NOTES 1
Positions given as;
I.e. (13583-6018), are;
RIGHT ASCENSION
13h 58.3m
DECLINATION
-60° 15'
EPOCH
2000.0
This follows the current
WDS Conventions. |
NOTES 2
S E P A R A T I O N
" or "arcsec
In arc seconds or
' or 'arcmin
In arc minutes or
mas - milli arc seconds
POSITION ANGLE
( ° ) Angle in degrees.
Measured from
North through East
M A G N I T U D E S
v - visual (naked-eye)
p - photographic
V - Photometric Visual
B - Photometric Blue
MV - Absolute @ 10pc.
ABBREVIATIONS
pc. - parsecs
ly. - light-years
AU - Astronomical Unit
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NOTES 3
O R B I T A L
E L E M E N T S
T: Periastron (yr.)
P: Period (yr.)
a: Semi-Major Axis (arc sec.)
e: Eccentricity
i: Inclination
Ω: Orbital Node (°)
ω: Angle True Orbit (°)
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SELECTED SOUTHERN DOUBLES and VARIABLES
R.A. 22 Hours
SEE 466 (22050-3933)
is an easily found faint pair placed 15.2'SW
(0.25°) of the orangish λ
Gruis. The pair is 9.3 and 10.0 mag,
respectively, and I see each star as yellow and
white. Separation is 1.8 arcsec - so 15cm or
20cm using medium magnification is needed to see
it. I had to inspect ech of the three faint
stars in the area to really identify it.
Since the first measures in 1896, the separation
has not changed, but the position angle has
decreased from 10° to 254°
between 1896 and 1976 at a rate of
14° each decade. I examined this pair
in 1994, and estimated the PA as 230°
but thought the separation just a little wider.
Based on the proper motions and the changes in
position angle, it is likely that the pair is a
true binary. The system’s period maybe
somewhere between 160 and 300 years.
HJ 5319 (22120-3819)
is a bright yellow pair is located
1.7°NE of Lambda (λ) Gruis.
Herschel discovered this pair in 1836, and
little has changed in the 2.1 arcsec separation since
this time. From the last measure in 1985, only
the position angle has been found to have
decreased from 110° to
130°. On the 10th October 1879,
Hargrave, using the (18cm.) 7.25-inch Merz Refractor
at Sydney Observatory, states that he could not
find the pair (and he looked, in good seeing,
several times in the ensuing weeks) - an amazing
discrepance considering the aperture and the
brightness of the two stars. Stellar magnitudes
are given as 7.6 and 7.7. It would take 15cm to
be able to separate the pair cleanly. Examining
the proper motions of the two stars, it is
uncertain if these two stars are associated.
Δ238
(22258-7500) is a fairly brightish wide pair
lies in the southernmost constellation of Octans
merely some 39'S from the northern border with
Indus - though the field itself is marked by
mainly fainter stars below naked-eye visibility.
From Australia, this pair is circumpolar. This
yellow and orange pair was discovered by John
Dunlop in 1828, who did not state any position
angle but only its first estimated separation of
14 arcsec “f - following”. John
Herschel's first measure occured some four years
later, and since then, the pair has increased by
a roughly further 2.5 arcsec to today’s
20.6 arcsec (1999), but the PA of 80°
has decreased by only 3°.
There is seemingly something wrong with
Dunlop’s observations, and at first this
made me suspicious that this might not be the
pair he is taking about. Dunlop’s
magnitudes are given as “8,12” thus
being substantially different than ‘6.1
and 9.4’ magnitude given today. His
position is given as 22h 08m 56s -75°
58' (1828), which precesses to in 22h 24m 03s
-74° 44' (2000). Differences between
today’s positions and Dunlop’s given
placement are about 18'NNW, but considering the
effects of precession of such polar
declinations, so the error is likely not so
terrible. As there are no other pairs in the
vicinity, it is likely Herschel’s
conclusion that this is Δ238 is what it is
- even though the magnitudes are so disturbingly
wrong. Another peculiarity appears in the
Delta-m catalogue of the WDS 2002 (Nov).
Dunlop’s 12th magnitude of the companion
is strange, but so is the WDS and the
catalogues. The parameters of these stars appear
in the Table below;
|
Dunlop (1828) |
Pickering (1919) |
Walliquest (1948) |
Tycho-2 |
Hipparcos |
WDS96 |
WDS02 (Nov) |
A
|
8th |
-- |
-- |
6.12V |
6.12V |
6.1v |
6.19V |
B
|
12th |
-- |
-- |
8.72V |
9.35V |
9.4v |
8.85V |
Δm
|
4(v) |
2.38p |
2.87p |
2.60V |
3.23V |
3.3v |
2.66V |
Is this an indication of a variable component?
Hipparcos Data.
"A" |
HIP 110712 |
B-V=+0.601 |
"B" |
HIP 110709 |
B-V=+1.095 |
Data in the WDS 2002 gives the following data;
Star |
Magnitude |
Star |
Magnitude |
PA (1826) |
Sep (1826) |
PA (1991) |
Sep (1991) |
A |
6.19V |
B |
8.85V |
80° |
14.0 arcsec |
90° |
20.6 arcsec
|
Spectra : G3V
In the same field is a notably 7.4 magnitude red
star SAO 258024 / PPM 375319 (22212-7458)
whose spectral class is M3 III. Nothing is
really known about this star, though it appears
not to be variable. It is hard to decide if this
is because the star is not variable or due to
sheer lack of observations.
Δ238 : Pair
1 (22228-7503) lies some 12'W of DUN 238 and
roughly in align with the red star mentioned
above. This very faint pair listed as non-stars
in the GSC, being listed as 13.6 and 14.1
magnitude. Presently these two star are
separated by 5.7 arcsec along the NW PA of
314°. The STScI images shows both
stars do actually exist, but the PA looks wrong.
U0075-06942218/ “Mysterious Galaxy” (22237-7501) is a “presumed”
bright galaxy that I could not identify lies between the double and
the red star. It lies 4.16' at PA 66° from the mean separation
centre of Δ238 : Pair 1 (22228-7503) mention above. This
USNO-A2.0 catalogue identifies the objects as the intimidatingly
named U0075-06942218, and through SIMBAD’s viewer aptly named “ALADIN”
(especially for this object gives the precise position as 22 23m
44.848s -75° 01' 18.92″. It also appears in the Guide Star
Catalog as GSC 2.2 S3101111114, which again gives the bright
magnitudes as 11.17F and 11.53J.
It does not appear in any of the more common catalogues but with
the 10.7B blue plate and 11.6R plate magnitude, you would expect that
it would. Compared to the stars in Δ238 :
Pair 1 (22228-7503) mentioned above, the core’s brightness seems comparable, if not
slightly fainter, to the star placed here. Something this bright
should be easily visible in moderate telescopes. However, after
looking at the STScI image, it more looks like a much fainter for
nearly all amateur telescopes. What is wrong here - the magnitudes or
is it just another neglected galaxy in a dim and uninteresting part
of the sky?
V360 Lac / V360 Lacertae / 14 Lac
(22504+4157) lies in the northern constellation of Lacerta,
surrounded by the stars 13, 15 and 16 Lacertae, and lies near the
border star of Omicron (ο) Andromedae. Fairly dim to the
naked eye, this 5.92v magnitude star shows the variability of only
0.05 magnitudes over the period of about five days. Calculation of
the orbital parameters remains difficult, however this system seems
to have an orbital tilt above the inclination of about 65° that
would normally cause eclipses to be seen. Distance is presently
estimated to be c.185pc. or 600 ly.
“Southern Astronomical Delights”
© (2009) |
LAST UPDATED
10 Mar 2009 |
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