Beta Scorpii – Graffias
RA: 16h 05m Dec: -19°48′
Mag: 2.6, 4.5 Sep: 13.6″ PA: 20°
Distance: 550 ly
Spectral type: B2
This is what I call a “60mm jewel.” That is, when you see this star at medium power in a good 60mm scope it evokes an “oh wow” response. And it’s much deserved – for this is a very luminous, very young system of at least five stars – though all we see in a small scope is two. Graffias splits easily and shows you two nice round bullets, snowman fashion, one on top of the other – with the one on “top” being the smaller, dimmer, bluer of the pair. The primary is generally called “white” – I see it as having just a touch of blue. The secondary is usually seen as blue, or “cobalt blue,” or even greenish. I see it as a very deep, rich violet. I used the 60mm Unitron and Televue Plossls. While it split at 28X, it was best at 69X.
These two stars are around 2200 astronomical units apart and take more than 16,000 years to orbit each other. Jim Kaler says that “though both should appear blue-white to the eye, the brightness difference makes them look different through the telescope, the fainter one seeming a bit ashen, rather yellowish. ” Wow! What I would say is this pair of stars evokes a lot more variations of color descriptions than most. How do you see them? Here’s how Kaler describes describes what we don’t see:
The fun begins with closer examination. Beta-1 has a tenth magnitude closer companion only half a second of arc (projected 80 astronomical units) away, so Graffias now seems triple. More, Beta-1 proper (the brighter) is a “spectroscopic binary,” the spectrum showing two stars in orbit with a period of 6.8 days, the separation a mere 0.001 seconds, 0.3 AU, closer than Mercury is from the Sun. Still more, Beta-2 has a fainter companion a tenth of a second away from it. . . . What a sight it would be from an “earth” orbiting Beta-1 and its two companions, say at 150 astronomical units where we could survive. We would have a triple Sun, and off in the distance the double Beta-2 would shine 50 times brighter than our full Moon.
You can read more on Kaler’s web site here.
Graffias – and it’s neighbors – also gets a good deal of attention in “Turn left at Orion,” the wonderful observing guide produced by Guy Consolmagno and Dan M. Davis. This is a guide for beginners, yet I find myself checking it frequently and after half a century I think I’m out of the beginner category 😉 But I plan to come back to this and take the whole tour through the vicinity of Graffias. In fact, these southern constellations hold mostly new observing ground for me because they are hidden by the treeline in my backyard where I usually observe. One thing the 60mm telescope does well, however, is encourage you to pick it up and walk to your good neighbors yard where the view to the south is much better. So I plan to do more of that kind if grabbing and going!