Spectroscopic classification of 2017jmk as a type II supernova and Early follow-up observationsстатья Электронная публикация

Дата последнего поиска статьи во внешних источниках: 11 сентября 2018 г.

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[1] Spectroscopic classification of 2017jmk as a type ii supernova and early follow-up observations / S. Bose, D. Subo, A. Pastorello et al. // The Astronomer’s Telegram. — 2018. — no. 11152. — P. 1–1. We report optical spectroscopic observations of the supernova (SN) candidate 2017jmk located in the NGC 7541. Two optical spectra were obtained on UT 2018-01-05.1 and UT 2018-01-06.6 with the MDM 2.4m telescope (+ OSMOS; spectral range 398-686 nm) at KPNO and the 2.4m telescope (LJT + YFOSC) located in Lijiang, China, respectively. The OSMOS spectrum exhibits a broad and weak P-Cygni H_alpha profile. The estimated H_alpha expansion velocity is ∼4700 km/s, which is relatively low for a normal type II SN at a relatively young age (as indicated from the SN imaging data obtained from the recent, pre-discovery HST observations; see #Atel 11119). The peak of H_alpha is slightly blueshifted (by ∼1000 km/s) from the rest velocity, which is commonly seen in relatively young SNe II. We also identify host H, N, and S emission lines along with narrow Na I D lines at z = 0.0095, which is consistent with the redshift of the host galaxy NGC 7541 at z = 0.0090 via NED. The Na I D lines are partially resolved, and the corresponding D1 and D2 lines have equivalent widths of approximately 0.12 nm and 0.10 nm, indicative of significant host-galaxy dust extinction. We perform multi-band imaging follow-ups from the SAO 1-m Zeiss reflector with the CCD photometer based on EEV CCD42-40 chip, the 24-in telescope at Post Observatory as well as Swift UVOT. The Zeiss-100 BVRI photometry is presented. The position of SN 2017jmk was serendipitous observed by the Hubble Space Telescope on multiple occasions during the three months prior to discovery, as part of program 15145 (PI: Riess). As mentioned in ATel #11119, examination of the pre-explosion images reveal no obvious coincident progenitor candidate. In light of the reddening and distance to SN 2017jmk, it may be challenging to obtain good constraints on the pre-explosion luminosity of the progenitor.

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