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[vsnet-chat 2744] Re: [vsnet-alert 4413] HadV46 page
- Date: Thu, 16 Mar 2000 13:06:24 +0200
- To: <tkato@kusastro.kyoto-u.ac.jp>, <vsnet-chat@kusastro.kyoto-u.ac.jp>
- From: "Berto Monard" <LAGMonar@csir.co.za>
- Subject: [vsnet-chat 2744] Re: [vsnet-alert 4413] HadV46 page
- Disclaimer: The CSIR exercises no editorial control over E-mail messages originating in the organisation and the views in this message are therefore not necessarily those of the CSIR and/or its employees.
- Sender: owner-vsnet-chat@kusastro.kyoto-u.ac.jp
Hi,
So far there is no clear indication that HadV46 is not a high amplitude
Mira.
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.
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.
Stars with negative (USNO) B-R can often be expected to be variables (red
or blue) and at B=R they are often galaxies and AGNs....
Possibly Had V46 is a cv, but we need contemporary measures in B and V (or
R) to know that.
Regards,
Berto Monard
Pretoria
PS this variable is a just a little bit too North for me to see it at
altitudes far away from zenith...
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