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More Southern Doubles
For the benefit of Bigjoe and his 'trickledown' followers, I have included a short list of easy doubles near Pointers and Crux. More will follow when the snail weather along the east coast clears. Thanks Bigjoe for keeping this up and for the useful sites:
Around the Southern Cross 1. (10"F5 Dob)
1) Delta (Δ) 159.Centauri: [RA 14.22.6; Dec -58.28; mag 5/7.6 Sep 9.1” PA 157°] Most of us are all too familiar with The Pointers but nearby and forming the apex of a triangle on the north side of the pointers lurks this fine double star . Through a small telescope this mag 5 yellowish star has a blue companion easily spotted at moderate power.
2) Delta (Δ) 141; Q Centauri: [RA 13.41.7; Dec -54.34’mag 5.2/6.5 Sep 5.4” PA 163.]This mag 5 golden star and its 6.5 mag companion lie just south of Epsilon Centauri (ε), which itself forms the apex of a triangle with the pointers. Although closer than the last pair at 3.4” separation, in steady atmosphere the rose coloured companion is just separated at moderate power. Q itself forms a neat triangle with two other fainter stars in the field.
3) Delta (Δ) 133; J Centauri: [RA13.22.6;Dec -60.59’ mag 4.5/6.2 Sep 61” PA 345]This 4.5 and 6.2 pair lie about halfway between Beta Centauri (the westerly Pointer) and Mimosa or Beta Crux. It lies just south of an ‘L’ shaped group of mag 5 stars. This is a wide pair suitable for small optics and the colour contrast of White and Blue is pretty. Another star lies in the field.
4) Delta (Δ) 126; Mu (μ) Crucis: [ RA 12 54.6 Dec -57 11; mag 3.9/5.0; Sep 37” PA 24]Yet another fine Dunlop double is found just over the border in Crux and this one lies at the apex of a triangle formed with Gamma and Beta Crucis. This very light yellow mag 3.9 star is an easy separation from its light blue mag 5 companion at a wide 37”. The view is rich with two other stars in the field at moderate power.
5) Delta (Δ) 252; Alpha Crucis:[12 hr 26.6m; -63 06 S, mag 1.4 and 1.9, sep 4” PA 110, and C star mag 4.9, sep 90”].
Finally, no search for double stars in this area of sky is complete without turning your instrument to a stunning binary. In finder scope and binoculars Acrux is a delightful brilliant white star with a wide blue companion. The telescope reveals that the brilliant ‘A’ star can be split into a fine binary ‘A 1 and A2’. The period of this pair is a whopping 1,500 years. Further spectrum analysis reveals ‘A1’ is an eclipsing binary with an orbit of 76 days! Acrux is 25,000 times brighter than our sun and 320 ly away.
The wide third blue companion ‘C’ is also a binary and nearby fainter stars are now thought to be related. This is truly a stunning multiple system. I found alpha hard to split at high power but my 4” offset mask revealed two clean points of light. Eugene
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