Browsing by Author "Schmidt, B. P."

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    450 d of Type II SN 2013ej in optical and near-infrared
    (OXFORD UNIV PRESS, 2016) Yuan, Fang; Jerkstrand, A.; Valenti, S.; Sollerman, J.; Seitenzahl, I. R.; Pastorello, A.; Schulze, S.; Chen, T. W.; Childress, M. J.; Fraser, M.; Fremling, C.; Kotak, R.; Ruiter, A. J.; Schmidt, B. P.; Smartt, S. J.; Taddia, F.; Terreran, G.; Tucker, B. E.; Barbarino, C.; Benetti, S.; Elias Rosa, N.; Gal Yam, A.; Howell, D. A.; Inserra, C.; Kankare, E.; Lee, M. Y.; Li, K. L.; Maguire, K.; Margheim, S.; Mehner, A.; Ochner, P.; Sullivan, M.; Tomasella, L.; Young, D. R.
    We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450 d after the explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due to its relatively fast decline following the initial peak. It has a relatively high peak luminosity (absolute magnitude M-V =-17.6) but a small 56Ni production of similar to 0.023 M-circle dot. Its photospheric evolution is similar to other Type II SNe, with shallow absorption in the H a profile typical for a Type IIL. During transition to the radioactive decay tail at similar to 100 d, we find the SN to grow bluer in B - V colour, in contrast to some other Type II supernovae. At late times, the bolometric light curve declined faster than expected from Co-56 decay and we observed unusually broad and asymmetric nebular emission lines. Based on comparison of nebular emission lines most sensitive to the progenitor core mass, we find our observations are best matched to synthesized spectral models with a M-ZAMS = 12-15 M-circle dot progenitor. The derived mass range is similar to but not higher than the mass estimated for Type IIP progenitors. This is against the idea that Type IIL are from more massive stars. Observations are consistent with the SN having a progenitor with a relatively low-mass envelope.
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    A high obliquity orbit for the hot-jupiter Hats-14b Transiting A 5400 K Star
    (2015) Zhou, G.; Bayliss, D.; Hartman, J. D.; Fulton, B. J.; Bakos, G. Á.; Howard, A. W.; Isaacson, H.; Marcy, G. W.; Schmidt, B. P.; Jordán Colzani, Andrés Cristóbal; Brahm, R.
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    On the nature of hydrogen-rich superluminous supernovae
    (2018) Inserra, C.; Smartt, S. J.; Gall, E. E. E.; Leloudas, G.; Chen, T-W.; Schulze, S.; Jerkstrand, A.; Nicholl, M.; Anderson, J. P.; Arcavi, I.; Benetti, S.; Cartier, R. A.; Childress, M.; Della Valle, M.; Flewelling, H.; Fraser, M.; Gal-Yam, A.; Gutierrez, C. P.; Hosseinzadeh, G.; Howell, D. A.; Huber, M.; Kankare, E.; Kruehler, T.; Magnier, E. A.; Maguire, K.; McCully, C.; Prajs, S.; Primak, N.; Scalzo, R.; Schmidt, B. P.; Smith, M.; Smith, K. W.; Tucker, B. E.; Valenti, S.; Wilman, M.; Young, D. R.; Yuan, F.
    We present two hydrogen-rich superluminous supernovae (SLSNe): SN2103hx and PS 15br. These objects, together with SN2008es, are the only SLSNe showing a distinct, broad H alpha feature during the photospheric phase; also, they show no sign of strong interaction between fast moving ejecta and circumstellar shells in their early spectra. Despite the fact that the peak luminosity of PS 15br is fainter than that of the other two objects, the spectrophotometric evolution is similar to SN2103hx and different from any other supernova in a similar luminosity space. We group all of them as SLSNe II and hence they are distinct from the known class of SLSN IIn. Both transients show a strong, multicomponent H alpha emission after 200 d past maximum, which we interpret as an indication of the interaction of the ejecta with an asymmetric, clumpy circumstellar material. The spectra and photometric evolution of the two objects are similar to Type II supernovae, although they have much higher luminosity and evolve on slower time-scales. This is qualitatively similar to how SLSNe I compare with normal type Ic, in that the former are brighter and evolve more slowly. We apply a magnetar and an interaction semi-analytical code to fit the light curves of our two objects and SN2008es. The overall observational data set would tend to favour the magnetar, or central engine, model as the source of the peak luminosity, although the clear signature of late-time interaction indicates that interaction can play a role in the luminosity evolution of SLSNe II at some phases.