Double Star of the Month in Cepheus

• November 2024 - Double Star of the Month

  George Knott was a Victorian amateur astronomer with an interest in double stars. Using a 7.3-inch Clark refractor which once belonged to W. R. Dawes at his observatory in Cuckfield, West Sussex, he made a number of discoveries, five of which can be found in the current Washington Double Star catalog.

  The primary star of KNT 1 (01 02 18.34 +81 52 32.1) is the variable star U Cephei. It is an eclipsing binary with a period of 2.5 days and in mid-eclipse the star drops by almost three magnitudes. At maximum, it is V = 6.7 and has a faint companion of magnitude 11.8 some 14" distant in PA 63 degrees.

  

  Rather surprisingly both stars lie at the same distance (632 light-years) and have very similar proper motions. A slighter fainter, and definitely unconnected, third star can be found at PA 315 degrees (increasing) and 24" (decreasing).

  Another pair of stars with a variable primary is HJ 3476 (02 00 26.77 -08 31 25.8). This is AR Cet which is probably a semi-regular variable. John Herschel swept them up from Feldhausen and noted Large star very yellow. The primary is an M3 giant and its catalogue magnitude is given as 5.7 with the companion 61" away in PA 202 degrees. Herschel noted magnitudes 6 and 10.

  

  The position angle has reduced 20 degrees since discovery but this is due to the proper motion of the primary star which is 536 light-years away whilst its faint companion lies 2160 light-years distant.

  HJ 3476 lies about 3 degrees NE of zeta Cet which is also known as Baten Kaitos. This, too, is a very unequal and wide double with the components of 3.8 and 10.5 being divided by 106".

  Bob Argyle - Double Star Section Director

• September 2024 - Double Star of the Month

  Just two and a bit degrees north of the Saturn Nebula (NGC 7008) is the long period binary STF 2751 (21 02 09.00 +56 40 11.1). This pair of white stars should be divided easily in 10-cm and may be split in a good 7.5-cm aperture.

  

  Since 1828 when an early measure by the discoverer F G W Struve gave 343 degrees and 1".5 the stars have now moved on to 356 degrees and 1".6. Gaia DR3 indicates that the stars are at the same distance from us at least within the formal quoted errors. They lie 1,100 light-years away and are moving across the sky at close to 0".1 per year.

  Three degrees due south of the first magnitude Achernar in Piscis Austrinus is delta PsA (22 55 56.89 -32 32 22.9) which was found to be double by Herbert Howe in Cincinnati in 1876 and is number 91 in his catalogue, although the Washington Double Star catalog (WDS) also call this system BU 772 which reflects an independent, but later, discovery by S. W. Burnham.

  

  The WDS gives magnitudes of 4.3 and 9.3 whilst the Gaia DR3 catalogue records G magnitudes (similar to visual) of 3.9 and 9.8. As the current separation is 4".7 this is a pair which needs a night of steady seeing and, given its very low declination from the UK, probably 15-cm aperture. The stars appear to form a physical system and are 171 light-years away. Both beta PsA and gamma PsA are pairs with bright primaries and considerably fainter comites (see this column for Oct 2016 and Oct 2012 respectively).

  Bob Argyle - Double Star Section Director

• September 2021 - Double Star of the Month

  STF 2883 (22 10 38.8 +70 07 57.2) is located in the pentangle of Cepheus, about 3 degrees following beta Cephei, which is itself a fine pair (see this column for Sept 2012).

  

  This pair was somehow missed in my early survey carried out in the late 1960s, probably because of its high declination. It also eluded the elder Herschel and only made it into his final double star catalogue of 1822 as H N 121. It was subsequently observed by South and John Herschel and they noted the stars were white and blue with the colours very decided. I measured it with the Cambridge 8-inch in 2003 (253, 14".4) and at the time I noted another fainter and wider pair about 15 arc minutes south-west (7.9, 8.1, 207 degrees, 66").

  STF 2883 is almost certainly a long period binary. The distances as they appear in Gaia EDR3 are almost identical and the proper motions are similarly equal. The stars lie 106.29 light-years away. This is a nice pair for the small telescope with the stars shining at magnitudes 5.6 and 8.6.

  HIP 110109 (22 18 15.6 -53 37 38) is a Sun-like star of magnitude 5.4 located in the south-western corner of Grus and which can be found six degrees due north of alpha Tucanae.

  

  During the period in the late nineteenth century when observers from Harvard were site-testing at Arequipa in Peru, they discovered a number of new double stars and this star appeared in that list (HDO) as number 298. When first observed the magnitude 9.7 companion was 2".5 distant in position angle 10 degrees but since then the stars have closed and the last measurement in 2015 found the companion at 10 degrees and 1".8.

  Hipparcos found both stars to have the same distance (45 light-years) within the admittedly large errors on each parallax.

  Bob Argyle - Double Star Section Director

• September 2020 - Double Star of the Month

  STF2872 (22 08 36.04 +59 17 22.2) is located in Cepheus about 1¼ degrees north and slightly west of zeta Cep (a distinctly reddish star of magnitude 3.4). To the small telescope it appears as a wide pair. The catalogue magnitudes are 7.1 and 8 and the current separation almost 22 arc seconds.

  

  When F. G. W. Struve examined the system during his great survey at Dorpat he noted that the companion was a close pair with a separation of around 0".5. Since then the position angle has decreased about 40 degrees and the separation has slowly increased giving a position angle of 296 degrees and separation 0".80 in autumn 2020. I was able to measure this pair in 2016 with the Cambridge 20-cm refractor and it may be divisible in 15-cm. The 840 year orbit shows the stars slowly closing, reaching 0".2 in 100 years time, but for the foreseeable future a moderate aperture will suffice. Gaia DR2 does not show BC as two stars, rather surprising as many pairs wider than 0".5 appear as two entries in that catalogue.

  

  Surprisingly missing from Hartung's Astronomical Objects for Southern Telescopes, 57 Aql (19 54 37.65 -08 13 38.3) is one of the finest pairs in Aquila. The stars are of magnitude 5.7 and 6.4 and both are late B dwarf stars.

  It might be expected that both stars appear white but there have been wide variations in reported colours. Webb in 1851 thought they were distinctly contrasted pale yellow and pale blue whilst he notes in 1855 cols. entirely diff. Smyth though both were pale blue whilst Struve reported both stars as white. I have often wondered if the colour of a star can appear to change if it is a spectroscopic binary, especially if the components have different spectral types and the orbits are almost edge-on to the plane of sight. The WDS notes tell us that both components are, in fact, SBs, whilst the paper by Chini et al. in 2012 notes both stars have constant radial velocities.

  There has been no change in relative position in the last 200 years with the two stars fixed at 171 degrees and 35".5. William Herschel noted 29".5 in 1781 which may suggest a misreading of his micrometer screw. Gaia DR2 places them 440 light years away; within the search radius of 150 arc-seconds, I also noted a magnitude 20 star with nominal parallax slightly greater than 57 Aql A and B but with an error of 30%.

  Bob Argyle - Double Star Section Director

• October 2019 - Double Star of the Month

  STTA 1 in Cepheus (00 14 02.61 +76 01 37.2) can be found 2.5 degrees south-east of gamma Cephei. It is the first entry in the appendix catalogue of 256 pairs with separations between 32" and 2' which Otto Struve compiled when he surveyed the heavens for new close pairs with the large refractor at Poulkova.

  Gaia DR2 confirms that the difference in the stars' distances is more than 300 light-years. The primary is an M4 giant whilst the secondary is spectral type G5.

  Just over one degree north is the binary STF 13.

  In late 2019 the stars can be found at 48 degrees and 1". The writer always found it somewhat difficult to see clearly due to the difference in the magnitudes, but the Washington Double Star Catalog (WDS) gives 7.0 and 7.1, whilst in the G-band, similar to V, DR2 gives a deltaM of about 0.4.

  About 4.5 degrees north and east of the first magnitude star Fomalhaut is epsilon PsA, a star of magnitude 4.2. Head due south by about 1.5 degrees and you will alight on the wide pair H VI 119, (22 39 44.12 -28 19 32.0) an object found by the elder Herschel in 1783.

  The current position is 159 degrees and 86" and the magnitudes are 6.4 and 7.5. Even with small apertures, however, it should be apparent that B itself is a double star, a fact that Herschel discovered when he revisited the system around 1800 and called it H N 117. The close pair was rediscovered by John Herschel in 1834, giving it the number HJ 5356, but this has now been discontinued.

  Ross Gould, who has observed it with 175-mm, notes that the primary is deep yellow whilst both stars in the close double companion are pale yellow. The 7.5 and 8.6 magnitude stars are separated by 3" in PA 70 degrees with both these values increasing slowly since discovery. This is a physical triple - DR2 shows almost identical parallaxes and proper motions.

  Bob Argyle - Double Star Section Director

• September 2016 - Double Star of the Month

  Located in Cepheus, STT 461 = 15 Cephei (22 03 53.86 +59 48 52.5) offers a stellar grouping which more resembles an asterism than a multiple star. On the basis that a picture is worth a thousand words, an image from the POSS Quick V survey is appended showing the main components of the group.

  

  STT 461 is located close to the galactic equator and can be found about 2 degrees north-west of the orange supergiant zeta Cep. (mag. 3.4), the most south-easterly of the five bright stars in the pentangle of Cepheus. W. J. Hussey, who re-observed the complete STT catalogue using the Lick 36-in (1901) merely measured AB and the 9th magnitude companion C. The WDS lists eight stars to mag 14.3; the primary star is a hot B1 dwarf of magnitude 6.6 and has B (mag 11.4) 11" distant in PA 297. C which is a K0 giant is 90" away in PA 40. There is little relative motion in the group, which, if the stars are all at the same distance as A, lies about 1500 light years away.

  One of S. W. Burnham's earlier discoveries (BU 172), made with the 6-inch Alvan Clark refractor, was 51 Aquarii (22 24 06.87 -04 50 13.2). At that time Burnham's telescope was not fitted with a micrometer so his friend and colleague, Baron Ercole Dembowski in Italy measured the pair for him. In 1875 the two stars were at PA 20 degrees and separated by 0".46 so offered a tough test for Dembowski's 7.5-inch refractor.

  The pair then slowly closed through most of the last century, reaching a minimum distance of 0".11 around 1987 when the position angle was changing by 20 degs per year. A good set of speckle measures since then means that the orbit is now tolerably well-known. The period is 145 years and at the time of writing the separation was just under 0".5 and widening, with the companion almost at the point in the orbit where it was discovered last time around.

  A good 20-cm should show the pair but its fairly low altitude means the air needs to be steady. On 1782 Oct 2, William Herschel noted three faint and distant companions to 51 Aqr, but the duplicity of the primary star, then close to its maximum separation of 0".6, escaped him.

  Bob Argyle - Double Star Section Director

• October 2015 - Double Star of the Month

  STF 2816 (21 38 57.62 +57 29 20.5) which sits within the cluster Trumpler 37 (and the HII region IC 1396) and is a multiple star with three stars visible to the small aperture.

  AC are stars of magnitudes 5.7 and 7.5 separated by 12" in PA 120 and with little motion visible. The primary is a very hot star of spectral type O6f. Some 20" away in PA 338 is a further star (D) of magnitude 7.8. This in turn has a 13.2 mag comes at 351 degs and 55". In 1889, using the Lick 36-inch refractor, S. W. Burnham added a 13.3 star to A at a distance of 1".7. At the highest angular resolutions A is double again with a companion at a distance of 0".1 and it is also a double-lined spectroscopic binary with a period of 3.7 days so it seems likely that this is a very close triple.

  For the binocular user, the stars that make up the wide pair of pi1 and pi2 Gruis make a splendid sight. They lie about halfway between alpha and beta Gruis and a degree north of that line.

  The brighter of the two is pi1 Gru (22 22 44.2 -45 56 52.61) at V = 5.62. This is a F3 star which is a giant or sub-giant and which has a large annual proper motion. Its distance is correspondly small - 130 light years. Some 269" east and slightly north is pi2 at V = 6.55 but extremely red in colour. It is a member of the rare spectral class S and has a (B - V) index of 2.1. Looking at it on the POSS images it appears slightly brighter than pi1 but when the 2MASS survey image is examined, its overwhelmingly bright image practically obliterates that of its companion.

  Both stars are double and both were discovered by Robert Innes. Pi1 is I 135 - the companion is a GO dwarf, magnitude 10.7, distant 2".5 in PA 200, although observations of the system with VLTI show a spiral-shaped arc of emission which may be due to orbital motion of this dwarf and indicates the possibility of a third star, much closer in with a period of less than 10 years. Pi2 is I 382 where the 11.4 mag companion has moved from a separation of 4".6 to 11" over the course of a century, due to the large motion of A.

  Bob Argyle - Double Star Section Director

• October 2014 - Double Star of the Month

  About 2 degrees north of iota Cephei can be found the pair STF2947 (22 49 00.68 +68 34 12.2). This neat 4".6 pair can be well seen in 15-cm and the magnitudes are 6.9 and 7.2. Sissy Haas notes that iota is golden colour and STF2947 is a pair of yellowish-peach stars. Hipparcos does not appear to have observed this pair but it does appear in the 1952 Yale Catalogue of Parallax where the distance is given as 120 light years but with an uncertainty of 20%. A third star of magnitude 12.5 can be found at 208 degrees and 121" but it does not share the space motion of the close pair. About two degrees south is STF2948 (7.3, 8.6, 4 degs, 2".6))

  Theta Gruis (23 06 52.77 -43 31 17.2) is the brighter component of the very wide pair SHY 366. The nomenclature refers to Shaya and Olling who in 2010 made a study of wide pairs in the Hipparcos catalogue for which the proper motions were very similar. In the case of Theta Gruis they concluded that the likelihood that A and C (mags 4.5 and 7.8, 292 degs, 159") were physical was 100%. The distances to A and C are respectively 131.9 and 130.4 light years. Jacob then discovered that A itself was a close pair with star B of magnitude 6.6, being found at 114 degrees and 1".5 in 2009. William Stephen Jacob was an Army engineer with a deep interest in astronomy an during secondment on duty in India in the 1840s managed to make some observations of double stars. He used the 6.3-inch Lerebours refractor at Madras to make some micrometric measurements and also discovered a number of new pairs. The WDS contains 24 pairs bearing his discovery number which also includes the binary JC 8 and the Antares lookalike-pair 21 Sgr = JC 6 (see the column for Sep 2008).

  Bob Argyle - Double Star Section Director

• September 2014 - Double Star of the Month

  H 1 48 (21 13 42.46 +64 24 15.1) is a very rare example of one of William Herschel's close discoveries which retains its original designation instead of being absorbed into the catalogue of F. G. W. Struve, as many of his pairs were. It is also remarkable as being a fairly short period system which has both high eccentricity and high inclination. It is characterized by periods of rapid angular motion at very small separations and then stretches of decades when it is visible to the medium aperture. The brightness of the stars (7.2 and 7.3) means that it is never an easy object in small telescopes but may well be visible in 15-cm after 2020 or so when the separation slowly increases to 0".9. The ephemeris for the 81.7 year orbit by Marco Scardia and colleagues gives a separation of 0".72 and PA 243° for 2015.0. The pair can be found 1 deg south preceding 6 Cephei which is, in turn, 3 degrees north of alpha Cephei.

  BSO 15 (21 48 15.75 -47 18 13.0) is a naked eye star in Gruis about 4 degrees preceding and slightly south of alpha. It was found to be double by Thomas Brisbane in the early 1830s. The primary is a GO dwarf of V = 5.6. Hipparcos places this star at a distance of only 52 light years and as a consequence it has a fairly substantial proper motion of almost one-third of an arc second per year. The mag 8.8 companion is not connected and is being rapidly left behind by the proper motion of A. The pair was first accurately measured by John Herschel in 1836 when he found B at a separation of 30.3" in PA 14°. Last year the writer measured the pair again and found a distance of 78".9 in PA 350.2°, in good agreement with the prediction given in the USNO Linear Elements Catalogue. This pair has not been observed by either Hartung or Haas and the writer didn't note any significant colour in either component. Recent observations by the infra-red Herschel telescope show there is a large proto-planetary dust ring around this star stretching from about 100 to 180 AU.

  Bob Argyle - Double Star Section Director

• Double Star of the Month - October 2013

  In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.

  Delta Cephei (22 29 10.25 +58 24 54.7) is the prototype pulsating variable the period of which holds the key to its distance. Thanks to Hipparcos this distance has also been determined geometrically and it comes out at 865 light years with a formal error of 37 light years. Regrettably few Cepheids were in range of the satellite during its operation between 1989 and 1993 but its successor, GAIA, will sweep up many more when it launches later this year. Delta is also a most attractive double star and its mag 6.1 companion is probably visible in regular binoculars. It can be found 41" distant from delta in PA 191°. This is formally star C in the system as S. W. Burnham found a much fainter (mag 13) and somewhat closer star (B) using the 18.5-inch refractor at Dearborn. Matt Heijen using a 30-cm Orion records the colours on his StarObserver.eu website and notes 'yellow, almost orange and bluish white'. There are three more distant comites between mag 13.5 and 14. C was noted as a spectroscopic binary by Belopolsky more than 100 years ago but little seems to be known about it now and it does not appear in the Ninth Catalogue of Spectroscopic Binary Orbits. Recent radio observations of delta reveal an extended nebula of ionized hydrogen surrounding the star which infers that mass loss is taking place at a level of around 10-6 solar masses per year. This may go some way to explaining the discrepancy between the mass derived from stellar evolutionary models and that obtained from stellar pulsation and dynamical techniques.

  STF2944 in Aquarius (22 47 50.19 -04 13 44.8) is a nice triple star which contains a visual binary system. It is 2.5 degrees following the pretty, coarse pair kappa Aqr which has an orange primary star. The closer AB pair consists of stars with magnitudes 7.3 and 7.7 which have closed up considerably since discovery in 1782. In the same time the position angle has increased by almost 60°. For the end of 2013 the stars can be found at 303° and 1".86. C which is mag 8.6 is 60" away in position angle 86°. This is not physically connected to AB and is being left behind by the rather considerable proper motion of the close pair, some 0".4 per year. It is large enough to have attracted the attention of Willem Luyten and both components are in the NLTT (Not Less than Two-Tenths) Catalogue. The colours in these stars are not too obvious given that they are rather faint, but at low power Sissy Haas gets beige white and arctic blue for AB combined and C. Hipparcos confirms the proximity of the system to the Sun - the parallax yields a distance of 105 light years.

  Bob Argyle - Double Star Section Director

• Double Star of the Month - December 2012

  In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.

  The conventional long-focus refractor user is at a disadvantage when it comes to examining that part of the sky near the celestial poles. This is a pity since there are a number of systems north of +75 which are worth looking out - amongst the binaries are STF2 and pi Cep and the beautiful optical pairs 19 Cam, STF1694 and kappa Cephei, not to mention the Pole Star itself.

  The writer measured STF460 in Cepheus (04 10 02.74 +80 41 55.2) on three nights in 1994 but has not examined this slow moving binary since. The period appears to be about 415 years so it has moved almost half an orbital revolution since discovery in 1828. The position angle is increasing and anyone observing it in late 2012 should see the companion at about 149° and 0".69. Having reached a maximum apparent separation in the 1920s the pair is now closing and should reach 0".65 in around 2030. The stars are visual mags 5.6 and 6.3, and Webb gives colours of yellowish and bluish whilst Sissy Haas notes only that the primary is straw yellow.

  32 Eri (93 54 17.49 -02 57 13.0) is another of William Herschel's discoveries, but being close to the equator is comfortably within reach of many latitudes and the smallest telescopes. The stars are mags 4.8 and 5.9 and the colours ascribed to stars by Hartung deep yellow and white seem to chime perfectly with the given spectral types of G8III and A2V. Only the earliest measures of the elder Herschel seem to disagree with the general finding that the separation is around 6".5. Is this an error by WH or evidence of rather swifter orbital motion which has not manifested itself since? Between the measures of Struve in 1822 and today there seems to have been no significant movement in separation or position angle but as the stars have similar proper motions there seems no doubt that they form a binary pair. At 165" there is a 10.5 magnitude third star - it too shows no apparent motion over 150 years, so is it also a member of the system?

  Bob Argyle - Double Star Section Director

• Double Star of the Month - September 2012

  In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.

  beta Cep (21 28 39.58 +70 33 38.5) was observed as a double star by both William Herschel and Piazzi. The mag 3.2 primary is accompanied by a companion of magnitude 8.6 some 14" distant in position angle 251 and there has been little change in this relative position in more than 200 years. Beta Cep is a distant star - Hipparcos puts it at almost 700 light years. It is clearly also a very luminous star, the WDS catalogue marks it out as a giant of spectral class B3. Interest in beta was reawakened in the 1970s when Antoine Labeyrie, the father of speckle interferometry, found the brighter star to be a close but unequal binary. Paul Couteau the famed visual observer tried to resolve it with the telescope at Nice but failed and subsequent observations have shown the magnitude difference in the visual to be more than 3. The orbit of Aa is very highly inclined and motion is almost all in distance - ranging from 0".33 at greatest separation (to be reached in 2035) to less than 0".01 near periastron. AB is noted as a showcase pair by Sissy Haas and she gives the colours as brilliant white and green. Smyth notes white and blue and also that there is a coarse but very minute double star preceding. Beta Cephei is probably more well-known as the prototype of a class of pulsating variable stars similar to Cepheids but with lower amplitude and range of magnitude. In this case the period is about 4 hours and the star varies by about 0.03 in V.

  MLO 6 (21 27 01.62 -42 32 52.5) is located in Microscopium - close with the border with Grus and sadly too far south to be seen from the UK. Hartung gives colours of deep yellow and white which is surprising given that the primary is an A star but with metallic lines in its spectrum. The distance is 184 light years and the small change in relative position (146°, 4".2 in 1879, to 150°, 2".9 in 2008) suggest that this is a long period physical system. The magnitudes of 5.63 and 8.15 means that a good view of both stars would be gained with apertures of 15-cm or more.

  Bob Argyle - Double Star Section Director

• Double Star of the Month - October 2011

  In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.

  Located in northern Cepheus and about 15 degrees from the NCP, pi Cep (230753.8 +752315) is an awkward target for the user of the classical refractor and the writer has only measured this binary once, in 1994, when the position angle was 347° and the separation 1".1. Since then direct motion of 10 degrees has occurred with virtually no change in separation. It has now almost reached the point where Otto Struve first measured it in 1846 and the current period is given as 163 years. Around 1920, a number of observers recorded the star as single but the current orbit predicts separation in the 0.5 to 0.6 arc second range so it is not clear why the star should have been unresolved. Is the companion perhaps a variable? The primary is an early G star and both Webb and Smyth thought it very yellow or deep yellow, respectively, with both men agreeing that the secondary appeared purple. It is also a spectroscopic binary with a period of 556 days and it is speculated that the invisible companion is itself a short period binary. John Herschel found a 12.2 mag. comes at 58". Pi Cep is an attractive object but the stars are more than 2 magnitudes apart and it needs good optics and a steady air to resolve it cleanly. It will remain in range of 15-cm or so for a few decades to come.

  Sculptor contains a few nice pairs and one of these, kappa1 Scl (000921.0 -275917) is a good test for a 10-cm as the stars are magnitudes 6.1 and 6.2 and currently 1".3 apart. It was found low in the Chicago sky by Burnham using his 6-inch refractor when it was considerably closer than it is today and a preliminary orbit gives a period of over 600 years. Willem Luyten, in his proper motion survey work, found an 18th magnitude companion at a distance of 73" moving through space with the bright pair, making this a physical triple. Hipparcos puts the bright pair at a distance of 256 light years, some 10 light years more distant than pi Cep. The low power field also contains kappa2 Scl, a 5.4 mag. K giant, and most curiously, this too has a very faint (mag. 21) cpm companion found by Luyten which appears in the WDS as LDS2099.

  Bob Argyle - Double Star Section Director

• Double Star of the Month - September 2009

  In this series of short articles, a double star in both the northern and southern hemispheres will be highlighted for observation with small telescopes, with new objects being selected for each month.

  Two high declination systems are the subject of this month's column.

  Cepheus is a rich hunting ground for the northern double star enthusiast and Webb lists about 80 pairs in this constellation, many of which are suitable for the small aperture. xi Cep (22 03 47.2 +64 37 40) did not attract much interest from Smyth as the binary nature of the system was not then apparent, the change in angle having amounted to only 3 degrees from the observation of Herschel some 80 years previously. Since then the curvature of the apparent orbit has tempted the production of an orbit of period 3800 years and in 2010 the companion can be found at 274 degrees and 8".34. The system is relatively close by (30 parsecs) and the main interest for the small telescope observer are the colours of the two components. Webb called them white and tawny or ruddy whilst Smyth thought them both bluish. Sissy Haas considers them lemon white and royal blue. The spectral types are A3 and F8. For the large telescope observer, the A component is a close interferometric and spectroscopic binary of period 2.254 years and the separation never exceeds 0".06.

  In the far south Octans straddles the celestial pole. Lambda Oct (21 50 54.5 -82 43 08) precedes beta Oct by a few degrees in a rather sparse area of the sky but the effort of finding it is certainly worthwhile. It is one of John Herschel's discoveries from South Africa (HJ 5278) and is one of the more attractive ones. Hartung calls it a `bright elegant close pair, deep yellow and white.' It is clearly a physical pair and the position for 2002, when it was last measured according to the WDS, is 63 degrees and 3".5. This is a distant pair, more than 400 light years away according to Hipparcos, and the spectra are G8 and KOIII which makes Hartung's comments about colour all the more interesting. The magnitudes are 5.6 and 7.3. For more observations of Octans pairs, see the article by Magda Streicher in Deep-Sky Observer 145, 2008.

  Bob Argyle - Double Star Section Director