Browsing by Subject "ubvri photometry"
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Item Discovery Of The Ultra-Bright Type II-L Supernova 2008es(2009-01) Gezari, S.; Halpern, J. P.; Grupe, D.; Yuan, F.; Quimby, Robert; McKay, T.; Chamarro, D.; Sisson, M. D.; Akerlof, C.; Wheeler, J. Craig; Brown, Peter J.; Cenko, S. Bradley; Rau, A.; Djordjevic, J. O.; Terndrup, D. M.; Wheeler, J. CraigWe report the discovery by the Robotic Optical Transient Search Experiment (ROTSE-IIIb) telescope of SN 2008es, an overluminous supernova (SN) at z = 0.205 with a peak visual magnitude of -22.2. We present multiwavelength follow-up observations with the Swift satellite and several ground-based optical telescopes. The ROTSE-IIIb observations constrain the time of explosion to be 23 +/- 1 rest-frame days before maximum. The linear decay of the optical light curve, and the combination of a symmetric, broad Ha emission line profile with broad P Cygni H beta and Na lambda 5892 profiles, are properties reminiscent of the bright Type II-L SNe 1979C and 1980K, although SN 2008es is greater than 10 times more luminous. The host galaxy is undetected in pre-supernova Sloan Digital Sky Survey images, and similar to Type II-L SN 2005ap (the most luminous SN ever observed), the host is most likely a dwarf galaxy with M(r) > - 17. Swift Ultraviolet/Optical Telescope observations in combination with Palomar 60 inch photometry measure the spectral energy distribution of the SN from 200 to 800 nm to be a blackbody that cools from 14000 K at the time of the optical peak to 6400 K 65 days later. The inferred blackbody radius is in good agreement with the radius expected for the expansion speed measured from the broad lines (10000 km s(-1)). The bolometric luminosity at the optical peak is 2.8 x 10(44) erg s(-1), with a total energy radiated over the next 65 days of 5.6 x 10(50) erg. The exceptional luminosity of SN 2008es requires an efficient conversion of kinetic energy produced from the core-collapse explosion into radiation. We favor a model in which the large peak luminosity is a consequence of the core collapse of a progenitor star with a low-mass extended hydrogen envelope and a stellar wind with a density close to the upper limit on the mass-loss rate measured from the lack of an X-ray detection by the Swift X-Ray Telescope.Item From Shock Breakout To Peak And Beyond: Extensive Panchromatic Observations Of The Type Ib Supernova 2008D Associated With Swift X-Ray Transient 080109(2009-09) Modjaz, M.; Li, W.; Butler, N.; Chornock, Ryan; Perley, D.; Blondin, S.; Bloom, Joshua S.; Filippenko, Alexei V.; Kirshner, Robert P.; Kocevski, D.; Poznanski, D.; Hicken, M.; Foley, Ryan J.; Stringfellow, Guy S.; Berlind, Perry; Navascues, D. B. Y.; Blake, C. H.; Bouy, H.; Brown, Warren R.; Challis, Peter; Chen, H.; de Vries, W. H.; Dufour, Patrick; Falco, E.; Friedman, A.; Ganeshalingam, Mohan; Garnavich, Peter; Holden, B.; Illingworth, G.; Lee, N.; Liebert, James; Marion, G. H.; Olivier, S. S.; Prochaska, J. X.; Silverman, Jeffrey M.; Smith, N.; Starr, D.; Steele, Thea N.; Stockton, A.; Williams, G. G.; Wood-Vasey, W. M.; Marion, G.H.We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift X-ray transient (XRT) 080109. Our data span a time range of 5 hr before the detection of the X-ray transient to 150 days after its detection, and a detailed analysis allowed us to derive constraints on the nature of the SN and its progenitor; throughout we draw comparisons with results presented in the literature and find several key aspects that differ. We show that the X-ray spectrum of XRT 080109 can be fit equally well by an absorbed power law or a superposition of about equal parts of both power law and blackbody. Our data first established that SN 2008D is a spectroscopically normal SN Ib (i.e., showing conspicuous He lines) and showed that SN 2008D had a relatively long rise time of 18 days and a modest optical peak luminosity. The early-time light curves of the SN are dominated by a cooling stellar envelope (for Delta t approximate to 0.1-4 days, most pronounced in the blue bands) followed by (56)Ni decay. We construct a reliable measurement of the bolometric output for this stripped-envelope SN, and, combined with estimates of E(K) and M(ej) from the literature, estimate the stellar radius R(star) of its probable Wolf-Rayet progenitor. According to the model of Waxman et al. and Chevalier & Fransson, we derive R(star)(W07) = 1.2 +/- 0.7 R(circle dot) and R(star)(CF08) = 12 +/- 7 R(circle dot), respectively; the latter being more in line with typical WN stars. Spectra obtained at three and four months after maximum light show double-peaked oxygen lines that we associate with departures from spherical symmetry, as has been suggested for the inner ejecta of a number of SN Ib cores.Item Optical Observations Of The Type Ic Supernova 2007 gr In NGC 1058(2014-08) Chen, Juncheng; Wang, Xiaofeng; Ganeshalingam, Mohan; Silverman, Jeffrey M.; Filippenko, Alexei V.; Li, Weidong; Chornock, Ryan; Li, Junzheng; Steele, Thea; Silverman, Jeffrey M.We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t = -8 days) shows a possible signature of helium (He I lambda 5876 at a velocity of similar to 19,000 km s(-1)). Moreover, the larger intensity ratio of the [O I] lambda 6300 and lambda 6364 lines inferred from the early nebular spectra implies a lower opacity of the ejecta shortly after the explosion. These results indicate that SN 2007gr perhaps underwent a less energetic explosion of a smaller-mass Wolf-Rayet star (similar to 8-9 M-circle dot) in a binary system, as favored by an analysis of the progenitor environment through pre-explosion and post-explosion Hubble Space Telescope images. In the nebular spectra, asymmetric double-peaked profiles can be seen in the [O I] lambda 6300 and Mg I] lambda 4571 lines. We suggest that the two peaks are contributed by the blueshifted and rest-frame components. The similarity in velocity structure and the different evolution of the strength of the two components favor an aspherical explosion with the ejecta distributed in a torus or disk-like geometry, but inside the ejecta the O and Mg have different distributions.Item Type IIb Supernova Sn 2011dh: Spectra And Photometry From The Ultraviolet To The Near-Infrared(2014-02) Marion, G. H.; Vinko, Jozsef; Kirshner, Robert P.; Foley, Ryan J.; Berlind, Perry; Bieryla, Allyson; Bloom, Joshua S.; Calkins, Michael L.; Challis, Peter; Chevalier, Roger A.; Chornock, Ryan; Culliton, Chris; Curtis, Jason L.; Esquerdo, Gilbert A.; Everett, Mark E.; Falco, Emilio E.; France, Kevin; Fransson, Claes; Friedman, Andrew S.; Garnavich, Peter; Leibundgut, Bruno; Meyer, Samuel; Smith, Nathan; Soderberg, Alicia M.; Sollerman, Jesper; Starr, Dan L.; Szklenar, Tamas; Takats, Katalin; Wheeler, J. Craig; Marion, G. H.; Vinko, Jozsef; Wheeler, J. CraigWe report spectroscopic and photometric observations of the Type IIb SN 201 ldh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2000 angstrom in the ultraviolet (UV) to 2.4 mu m in the near-infrared (NIR). Optical spectra provide line profiles and velocity measurements of H I, He I, Call, and Fe It that trace the composition and kinematics of the supernova (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 Space Telescope Imaging Spectrograph reveals that the UV flux for SN 2011dh is low compared to other SN IIb. Modeling the spectrum with SYNOW suggests that the UV deficit is due to line blanketing from TinH and Co II. The HI and He I velocities in SN 2011dh are separated by about 4000 km s(-1) at all phases. A velocity gap is consistent with models for a preexplosion structure in which a hydrogen-rich shell surrounds the progenitor. We estimate that the H shell of SN 2011dh is approximate to 8 times less massive than the shell of SN 1993J and approximate to 3 times more massive than the shell of SN 2008ax. Light curves (LCs) for 12 passbands are presented: UVW2, UVM2, UVW1, U, u', B, V, r', i', J, H, and Ks. In the B band, SN 2011dh reached peak brightness of 13.17 mag at 20.0 +/- 0.5 after the explosion. The maximum bolometric luminosity of 1.8 +/- 0.2 x 10(42) erg s(-1) occurred approximate to 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations, and the NIR contribution 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 LCs of SN 2011dh, SN 2008ax, and SN 1993J. The LC are very different for the first 12 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 have a wide range of masses. SN 2011dh was well observed, and a likely progenitor star has been identified in preexplosion images. The detailed observations presented here will help evaluate theoretical models for this SN and lead to a better understanding of SN IIb.