[vsnet-chat 2745] Re: HadV46 page

[Taichi Kato <tkato>]

Re: HadV46 page

Berto,

> The perceived blue colour of this variable from the USNO data invites
> one to think in terms of CVs or other blue stars. But we have to keep in
> mind that the B and R (USNO) magnitudes were probably measured at
> different periods, which mean they could have many different values. I
> had the same problem sometime ago, not knowing that those B and R
> magnitudes were taken weeks apart. 

   Please keep in mind the presumed identification with the 15-th mag USNO
star has been rejected.  There is no recorded counterpart in the USNO
catalog (nor on DSS).

> Mira stars have low emissions at blue wavelengths near their minimum and
> show therefore much more dramatic brightenings in B towards their
> maximum. This phenomenon can be approximated by looking at the
> theoretical radiances at 500nm and lower wavelengths from a Planckian
> (blackbody) source that heats up from 2800 K to 3300 K. Although a bit
> simplistic, this comparison ought to hold.

   Mira stars at maximum have M-type spectra, i.e. B-V > 1.0.

Regards,
Taichi Kato

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp