Progenitor, environment, and modelling of the interacting transient, AT 2016jbu (Gaia16cfr)

Abstract

In the second of two papers on the peculiar interacting transient AT 2016jbu, we present the bolometric lightcurve, identification and analysis of the progenitor candidate, as well as preliminary modelling to help elucidate the nature of this event. We identify the progenitor candidate for AT 2016jbu in quiescence, and find it to be consistent with a ∼ 20 M yellow hypergiant surrounded by a dusty circumstellar shell. 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 resolved stellar population surrounding AT 2016jbu, as well as integral-field unit spectra of the region support a progenitor age of >16 Myr, again consistent with a progenitor mass of ∼20 M . Through a joint analysis of the velocity evolution of AT 2016jbu, and the photospheric radius inferred from the bolometric lightcurve, we find that the transient is consistent with two successive outbursts or explosions. The first outburst ejected a shell of 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, as the required ejecta mass is relatively low (few tenths of M ). We also place a restrictive upper limit on the ejected 56 Ni mass of <0.016 M . Using the BPASS code, we explore a wide range of possible progenitor systems, and find that the majority of these are in binaries, some of which are undergoing mass transfer or common envelope evolution immediately prior to explosion. Finally, we use the SNEC code to demonstrate that the low-energy explosion of some of these systems together with sufficient CSM can reproduce the overall morphology of the lightcurve of AT 2016jbu.

SN 2019zrk, a bright SN 2009ip analog with a precursor

“…The high mass range for the progenitors of the 09ip-class of SNe has been questioned by Kilpatrick et al (2018) and Brennan et al (2021b) in relation to AT 2016jbu. For this SN, multiband HST photometry of the progenitor ∼ 10 years before the main event indicate a yellow hypergiant with mass 17 − 22 M (Brennan et al 2021b), which is also consistent with the local stellar population in the neighborhood.…”

“…The low limits for the 56 Ni production, discussed above, may be a problem for stars with ZAMS masses > ∼ 12 M , while lower masses only produce smaller amounts of 56 Ni, compatible with the limits for the 09ip-class. Brennan et al (2021b) and Pastorello et al (2019) also discuss luminous red novae, proposed as a result of mergers between two massive stars as a possible channel for the 09ip-class of SNe. As Brennan et al (2021b) point out, the peak magnitudes of these mergers are, however, ∼ 3 mags fainter than the peak magnitude of SN 2009ip and AT 2016jbu, and ∼ 4 mag fainter compared to SN 2019zrk.…”

“…Brennan et al (2021b) and Pastorello et al (2019) also discuss luminous red novae, proposed as a result of mergers between two massive stars as a possible channel for the 09ip-class of SNe. As Brennan et al (2021b) point out, the peak magnitudes of these mergers are, however, ∼ 3 mags fainter than the peak magnitude of SN 2009ip and AT 2016jbu, and ∼ 4 mag fainter compared to SN 2019zrk.…”

The Automated Photometry Of Transients (AutoPhOT) pipeline

“…With the deprecation of Python 2 and popular photometry packages within IRAF, AutoPhOT provides accurate photometry with little User setup or monitoring. AutoPhOT has already been used in several scientific publications (Chen et al 2021, Fraser et al 2021, Brennan et al 2021a, Brennan et al 2021b at the time of writing.…”

Binary pathways to SLSNe-I: SN 2017gci

“…These simulations have a wide scope and have been used in a large array of applications: to better understand and age stellar populations (e.g. Wofford et al 2016;Stevance et al 2020b;Brennan et al 2021), study nebular emission (e.g Xiao et al 2018Xiao et al , 2019, investigate the reionization of the universe (e.g Stanway et al 2016;Ma et al 2016), and predict binary black-hole mergers , to name a few. Our main goal is to check whether matching progenitors can be found natively in stellar evolution models that self-consistently recreate the characteristics of stellar populations found in the Universe.…”