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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Calcium rich gap transients represent an intriguing new class of faint andfast evolving supernovae that exhibit strong [Ca II] emission in their nebularphase spectra. In this paper, we present the discovery and follow-upobservations of iPTF 16hgs -- an intermediate luminosity and fast evolvingtransient that exhibited a double peaked light curve. Exhibiting a typical TypeIb spectrum in the photospheric phase and an early transition to a [Ca II]dominated nebular phase, we show that iPTF 16hgs shows properties consistentwith the class of Ca-rich gap transients, with two interesting exceptions.First, while the second peak of the light curve is similar to other Ca-rich gaptransients (suggesting $M_{ej}$ of 0.4 M$_\odot$ and peak luminosity of $3\times 10^{41}$ ergs s$^{-1}$), we show that the first blue and fast declining(over $2$ days) peak is unique to this source. Second, with Integral Field Unitobservations of the host galaxy, we find that iPTF 16hgs occurred in theoutskirts (projected offset of $6$ kpc $ = 1.9 R_{eff}$) of a low metallicity(0.4 Z$_\odot$), star forming, dwarf spiral galaxy. Using deep late-time VLAand uGMRT observations, we place stringent limits on the local environment ofthe source, ruling out a large parameter space of circumstellar densities andmass loss environments of the progenitor. If iPTF 16hgs shares explosionphysics with the class of Ca-rich gap transients, the presence of the firstpeak can be explained by enhanced mixing of 0.01 M$_\odot$ of $^{56}$Ni intothe outer layers the ejecta, reminiscent of some models of He-shell detonationson WDs. On the other hand, if iPTF 16hgs is physically unrelated to the class,the first peak is consistent with shock cooling emission (of an envelope with amass of 0.08 M$_\odot$ and radius of 13 R$_\odot$) associated with acore-collapse explosion of a highly stripped massive star in a close binarysystem.

iPTF 16hgs: A double-peaked Ca-rich gap transient in a metal poor, star forming dwarf galaxy