Re: SN 1998ax

From: Andy Howell (DAHowell@lbl.gov)
Date: Mon May 19 2003 - 14:35:36 PDT

  • Next message: Lifan Wang: "Re: SN 1998ax"

    Lifan,

    I think there is no doubt SN 1998ax/98109 is a Ia.
    -- We have a redshift from the galaxy, so your first two fits are ruled out
    -- Years ago I showed on the spectroscopy web page that it matches a
    Ia, using Isobel's program.
    -- The light curve matches a Ia
    -- Just to erase any doubt I refit it with my program. My best match
    is to SN 1992A at +11d.
    This agrees perfectly with the epoch determined from the light curve.
    The date of max was
    MJD=50889. The spectrum was taken on 50900. You can see my fit, which
    accounts for
    every significant wiggle, and subtracts only a tiny bit of spiral host here:
    http://panisse.lbl.gov/collab/data/spec/homesp/eso_mar98/reduc_tel/andynotes.html
    This checked it against every type of SN.

    Please check the spectroscopy web pages to see if a SN has been
    investigated before sending
    an email to all of deepnews. I put a lot of work into maintaining them
    as an archive to avoid
    just such time-wasting discussions. No sense raising Rob's blood
    pressure for no good reason :)

    -Andy

    Lifan Wang wrote:

    >>Yes, quite a bit. My best thought for it was an early Type II at a z ~
    >>0.2. Andy thinks that a Ia at z~0.5 is ok.
    >>
    >>He has a link to it on the web-page:
    >>
    >>http://panisse.lbl.gov/groupwork/data/spec/homesp/eso_mar98/reduc_tel/andynotes.html
    >>
    >>
    >>
    >
    > The best fit to the spectrum is a nearly 100% elliptical galaxy at 0.11, 2nd best is
    >a combination of 70% SN and 30% elliptical at z=0.17, the third best fit redshift is
    >a Ia at 0.495 for 100% SN and the third is significantly worse than the first two. I
    >cannot find the the original finder charts to assess the rough fraction of SN light,
    >can someone help ? If the host is insignificant before discovery, then we can say
    >this is an SN with spectral features consistent with a Ia.
    >
    > I have not checked SN II possibility, but believe Peter's suggestion of II is
    >reasonable from the information that I can find about this SN.
    >
    > The reason for the uncertainty is mostly because the quality of the spectrum is actually
    >one of the worst of all the HST spectra.
    >
    >
    >Cheers,
    >
    >Lifan
    >
    >

    This archive was generated by hypermail 2.1.4 : Mon May 19 2003 - 14:36:01 PDT