[vsnet-alert 25773] Re: V1405 Cas brightening

[Kenta TAGUCHI]

Dear Kato-san,

>     Taguchi-san, do you have any estimate for
> the bolometric luminosity during the premaximum
> halt?  If the bolometric correction is large,
> the discrepancy may be avoided.
I think it should be large.

According to Munari et al. (ATel #14476), E(B-V)=0.55 is estimated.
Also, assuming it and m_B - m_V = 0.4 from the AAVSO lightcurve, 
extinction-free B - V will be -0.15.

If it is true, the temperature is high and the bolometric correction for 
V will be -1.2 or -1.3 from Pecaut & Mamajek (2013).

Is my answer OK?
I am unconfident about it, so please teach me if you find anything wrong.

Best Regards,
Kenta


On 2021/04/28 8:46, Taichi Kato wrote:
> V1405 Cas brightening
>
>     V1405 Cas is brightening now.  Several observers
> in Japan reported vis or V=7.4 on Apr. 26.
>
>    YYYYMMDD(UT)   mag  observer
>    20210421.726    79  (Hiroyuki Maehara)
>    20210421.876    79  (Gary Poyner)
>    20210422.233  8.18C  (Gary Poyner)
>    20210422.875    79  (Gary Poyner)
>    20210424.228  7.97TG  (Gary Poyner)
>    20210425.882    77  (Gary Poyner)
>    20210427.219  7.51TG  (Gary Poyner)
>
>     The recent change in the spectrum (ATel #14577,
> V1405 Cas (= PNV J23244760+6111140) now displaying
> Fe II emission) most likely reflected this state
> change.  The nova before this brightening was
> apparently in "premaximum halt" and the unusual
> (He/N) spectroscopic feature for a slow nova
> may have been because the nova was still well
> before the maximum.
>
>     The change from premaximum halt to maximum
> is different from what was observed in V723 Cas
> https://ui.adsabs.harvard.edu/abs/1998A%26A...338.1006I/abstract
>
>     Assuming V=8.0 for the premaximum halt and
> an extinction of 1.3 mag, M(V) of the premaximum
> halt is -4.6.  Using the relation in Hachisu and Kato
> (2004 ApJ 612, 57), this value yields an unacceptably
> small mass of the white dwarf.  If the extinction
> is not severely underestimated, the result suggests
> that Hachisu and Kato's assumption that the premaximum
> halt reflects the Eddington luminosity would be
> invalidated.
>
>     Taguchi-san, do you have any estimate for
> the bolometric luminosity during the premaximum
> halt?  If the bolometric correction is large,
> the discrepancy may be avoided.
-- 
________________________________________________________________
  田口 健太　(TAGUCHI, Kenta)
  京都大学大学院理学研究科宇宙物理学教室
  (Department of Astronomy, Graduate School of Science, Kyoto University)
kentagch at kusastro.kyoto-u.ac.jp <mailto:kentagch at kusastro.kyoto-u.ac.jp>
  09090536980