Southern Doubles, Stars and Variables
SOUTHERN ASTRONOMICAL DELIGHTS : Presented by Andrew James
PAGE DS 022
LAST UPDATED
10 Mar 2009
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RA : 22h
Dec : -30° to -90°
Constellations : PsA, Gru, Tuc, Ind, Oct.
Best Observed : Jul - Dec (Text Ordered by RA)
RA : 22h
Dec : -30° to -90°
DS 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 10h 11h
NEW 12h 13h 14h 15h 16h 17h 18h 19h 20h 21h 22h 23h
PAGE INDEX

SOUTHERN DOUBLES
SEE 466
HJ 5319
Δ238
Δ238 : Pair 1
SOUTHERN VARIABLES
None Listed
BRIGHT STARS
None Listed
OTHER DOUBLES
and VARIABLES

V 360 Lac
DEEP SKY
None Listed

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

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 (°)

See BASIC
DOUBLE STAR
INFORMATION

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 systems 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 todays 20.6 arcsec (1999), but the PA of 80° has decreased by only 3°.

There is seemingly something wrong with Dunlops observations, and at first this made me suspicious that this might not be the pair he is taking about. Dunlops 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 todays positions and Dunlops 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 Herschels 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). Dunlops 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 SIMBADs 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 cores 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.


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Southern Astronomical Delights”
© (2009)
LAST UPDATED
10 Mar 2009