Examinando por Autor "Zheng, W."

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    500 days of SN 2013dy: Spectra and photometry from the ultraviolet to the infrared
    (Oxford University Press, 2015-07) Pan, Y.-C.; Foley, R.J.; Kromer, M.; Fox, O.D.; Zheng, W.; Challis, P.; Clubb, K.; Filippenko, A.V.; Folatelli, G.; Graham, M.L.; Hillebrandt, W.; Kirshner, R.P.; Lee, W.H.; Pakmor, R.; Patat, F.; Phillips, M.M.; Pignata, G.; Röpke, F.; Seitenzahl, I.; Silverman, J.M.; Simon, J.D.; Sternberg, A.; Stritzinger, M.D.; Taubenberger, S.; Vinko, J.; Wheeler, J.C.
    SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to ~ 500 d after explosion. We present 10 epochs of ultraviolet (UV) through near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), and more than 500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and slowly declining light curve (Δm15(B)=0.92 mag), shallow Si II λ6355 absorption, and a low velocity gradient. We detect strong C II in our earliest spectra, probing unburned progenitor material in the outermost layers of the SN ejecta, but this feature fades within a few days. The UV continuum of SN 2013dy, which is strongly affected by the metal abundance of the progenitor star, suggests that SN 2013dy had a relatively high-metallicity progenitor. Examining one of the largest single set of high-resolution spectra for an SN Ia, we find no evidence of variable absorption from circumstellar material. Combining our UV spectra, NIR photometry, and high-cadence optical photometry, we construct a bolometric light curve, showing that SN 2013dy had a maximum luminosity of 10.0+4.8 -3.8 × 1042 erg s-1. We compare the synthetic light curves and spectra of several models to SN 2013dy, finding that SN 2013dy is in good agreement with a solar-metallicity W7 model. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
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    Extensive HST ultraviolet spectra and multiwavelength observations of SN 2014J in M82 indicate reddening and circumstellar scattering by typical dust
    (Oxford University Press, 2014) Foley, Ryan J.; Fox, O.D.; McCully, C.; Phillips, M.M.; Sand, D.J.; Zheng, W.; Challis, P.; Filippenko, A.V.; Folatelli, G.; Hillebrandt, W.; Hsiao, E.Y.; Jha, S.W.; Kirshner, R.P.; Kromer, M.; Marion, G.H.; Nelso, M.; Pakmor, R.; Pignata, G.; R̈opke, F.K.; Seitenzahl, I.R.; Silverman, J.M.; Skrutskie, M.; Stritzinger, M.D.
    SN 2014J in M82 is the closest detected Type Ia supernova (SN Ia) in at least 28 yr and perhaps in 410 yr. Despite its small distance of 3.3 Mpc, SN 2014J is surprisingly faint, peaking at V = 10.6 mag, and assuming a typical SN Ia luminosity, we infer an observed visual extinction of AV = 2.0 ± 0.1 mag. But this picture, with RV = 1.6 ± 0.2, is too simple to account for all observations. We combine 10 epochs (spanning a month) of HST/Space Telescope Imaging Spectrograph (STIS) ultraviolet through near-infrared spectroscopy with HST/Wide Field Camera 3 (WFC3), Katzman Automatic Imaging Telescope, and FanCam photometry from the optical to the infrared and nine epochs of high-resolution TRES (Tillinghast Reflection Echelle Spectrograph) spectroscopy to investigate the sources of extinction and reddening for SN 2014J. We argue that the wide range of observed properties for SN 2014J is caused by a combination of dust reddening, likely originating in the interstellar medium of M82, and scattering off circumstellar material. For this model, roughly half of the extinction is caused by reddening from typical dust (E(B − V) = 0.45 mag and RV = 2.6) and roughly half by scattering off Large Magellanic Cloud-like dust in the circumstellar environment of SN 2014J.
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    EXTENSIVE SPECTROSCOPY AND PHOTOMETRY OF THE TYPE IIP SUPERNOVA 2013ej
    (IOP PUBLISHING, 2016) Dhungana, G.; Kehoe, R.; Vinko, J.; Silverman, J. M.; Wheeler, J. C.; Zheng, W.; Marion, G. H.; Fox, O. D.; Akerlof, C.; Biro, B. I.; Borkovits, T.; Cenko, S. B.; Clubb, K. I.; Filippenko, A. V.; Ferrante, F. V.; Gibson, C. A.; Graham, M. L.; Hegedus, T.; Kelly, P.; Kelemen, J.; Lee, W. H.; Marschalko, G.; Molnár, L.; Nagy, A. P.; Ordasi, A.; Pal, A.; Sarneczky, K.; Shivvers, I.; Szakats, R.; Szalai, T.; Szegedi-Elek, E.; Székely, P.; Szing, A.; Takáts, K.; Vida, K.
    We present extensive optical (UBV RI, g' r' i' z', and open CCD) and near-infrared (ZY JH) photometry for the very nearby Type IIP SN. 2013ej extending from + 1 to + 461 days after shock breakout, estimated to be MJD 56496.9 +/- 0.3. Substantial time series ultraviolet and optical spectroscopy obtained from + 8 to + 135 days are also presented. Considering well-observed SNe IIP from the literature, we derive UBV RIJHK bolometric calibrations from UBV RI and unfiltered measurements that potentially reach 2% precision with a B - V color-dependent correction. We observe moderately strong Si II lambda 6355 as early as + 8 days. The photospheric velocity (vph) is determined by modeling the spectra in the vicinity of Fe II lambda 5169 whenever observed, and interpolating at photometric epochs based on a semianalytic method. This gives vph= 4500. 500 km s(-1) at + 50 days. We also observe spectral homogeneity of ultraviolet spectra at + 10-12 days for SNe IIP, while variations are evident a week after explosion. Using the expanding photosphere method, from combined analysis of SN 2013ej and SN 2002ap, we estimate the distance to the host galaxy to be 9.0(-0.6)(+0.4) Mpc, consistent with distance estimates from other methods. Photometric and spectroscopic analysis during the plateau phase, which we estimated to be 94 +/- 7 days long, yields an explosion energy of 0.9 +/- 0.3 x 10(51) erg, a final pre-explosion progenitor mass of 15.2 +/- 4.2 M-circle dot and a radius of 250 +/- 70 R-circle dot. We observe a broken exponential profile beyond + 120 days, with a break point at + 183 +/- 16 days. Measurements beyond this break time yield a Ni-56 mass of 0.013 +/- 0.001. M-circle dot.
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    Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631
    (EDP Sciences, 2022-11-01) Cai, Y.-Z.; Pastorello, A.; Fraser, M.; Wang, X.-F.; Filippenko, A.V.; Reguitti, A.; Patra, K.C.; Goranskij, V.P.; Barsukova, E.A.; Brink, T.G.; Elias-Rosa, N.; Stevance, H.F.; Zheng, W.; Yang, Y.; Atapin, K.E.; Benetti, S.; De Boer, T.J.L.; Bose, S.; Burke, J.; Byrne, R.; Cappellaro, E.; Chambers, K.C.; Chen, W.-L.; Emami, N.; Gao, H.; Hiramatsu, D.; Howell, D.A.; Huber, M.E.; Kankare, E.; Kelly, P.L.; Kotak, R.; Kravtsov, T.; Lander, V. Yu.; Li, Z.-T.; Lin, C.-C.; Lundqvist, P.; Magnier, E.A.; Malygin, E.A.; Maslennikova, N.A.; Matilainen, K.; Mazzali, P.A.; Mccully, C.; Mo, J.; Moran, S.; Newsome, M.; Oparin, D.V.; Padilla Gonzalez, E.; Reynolds, T.M.; Shatsky, N.I.; Smartt, S.J.; Smith, K.W.; Stritzinger, M.D.; Tatarnikov, A.M.; Terreran, G.; Uklein, R.I.; Valerin, G.; Vallely, P.J.; Vozyakova, O.V.; Wainscoat, R.; Yan, S.-Y.; Zhang, J.-J.; Zhang, T.-M.; Zheltoukhov, S.G.; Dastidar, R.; Fulton, M.; Galbany, L.; Gangopadhyay, A.; Ge, H.-W.; Gutiérrez, C.P.; Lin, H.; Misra, K.; Ou, Z.-W.; Salmaso, I.; Tartaglia, L.; Xiao, L.; Zhang, X.-H.
    We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6×1041 erg s-1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊗ progenitor candidate with log (L/L⊗) = 5.0 dex and Teff 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊗ primary component. © Y.-Z. Cai et al. 2022.