Close doubles

Solanum · #1 09-07-2007, 11:39 PM

Not sure whether this makes me really sad, but I always enjoy flicking over to Rigel Kent and seeing alpha and beta nicely separated. it's something about splitting what I can see with the naked eye into multiple stars I guess.

Anyway, can anyone recommend other doubles that are close but can be separated in a 10" dob with 9-15mm or eyepiece?

Incidentally, superb seeing with Jupiter tonight, as well as an amazing amount of detail in the belts (festoons etc.) I could actually see Io itself during the transit for the first time. Had high winds and clouds for the last couple of weeks which made it all the better.

Gargoyle_Steve (Steve) · #2 10-07-2007, 12:37 AM

Acrux is a similar double to Rigel Kent and near enough to make a quick and easy comparison, but the Acrux double is slightly closer again. I recall plenty of nights of imperfect seeing when you could get the split in Rigel Kent but Alpha Crux was more of a "broad smear" with no precise split. In good seeing it's easy and clean to split in a 10" and worth a look.

Gas Giant (Andrew) · #3 10-07-2007, 08:26 AM

When you get the chance, check out gamma-Aries. Supurb!

CoombellKid · #4 10-07-2007, 08:37 AM

I have always found this site quite good for double stars, basicly
it lists the easier of 33 doubles found in each constellation. Mostly
for northern hemisphere observers, but there are tons to be nab
from the southern hemisphere. Star charts are supplied.

http://www.carbonar.es/s33/33.html or http://www.s33.org/

Click on the link in the upper right "Observing Projects" a list of
constellations will appear. Click on one it'll take you to the list
in that constellation.

hope this helps, if it does enjoy

regards,CS

snug · #5 10-07-2007, 12:34 PM

Ok guys

for a L'plater...whats a 'double' and how are u 'splitting' them...

Snug

erick (Eric) · #6 10-07-2007, 01:51 PM

Point your telescope at the "bottom" of the two pointers (the one furtherest from the Southern Cross, known as alpha Centauri, also as Rigil Kent), and increase the magnification. What do you see?

Our sun is in a minority of stars, living all by itself, no star closer than 4 light years. The majority of stars have companions, one, two, maybe more? Bound together by gravity they orbit around each other. Hence "double stars". "Splitting them" means resolving the two stars in your binoculars or telescope, to see each of them clearly. Some are easy to do, some hard, some impossible with our basic technology (yours and my 8" reflectors on earth's surface). Depends on the distance they are apart, and that is from our point of view (If they are orbiting each other, their apparent separation distance (usually measured as an angle) will vary from a maximum to where they appear to be "on top" of each other. Also depends on the relative magnitude of the stars. Much the same magnitude (as are alpha Centauri A and alpha Centauri B - well close enough anyway) and its easier to see each of the pair than one very bright and one very faint in a double.

Have a look here:-

http://www.iceinspace.com.au/forum/s...ad.php?t=21264

and some other recent threads that Dennis has started.

Solanum · #7 10-07-2007, 02:24 PM

Quote:

Originally Posted by CoombellKid

I have always found this site quite good for double stars, basicly
it lists the easier of 33 doubles found in each constellation. Mostly
for northern hemisphere observers, but there are tons to be nab
from the southern hemisphere. Star charts are supplied.

http://www.carbonar.es/s33/33.html or http://www.s33.org/

Thanks, that site looks excellent. Looks like enough to keep me amused for the rest of my life!

Tertiary questions then:
1) are there any naked eye stars which split into more than double with a 10" scope, (I seem to remember that Rigel Kent is now know to be 4 but we can't see two of the companions in amateur scopes), to make it more difficult, that excludes any naked eye doubles (takes the fun out of it!),
2) are there any doubles that can be split with a 10" scope that have orbits fast enough to see movement over a few days/weeks?

Thanks to the other replies also, I looked at alpha-crux once and couldn't split it - last night would have been good, but I forgot about it till after I put the scope away. Will check out gamma-aries when I can.

Stephen65 · #8 10-07-2007, 04:23 PM

Quote:

2) are there any doubles that can be split with a 10" scope that have orbits fast enough to see movement over a few days/weeks?

Not really what you are asking, but I was just thinking the other day have much closer Alpha Centauri B is to A than it was when I first looked at it through a scope 25 years ago

CoombellKid · #9 10-07-2007, 05:48 PM

Quote:

Originally Posted by Solanum

Thanks, that site looks excellent. Looks like enough to keep me amused for the rest of my life!

Tertiary questions then:
1) are there any naked eye stars which split into more than double with a 10" scope, (I seem to remember that Rigel Kent is now know to be 4 but we can't see two of the companions in amateur scopes), to make it more difficult, that excludes any naked eye doubles (takes the fun out of it!),

Alpha Centuri would be the brightest, looks like a set of car head lights
coming at you. One of my fav's is Sigma Orionis a multiple system of four
that can be easily split in my 8"

Quote:

Originally Posted by Solanum

2) are there any doubles that can be split with a 10" scope that have orbits fast enough to see movement over a few days/weeks?

None that I know of, I think the fastest is something like 25yrs the name
of which I cant recall. But dont quote lol

Quote:

Originally Posted by Solanum

Thanks to the other replies also, I looked at alpha-crux once and couldn't split it - last night would have been good, but I forgot about it till after I put the scope away. Will check out gamma-aries when I can.

You might like to track down some carbon stars, they're beautiful to look
at for their orange/red colour. Hinds crimsom star in Lepus (you'll have to
wait for that one, but you might be able to nab it in the morning close to
twilight. The other fav of mine is the one next to Beta Crux and also V Aquilae.

But this is getting off topic for you.

regards,CS

CoombellKid · #10 10-07-2007, 05:59 PM

Antares is easily doable in an 8" under good conditions. I think the first thing
that is very good to learn is what the distance should look like through the
ep. Along with positon angle. Start off with a few simple ones then look for
more with similar distances. I found once I started to get that under my belt
it was easier to search out new ones to go after

regards,CS

ving (David) · #11 11-07-2007, 10:49 AM

if you click on the link in my signature it will take kyou to my doubles listings. hope you enjoy them

Gargoyle_Steve (Steve) · #12 11-07-2007, 08:12 PM

"Easily doable" Rob - damn I wish I had your skies where I live!

I was never able to split it while I had my 10", and so far I haven't managed it with my 12" - I even tried as the pup preceded Antares from behind the moon during the occultation last Easter but we had a sheet of hazy cloud over the moon, thin enough that I could see the lit portion of the moon, but thick enough to completely even the outline of the earthshine area. We managed to get a little "pop" of light visible through the cloud as Antares itself resurfaced, but never a glimpe of the pup!

Having said that Antares is at a GREAT position in the night sky now so I must give it a go again from Ron's place Saturday night.

Cheers!

ballaratdragons (Ken) · #13 11-07-2007, 09:15 PM

Don't sit and wait for Proxima Centauri to orbit it's parent Double Stars. It takes 1 million years!!!!

Solanum · #14 11-07-2007, 11:41 PM

Tried Antares tonight with my 10", no chance, not even a hint. Seeing wasn't great though. On the other hand I had a good go at the Crux list from s33.org I could almost convince myself I got Holden 116 at moments of good seeing, didn't try Cape Obs 12, but could split all the ones of 4" and above separation. Brisbane 8 was my fave, nearly the same mag, close together but very clear in my 9 mm Plossl.

So thanks for the tips guys, this double star business is a whole new area for me to explore. Pity I don't have enough nights to cover 10% of what I'd like to observe....