[vsnet-campaign-sn 82] Re: SN observation from IAUC 7491

[Hitoshi YAMAOKA <yamaoka@rc.kyushu-u.ac.jp>]

>> # Despite of my imaginary fears ;-), SN 2000dj has been turned out to
>> # be a real SN of type II.  It is possibly in the plateau phase now.
>> #                                                   H. Yamaoka
>
>   Plateau stage already?  I'd suspect it around maximum ??

  The light curves of SNe IIP (with plateau type) are quite various. 
Some shows lile: (see with the constant-width font)

       *
      * *
     *   *******  <  plateau
    *          *
   *           *
  *            *****
 *                 ****
*                      ****

Some other shows like:

      **************  <  plateau
   ****             *
   *                *
  *                  *
  *                   ****
 *                        ****
 *                            ****

  Theoretically, the plateau is explained as a constant radius of the 
photosphere which is defined by the ionization (recombination) front
of the hydrogen ion.  In the mass coordinate, the photosphere proceed
inward as being cooled.  On the other hand, the ejecta expands
spacially.  Consequently, the radius of the photosphere remains nearly
constant for a while.  It can be occur after the maximum, around a
mamimum, or (in the special case; like as SN 1987A) before the
maximum. 

  For the extreme case, SN 1987A makes a short (1 or 2 days) plateau
phase just a few days after the explosion, at about mag 5, well before
the main plateau.  It was thought that the photosphere at that time
was defined by the recombination front of Herium, whose radius
remained constant.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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