The optical properties of three Type II supernovae : 2014cx, 2014cy, and 2015cz

• We present the photometric and spectroscopic analysis of three Type II supernovae (SNe): 2014cx, 2014cy, and 2015cz. SN 2014cx is a conventional Type IIP with shallow slope (0.2 mag/50 d) and an atypical short plateau (∼86 d). SNe 2014cy and 2015cz show relatively large decline rates (0.88 and 1.64 mag/50 d, respectively) at early times before settling to the plateau phase, unlike the canonical Type IIP/L SN light curves. All of them are normal luminosity SN II with an absolute magnitude at mid-plateau of M50V,14cx=−16.6±0.4mag⁠, M50V,14cy=−16.5±0.2mag⁠, and M50V,15cz=−17.4±0.3mag⁠. A relatively broad range of 56Ni masses is ejected in these explosions (0.027–0.070 M⊙). The spectra shows the classical evolution of  SNe  II, dominated by a blue continuum with broad H lines at early phases and narrower metal lines with P Cygni profiles during the plateau. High-velocity H  i features are identified in the plateau spectra of SN 2014cx at 11 600  kms −1, possibly a sign of ejecta-circumstellar interaction. The spectra of SN 2014cy exhibit strong absorption profile of H i similar to normal luminosity events whereas strong metal lines akin to sub-luminous SNe. The analytical modelling of the bolometric light curve of the three events yields similar progenitor radii within errors (478, 507, and 660 R ⊙ for SNe 2014cx, 2014cy, and 2015cz, respectively), a range of ejecta masses (15.0, 22.2, and 20.6 M ⊙ for SNe 2014cx, 2014cy, and 2015cz), and a modest range of explosion energies (3.3–7.2 foe where 1 foe=10 51erg).

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

techniques: photometric

techniques: spectroscopic

supernovae: general

supernovae: individual: SN 2014cx

SN 2014cy

SN 2015cz

galaxies: individual: NGC 337

NGC 7742

NGC 582

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