Some 10 years ago I used to roam the LMC field with my 5" apogee refractor
and monitored a rather largish (?) number of probable variables. Most of them
were classified as S Dor and S Dor:.
After a while I got the impression that most bright stars around that
region got a life of their own and seem to vary.
Without a steady magnitude reference platform I got confused and
gradually lost interest.
A few of those variables kept my interest alive for a while, ao HD(E)
269858 which had a (probable S Dor type) outburst ongoing and evolved around
magnitude 9.2. It's nice to see that this S Dor ? variable is recently reported
on. I see it around 10.3, a full magnitude fainter than in the early
nineties.
Another such unpublished variable (if it is indeed one) was in the field of
S Dor itself at (2000) coordinates 051805-6914. It was documented to be at 11.5
and my estimates gave it around 12.6, I think I must have a look again.
Another interesting target was HD 269582 (S Dor: / Z And:). A range of
10.3-11.8 was given. I saw it around 12.4 then. Possibly it is
fainter still now.
I could go on for a few more but I rather stop here.
Some speculation: most of those 'stars' are bluish and are becoming partly
obscured and reddened by nebulous environments. Possibly that is what
causes their variability to a certain (possibly total) extent. B-V-R
measures over time would certainly reveal this possibility.
>>> "Sebastian Otero" <varsao@fullzero.com.ar>
12/25/00 09:50PM >>>
Dear friends:
Observing some variables
in the LMC, I used one B spectral type star as a
comparison and then found
that the published V values suggested variability
and furthermore, they had
nothing to do with my observation...
When I looked for the star in the
Tycho and Tycho 2 catalogues, I noticed
that there are two stars close from
each other labelled with different names
but sharing some particular
features:
Tycho recorded TYC 9167-00383-1, position 5h 39m 05.52s
-6929' 22.5" , Vt
12.36 and B-V -0.49 ,
while Tycho 2 doesn't include
that star but do include TYC 9167-00759-1 ,
position 5h 38m 58.85s -69
29' 22.0" , Vt 11.72 and B-V -0.41
The Tycho Input Catalogue agrees
with the Tycho 2 entry and gives a rough
9.8 V magnitude.
From Tycho
numbers I see there is a great error, since a color index bluer
than -0.4 is
impossible and the UBV measurements are +0.12.
Searching in the Washington
Double Star catalogue, I found there is a double
star near the same position.
Magnitudes mentioned are 10.8 and 12.8. It is
DM-69 468 which turns out to be
HD 269927.
The question is: Is HD 269927 the same star as TYC 9167-00759-1
?
And what is TYC 9167-00383-1? A mistake? Or both Tycho 1 and Tycho 2
stars
are the individual components of the WDSC pair?
At the time of
my observation there was no other star that could be
misidentified nearby. At
least not a 10 or 11 magnitude one.
Measurements:
V measurements
in the GCPD are 10.96, B-V 0.12 and 10.64 (They are for the
AB pair, so
it's supposedly the brighter I should be observing.) SIMBAD
lists
the object as V= 10.69, B-V 0.11.
My observation last night is 10.3,
comparing the star with nearby stars that
looked okay and with good PEP(V)
values.
Some
clarification?
Thanks,
Sebastian.
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