[vsnet-chat 4433] Re: R Hya's standstill

["Stan Walker" <astroman@voyager.co.nz>]

Hi Sebastian,

I'm intrigued by your observations. This stillstand has been observed in the
past - it shows in some of Albert Jones' measures about 1960 and also in
photoelectric measures made at Auckland Observatory around 1980. The latter
are interesting as the B-V and U-B colours were rather unusual as the cycle
developed. Unfortunately the project was not continued with. The pe measures
showed a slight decline before the final rise to maximum in the only cycle
we observed even slightly well.

As I mentioned earlier I'm interested in double peaked Miras. One of these
is BH Crucis which is now increasing dramatically in period - about 100 days
in 25 years. R Hydrae, of course, is famous for a period change of the
opposite nature. Since all of the double peaked Miras have periods in the
400-500 day range I have often wondered whether R Hydrae is approaching this
stage. The double peaked nature of BH Crucis is much less pronounced with
the longer period - sometimes the first peak is merely a bump on the light
curve.

It would be useful doing a full analysis of this star. R Centauri is another
of the 500plus day group with a quickly changing period. My feeling is that
the 400+ day Miras (and R Hydrae is still close to this period - it may
bounce back or prove the lower bioundary is ~350 days) are evolving in a
manner much different and faster than the rest of the group.

Keep observing.

Regards,
Stan

----- Original Message -----
From: Sebastian Otero <varsao@fullzero.com.ar>
To: vsnet-chat <vsnet-chat@kusastro.kyoto-u.ac.jp>
Sent: Friday, May 11, 2001 10:40 AM
Subject: [vsnet-chat 4431] R Hya's standstill


> Hi,all:
>          I'd like to hear some comments on the current standstill of R
Hya.
> Specially concerning the past behaviour of the star.
> Has the lightcurve been showing this feature in the past?
>
> My recent observations indicate that R Hya was in the rising branch at the
> end of March and since then has stayed at the same brightness. And it's
been
> more than a month now...
>
> Observations (already reported to vsnet-obs):
>
> 20010218.2    7.9
> 20010328.1    6.8:
> 20010407.1    6.7
> 20010410.1    6.7:
> 20010415.1    6.7
> 20010421.0    6.7
> 20010425.1    6.7
> 20010426.0    6.7:
> 20010504.0    6.7
> 20010510.1    6.7
>
>
> Best regards,
> Sebastian.
>
>
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