اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe possible detection of a binary companion to a Type Ibn supernova progenitor
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We present late-time observations of the site of the Type Ibn supernova (SN) 2006jc acquired with the Hubble Space Telescope Advanced Camera for Surveys. A faint blue source is recovered at the SN position with brightness $m_{F435W}=26.76pm0.20$, $m_{F555W}=26.60pm0.23$ and $m_{F625W} = 26.32pm0.19$ mags, although there is no detection in a contemporaneous narrow-band $mathrm{Halpha}$ image. The spectral energy distribution of the late-time source is well fit by a stellar-like spectrum ($log T_{eff} > 3.7$ and $log L / L_{odot} > 4$) subject to only a small degree of reddening consistent with that estimated for SN~2006jc itself at early-times. The lack of further outbursts after the explosion of SN~2006jc suggests that the precursor outburst originated from the progenitor. The possibility of the source being a compact host cluster is ruled out on the basis of the sources faintness, however the possibility that the late-time source maybe an unresolved light echo originating in a shell or sphere of pre-SN dust (within a radius $1mathrm{pc}$) is also discussed. Irrespective of the nature of the late-time source, these observations rule out a luminous blue variable as a companion to the progenitor of SN~2006jc.
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We present our photometric and spectroscopic observations on the peculiar transient AT2018cow. The multi-band photometry covers from peak to $sim$70 days and the spectroscopy ranges from 5 to $sim$50 days. The rapid rise ($t_{mathrm{r}}$$lesssim$2.9
days), high luminosity ($M_{V,mathrm{peak}}sim-$20.8 mag) and fast decline after peak make AT2018cow stand out of any other optical transients. While we find that its light curves show high resemblance to those of type Ibn supernovae. Moreover, the spectral energy distribution remains high temperature of $sim$14,000 K after $sim$15 days since discovery. The spectra are featureless in the first 10 days, while some broad emission lines due to H, He, C and O emerge later, with velocity declining from $sim$14,000 km s$^{-1}$ to $sim$3000 km s$^{-1}$ at the end of our observations. Narrow and weak He I emission lines emerge in the spectra at $t>$20 days since discovery. These emission lines are reminiscent of the features seen in interacting supernovae like type Ibn and IIn subclasses. We fit the bolometric light curves with a model of circumstellar interaction (CSI) and radioactive decay (RD) of Ni and find a good fit with ejecta mass $M_{mathrm{ej}}sim$3.16 M$_{odot}$, circumstellar material mass $M_{mathrm{CSM}}sim$0.04 M$_{odot}$, and ejected Ni mass $M_{^{56}mathrm{Ni}}sim$0.23 M$_{odot}$. The CSM shell might be formed in an eruptive mass ejection of the progenitor star. Furthermore, host environment of AT2018cow implies connection of AT2018cow with massive stars. Combining observational properties and the light curve fitting results, we conclude that AT2018cow might be a peculiar interacting supernova originated from a massive star.
We have identified a progenitor candidate in archival Hubble Space Telescope (HST) images for the Type Ic SN 2017ein in NGC 3938, pinpointing the candidates location via HST Target-of-Opportunity imaging of the SN itself. This would be the first iden
tification of a stellar-like object as a progenitor candidate for any Type Ic supernova to date. We also present observations of SN 2017ein during the first ~49 days since explosion. We find that SN 2017ein most resembles the well-studied Type Ic SN 2007gr. We infer that SN 2017ein experienced a total visual extinction of A_V~1.0--1.9 mag, predominantly because of dust within the host galaxy. Although the distance is not well known, if this object is the progenitor, it was likely of high initial mass, ~47--48 M_sun if a single star, or ~60--80 M_sun if in a binary system. However, we also find that the progenitor candidate could be a very blue and young compact cluster, further implying a very massive (>65 M_sun) progenitor. Furthermore, the actual progenitor might not be associated with the candidate at all and could be far less massive. From the immediate stellar environment, we find possible evidence for three different populations; if the SN progenitor was a member of the youngest population, this would be consistent with an initial mass of ~57 M_sun. After it has faded, the SN should be reobserved at high spatial resolution and sensitivity, to determine whether the candidate is indeed the progenitor.
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