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

Abstract

We present the photometric and spectroscopic analysis of three Type II SNe: 2014cx, 2014cy and 2015cz. SN 2014cx is a conventional Type IIP with shallow slope (0.2 mag/50d) and an atypical short plateau (∼86 d). SNe 2014cy and 2015cz show relatively large decline rates (0.88 and 1.64 mag/50d, 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 M$_{V,14cx}^{50}$ = $-16.6\, \pm \, 0.4\, \rm {mag}$, M$_{V,14cy}^{50}$ = $-16.5\, \pm \, 0.2\, \rm {mag}$ and M$_{V,15cz}^{50}$ = $-17.4\, \pm \, 0.3\, \rm {mag}$. A relatively broad range of 56Ni masses is ejected in these explosions (0.027-0.070 M⊙). The spectra shows the classical evolution of Type II SNe, 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 11600 km s−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 radii for the three objects within errors (478, 507 and 608 R⊙ for SNe 2014cx, 2014cy and 2015cz, respectively) and a range of ejecta masses (15.0, 22.2 and 18.7 M⊙ for SNe 2014cx, 2014cy and 2015cz), and a modest range of explosion energies (3.3 - 6.0 foe where 1 foe = 1051 erg).

On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies

“…Studies of dust across a range of environments, from the SMC (Welty et al 2006(Welty et al , 2012 to the ISM of QSO host galaxies (Baron et al 2016), have likewise indicated that E(B −V ) values of 0.05 mag are associated with higher W r (Na I) than implied by Poznanski et al (2012). As the Poznanski et al (2012) relation is commonly invoked to estimate the reddening of both type I and II supernovae in combination with measurements of W r (Na I) in spectroscopy of these objects (e.g., Smith & Andrews 2020;Bruch et al 2021;Dastidar et al 2021), it is important to appreciate potential biases that may arise from this calibration (e.g., Phillips et al 2013). Moreover, given the wide range in stellar masses of our GOTOQ host galaxies, we suggest that our sample may better represent the varied dust and ISM properties of supernova host galaxies than those focused purely on the Milky Way, SMC, or QSO host systems.…”