Two new variable stars in Crux

(vsnet-obs 3179, Fraser Farrell)

G'day all,

I would like to get more info on these (apparently unknown) variable stars in Crux. Any observations, images, etc you may have of these stars would be useful in unravelling their behaviour. 

GSC 8979.00902 (12h26m31.3s -62d26'41.6"  J2000)
------------------------------------------------

This star is within VSS,RASNZ Chart 955 (BI & BP Cru) but is not plotted. First noticed by Justin Tilbrook (Clare, South Australia). Observations to end of 1996 June: 

observer  JD 2400000+     mag
     Tz    49858.938     11.0
     Fm    49858.987     11.1
     Fm    49859.085     11.0
     Tz    49859.871     11.2
     Tz    49859.911     11.2
     Tz    49867.904     11.0
     Nn    49867.949     10.7
     Fm    49868.171     11.4
     Fm    49869.210     11.0
     Tz    49877.881     11.4
     Tz    49888.917     10.8
     Tz    49892.966     11.3
     Tz    49905.932     10.7
     Nn    49908.048     11.0
     Tz    49915.926     10.8
     Tz    49937.944     10.8
     Nn    49941.913     10.7
     Nn    49942.917     10.4
     Tz    49942.942     10.3
     Tz    49944.949     10.3
     Nn    49945.017     10.7
     Tz    49945.924     10.4
     Nn    49947.953     10.7
     Tz    49950.935     10.3
     Nn    49976.982     10.7
     Tz    49978.939     10.8
     Nn    49979.954     10.0
     Tz    49986.917     10.9
     Tz    50000.926     10.9
     Tz    50005.918     10.8
     Tz    50067.067     11.6
     Tz    50071.015     11.4
     Fm    50076.246     11.4
     Fm    50105.083     11.0
     Fm    50106.092     11.2
     Tz    50126.989     11.2
     Fm    50127.267     11.4
     Tz    50132.996     11.4
     Tz    50134.992     11.3
     Tz    50138.003     11.4
     Tz    50152.943     11.2
     Fm    50153.026     11.2
     Tz    50154.953     11.3
     Tz    50159.937     11.3
     Tz    50168.952     11.2
     Tz    50170.003     11.2
     Tz    50181.915     11.2
     Tz    50186.014     11.1
     Fm    50190.024     11.0
     Fm    50194.014     11.4
     Tz    50194.915     11.1
     Tz    50195.994     11.0
     Fm    50197.285     11.2
     Tz    50197.913     11.2
     Fm    50197.992     11.2
     Tz    50198.996     11.0
     Tz    50208.910     11.1
     Tz    50211.934     11.1
     Tz    50217.925     10.9
     Tz    50219.978     10.7
     Fm    50220.058     11.2
     Fm    50227.933     11.2
     Tz    50230.964     10.7
     Tz    50238.901     10.7
     Fm    50244.007     11.4
     Tz    50244.938     10.8
     Fm    50245.042     11.3
     Fm    50247.113     11.0
     Tz    50253.940     10.6
     Fm    50255.041     11.1

VSS,RASNZ observer codes:
Fm = Fraser Farrell,  Nn = Peter Nation,  Tz = Justin Tilbrook


Comparison of blue- and red-sensitive photographs indicate GSC
8979.00902 is a red star.  Observations to date suggest small but
rapid variations - possible ZAND type??




EsB 365  (12h47m24.6s -59d41'41"  J2000) = DY Cru
-------------------------------------------------




Also known as: Henize 183, W79-2, CCCS 2031, GSC 8659.01394


This is an extremely red carbon star which is familiar to many
southern hemisphere observers - it is just 2.4' @ 260d from Beta
Crucis; and reducing Beta's glare is essential.

Various catalogues quote different magnitudes for this star.
*Anecdotal* evidence over several decades indicates "bright" and
"faint" episodes as well as constancy; and frankly I was surprised
not to find this star mentioned in the NSV or GCVS.  I first
noticed variations in 1990 while using Beta Crucis as an
astrophotography guide star!


A preliminary VSS, RASNZ chart was issued about five years ago.
Observations for the last couple of years are listed below:



observer  JD 2400000+     mag
     Fm    49502.012     10.7
     Fm    49503.968     10.5
     Nn    49512.946     10.2
     Fm    49515.038      9.6
     Nn    49530.927     10.2
     Nn    49533.967     10.5
     Fm    49534.024     10.3
     Tz    49538.921      9.8
     Fm    49541.045     10.1
     Fm    49541.965     10.3
     Fm    49548.043     10.0
     Tz    49561.905     10.5
     Fm    49561.978      9.4
     Fm    49573.975     10.0
     Fm    49577.920      9.5
     Nn    49591.993      9.6
     Fm    49592.012      9.9
     Nn    49666.210      9.2
     Fm    49689.253     10.3
     Fm    49696.169      9.9
     Fm    49700.256      9.7
     Fm    49712.164      9.9
     Fm    49713.180     10.1
     Nn    49714.092     10.5
     Fm    49714.215     10.4
     Fm    49716.192      9.8
     Nn    49717.133      9.6
     Fm    49717.164     10.0
     Fm    49718.155     10.3
     Fm    49722.226     10.1
     Fm    49725.060     10.7
     Nn    49725.123     10.4
     Fm    49728.248     10.1
     Nn    49740.010      9.5
     Fm    49748.061      9.7
     Fm    49749.253     10.1
     Fm    49773.145     10.3
     Fm    49774.014     10.7
     Fm    49778.161     10.7
     Fm    49780.200     10.5
     Fm    49808.127     10.1
     Fm    49847.027      9.9
     Nn    49858.048      9.6
     Fm    49858.085     10.2
     Fm    49858.976     10.3
     Nn    49867.953      9.9
     Fm    49868.161     10.2
     Fm    49869.212     10.1
     Fm    49870.191     10.3
     Fm    49893.047     10.9
     Nn    49941.918      8.8
     Nn    49942.922      8.8
     Fm    49942.948     10.6
     Nn    49945.021      8.6
     Nn    49947.959      8.6
     Nn    49976.967      8.6
     Fm    50054.252      9.6
     Fm    50076.234      9.9
     Fm    50105.081      9.7
     Fm    50112.292      9.9
     Fm    50127.261      9.2
     Fm    50128.258      9.7
     Fm    50138.070     10.3
     Fm    50153.022     10.1
     Fm    50190.023     10.7
     Fm    50191.026     10.5
     Fm    50192.308     10.0
     Fm    50194.015     10.3
     Fm    50197.288      9.9
     Fm    50197.992      9.9
     Fm    50220.060     10.0
     Fm    50227.936      9.6
     Fm    50244.005     10.8
     Fm    50245.047     10.9
     Fm    50247.111     11.1
     Fm    50250.056      v=m   (m is 11th mag)
     Fm    50255.056      v=p   (p is 12th mag)

VSS,RASNZ observer codes:
Fm = Fraser Farrell,  Nn = Peter Nation,  Tz = Justin Tilbrook




There are suggestions of periodicity in the lightcurve, but with
all observers being in the same part of the world there have been
many gaps in coverage. I hypothesize that this star may be an RV, or
possibly an RCB
variable.



Further observations of both stars are encouraged.  I will attempt
to upload suitable charts to
the VSNET and AAVSO FTP sites during
the next few days.  Incidentally, if these variables *have* been
discovered before, please let me know.  My literature searches
have turned up nothing so far....


cheers,

Fraser Farrell (
fraserf@dove.mtx.net.au)

Variable Stars Group

Astronomical Society of South Australia








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