Southern Doubles, Stars and Variables
10 Mar 2009
RA : 09h
Dec : -30° to -90°
Constellations : Pyx, Vel, Car, Vol, Cha, Oct.
Best Observed : Jan - May (Text Ordered by RA)
RA : 09h
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

HJ 4171 Vol
SEE 109 / λ Vel
HJ 4164 Car
HU 1457 Car
R 107 Car
FIN 133 Car
RMK 10 Car
R 110 Car
SYO 1 Vel
R 123 Vel
RST 413 Vel
JC 5 Pyx
BRT 2548
RST 408 / NSV 4516 Vel
R 119 Car
R 120 Car
R 122 Car
HJ 4240 Car
R 133 Cha
HJ 4252 Car
RMK 11 / υ Car
Δ81 Vel
V345 Car / E Car
TX Vel>
LW Car
V Vel
NSV 4516 / RST 408 Vel
N Vel
GW Car
λ Vel / SEE 109 / Al Sahail
β Car / Miaplacidus


He2-32 / ESO 166-19 Vel

Positions given as;
I.e. (13583-6018), are;
13h 58.3m
-60° 15'
This follows the current
WDS Conventions.

" or "arcsec
In arc seconds or
' or 'arcmin
In arc minutes or
mas - milli arc seconds

( ° ) Angle in degrees.
Measured from
North through East

v - visual (naked-eye)
p - photographic
V - Photometric Visual
B - Photometric Blue
MV - Absolute @ 10pc.

pc. - parsecs
ly. - light-years
AU - Astronomical Unit


T: Periastron (yr.)
P: Period (yr.)
a: Semi-Major Axis (arc sec.)
e: Eccentricity
i: Inclination
Ω: Orbital Node (°)
ω: Angle True Orbit (°)


R.A. 09 Hours

HJ 4171 (09000-6444) (Vol) lies due 1.0°W of Miaplacidus and is yet another faint pair. Quoted magnitudes are 10.1 and 11.1 as first measured by Innes in 1918. Contained in a starry field, the pair is separation is 14.6 arcsec at PA of 237°. and is visible in 7.5cm. Although separation of the pair is easy for small apertures, the magnitude of the stars may require 10.5cm. to see it clearly in less than perfect skies.

GP Vel / Vel X-1 / HD 77581 (09021-4033) is one truly remarkable astronomical object which lies 3.0°NW of NGC 2792. At first glance it appears just to be another eclipsing binary with small fluctuations in brightness, but it has proved to be much more complicate object, as one of the components is an example of an Alpha Cygni (ACYG) variable, also being the X-ray source Vel X-1. (This should not to be confused with the radio source Vel X nor the Vela Pulsar associated with the Vela Supernova Remnant or VSR.) It is also an spectroscopic binary associated with HD 77581. Vela X-1s optical component is also being known as EQ Vel.

GP Vel itself varies between 6.79 and 6.99 in the period of 8.9647 days, based on the rough epoch 2444275.20. The primary is extremely luminous being of spectral class B0.5 Ia+ and shows extremely violet-shifted Hα absorption lines with a velocity of some 400kms-1. The companion star is much smaller in mass whose influence is significant enough to cause gas to stream between the two stars. We know this because the spectra of the primary star has several superimposed bright emission lines characteristic of a gas stream. What is unusual about this system is the longer than expected period compared to other sources, but if the orbit eccentricity is significant, this may only be contrived effect - the conclusion that Hutchings (1974) and Bessell (1975) first suggested. Based on the observed radial velocity of the components (~+300 kms-1 and ~+20kms-1) the mass of the companion is between 1.5M⊚ and 2.0M⊚, suggesting a neutron star. Its size is exactly in between what would be expected for either a white dwarf or black hole.

GP Vel is one of the closest of the eclipsing X-ray sources known whose distance maybe anywhere between 1.0kpc and 1.6kpc.

References for Vel X-1 / GP Velorum
1. Bessell, M.S., Astroph. J., 195, L113 (1975)
2. Heintz, W.D., Double Stars p.162. (1978) Pub. D.Reidel Pub.
3. Hutchings, J.B., Astroph. J, 180, 151 (1974)

E Carinae/ V345 Car / SAO 256583 (09057-7032) is a Gamma Cassiopeia (GCAS) type variable. This blue-white 4.67 mag star lies 24.6'SW (0.97°) of Miaplacidus, and is one of the brightest of its class. Most of these types of stars often vary by up to 1.5 magnitudes that normally appear without any known periodicity. They are peculiar to the spectral class of sub-giants B-type (B0 III-B3 V), and are exhibited in about 0.4% of all known variable stars. Known as shell stars, they are subject to temporary fades of one to three magnitudes. The variation of this one is only 0.11 magnitudes that vary between 4.67 and 4.78. V348 Carinae has the spectral class of B2Vne.

λ Vel / Lambda Velorum / SEE 109 / HIP 44816 / PPM313999 / SAO 220878 / HD 78647 (09080-4326) is commonly named Al Suhail or just Suhail, and can be usefully employed to find NGC 2792, and appears in the north-western part of Vela. As the 55th brightest star in the sky, this orange star is 2.14v magnitude and is an example of the rare Lc-type irregular variable stars -one of only forty-five known. Sharing kinship with Taurus first magitude star Aldebaran, it holds the honour of being the second brightest example of its class. Brightness fluctuations have been observed to diverge by some 0.08 magnitudes. The Lc variables are significant because they sometimes show complete absence of periodicity in their light-curves where as other show at least some. A few examples show the brightness changes that are slow and continuous, but several have changed quite abruptly. Most display spectral types between K and S and are exactly the same of the more common Lb-type irregular variables except for being supergiants. Vel is classed as K4 Ib-II, upgraded from the K5 data. Lambda Velorum shares kinship with the first magnitude Alpha Tauri, Aldebaran, which is an Lb-type that varies roughly by only about 0.2 magnitudes. However, although Aldebaran is of similar spectral type, K5, it is just a giant star of luminosity class III. Other bright Lc variables include Beta (β) Gruis, Omicron 1 (ο1) Canis Majoris, Psi (ψ) Aurigae and Eta (η) Aurigae.

The orangery-redness of the star is shown with the B-V is 1.665±0.013 (HIP) and 1.685±0.006 (Tycho) Hipparcos found the parallax of 5.69±0.53 giving the distance of 177±16.5pc. Proper motions are in RA -23.31±0.50 and 14.28±0.41, and this is similar to the PPM and Tycho data.

Suhail is also the double star SEE 109, however, it is a very difficult object to resolve as the magnitude difference is 12.6. Since discovered in 1897, no change has been observed in the position angle or separation, which is given as 18.2 arcsec along PA 137°.

TX Vel (09130-5449) is an irregular variable star that varies between 10.0 and 13.0. Placed a mere 10.4'W from the planetary He2-22 (PA 287°), I saw the magnitude as 10.5, based on two or three nearby field stars of known magnitude. Little is known about this star, except that it is a yellow G5 supergiant, though I did not see any colour in 30cm.

Two pairs are found in the southern part of the same field, but both could be clearly separated using a high magnification.

β Car / Beta Carinae / Miaplacidus (09132-6943) is one of the brighter stars of the southern skies, and can be found about halfway between the Southern Cross and Canopus. From Sydney it is a circumpolar star, and although it is today placed in the modern day constellation of Carina, it was once, prior to the mid-17th Century, lay within the super-constellation of Argo Navis. Later, Argo gained a new sub-constellation called Robur Carolinum. Created by Edmond Halley and officially published in 1679, Robur was made to commemorate the place known as the Royal Oak. This location protected the defeated Charles II, after his army was routed by Oliver Cromwell at the Battle of Worcester in September 1651. La Caille complained bitterly about Halleys addition because it destroyed most of the prominent stars in the Ship. (Halley, however, didnt complain. It ensured that he received his Masters Degrees by royal proclamation!) From about 1720, popularity for the constellation of The Oak was slowly reclaimed back into Argo Navis. Its common usage probably ended in 1800 with Johann Elert Bodes star atlas Uranographica. From then, like many others, Robur simply fell into antiquity as an obscure constellation. American astronomer Benjamin Apthorp Gould in 1879 subdivided this part of Argo Navis into smaller constellations, and Miaplacidus became part of Carina. This change was permanently adopted by the IAU in 1930.

Once known as Alpha Roburis, Miaplacidus was supposed to have been derived from the Arabic Miak or waters, while the Latin 'placidus' was added much later. I assume that from Arabia, the Chaldeans would have seen this bright star in Summer glimmering close to the southern horizon of the Indian Ocean. Today, however, Miaplacidus is fully translated to mean placid waters - appropriate because the star lies in the bilge of the ship!

This white star culminates annually at 9 pm on the 26th March. In order of brightness, at 1.674v magnitude, makes 28th among the naked-eye stars. Distance is given as 26.1pc. or 85 ly., although the latest information by Hipparcos gives the much further distance of 34.09pc. or 111.2 ly. The spectrum of this giant star was for many years given as A0 III, though it has recently been downgraded to an A2 IV, indicating a surface temperature of 8 700K. Measurements suggest an absolute magnitude of -0.4, so the true luminosity is about sixty times brighter than the Sun. Miaplacidus has been shown from the radial velocity that it is approaching us at a pedestrian 5kms-1. This is similar to the first measure in 1927, from the famous southern station of Harvard University in Chile. By 1970, careful inspection of the broadening of the spectral lines showed that the rotational (V.sin i.) velocity is c.145kms-1. Using general stellar evolution theory, the rotation of the star would have a period possibly as long as c.2.5 days or 60 hours for its nine million kilometre girth. Proper motion measures is 36.7 arcsec per 100 yr.-1 towards the constellation of Volans, which it will crawl into about the year 9 800 AD. Also in the future it will become the southern pole star in 6 200 AD, approaching by some 5° 42'. It is interesting to note that about the same time, Alpha and Beta Centauri will also be making their closest approach of 23'. Today, it stands as a lonely sentinel on the edges of the magnificent southern Milky Way.

HJ 4164 (09135-6455) is in the same field as NGC 2808, some 9.5' ESE, is this John Herschel pair first measured by Russell in 1879. The stars are 10.0 and 10.6 mag, separated by 16.4 arc sec along position angle 64°.

HU 1457 (09144-5500) is the first, which was discovered by Hussey in 1913. Both these white stars are of near equal magnitude, which is stated as 10.3 and 10.8, respectively. Separated by 1.3 arcsec at PA 260°. Since the last measure in 1957, the position angle has reduced by 10° since discovery. The proper motions suggest that the two are likely physically associated.

I 11 (09152-4533) is a wonderful close and near equal brightness pair some 10.7'WSW (PA 244°) from the planetary known as Pb5 or He2-24, and hence, is useful for finding this PNe. I saw this pretty bluish-white / white pair being resolved with some difficulty using the 20cm (C8) at 234X. (AOST2 describes I 11 as having perceivable colour difference.) My own estimates for the Δm was 0.6, and this is quite comparable with the WDS 2001 that gives 0.8 from the 6.7 and 7.5 listed magnitudes. AOST2 claims it can be split in 15cm, though at present time, it would have to be the best observing conditions to do so, as the pair's distance is slowly diminishing. I would consider 20cm is closer to the mark but using telescopes greater than 30cm will become much easier. I 11 was first discovered by Innes in 1895 and was first measured by R.P. Sellors in early 1896. Since this time the PA has increased (direct motion) from 271° to 292° - nearly 30° while the separation has decreased by about 0.15 arcsec. (2002) The spectral class of the duo is B8V. This system is without doubt a binary system of a moderately long period and will be worth watching in the coming decades. A nice pair.

LW Car (09157-6921) is some 7'E is the faint galactic RR Lyrae variable. I only mention it, as photographers can easily detect it it. LW Cars magnitude varies between 14.5 and 15.5 and has a poorly estimated period.

R 107 (09165-5824) was discovered by H.C. Russell, sometime in 1881, as he unfortunately gives no specific date for this object's first observation. He estimated separation as 8 arcsec, and said the magnitudes were 9th and 10th. Of the three observations between 1882 and 1917, separation has remained at 9.5 arcsec at PA 285°. Observers can find it near a bluish 6.1 mag star in Carina (SAO 236772; Spectra B5), some 10'S and 39' due west of NGC 2867. Stated magnitudes are 9.5 and 11.2, making an attractive contrast, and the pair is in a rather pretty field of moderately bright stars. It is easily visible in 7.5cm, though I could not distinguish any colour. This was the same in both the 20cm (C-8) and 10.5cm refractor.

FIN 133 (09166-5506) is the second and lies 19'SE. Using the triple star mentioned in the text with He2-22, continuing along the same direction until the solitary 10th magnitude is found. This is the pair. Discovered by Finsen in 1930, this pair is almost identical to HU 1457. Magnitudes are given as 10.3 and 10.4, and are separated by 1.7 arcsec. at PA 273o. Again the proper motions suggest that the stars are associated. In all, both stars can be separated in 15cm, with care, and easily in 20cm.

RMK 10 (09179-6948) is a white and yellowish pair of magnitude 7.8 and 8.1 magnitude, first discovered by Rümker at Parramatta. The pair lies 24'E of 2nd magnitude Beta Carinae. Of the nine measures, last in 1958, the positions remain 10.5 arcsec and PA 18°. No significant change has been observed with this pair. It is possible that it is a true binary, though its period is probably very long. In the same field as RMK 10, is the pair R110.

R110 (09182-6941), that H.C. Russell first found using the 29cm.(11.5-inch) at Sydney Observatory on 21st May 1881. Russells measures revealed a PA of 26.6° and a separation of 11.1 arcsec. The magnitude of the two stars is 10 and 11. Little has changed with the pair, and is likely to be just an optical system.

R111 (09208-5716) is found in a starry field some 55'SWW of IC2488 (See last month) or exactly 1.0° of NGC 2867. Within a small horseshoe-shaped asterism, R 111 lies next to another field 9.8 mag star to the east. Discovered by Russell at Sydney Observatory on the 5th March, 1873, with the first measure occurring on the 7th May 1880. His observations records 11th and 12th magnitude, separated by 8.52 arcsec at PA 209.1°. Later observations have determined the respective as 10.0v and 11.0v magnitudes, with only three measures since this time, with the latest being in 1948. This last observation shows an increase separation to 9.2 arcsec at position angle 213°. My estimate in 1992 suggests the separation has increased to about 11 arcsec. We know few details about this pair, and glancing at the proper motions of the components, it is likely that this is a chance alignment of an optical system.

V Velorum (09223-5558) is a Cepheid variable that fluctuates between 7.19v and 7.95v magnitude over 4.370991 days, whose period is set from 30th May 1970 (JD2440736.25) at 18h UT. The rise in magnitude in the outward pulse takes about 1.3 days to reach maximum brightness. Spectrally, this sub-giant varies between F6 at maxima and F9 at minima.

Jacob 5 / JC 5 / ADS 7379 (09267-2847) was discovery in 1858 to lie 40'E of λ Pyxis and halfway towards the variable S Antliae but still within the constellation of Pyxis. Jacob 5 is the close 0.6 arcsec bluish-white coloured pair of 6.5 and 7.2 magnitude. (Burnham's Celestial Handbook, incorrectly states that the stars are 8 and 8.5 magnitude.) A 30cm telescope can probably resolve the two, using high magnifications and under good seeing. Since, the separation between the two stars has remained fixed but has PA has decreased by 40° since this time. It seems likely that this is a true binary system with several hundred years as the period. The spectrum reveals a B8 star, with the individual component spectral classes still unknown.

BRT 2548 (09281-5652) is some 6'NE from the planeary nebulae IC 2488's centre, and is placed near the clusters edge. (Top left in Figure 4) Discovered by S.J.Barton in 1924, this faint pair is 11.0 and 12.0 magnitude, whose solitary micrometric measurement gives the separation as 3.6 arcsec at PA 174°.

RST 408 / NSV 4516 (09304-5822) appears as a naked-eye brightish red star some 35'SW of R123 (PA 235°) position. This pair is very difficult as the magnitudes are 5.9 and 13.5 (Δm=7.6) and the two are separated by 2.3 arcsec along position angle 98°. Since discovered and measured by R.A. Rossiter in 1930 there has been no further measures. Whether the companion is still in this position some seventy-five years later is anyones guess.

I could not see the companion in 20cm the two times I looked at RST 408 even when I tried using an occultation bar to eliminate some of the primarys overwhelming light. I suspect either 30cm to 40cm could see the stars elongated and under very good seeing split the duo.

Both the GVSC4 and the WDS03 Notes lists the primary as the suspected irregular variable NSV 4516 / HR 3793 (09304-5821) that changes between 5.86V and 5.94V is an uncertain period. It nature is yet to be determined.

Catalogued as HIP 46620 / PPM 338035/ SAO 237056/ HD 82536 this average 5.88 mag. star shows a B-V of +1.676 and the spectral class of M2 III. Hipparcos gives the parallax as 3.08±0.55giving the distance as 325±56pc. or 1060±195ly. It is unknown from the available information if the stars are associated.

N Vel / SAO 237067 (09312-5702) is an orange K5 III star (B-V of +1.538) that is listed in the GCSV4 as possible variable star. It is suggested that changes between 3.12V and 3.15V magnitude in a unknown period, but little change has been seen in recent decades. However the designation of CST: means this star actually shows constant light. The N Velorum designated name is also misleading, as all variables may only be in the range between R and Z in any particular constellation. N Velorum is the Roman letter given to the star by Bayers original Uranometria when Carina and Vela were in the grander constellation of Argo Navis. This star locates the double star SYO 1 which is only 13.2' away. Hipparcos gives the parallax as 13.72±0.51 that calculates the true distance as 72.9±2.7pc. or 238±8ly. It is possible this might be a secular variable.

R119 (09316-5602) is another fainter pair 3'W of R120. Discovered on the same night as R122 and R120, the magnitudes of this duo are 10.6 and 11.5. Separation is a wide 17.0 arcsec at position angle 200°. These last measures were taken 1934. Little has changed since then. Faint but visible in 7.5cm.

R120 / SAO 237073 (09319-5602) is some 3'W of R122, and was discovered on the same night as R122. Russells original measures show a separation of 9.59 arcsec at PA 34.5° Later observations of R120 show that Russell PA was out by 180°, a common problem sometimes facing double star observers. The current PA is 215°. Both are written as 10th magnitude, though later observations suggest the respective 9.2 and 10.2 mag. I saw both colours as slighly bluish. In all, R122 (and R119 and R120) are contained in a starry background and easily found some 42'ENE of the planetary NGC 2899 or 20'NNE from the planetary, Sa3-10. A 7.5cm will ind these pairs faint but certainly it would be better placed in 10cm or above.

R122 / SAO 237078 / HD 82789 (09322-5601) was discovered by H.C. Russell at Sydney Observatory using the 17.5cm. (7.3-inch) on the 18th March 1873. The magnitudes of this yellow and white pair are 8.4 and 10.2. Separation is 2.5 arcsec at PA 110° , and these values have slowly been decreasing since discovery. Right now it is uncertain if this is a physical system or an optical pair, but if it is a true binary, the period must be more than three hundred years. This pair will be interesting to watch over the ensuing decades.

In all, these three pairs above are contained in a starry background, and can be easily found some 42'ENE of NGC 2899 or 20'NNE of planetary nebula SA3-10. A 10cm is required to see R119, R120, R122 clearly.

Jacob 5 / S Ant/ S Antliae (09323-2838) is the brightest example of this class even though it is ignored in the literature. S Ant lies close to Antlia's border with Pyxis, being 2°E of yellow 4.7 magnitude Lambda (λ) Pyxis. Also, exactly halfway to S Antliae is the 6th magnitude close pair Jacob 5. Magnitudes vary between 6.4 and 6.92, changing equally in both the primary and secondary minima by the 0.5 magnitudes every 15.92 hours. (0.6484 days) The period between successive magnitude drops have been measured as 07 hrs 46 min 50 sec. S Antlia lies within a starry field and 20'W is two faint 7th magnitude stars that are suitable comparison. The variable has a magnitude greater at maximum and lesser at minimum than these stars.

In real terms, both S Ant's stars are separated by only 2.2 million kilometres, with each star having an average diameter of 2.4 million and 1.3 million kilometres, respectively. Due to this close separation, both stars are highly distorted, with mass transfer as presently observed being a real possibility. Total mass is the same as the Sun, with the individual masses dividing as 0.68 M⊚ and 0.32 M⊚. Surface temperatures are 8 300K and 7 350K. In solar terms, the luminosity output of the components is 12 times for the primary and 2.3 times for the secondary. Present distance for S Ant is estimated to be 91pc or 300 ly.

SYO 1 (09328-5706) is a charming blue-white and white pair lies 1.8'S of the southern Vela border with Carina being suitably placed 13.2' ESE (PA 107°) from 3.1 mag. variable star, N Velorum. The pair can be seen in 7.5cm but would be better in anything over 15cm. An obvious 8½th magnitude yellow field star also lies 3.8'SE of the SYO 1.

Discovered probably by R.T.A. Innes before he moved to South Africa, as the first pair in the Sydney Observatory double star catalogue of 1895, it is listed in the WDS Reference file from additional DD list. This should not be confused with the H.C. Russells Second New Double Stars list presented to the Royal Society of N.S.W. on the 5th September 1883 that Russell later published himself. (See WebPage) SYO 1 is also the first of the pairs discovered away from the influence H.C. Russells earlier double star work - properly named for the Observatory ad not the individual Government Astronomer. (In 1893 Russell had long stopped his work of double stars almost twelve years earlier.)

SYO 1 itself is a 7.1 and 11.0 (7.12V and 11.06V) magnitude star that is separated by 10.7 arcsec along position angle 20°. Little has changed in the relative positions of the two stars since discovery. It is likely these two are a true pair as the motions are similar but the orbital period of this must be very long. Spectral type in the WDS03 as B6/7II/III.

R 123 (09333-5758) has a combined magnitude of 6.1 making it a naked-eye star in Carina. It lies 1.0° SSE of N Velorum or some 2°E from the planetary NGC 2867. This wonderful near equally bright blue / bluish pair can be seen in 7.5cm but is fairly attractive in 15cm or 20cm. Magnitudes were visually estimated as 7.8 and 7.9, but the latest Tycho data suggests it is brighter than this giving 6.82V and 6.96V.

Russell discovered this pair on the night of the 5th March 1873, describing it as 8 and 8 appearance in the field saying This is the following star of a small triangle. In the telescope I could not identify these stars.

Up till the last measures in 1977, the pair seems to be fixed, but there is evidence that now shows direct motion that has increase +4° to position angle 34°. However, the separation is clearly closing. In 1880 this was 2.5 arcsec and this has reduced to 1.9 arcsec. If the trends continue, the stars will become difficult in about 2200AD with closest approach being in 2340AD. Spectral Class of both is B8V. An attractive and enticing duo in a field of scattered stars.

Nearby Planetary

He2-32 / Sa3-9 / ESO 166-19 / Wray 16-49 / PK 278-4.1 / PNG 278.5-4.5 (09309-5737) is a faint PNe that is listed as 16.1p and subtends some 56&215;31 arcsec. Double star R123 lies within the same field some 28'SE (PA 137°). It is likely invisible to most amateur telescopes except perhaps the larger Dobsonians.

RST 413 (09335-5823) lies 25'S of R 123s position and is a very difficult pair that would be a true challenge for any southern amateur to either see elongated or clearly separated. If the Hipparcos separation of 0.396±0.002 arcsec, however, is true then it is unlikely to be split. I have never divided this pair R.A. Rossiter found this pair in 1929 and it has been measured five times in the ensuing years. The star at low magnification looks like a 7.2 magnitude blue star. When divided, the stars appear visually as 7.9 and 8.0 mag, however more recent photoelectric estimates give 8.10 and 10.04. Since found the separation remains unchanged at 0.4 arcsec, but the position angle seems to be prograde and now orientated at 237°. A pair to watch in the future to see if the two are attached.

GW Car (09364-5959) is an EB/KE* eclipsing binary that lies in the same field as the planetary IC2501, some 1.9' along PA 287°. Visual magnitude variations change between 9.55 and 10.1 in the period of 1d 03h 05.6m (1.128911 days.), based on the starting date on the 23rd October 1941(JD 2430291.0395). The blue B1 III star show nebulose characteristic in the spectra, suggesting that the stars are, or have been, in the process of mass transfer.

* KE classification is a contact binary whose components have early spectral types in the range of O-types and A4 spectral types.

R133 (09432-8120) has magnitudes 9.5 and 9.5 was first discovered by H.C. Russell from Sydney Observatory on the 26th May 1880. His observation is given as 3.5 arcsec and the PA of 44°. In 1983, the separation was measured at 3.65 arcsec while the PA was given as 46°, indicating little change. This is a delightful even pair, with yellowish components. As both have similar common proper motions, it is likely that these stars maybe associated. If it is a true binary then the period is probably very long.

HJ 4240 (09433-6002) is an 8th and 10th magnitude pair 34'E of the small planetary IC2501. Although discovered by Sir John Herschel, Lawrence Hargrave made the first measures at Sydney Observatory on the 12th May 1882. Separated by 12.4 arcsec at PA 57°, little has changed in the positions in the last 116 years. I saw the colours as bluish and white, which is easily visible in 7.5cm According to the WDS96, the magnitudes are 7.5 and 10.0, with the primary's spectra being B5V.

W UMa / W Ursa Majoris (09438+5557) is one of the most famous and interesting of the EW eclipsing binary systems that is not visible from Sydney's -33° latitude. W Ursa Majoris varies from 7.9v to 8.63v over 0.3333639 days - or nearly exactly 8 hours. Both appear as dwarf F8V spectral class stars, both containing peculiarities in their spectrum. W UMa has the true separation of 3.6 million kilometres, each with diameters of 2.6 and 1.1 million kilometres, respectively. Luminosities are comparable with the Sun, being 1.3 L⊚ and 0.8 L⊚, while both the temperatures are 5 920K and 6 140K and masses are 1.3 M⊚ and 0.76 M⊚. Both stars appear grossly distorted, surrounding the whole system with a bright glowing gas, torn either by mass transfer between the stars or material is stripped from their surfaces. Some of these energies appear strongly in X-ray. Distance to W UMa is 55pc. or 180ly. from us.

υ Car / Upsilon Carinae / RMK 11 (09471-6504) is one of the brightest double stars in the southern skies and rates among the very best pairs for small apertures. Discovered by Charles Rümker and later measured by John Herschel in 1836 this magnificent double star is listed as 3.0 and 6.0 visual magnitude on a continuing virtual fixed position of 5.0 arcsec along the 128° position angle. Both stars are pale bluish-white to white and yellowish - though some say the companions colour is yellow being likely a slight contrast effect but does agree with the spectral class of A8Ib or A9.

E.J. Hartung says of this pair;

...there has been no real change in this very fine pair, and the proper motions are sufficiently similar to indicate a long period binary. It is an admirable object for small apertures.

Canberra observer Ross Gould in "Seeing Double" (Southern Astronomy, Mar/ Apr 1994 pg.52-53)

The 18cm refractor showed it as an easy and beautiful pair at x180.

This is a wonderful pair especially as it shares the field with the faint and just as easy HJ 4252. The main star of υ Car is catalogued as HIP 48002 / T8950:2272:1/ PPM 357553/ SAO 250695/ HD 85123 whose exact position is RA: 09h 47m 06.14s and Dec: -65° 04' 19.3″ and the given visual magnitude is 2.92 with a B-V of +0.273. Tycho gives the primary as 3.01V magnitude and the B-V of +0.267.

Proper motions here are quite similar and it is highly likely that the two are physically attached. Hipparcos parallax is 2.01±0.04mas giving the distance of 498±10pc. (1620±32ly.) calculating the current true separation as 6 500AU. Estimates of the orbital period maybe as long as 200 000 years. Absolute magnitudes (Mv) are -5.4 and -2.5, respectively, with the sum mass (ΣM⊚) of 17.8M⊚. Using the Mass-Luminosity Relationship (MLR) for supergiant stars, the masses divide into roughly as 12.0M⊚ and 5.8M⊚ suns.

This is a wonderful pair - especially as it shares the field with the faint and easy HJ 4252. A really "must see" pair!

HJ 4252 (09478-3507) lies only 5.4'SE (PA 123°) from Upsilon (υ) Carinae / RMK 11. This bluish-white stars are 9.3v and 9.5 magnitude (or 8.74V and 9.13V) and are presently separated by 12.2"arcsec along PA 303°. Both stars continue to slowly reduce in distance, going from the Herschel measure of 13.0" (1836) to 12.2" (1991). As the proper motions are similar, it is likely these two stars are attached. Assuming the parallax is 12.10±0.84mas is correct, being the distance of 83.3±5.9pc (279±19ly.), then the true separation is now around 1 100 AU with the a period being around of 20 000 years.

Hartung (AOST1) states under his description of Upsilon Car;

...a small pair h.4242 (9.3 9.5 12" 303°) almost 5'Sf. is also easy.

Ross Gould in "Seeing Double" (Southern Astronomy, Mar/Apr 1994 pg.52-53) states;

...5' South-east is HJ4252, a wide faintish fixed pair...[and] showed well with 18cm at 180x.

This is interesting pair that shares the same field as υ Car that best is seen using medium to moderately high magnification. A true southern splendour.

Δ81 / DUN 81 (09543-4517) also known as Bode star 524 Argus, is one of the most magnificent jewels of the southern sky and not to be left out of in any southern observers object lists. Hartung describes it as ornaments, a lovely field, a real treat to see.

I saw the colours as pale yellow and bluish, seemingly being twos colour little more prominent than when Dunlop saw the pair in 1827. Dunlop measured the pair first, but for some reason the first recognised measures were achieved by John Herschel in 1836 (as stated in AOST2). Dunlop actually did measure this star first, giving the PA as 30° 34'sp. equally the PA of 270° - 30.57° = 239.4° and 4 arcsec. Little change has occurred in these star since Dunlop found the duo in 1836. Presently the PA is 240° with the separation of 5.4 arcsec, and the stated magnitudes are 5.8v and 7.9v. As there is little movement in positions it is uncertain if these two are connected, but there is evidence of similar common proper motion. If they are really attached the period will be very long.

Southern Astronomical Delights”
© (2009)
10 Mar 2009