SN 2015an: a normal luminosity type II supernova with low expansion velocity at early phases. (arXiv:1909.10602v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Dastidar_R/0/1/0/all/0/1">Raya Dastidar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Misra_K/0/1/0/all/0/1">Kuntal Misra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valenti_S/0/1/0/all/0/1">Stefano Valenti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burke_J/0/1/0/all/0/1">Jamison Burke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hosseinzadeh_G/0/1/0/all/0/1">Griffin Hosseinzadeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gangopadhyay_A/0/1/0/all/0/1">Anjasha Gangopadhyay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Howell_D/0/1/0/all/0/1">D. Andrew Howell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Singh_M/0/1/0/all/0/1">Mridweeka Singh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arcavi_I/0/1/0/all/0/1">Iair Arcavi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kumar_B/0/1/0/all/0/1">Brijesh Kumar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McCully_C/0/1/0/all/0/1">Curtis McCully</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sanwal_P/0/1/0/all/0/1">Pankaj Sanwal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pandey_S/0/1/0/all/0/1">S. B. Pandey</a>
We present the photometry and spectroscopy of SN 2015an, a Type II Supernova
(SN) in IC 2367. The recombination phase of the SN lasts up to $sim$120 d,
with a decline rate of 1.24 mag/100d, higher than the typical SNe IIP. The SN
exhibits bluer colours than most SNe II, indicating higher ejecta temperatures.
The absolute $V$-band magnitude of SN 2015an at 50 d is $-$16.83$pm$0.04 mag,
pretty typical for SNe II. However, the $^{56}$Ni mass yield, estimated from
the tail $V$-band light curve to be 0.021$pm$0.010 M$_odot$, is comparatively
low. The spectral properties of SN 2015an are atypical, with low H$alpha$
expansion velocity and presence of high velocity component of H$alpha$ at
early phases. Moreover, the continuum exhibits excess blue flux up to $sim$50
d, which is interpreted as a progenitor metallicity effect. The high velocity
feature indicates ejecta-circumstellar material interaction at early phases.
The semi-analytical modelling of the bolometric light curve yields a total
ejected mass of $sim$12 M$_odot$, a pre-supernova radius of
$sim$388~R$_odot$ and explosion energy of $sim$1.8 foe.
We present the photometry and spectroscopy of SN 2015an, a Type II Supernova
(SN) in IC 2367. The recombination phase of the SN lasts up to $sim$120 d,
with a decline rate of 1.24 mag/100d, higher than the typical SNe IIP. The SN
exhibits bluer colours than most SNe II, indicating higher ejecta temperatures.
The absolute $V$-band magnitude of SN 2015an at 50 d is $-$16.83$pm$0.04 mag,
pretty typical for SNe II. However, the $^{56}$Ni mass yield, estimated from
the tail $V$-band light curve to be 0.021$pm$0.010 M$_odot$, is comparatively
low. The spectral properties of SN 2015an are atypical, with low H$alpha$
expansion velocity and presence of high velocity component of H$alpha$ at
early phases. Moreover, the continuum exhibits excess blue flux up to $sim$50
d, which is interpreted as a progenitor metallicity effect. The high velocity
feature indicates ejecta-circumstellar material interaction at early phases.
The semi-analytical modelling of the bolometric light curve yields a total
ejected mass of $sim$12 M$_odot$, a pre-supernova radius of
$sim$388~R$_odot$ and explosion energy of $sim$1.8 foe.
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