| 1. |
- Fox, Ori D., et al.
(författare)
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UNCOVERING THE PUTATIVE B-STAR BINARY COMPANION OF THE SN 1993J PROGENITOR
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 790:1, s. 17-
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Tidskriftsartikel (refereegranskat)abstract
- The Type IIb supernova (SN) 1993J is one of only a few stripped-envelope SNe with a progenitor star identified in pre-explosion images. SN IIb models typically invoke H envelope stripping by mass transfer in a binary system. For the case of SN 1993J, the models suggest that the companion grew to 22M(circle dot) and became a source of ultraviolet (UV) excess. Located in M81, at a distance of only 3.6 Mpc, SN 1993J offers one of the best opportunities to detect the putative companion and test the progenitor model. Previously published near-UV spectra in 2004 showed evidence for absorption lines consistent with a hot (B2 Ia) star, but the field was crowded and dominated by flux from the SN. Here we present Hubble Space Telescope Cosmic Origins Spectrograph and Wide-Field Camera 3 observations of SN 1993J from 2012, at which point the flux from the SN had faded sufficiently to potentially measure the UV continuum properties from the putative companion. The resulting UV spectrum is consistent with contributions from both a hot B star and the SN, although we cannot rule out line-of-sight coincidences.
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| 2. |
- Silverman, Jeffrey M., et al.
(författare)
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SN 2000cx and SN 2013bh : extremely rare, nearly twin Type Ia supernovae
- 2013
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 436:2, s. 1225-1237
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Tidskriftsartikel (refereegranskat)abstract
- 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 (similar to 12 000 km s(-1)) and HVFs (similar to 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 (similar to 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 similar to 1 M-circle dot of Ni-56 and (4.3-5.5) x 10(-3) M-circle dot of fast-moving Ca ejecta.
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| 3. |
- Stritzinger, Maximilian, et al.
(författare)
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Multi-wavelength Observations of the Enduring Type IIn Supernovae 2005ip and 2006jd
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 756:2
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Tidskriftsartikel (refereegranskat)abstract
- We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broadband UV, optical, and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Our observations of SN 2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are compared to reported X-ray measurements to understand the nature of the progenitor. Both objects display a number of similarities with the 1988Z-like subclass of SN IIn including (1) remarkably similar early- and late-phase optical spectra, (2) a variety of high-ionization coronal lines, (3) long-duration optical and near-IR emission, and (4) evidence of cold and warm dust components. However, diversity is apparent, including an unprecedented late-time r-band excess in SN 2006jd. The observed differences are attributed to differences between the mass-loss history of the progenitor stars. We conclude that the progenitor of SN 2006jd likely experienced a significant mass-loss event during its pre-SN evolution akin to the great 19th century eruption of η Carinae. Contrarily, as advocated by Smith et al., the circumstellar environment of SN 2005ip is found to be more consistent with a clumpy wind progenitor.
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