Ia NIR light curves and their relative insensitivity to
reddening make these objects attractive candidates for future cosmological
work.Comment: 37 pages. 8 Figures. 3 Tables. Revised to ApJ-accepted versio
Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared
We report spectroscopic and photometric observations of the Type IIb SN
2011dh obtained between 4 and 34 days after the estimated date of explosion
(May 31.5 UT). The data cover a wide wavelength range from 2,000 Angstroms in
the UV to 2.4 microns in the NIR. Optical spectra provide line profiles and
velocity measurements of HI, HeI, CaII and FeII that trace the composition and
kinematics of the SN. NIR spectra show that helium is present in the atmosphere
as early as 11 days after the explosion. A UV spectrum obtained with the STIS
reveals that the UV flux for SN 2011dh is low compared to other SN IIb. The HI
and HeI velocities in SN 2011dh are separated by about 4,000 km/s at all
phases. We estimate that the H-shell of SN 2011dh is about 8 times less massive
than the shell of SN 1993J and about 3 times more massive than the shell of SN
2008ax. Light curves (LC) for twelve passbands are presented. The maximum
bolometric luminosity of erg s occurred
about 22 days after the explosion. NIR emission provides more than 30% of the
total bolometric flux at the beginning of our observations and increases to
nearly 50% of the total by day 34. The UV produces 16% of the total flux on day
4, 5% on day 9 and 1% on day 34. We compare the bolometric light curves of SN
2011dh, SN 2008ax and SN 1993J. The LC are very different for the first twelve
days after the explosions but all three SN IIb display similar peak
luminosities, times of peak, decline rates and colors after maximum. This
suggests that the progenitors of these SN IIb may have had similar compositions
and masses but they exploded inside hydrogen shells that that have a wide range
of masses. The detailed observations presented here will help evaluate
theoretical models for this supernova and lead to a better understanding of SN
IIb.Comment: 23 pages, 14 figures, 9 tables, accepted by Ap
Supernova SN 2011fe from an exploding carbonâoxygen white dwarf star
Type Ia supernovae (SNe Ia) have been used empirically as standardized
candles to reveal the accelerating universe even though fundamental details,
such as the nature of the progenitor system and how the star explodes, remained
a mystery. There is consensus that a white dwarf star explodes after accreting
matter in a binary system, but the secondary could be anything from a main
sequence star to a red giant, or even another white dwarf. The uncertainty
stems from the fact that no recent SN Ia has been discovered close enough to
detect the stars before explosion. Here we report early observations of SN
2011fe (PTF11kly) in M101 at a distance of 6.4 Mpc, the closest SN Ia in the
past 25 years. We find that the exploding star was likely a carbon-oxygen white
dwarf, and from the lack of an early shock we conclude that the companion was
most likely a main sequence star. Early spectroscopy shows high-velocity oxygen
that varies on a time scale of hours and extensive mixing of newly synthesized
intermediate mass elements in the outermost layers of the supernova. A
companion paper uses pre-explosion images to rule out luminous red giants and
most helium stars as companions.Comment: 20 pages, 5 figures, 1 table, in pres