Asiago spectroscopic classification of six transients

ATel #10863; L. Tomasella, S. Benetti, E. Cappellaro (INAF-OAPd)
on 18 Oct 2017; 09:03 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Stefano Benetti (stefano.benetti@oapd.inaf.it)

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The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of SN 2017hix (aka Gaia17cpj), bright nuclear candidate SN discovered by Gaia satellite in galaxy LEDA 2723806; AT 2017hkm (aka Gaia17cqc); SN 2017hiq discovered by B. Mikuz at Crni Vrh Observatory in the course of the Comet and Asteroid Search Program (PIKA); SN 2017hjy (aka ATLAS17mgt), SN 2017hjw (aka ATLAS17mgh), and SN 2017hju (aka ATLAS17mgm), found by the ATLAS survey (see Tonry et al. ATel #8680) in SDSS J023602.15+432817.6, UGC 3245, and in anonymous galaxy close to NGC 0974, respectively.

The observations were performed with the Asiago 1.82 m Copernico Telescope equipped with AFOSC (range 340-820 nm; resolution 1.4 nm).

 
 
Survey Name   | IAU Name      | Discovery date (UT)  | Discovery mag | Observation (UT)    |  Type  | z        | Notes| 
Gaia17cpj     | SN 2017hix    |  2017-10-13 02:55:40 | G-gaia=16.87  |2017-10-17 18:21:21  |   Ic   |  0.020   | (1)  | 
Gaia17cqc     | AT 2017hkm    |  2017-10-15 20:03:50 | G-gaia=17.39  |2017-10-17 21:56:10  |   CV?  |          | (2)  | 
AT 2017hiq    | SN 2017hiq    |  2017-10-13 22:06:54 | 18.2          |2017-10-17 22:59:43  |   Ia   |  0.091   | (3)  | 
ATLAS17mgt    | SN 2017hjy    |  2017-10-14 11:55:40 | 17.98         |2017-10-18 00:36:15  |   Ia   |  0.007   | (4)  |   
ATLAS17mgh    | SN 2017hjw    |  2017-10-14 13:46:33 | 18.52         |2017-10-18 01:06:56  |   Ia   | 0.016161 | (5)  | 
ATLAS17mgm    | SN 2017hju    |  2017-10-14 12:00:00 | 18.36         |2017-10-18 01:53:53  |   Ia   |  0.022   | (6)  |     
 

(1) The spectrum is consistent with that of a Type Ic SN events (best match with SN 2007gr, Valenti et al. 2008 ApJ 673) few days after maximum light, at a redshift of about 0.020 (from SNID).

(2) the spectrum of Gaia17cqc shows an almost featureless blue continuum. A careful analysis, reveals the presence of weak and very broad Balmer lines at rest wavelength. An emission core increases going from Hepsilon 397.0 nm to Hbeta 486.1 nm, while Halpha emission core completely fills the corresponding absorption line. HeI 447.1 nm absorption line is barely visible. This object is possibly a CV.

(3) The low S/N spectrum of SN 2017hiq is consistent with those of Type Ia SNe around maximum light, assuming a redshift z=0.091 which is the photoZ of the host galaxy SDSS J005254.06+160654.7 reported by SDSS DR14.

(4) The spectrum of ATLAS17mgt = SN 2017hjy is consistent with several Type Ia SNe at maximum. The expansion velocity of the ejecta, as deduced from the position of SiII 635.5 nm absorption line, is about 11800 km/s when assuming a redshift z~0.007 (from SNID).

(5) The spectrum of ATLAS17mgh = SN 2017hjw shows that this transient is a Type Ia SN, about one week before maximum light. Assuming the redshift of the host galaxy UGC 3245 z=0.016161 (De Vaucouleurs et al. 1991, 3rd Reference Catalogue of Bright Galaxies, V.3.9, via NED), the expansion velocity of the silicon layer is around 12700 km/s. A hint of high velocity feature (at velocity of about 18300 km/s) is visible in the blue wing of the SiII 635.5nm absorption.

(6) The spectrum of ATLAS17mgm = SN 2017hju is consistent with several Type Ia SNe around one week before maximum. The expansion velocity of the ejecta, as deduced from the position of SiII 635.5 nm absorption line, is about 10500 km/s when assuming a redshift z~0.022 (from SNID).

Classifications were 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.