SIMBAD references

2008CBET.1285....1B - Central Bureau Electronic Telegrams, 1285, 1 (2008/March-0)

Supernova 2008ax in NGC 4490.

BLONDIN S., FILIPPENKO A.V., FOLEY R.J., LI W., DESSART L. and VAZ A.

Abstract (from CDS):

S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group; A. V. Filippenko, R. J. Foley, and W. Li, University of California, Berkeley; and L. Dessart, Steward Observatory, University of Arizona, report that a spectrum (range 350-740 nm) of the possible supernova announced on CBET 1280, obtained on Mar. 4.37 UT by A. Vaz with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a young, reddened, peculiar, type-II supernova. The spectrum is dominated by broad P-Cyg profiles of the Balmer series with a broad absorption around 545 nm due to He I (rest 587.6 nm). The spectrum is similar to an early spectrum of the peculiar type-II supernova 1987A taken on 1987 Feb. 25 UT (i.e., roughly two days past the neutrino outburst and 82 days before V-band maximum light; Phillips et al. 1988, A.J. 95, 1087), although the line widths and blueshifts are greater in 2008ax. Adopting a recession velocity of 589 km/s for the host galaxy of 2008ax (from The Updated Zwicky Catalogue, http://tdc-www.harvard.edu/uzc/), the maximum absorptions in the H_beta (rest 486.1 nm), He I (rest 587.6 nm), and H_alpha (rest 656.3 nm) lines are blueshifted by roughly 23500, 22800, and 26600 km/s, respectively (cf. 16000, 14900, and 18500 km/s for the aforementioned 1987A spectrum). The peak emissions also display significant blueshifts (6700 km/s for H_alpha), as observed in the early spectra of type-II supernovae (cf. Dessart and Hillier 2005, A.Ap. 437, 667). Also, interstellar Na I D absorption at the redshift of the host galaxy is visible in the spectrum, suggesting some reddening towards 2008ax. In the comparison plot (visible at website URL http://www.cfa.harvard.edu/supernova/spectra/SNngc4490_comp.gif), the spectrum of 2008ax is dereddened by E(B-V) = 0.6 mag to reproduce the overall spectral energy distribution of the 1987A comparison spectrum. Assuming that the host galaxy is in the Hubble flow and the supernova suffers from A_V about 2 mag of visual extinction, the discovery magnitude of 16.1 corresponds to an absolute magnitude of roughly -15.4, comparable to 1987A in its early stages [M_V = -14 on 1987 Feb. 27, adopting the apparent V-band magnitude of 4.45 reported by Hamuy et al. (1988, A.J. 95, 63) and a distance modulus of -18.5 to the LMC].

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2020.01.27-14:37:19

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