[vsnet-campaign-sn2002ap 201] SN 2002ap papers

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

SN 2002ap papers

   Two recent papers on SN 2002ap:

Paper: astro-ph/0204007
From: "Keiichi Maeda" <maeda@astron.s.u-tokyo.ac.jp>
Date: Sun, 31 Mar 2002 06:41:44 GMT   (171kb)

Title: The Type Ic Hypernova SN 2002ap
Authors: P. A. Mazzali, J. Deng, K. Maeda, K. Nomoto, H. Umeda, K. Hatano, K.
  Iwamoto, Y. Yoshii, Y. Kobayashi, T. Minezaki, M. Doi, K. Enya, H. Tomita,
  S.J. Smartt, K. Kinugasa, H. Kawakita, K. Ayani, T. Kawabata, H. Yamaoka,
  Y.L. Qiu, K. Motohara, C. L. Gerardy, R. Fesen, K. S. Kawabata, M. Iye, N.
  Kashikawa, G. Kosugi, Y. Ohyama, M. Takada-Hidai, G. Zhao, R. Chornock, A. V.
  Filippenko, S. Benetti, M. Turatto
Comments: Submitted to The Astrophysical Journal (Letters), 24 March 2002
\\
  Photometric and spectroscopic data of the energetic Type Ic SN 2002ap are
presented, and the properties of the SN are investigated through models of its
spectral evolution and its light curve. The SN is spectroscopically similar to
the "hypernova" SN 1997ef. However, its kinetic energy [$\sim (4-10) \times
10^{51}$ erg] and the mass ejected (2.5-5 $M_{\odot}$) are smaller, resulting
in a faster-evolving light curve. The SN synthesised $\sim 0.07 M_{\odot}$ of
$^{56}$Ni, and its peak luminosity was similar to that of normal SNe.
Brightness alone should not be used to define a hypernova, whose defining
character, namely very broard spectral features, are the result of a high
kinetic energy. The likely main-sequence mass of the progenitor star was 20-25
$M_{\odot}$, which is also lower than that of both hypernovae SNe 1997ef and
1998bw. SN 2002ap appears to lie at the low-energy and low-mass end of the
hypernova sequence as it is known so far. Observations of the nebular spectrum,
which is expected to dominate by summer 2002, are necessary to confirm these
values.
\\ ( http://arXiv.org/abs/astro-ph/0204007 ,  171kb)
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\\
Paper: astro-ph/0204008
From: Avishay Gal-Yam <avishay@wise.tau.ac.il>
Date: Sun, 31 Mar 2002 06:48:03 GMT   (136kb)

Title: Supernova 2002ap - The First Month
Authors: Avishay Gal-Yam, Eran O. Ofek and Ohad Shemmer
Comments: 5 pages, including 4 figures. MNRAS (pink pages) in press. Data
  available electronically from http://wise-obs.tau.ac.il/~avishay/local.html
\\
  Supernova (SN) 2002ap in M74 was discovered on January 29, 2002. Being one of
the nearest (10 Mpc) SN events in the last decades, and spectroscopically
similar to the so-called ``hypernovae'' 1997ef and 1998bw, both possibly
associated with gamma-ray bursts (GRBs), it is of great interest. Shortly after
its discovery, we launched an intensive photometric and spectroscopic
monitoring campaign of this event, and here we report the results of the first
month of observations. We use our UBVRI photometry to estimate the magnitudes
at, and dates of, peak brightness. Our data suggest that this object reached
its peak B-band luminosity on Feb. 7.1(-1.3)(+2) UT. Based on its similarity to
SN 1998bw, we estimate the range of possible dates for a GRB that may have been
associated with SN 2002ap. We find that it may include dates outside the time
frame for which all available gamma-ray data have been intensively scanned,
according to recent reports. The absolute magnitude at peak brightness of SN
2002ap (M_B = -16.9) shows that it was significantly fainter than SN 1998bw, or
normal type-Ia SNe, but similar to SN 1997ef. Our spectroscopic observations
confirm that SN 2002ap is strikingly similar to SNe 1998bw and 1997ef. We
briefly describe the spectral evolution of this object. To assist other
observers and to stimulate theoretical models, we make our entire data set
publicly available in digital form.
\\ ( http://arXiv.org/abs/astro-ph/0204008 ,  136kb)

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