Examinando por Autor "Folatelli, Gaston"
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Ítem A Multiwavelength View of the Rapidly Evolving SN 2018ivc: An Analog of SN IIb 1993J but Powered Primarily by Circumstellar Interaction(Institute of Physics, 2023-01-01) Maeda, Keiichi; Chandra, Poonam; Moriya, Takashi J.; Reguitti, Andrea; Ryder, Stuart; Matsuoka, Tomoki; Michiyama, Tomonari; Pignata, Giuliano; Hiramatsu, Daichi; Bostroem, K. Azalee; Kundu, Esha; Kuncarayakti, Hanindyo; Bersten, Melina C.; Pooley, David; Lee, Shiu-Hang; Patnaude, Daniel; Rodríguez, Ósmar; Folatelli, GastonSN 2018ivc is an unusual Type II supernova (SN II). It is a variant of SNe IIL, which might represent a transitional case between SNe IIP with a massive H-rich envelope and SNe IIb with only a small amount of the H-rich envelope. However, SN 2018ivc shows an optical light-curve evolution more complicated than that of canonical SNe IIL. In this paper, we present the results of prompt follow-up observations of SN 2018ivc with the Atacama Large Millimeter/submillimeter Array. Its synchrotron emission is similar to that of SN IIb 1993J, suggesting that it is intrinsically an SN IIb-like explosion of an He star with a modest (∼0.5-1M ⊙) extended H-rich envelope. Its radio, optical, and X-ray light curves are explained primarily by the interaction between the SN ejecta and the circumstellar material (CSM); we thus suggest that it is a rare example (and the first involving the “canonical” SN IIb ejecta) for which the multiwavelength emission is powered mainly by the SN-CSM interaction. The inner CSM density, reflecting the progenitor activity in the final decade, is comparable to that of SN IIb 2013cu, which shows a flash spectral feature. The outer CSM density, and therefore the mass-loss rate in the final ∼200 yr, is higher than that of SN 1993J by a factor of ∼5. We suggest that SN 2018ivc represents a missing link between SNe IIP and SNe IIb/Ib/Ic in the binary evolution scenario. © 2022. The Author(s). Published by the American Astronomical Society.Ítem Persistent C II absorption in the normal type Ia supernova 2002fk(Institute of Physics Publishing, 2014-07) Cartier, Régis; Hamuy, Mario; Pignata, Giuliano; Förster, Francisco; Förster, Francisco; Folatelli, Gaston; Phillips, Mark M.; Morrell, Nidia; Krisciunas, Kevin; Suntzeff, Nicholas B.; Clocchiatti, Alejandro; Coppi, Paolo; Contreras, Carlos; Roth, Miguel; Koviak, Kathleen; Koviak, Kathleen; González, Luis; González, Sergio; Huerta, LeonorWe present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from −4 to +95 days since maximum. Our observations show the presence of C ii lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s−1 and persisting until 8 days past maximum light with a velocity of ∼9000 km s−1. SN 2002fk is characterized by a small velocity gradient of v˙Si ii = 26 km s−1 day−1, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C ii in the early-time spectrum suggests that the observation of Cii could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H0 value based on near infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s−1 Mpc−1, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%–9%) H0 values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H0.