[vsnet-chat 7428] Re: Mira and VZ Cet resolved by Nakai-san

[arne]

Taichi Kato wrote:
>    Kenji Nakai-san has succeeded in resolving Mira AB (B = VZ Cet)
> and visually estimating magnitudes.  He also presented images of
> the resolved pair.  I wonder if there were past successful attempts
> with amateur telescopes?
> 
> http://homepage2.nifty.com/star-kn/Cet.html
> 
I don't think any ground-based telescope has recently resolved
the pair, especially at red wavelengths.  There was a paper
of speckle observations (Prieur et al.,2002ApJS..139..249P),
but since the pair are near their closest approach, visual
measurements are extremely difficult: Mira A swamps the
fainter star at almost all wavelengths, even when it is
near minimum like now.  If Nakai-san has cleanly separated the
pair at seemingly all colors and with a 25cm telescope, that
is pretty amazing!

I did U-band imaging (where you get the maximum contrast)
using the 1.0m telescope at NOFS during the minimum in early 2004
and could not separate the two stars.  With my pixelization,
I did not expect to split them, but there should have been
a definite elongation if both stars were present. What usually
happens is that someone uses a filter and the redleak
in the filter, along with atmospheric dispersion, causes a
second peak offset from the first, looking like a double star.
Mira may be 10th magnitude at V during minimum, but it is
more like 4th magnitude at I-band.

Nakai-san may have actually split the double, but I'd run some
experiments to test the validity of the observation just to
be sure.  See if the image of VZ Cet follows the parallactic angle,
or stays fixed in position angle.

MiraAB is a fun system that deserves more attention.
Arne