English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present results of the photometric (from 3 to 509 days past explosion) andspectroscopic (up to 230 days past explosion) monitoring campaign of theHe-rich Type IIb supernova (SN) 2015as. The {\it (B-V)} colour evolution of SN2015as closely resemble those of SN 2008ax, suggesting that SN 2015as belongsto the SN IIb subgroup that does not show the early, short-duration photometricpeak. The light curve of SN 2015as reaches the $B$-band maximum about 22 daysafter the explosion, at an absolute magnitude of -16.82 $\pm$ 0.18 mag. At$\sim$ 75 days after the explosion, its spectrum transitions from that of a SNII to a SN Ib. P~Cygni features due to He I lines appear at around 30 daysafter explosion, indicating that the progenitor of SN 2015as was partiallystripped. For SN~2015as, we estimate a $^{56}$Ni mass of $\sim$ 0.08M$_{\odot}$ and ejecta mass of 1.1--2.2 M$_{\odot}$, which are similar to thevalues inferred for SN 2008ax. The quasi bolometric analytical light curvemodelling suggests that the progenitor of SN 2015as has a modest mass ($\sim$0.1 M$_{\odot}$), a nearly-compact ($\sim$ 0.05$\times$10$^{13}$ cm) H envelopeon top of a dense, compact ($\sim$ 2$\times$10$^{11}$ cm) and a more massive($\sim$ 1.2 M$_{\odot}$) He core. The analysis of the nebular phase spectraindicates that $\sim$ 0.44 M$_{\odot}$ of O is ejected in the explosion. Theintensity ratio of the [Ca II]/[O I] nebular lines favours either a mainsequence progenitor mass of $\sim$ 15 M$_{\odot}$ or a Wolf Rayet star of 20M$_{\odot}$.

SN 2015as: A low luminosity Type IIb supernova without an early light curve peak