Publication Date:
2013-11-14
Description:
The Type Ia supernova (SN Ia) SN 2000cx was one of the most peculiar transients ever discovered, with a rise to maximum brightness typical of a SN Ia, but a slower decline and a higher photospheric temperature. 13 yr later SN 2013bh (also known as iPTF13abc), a near identical twin, was discovered and we obtained optical and near-infrared photometry and low-resolution optical spectroscopy from discovery until about 1 month past r -band maximum brightness. The spectra of both objects show iron-group elements [Co ii , Ni ii , Fe ii , Fe iii and high-velocity features (HVFs) of Ti ii ], intermediate-mass elements (Si ii , Si iii and S ii ) and separate normal velocity features (~12 000 km s –1 ) and HVFs (~24 000 km s –1 ) of Ca ii . Persistent absorption from Fe iii and Si iii , along with the colour evolution, implies high blackbody temperatures for SNe 2013bh and 2000cx (~12 000 K). Both objects lack narrow Na i D absorption and exploded in the outskirts of their hosts, indicating that the SN environments were relatively free of interstellar or circumstellar material and may imply that the progenitors came from a relatively old and low-metallicity stellar population. Models of SN 2000cx, seemingly applicable to SN 2013bh, imply the production of up to ~1 M of 56 Ni and (4.3–5.5) 10 –3 M of fast-moving Ca ejecta.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
Permalink