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

Unburned carbon is potentially a powerful probe of Type Ia supernova (SN)explosion mechanisms. We present comprehensive optical and near-infrared (NIR)data on the "transitional" Type Ia SN 2015bp. An early NIR spectrum ($t = -$9.9days with respect to B-band maximum) displays a striking C I$\lambda1.0693\,\mu \rm{m}$ line at $11.9 \times 10^3$~km s$^{-1}$, distinctfrom the prominent Mg II $\lambda1.0927\,\mu \rm{m}$ feature, which weakenstoward maximum light. SN 2015bp also displays a clear C II $\lambda6580$A notchearly ($t = -10.9$ days) at $13.2 \times 10^3$~km s$^{-1}$, consistent with ourNIR carbon detection. At $M_B = -$18.46, SN 2015bp is less luminous than anormal SN Ia and, along with iPTF13ebh, is the second member of thetransitional subclass to display prominent early-time NIR carbon absorption. Wefind it unlikely that the C I feature is misidentified He I$\lambda1.0830\,\mu\rm{m}$ because this feature grows weaker toward maximumlight, while the helium line produced in some double-detonation models growsstronger at these times. Intrigued by these strong NIR carbon detections, butlacking NIR data for other SNe Ia, we investigated the incidence of opticalcarbon in the sample of nine transitional SNe Ia with early-time data ($t\lesssim-$4 days). We find that four display C II $\lambda$6580A, while twoothers show tentative detections, in line with the SN Ia population as a whole.We conclude that at least $\sim$50% of transitional SNe Ia in our sample do notcome from sub-Chandrasekhar mass explosions due to the clear presence of carbonin their NIR and optical spectra.

Strong Near-Infrared Carbon Absorption in the Transitional Type Ia SN 2015bp