30616044
A Massive Progenitor of the Luminous Type IIn Supernova 2010jl
The bright, nearby, recently discovered supernova (SN) 2010jl is a luminous Type IIn SN. Here, we report archival Hubble Space Telescope (HST) observations of its host galaxy UGC 5189A taken roughly 10 yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a luminous, blue point source at the position of the SN, with an absolute magnitude of –12.0 in the F300W filter. If it is not just a chance alignment, the source at the SN position could be (1) a massive young (<6 Myr) star cluster in which the SN resided, (2) a quiescent, luminous blue star with an apparent temperature around 14,000 K, (3) a star caught during a bright outburst akin to those of luminous blue variables, or (4) a combination of option (1) and option (2) or (3). Although we cannot confidently choose between these possibilities with the present data, any of them imply that the progenitor of SN 2010jl had an initial mass above 30 M_☉. This reinforces mounting evidence that many SNe IIn result from very massive stars, that massive stars can produce visible SNe without collapsing quietly to black holes, and that massive stars can sometimes retain their H envelopes until shortly before explosion. Standard stellar evolution models fail to account for these observed properties.
17343652
The Type IIn Supernova 2002kg: The Outburst of a Luminous Blue Variable Star in NGC 2403
We show that Supernova (SN) 2002kg in NGC 2403, initially classified as Type II-narrow (IIn), has photometric and spectroscopic properties unlike those of normal SNe. Its behavior, instead, is more typical of highly massive stars which experience the short-lived luminous blue variable (LBV) phase toward the end of their lives. The star, in fact, most resembles the LBV S Doradus in outburst. The precursor of SN 2002kg is the irregular, bright blue variable star 37 (V37), catalogued by Tammann & Sandage in 1968. Using high-quality ground-based, multi-band images we can constrain the initial mass of V37 to be M_ini >~ 40 M_sun. We find that, although the spectra indicate a nitrogen enhancement, possibly revealing the products of CNO processing by V37 in the ejecta, the star lacks a substantial LBV nebula. The outburst from SN 2002kg/V37 is not nearly as energetic as the giant eruptions of the eta Carinae-like variables, such as SN 1954J/V12, also in NGC 2403. SN 2002kg/V37, however, is among a growing number of ``SN impostors'' exhibiting a broad range of outburst energetics during a pre-SN phase of massive-star evolution.
28101827
THE PROGENITOR OF SUPERNOVA 2011 dh / PTF 11 eon IN MESSIER 51
We have identified a luminous star at the position of supernova (SN) 2011dh/PTF11eon, in pre-SN archival, multi-band images of the nearby, nearly face-on galaxy Messier 51 (M51) obtained by the Hubble Space Telescope with the Advanced Camera for Surveys. This identification has been confirmed, to the highest available astrometric precision, using a Keck-II adaptive-optics image. The available early-time spectra and photometry indicate that the SN is a stripped-envelope, core-collapse Type IIb, with a more compact progenitor (radius ∼ 1011 cm) than was the case for the well-studied SN IIb 1993J. We infer that the extinction to SN 2011dh and its progenitor arises from a low Galactic foreground contribution, and that the SN environment is of roughly solar metallicity. The detected object has absolute magnitude M0 V ≈ −7.7 and effective temperature ∼6000 K. The star’s radius, ∼1013 cm, is more extended than what has been inferred for the SN progenitor. We speculate that the detected star is either an unrelated star very near the position of the actual progenitor, or, more likely, the progenitor’s companion in a mass-transfer binary system. The position of the detected star in a Hertzsprung–Russell diagram is consistent with an initial mass of 17–19 M . The light of this star could easily conceal, even in the ultraviolet, the presence of a stripped, compact, very hot (∼105 K), nitrogen-rich Wolf–Rayet star progenitor.
4807313
On the Progenitors of Two Type II-P Supernovae in the Virgo Cluster
Direct identification of the progenitors of supernovae (SNe) is rare because of the required spatial resolution and depth of the archival data prior to the SN explosions. Here we report on the identification of the progenitors of two nearby SNe in the Virgo Cluster: SN 2006my in NGC 4651 and SN 2006ov in M61. We obtained high-quality ground-based images of SN 2006my with the Canada-France-Hawaii Telescope, and are able to locate the site of the SN on pre-SN Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images to a high precision (1 σ uncertainty of ±0.05"). We pinpoint the site of SN 2006ov to within 0.02" from HST Advanced Camera for Surveys images of the SN. We detected a red supergiant progenitor for each SN within the error circles, with an inferred zero-age main-sequence mass (M_(zams)) of 10^(+5)_(-3) and 15^(+5)_(-3) M_⊙ for the progenitors of SNe 2006my and 2006ov, respectively. The mass estimates for the progenitors of both SNe confirm a suggested trend that the most common Type II-plateau SNe originate from low-mass supergiants with M_(zams) ≈ 8-20 M_⊙.
85440811
Luminous blue variable eruptions and related transients: diversity of progenitors and outburst properties
We present new light curves and optical spectra for a number of extragalactic optical transients or 'supernova impostors' related to giant eruptions of luminous blue variables (LBVs), and we provide a comparative discussion of LBV-like giant eruptions known thus far. New data include photometry and spectroscopy of supernovae (SNe) 1999bw, 2000ch, 2001ac, 2002bu, 2006bv and 2010dn. SN 2010dn appears to be a carbon copy of SN 2008S and NGC 300-OT, whereas SN 2002bu shows spectral evolution from a normal LBV at early times to a twin of these cooler transients at late times. SN 2008S, NGC 300-OT and SN 2010dn appear to be special cases of a broader eruptive phenomenon where the progenitor star was enshrouded by dust, perhaps from a previous unseen eruptive episode. Evidence suggests that their progenitors have initial masses in the range 10―20 M ⊙ , extending the range of masses susceptible to the violent eruptive phenomenon below the canonical LBV mass range. Examining the full sample, SN impostors are characterized by strong photometric variability on a range of time-scales from a day to decades, potentially suffering multiple eruptions of the same source. The upper end of the luminosity distribution overlaps with the least-luminous core-collapse SNe, but in most cases a distinction can be made based on spectra. The low end of the luminosity distribution is far less well defined, and a distinction between LBV giant eruptions, S Doradus phases of LBVs, novae and possible eruptions of intermediate-mass stars is not entirely clear. We discuss observational clues concerning stellar winds or shocks as the relevant mass-loss mechanism, and we evaluate possible ideas for the physical mechanisms of outbursts, but there is still a great need for theoretical work on this problem. Although known examples of these eruptions are sufficient to illustrate their remarkably wide diversity in the peak absolute magnitude, duration, progenitor stars, outburst spectra and other observable properties, their statistical distribution is an area that will benefit greatly from current and upcoming transient surveys. Based on the distribution of these eruptive properties, we propose that the prototypical object SN 1961V was not a member of this class of impostors after all, but was instead a true core-collapse Type IIn SN that was preceded by a giant LBV eruption.
18374707
The Carnegie Supernova Project: The Low-Redshift Survey
Supernovae are essential to understanding the chemical evolution of the universe. Type Ia supernovae also provide the most powerful observational tool currently available for studying the expansion history of the universe and the nature of dark energy. Our basic knowledge of supernovae comes from the study of their photometric and spectroscopic properties. However, the presently available data sets of optical and near- infrared light curves of supernovae are rather small and/or heterogeneous, and employ photometric systems that are poorly characterized. Similarly, there are relatively few supernovae whose spectral evolution has been well sampled, both in wavelength and phase, with precise spectrophotometric observations. The low-redshift portion of the Carnegie Supernova Project (CSP) seeks to remedy this situation by providing photometry and spectrophotometry of a large sample of supernovae taken on telescope/filter/detector systems that are well understood and well characterized. During a 5 year program that began in 2004 September, we expect to obtain high-precision ugriBVYJHKs light curves and optical spectrophotometry for about 250 supernovae of all types. In this paper we provide a detailed description of the CSP survey observing and data reduction methodology. In addition, we present preliminary photometry and spectra obtained for a few representative supernovae during the first observing campaign.
109503889
EM Calorimeter in BESIII Experiment
BESIII EM Calorimeter (EMC) is based on CsI crystals, working at upgraded Beijing Electron Positron Collider (BEPC), called BEPCII. The overall BEPCII and BESIII design and current status are briefly described. The design and construction of EMC and its performance are presented. EMC works very well and its performances reach the design expectations, it plays an important roll in detector operation and in the BESIII trigger. There are some special features in the EMC construction and reconstruction: the crystals are assembled without support wall to reduce dead area; the time information of the EM clusters can help to suppress the machine background; the detector noise is smaller than similar detectors; the energy reconstruction with TOF signals helps to improve the energy resolution, especially for low energy showers. Several physics papers mainly based on EMC information have been published.
15020605
The type Ia supernova 1997br in ESO 576-G40
The peculiar type Ia supernova SN 1997br in ESO 576-G40 was extensively observed at Beijing Astronomical Observatory and Lick Observatory. In this paper, we present and discuss the BVRI photometry and the spectra collected over 3 months, beginning 9 days before maximum brightness. The light curves of SN 1997br are similar to those of SN 1991T, with slow decline rates after the B maximum. Well-sampled data before the B maximum show unambiguously that SN 1997br rises more slowly and has a wider peak than normal type Ia supernovae. The optical color evolution of SN 1997br is also similar to that of SN 1991T. We estimate the extinction of SN 1997br to be E(B-V) = 0.35 ± 0.10 mag by comparing its BVRI light curves with those of SN 1991T and by measuring the equivalent width of interstellar Na I D absorption lines. We have conducted a thorough comparison of the spectroscopic evolution of SN 1997br, SN 1991T, and SN 1994D. Although SN 1997br is generally very similar to SN 1991T, it shows some interesting differences at various epochs. Spectra of SN 1997br seem to indicate an earlier transition to the dominant phase of Fe-peak elements after the B maximum. Si II lines in SN 1997br show a very short duration after the B maximum. We discuss the implications of our observations of SN 1997br for models of type Ia supernovae. Specifically, we suggest that some SNe Ia may result from decelerated detonations of white dwarfs.
119304446
Perturbations of W(infinity) CFTs
The holographic duals of higher spin theories on AdS_3 are described by the large N limit of a family of minimal model CFTs, whose symmetry algebra is equivalent to W(infinity)[lambda]. We study perturbations of these limit theories, and show that they possess a marginal symmetry-preserving perturbation that describes switching on the 1/N corrections. We also test our general results for the specific cases of lambda=0,1, where free field realisations are available.
119362823
Supernova 1954J (Variable 12) in NGC 2403 Unmasked
We have confirmed that the precursor star of the unusual supernova 1954J (also known as Variable 12) in NGC 2403 survived what appears to have been a superoutburst, similar to the 1843 Great Eruption of η Carinae in the Galaxy. The apparent survivor has changed little in brightness and color over the last 8 years, and a Keck spectrum reveals characteristics broadly similar to those of η Car. This is further suggested by our identification of the actual outburst-surviving star in high-resolution images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope. We reveal this "supernova impostor" as a highly luminous ( mag), very massive (Minitial 25 M⊙) eruptive star, now surrounded by a dusty (AV ≈ 4 mag) nebula, similar to η Car's famous Homunculus.
118424125
CP asymmetry in $B\to \phi K_S$ in a SUSY SO(10) GUT
We study the $B\to \phi K_S$ decay in a SUSY SO(10) GUT. We calculate the mass spectrum of sparticles for a given set of parameters at the GUT scale. We complete the calculations of the Wilson coefficients of operators including the new operators which are induced by NHB penguins at LO using the MIA with double insertions. It is shown that the recent experimental results on the time-dependent CP asymmetry $S_{\phi K}$ in $B\to \phi K_S$, which is negative and can not be explained in SM, can be explained in the model where there are flavor non-diagonal right-handed down squark mass matrix elements of 2nd and 3rd generations whose size satisfies all relevant constraints from known experiments ($\tau \to \mu \gamma$, $B\to X_S\gamma, B_s\to \mu^+\mu^-, B\to X_s \mu^+\mu^-, B\to X_s g, \Delta M_s$, etc.). At the same time, the branching ratio for the decay can also be in agreement with experimental measurements.