Examinando por Autor "Brown, P.J."
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Ítem Massive stars exploding in a He-rich circumstellar medium - IV. Transitional type Ibn supernovae(Oxford University Press, 2015-05) Pastorello, A.; Benetti, S.; Brown, P.J.; Tsvetkov, D.Y.; Inserra, C.; Taubenberger, S.; Tomasella, L.; Fraser, M.; Rich, D.J.; Botticella, M.T.; Bufano, F.; Cappellaro, E.; Ergon, M.; Gorbovskoy, E.S.; Harutyunyan, A.; Huang, F.; Kotak, R.; Lipunov, V.M.; Magill, L.; Miluzio, M.; Morrell, N.; Ochner, P.; Smartt, S.J.; Sollerman, J.; Spiro, S.; Stritzinger, M.D.; Turatto, M.; Valenti, S.; Wang, X.; Wright, D.E.; Yurkov, V.V.; Zampieri, L.; Zhang, L.We present ultraviolet, optical and near-infrared data of the Type Ibn supernovae (SNe) 2010al and 2011hw. SN 2010al reaches an absolute magnitude at peak of MR = -18.86 ± 0.21. Its early light curve shows similarities with normal SNe Ib, with a rise to maximum slower than most SNe Ibn. The spectra are dominated by a blue continuum at early stages, with narrow P-Cygni He I lines indicating the presence of a slow-moving, He-rich circumstellar medium. At later epochs, the spectra well match those of the prototypical SN Ibn 2006jc, although the broader lines suggest that a significant amount of He was still present in the stellar envelope at the time of the explosion. SN 2011hw is somewhat different. It was discovered after the first maximum, but the light curve shows a double peak. The absolute magnitude at discovery is similar to that of the second peak (MR = -18.59 ± 0.25), and slightly fainter than the average of SNe Ibn. Though the spectra of SN 2011hw are similar to those of SN 2006jc, coronal lines and narrow Balmer lines are clearly detected. This indicates substantial interaction of the SN ejecta with He-rich, but not H-free, circumstellar material. The spectra of SN 2011hw suggest that it is a transitional SN Ibn/IIn event similar to SN 2005la. While for SN 2010al the spectrophotometric evolution favours a H-deprived Wolf-Rayet progenitor (of WN-type), we agree with the conclusion of Smith et al. that the precursor of SN 2011hw was likely in transition from a luminous blue variable to an early Wolf-Rayet (Ofpe/WN9) stage. © 2015 The Authors.Ítem Photometric and spectroscopic evolution of the interacting transient at 2016jbu(Gaia16cfr)(Oxford University Press, 2022-07-01) Brennan, S.J.; Fraser, M.; Johansson, J.; Pastorello, A.; Kotak, R.; Stevance, H.F.; Chen, T.-W.; Eldridge, J.J.; Bose, S.; Brown, P.J.; Callis, E.; Cartier, R.; Dennefeld, M.; Dong, Subo; Duffy, P.; Elias Rosa, N.; Hosseinzadeh, G.; Hsiao, E.; Kuncarayakti, H.; Martin Carrillo, A.; Monard, B.; Nyholm, A.; Pignata, G.; Sand, D.; Shappee, B.J.; Smartt, S.J.; Tucker, B.E.; Wyrzykowski, L.; Abbot, H.; Benetti, S.; Bento, J.; Blondin, S.; Chen, Ping; Delgado, A.; Galbany, L.; Gromadzki, M.; Gutierrez, C.P.; Hanlon, L.; Harrison, D.L.; Hiramatsu, D.; Hodgkin, S.T.; Holoien, T.W.-S.; Howell, D.A.; Inserra, C.; Kankare, E.; Kozłowski, S.; Müller Bravo, T.E.; Maguire, K.; McCully, C.; Meintjes, P.; Morrell, N.; Nicholl, M.; O'Neill, D.; Pietrukowicz, P.; Poleski, R.; Prieto, J.L.; Rau, A.; Reichart, D.E.; Schweyer, T.; Shahbandeh, M.; Skowron, J.; Sollerman, J.; Soszyński, I.; Stritzinger, M.D.; Szymański, M.; Tartaglia, L.; Udalski, A.; Ulaczyk, K.; Young, D.R.; Van Leeuwen, M.; Van Soelen, B.We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼-18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s-1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s-1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He i, and Ca ii. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem Progenitor, environment, and modelling of the interacting transient AT 2016jbu (Gaia16cfr)(Oxford University Press, 2022-07-01) Brennan, S.J.; Fraser, M.; Johansson, J.; Pastorello, A.; Kotak, R.; Stevance, H.F.; Chen, T.-W.; Eldridge, J.J.; Bose, S.; Brown, P.J.; Callis, E.; Cartier, R.; Dennefeld, M.; Dong, Subo; Duffy, P.; Elias Rosa, N.; Hosseinzadeh, G.; Hsiao, E.; Kuncarayakti, H.; Martin Carrillo, A.; Monard, B.; Pignata, G.; Sand, D.; Shappee, B.J.; Smartt, S.J.; Tucker, B.E.; Wyrzykowski, L.; Abbot, H.; Benetti, S.; Bento, J.; Blondin, S.; Chen, Ping; Delgado, A.; Galbany, L.; Gromadzki, M.; Gutierrez, C.P.; Hanlon, L.; Harrison, D.L.; Hiramatsu, D.; Hodgkin, S.T.; Holoien, T.W.-S.; Howell, D.A.; Inserra, C.; Kankare, E.; Kozłowski, S.; Müller Bravo, T.E.; Maguire, K.; Mccully, C.; Meintjes, P.; Morrell, N.; Nicholl, M.; O'neill, D.; Pietrukowicz, P.; Poleski, R.; Prieto, J.L.; Rau, A.; Reichart, D.E.; Schweyer, T.; Shahbandeh, M.; Skowron, J.; Sollerman, J.; Soszyński, I.; Stritzinger, M.D.; Szymański, M.; Tartaglia, L.; Udalski, A.; Ulaczyk, K.; Young, D.R.; Van Leeuwen, M.; Van Soelen, B.We present the bolometric light curve, identification and analysis of the progenitor candidate, and preliminary modelling of AT 2016jbu (Gaia16cfr). We find a progenitor consistent with a ∼22-25 M⊙ yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong Hα emission consistent with pre-existing circumstellar material. The age of the environment, as well as the resolved stellar population surrounding AT 2016jbu, supports a progenitor age of >10 Myr, consistent with a progenitor mass of ∼22 M⊙. A joint analysis of the velocity evolution of AT 2016jbu and the photospheric radius inferred from the bolometric light curve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity ∼650 km s-1, while the second, more energetic event ejected material at ∼4500 km s-1. Whether the latter is the core collapse of the progenitor remains uncertain. We place a limit on the ejected 56Ni mass of [removed]Ítem SN 2021fxy: mid-ultraviolet flux suppression is a common feature of Type Ia supernovae(Oxford University Press, 2023-07-01) DerKacy, J.M.; Paugh, S.; Baron, E.; Brown, P.J.; Ashall, C.; Burns, C.R.; Hsiao, E.Y.; Kumar, S.; Lu, J.; Morrell, N.; Phillips, M.M.; Shahbandeh, M.; Shappee, B.J.; Stritzinger, M.D.; Tucker, M.A.; Yarbrough, Z.; Boutsia, K.; Hoeflich, P.; Wang, L.; Galbany, L.; Karamehmetoglu, E.; Krisciunas, K.; Mazzali, P.; Piro, A.L.; Suntzeff, N.B.; Fiore, A.; Gutiérrez, C.P.; Lundqvist, P.; Reguitti, A.We present ultraviolet (UV) to near-infrared (NIR) observations and analysis of the nearby Type Ia supernova SN 2021fxy. Our observations include UV photometry from Swift/UVOT, UV spectroscopy from HST/STIS, and high-cadence optical photometry with the Swope 1-m telescope capturing intranight rises during the early light curve. Early B − V colours show SN 2021fxy is the first 'shallow-silicon' (SS) SN Ia to follow a red-to-blue evolution, compared to other SS objects which show blue colours from the earliest observations. Comparisons to other spectroscopically normal SNe Ia with HST UV spectra reveal SN 2021fxy is one of several SNe Ia with flux suppression in the mid-UV. These SNe also show blueshifted mid-UV spectral features and strong high-velocity Ca II features. One possible origin of this mid-UV suppression is the increased effective opacity in the UV due to increased line blanketing from high velocity material, but differences in the explosion mechanism cannot be ruled out. Among SNe Ia with mid-UV suppression, SNe 2021fxy and 2017erp show substantial similarities in their optical properties despite belonging to different Branch subgroups, and UV flux differences of the same order as those found between SNe 2011fe and 2011by. Differential comparisons to multiple sets of synthetic SN Ia UV spectra reveal this UV flux difference likely originates from a luminosity difference between SNe 2021fxy and 2017erp, and not differing progenitor metallicities as suggested for SNe 2011by and 2011fe. These comparisons illustrate the complicated nature of UV spectral formation, and the need for more UV spectra to determine the physical source of SNe Ia UV diversity. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem Two transitional type Ia supernovae located in the Fornax cluster member NGC 1404: SN 2007on and SN 2011iv(EDP Sciences, 2018-03) Gall, C.; Stritzinger, M.D.; Ashall, C.; Baron, E.; Burns, C.R.; Hoeflich, P.; Hsiao, E.Y.; Mazzali, P.A.; Phillips, M.M.; Filippenko, A.V.; Anderson, J.P.; Benetti, S.; Brown, P.J.; Campillay, A.; Challis, P.; Contreras, C.; Elias De La Rosa, N.; Folatelli, G.; Foley, R.J.; Fraser, M.; Holmbo, S.; Marion, G.H.; Morrell, N.; Pan, Y.-C.; Pignata, G.; Suntzeff, N.B.; Taddia, F.; Robledo, S.T.; Valenti, S.We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Δm 15 (B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B- and H-band magnitudes differ by ~ 0.60 mag and ~0.35 mag, respectively. After correcting for the luminosity vs. decline rate and the luminosity vs. colour relations, the peak B-band and H-band light curves provide distances that differ by ~ 14% and ~ 9%, respectively. These findings serve as a cautionary tale for the use of transitional SNe Ia located in early-type hosts in the quest to measure cosmological parameters. Interestingly, even though SN 2011iv is brighter and bluer at early times, by three weeks past maximum and extending over several months, its B - V colour is 0.12 mag redder than that of SN 2007on. To reconcile this unusual behaviour, we turn to guidance from a suite of spherical one-dimensional Chandrasekhar-mass delayed-detonation explosion models. In this context, 56 Ni production depends on both the so-called transition density and the central density of the progenitor white dwarf. To first order, the transition density drives the luminosity-width relation, while the central density is an important second-order parameter. Within this context, the differences in the B - V colour evolution along the Lira regime suggest that the progenitor of SN 2011iv had a higher central density than SN 2007on. © ESO 2018.