Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra
Michael J. Childress, D. John Hillier, Ivo Seitenzahl, Mark Sullivan, Kate Maguire, Stefan Taubenberger, Richard Scalzo, Ashley Ruiter, Nadejda Blagorodnova, Ys… 展开作者
Michael J. Childress, D. John Hillier, Ivo Seitenzahl, Mark Sullivan, Kate Maguire, Stefan Taubenberger, Richard Scalzo, Ashley Ruiter, Nadejda Blagorodnova, Yssavo Camacho, Jayden Castillo, Nancy Elias-Rosa, Morgan Fraser, Avishay Gal-Yam, Melissa Graham, D. Andrew Howell, Cosimo Inserra, Saurabh W. Jha, Sahana Kumar, Paolo A. Mazzali, Curtis McCully, Antonia Morales-Garoffolo, Viraj Pandya, Joe Polshaw, Brian Schmidt, Stephen Smartt, Ken W. Smith, Jesper Sollerman, Jason Spyromilio, Brad Tucker, Stefano Valenti, Nicholas Walton, Christian Wolf, Ofer Yaron, D. R. Young, Fang Yuan, Bonnie Zhang
备注：
16 pages, 12 figures (main text), plus data tables in appendix. Spectra released on WISeREP. Submitted to MNRAS, comments welcome
The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of $^{56}$Ni to $^{56}$Co at early times, and the decay of $^{56}$Co to $^{56}$Fe from ~60 days after explosion. We examine the evolution of the [Co III] 5892 A emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of $^{56}$Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in $^{56}$Co decay, and long-term stability of the ionization state of the nebula. We compile 77 nebular spectra of 25 SN Ia from the literature and present 17 new nebular spectra of 7 SNe Ia, including SN2014J. From these we measure the flux in the [Co III] 5892 A line and remove its well-behaved time dependence to infer the initial mass of $^{56}$Ni ($M_{Ni}$) produced in the explosion. We then examine $^{56}$Ni yields for different SN Ia ejected masses ($M_{ej}$ - calculated using the relation between light curve width and ejected mass) and find the $^{56}$Ni masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s~0.7-0.9), $M_{Ni}$ is clustered near $M_{Ni}$ ~ 0.4$M_\odot$ and shows a shallow increase as $M_{ej}$ increases from ~1-1.4$M_\odot$; at high stretch, $M_{ej}$ clusters at the Chandrasekhar mass (1.4$M_\odot$) while $M_{Ni}$ spans a broad range from 0.6-1.2$M_\odot$. This could constitute evidence for two distinct SN Ia explosion mechanisms.
SN 2017ati: A luminous type IIb explosion from a massive progenitor
Chongqing University of Posts and Telecommunications（重庆邮电大学）；INAF - Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；International Centre of Supernovae, Yunnan Key Laboratory（国际超新星中心云南省重点实验室）；South-Western Institute for Astronomy Research, Yunnan Key Laboratory of Survey Science, Yunnan University（云南大学西南天文研究所云南省测绘科学重点实验室）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Ground-based and JWST Observations of SN 2022pul: I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova
