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Asiago spectroscopic classification of four SNe

ATel #8361; A. Pastorello, L. Tartaglia, S. Benetti, E. Cappellaro, N. Elias-Rosa, P. Ochner, G. Terreran, L. Tomasella, M. Turatto (INAF OAPd)
on 4 Dec 2015; 09:18 UT
Credential Certification: Lina Tomasella (lina.tomasella@oapd.inaf.it)

Subjects: Optical, Supernovae

The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classifications of PS15cym in GALEXASC J011024.12+232124.1, CSS151130:014258+273410 in an anonymous galaxy, PSN J05225991-0008174 in UGC 3301 and ASASSN-15tj in SDSS J075527.63+520911.1 (ATel #8358). The targets are supplied by the Pan-STARRS Survey for Transients (see Huber et al., ATel #7153), the Catalina Real-time Transient Survey (CRTS; Drake et al. 2009, 696, 870 ; http://crts.caltech.edu/ ). the All Sky Automated Survey for SuperNovae (ASAS-SN; see Shappee et al. 2014, ApJ, 788, 48 and http://www.astronomy.ohio-state.edu/~assassin/index.shtml ), and the TOCP webpages. PSN J05225991-0008174 was discovered by R. Gagliano, D. Post, J. Newton, and T. Puckett.

Information on these transients is available from the "Bright Supernova" website (http://www.rochesterastronomy.org/snimages/).

The observations were performed with the Asiago 1.82 m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.35 nm).

 
Name                    | Discovery UT | Obs. Date UT |   z      | Type |  Phase     | Notes 
PS15cym                 | 20151127.363 | 20151203.85  | 0.046    | Ia   | post-max   | (1)  
CSS151130:014258+273410 | 20151130     | 20151203.88  | ~0.04    | IIb? | young      | (2) 
PSN J05225991-0008174   | 20151202.295 | 20151203.98  | 0.034740 | II   | young	     | (3)  
ASASSN-15tj             | 20151203.540 | 20151204.02  | 0.022265 | Ia   | pre-max    | (4)  

(1) The redshift is determined from the position of the main SN features. A good match is obtained with the luminous SN Ia 1991T (Filippenko et al. 1992, ApJ 384, 15) about 16 days after maximum. The expansion velocity of the ejected material, as deduced from the position of the Si II 635.5 nm minimum, is about 9100 km/s.

(2) The low S/N spectrum is blue, almost featureless. Weak, low-contrast features are observed, especially at the blue wavelengths. We tentatively identify a broad, shallow Halpha, Hbeta and He I 587.6 nm at a host galaxy redshift z ~ 0.04, showing some affinity with early spectra of SN 2011fu (Morales-Garoffolo, A., et al. 2015, MNRAS, 454, 95), although different matches with other transients/redshifts cannot be totally ruled out.

(3) The value of the host galaxy redshift is taken from Ostriker et al. 1988, AJ, 96, 1775, via NED. The best match is obtained with SN 1999gi (Leonard et al. 2002, AJ 124, 2490) a few days after the explosion. The spectrum shows broad and shallow P-Cygni lines of H and He I. The ejecta velocity obtained from the position of the Hbeta minimum is about 9800 km/s.

(4) The adopted redshift is provided by the Sloan Digital Sky Survey Data Release 5, as obtained Jun. 28, 2006 from http://www.sdss.org/dr5/products/catalogs/index.html. An excellent match is obtained with the Type Ia SN 1999ee (Hamuy et al. 2002, AJ 124, 417; Stritzinger et al. 2002, AJ 124, 2100) about 9 days before the maximum light. The expansion velocity of the ejecta, measured from the position of the Si II 635.5 nm line, is about 15200 km/s.

Classification was done with GELATO (Harutyunyan et al. 2008, A&A, 488, 383) and SNID (Blondin and Tonry 2007, ApJ, 666, 1024). The Asiago classification spectra are posted at the website http://sngroup.oapd.inaf.it. Â

Padova-Asiago SN Group