Download Double Stars in Scorpio`s Claws

Double Stars in Scorpio’s Claws
Intermediate Level – requires binocular & telescope
As summer approaches, mighty Scorpius rises higher each night in the south. While many are familiar
with the brilliant red giant Antares (the ‘Rival of Mars’), the claws of Scorpio hold a wealth of double
stars that are a rewarding challenge to any astronomer. Some of these are actual double stars (pairs of
stars that orbit about each other), others are ‘apparent doubles’ – stars that simply lie along the same
line of sight, but are very distant from each other in space.
The map below indicates the location of several doubles. Tight doubles are indicated by a small circle
around the star. Stars marked with an asterisk* are actually in Ophiuchus, not Scorpio, even though
they are in the ‘claw’ region. The challenge is as follows:
1. Locate the indicated double in your scope at low power (25mm EP), can you see any indication
at this magnification?
2. Increase magnification until the star first indicates its double character; record this
magnification.
3. At the best magnification (the magnification that gives you the clearest split of the pair),
determine the spectral class (color) of each of the pair (or multiple group!). Sketch the pair at
this magnification in the space provided.
4. Given the magnitude of the brighter of the two, try and estimate the magnitude of the
companion star. Check your results on spectral class with Stellarium!
© 2012 by Daniel Barth
Free Educational Use is Permitted.
www.MauriceontheMoon.com
Sketch:
1. ω Scorpii Nice pair known as ω1 and ω2 respectively.
Easily split with 10x50’s.
2. 2 & 3 Scorpii Another pair that is easily split in 10x50’s.
3. Hip 77858 Just north of 2-Scorpii, this pair is not a true
double, you should be able to see a striking difference
in color between the two.
5. Move further south to ρ Scorpii, this is not a true double,
but you should be able to see two dim red stars that form
a line with brighter ρ Scorpii between them.
6. Hip 79050 On a direct line between η-Scorpii and Antares,
this faint pair is quite challenging both because of limited
separation, and its low magnitude. Just a bit further along
toward Antares is Hip 79192, an even fainter and closer pair.
7. δ-Scorpii or Dschubba is the central star in Scorpio’s claws.
Low magnification will reveal two nearby faint red stars,
(mag 9 or so) but Dschubba’s companion is faint and very
close. This is a great challenge and may only be visible in
larger scopes.
8. On a line between Dschubba and Antares, we find Al Niyat.
Lower magnification will reveal another nearby apparent
double, but high mag will reveal a very close companion star
Very challenging!
© 2012 by Daniel Barth
Free Educational Use is Permitted.
www.MauriceontheMoon.com
9. Moving back up to β-Scorpii, Acrab is a very bright star, the
upper most star in Scorpio’s claws. This double is more easily
split at modest power.
10. Nearby η-Scorpii is a thrilling group. Low power reveals a
group of 3 stars instead of one, higher power will split the
brighter η-Scorpii again into a tight binary pair!
11. Almost in a line with β and η Scorpii is ψ-Ophiuchus.
Moderate magnification reveals a nearby faint red star, not
a true binary, but a nice red-blue pair.
12. Further south toward Antares is σ-Ophiuchus. This is one of
the most exciting groups in the region! Modest magnification
reveals a group of 4 stars, two of which (σ-Ophiuchus and
Hip-80461, can be split into doubles with increased magnification!
13. The last target of the night is ι-Scorpii, modest magnification
will reveal a nearby star (Hip-80804). Rather tame compared
to σ-Ophiuchus, but still a nice target to round off your
double star quest!
Scorpio is well known for the red Giant Antares, as well as M-80 and M-4, but now you know a wealth
of targets to test your observing skill in this rich area of the sky!
© 2012 by Daniel Barth
Free Educational Use is Permitted.
www.MauriceontheMoon.com