Seeing double ~ Crux (opinions please)

[ving]

Seeing Double ~ Crux

Welcome to the first instalment of my new project, Seeing Double. My aim here is to show people who are new to astronomy some of the great double/multiple stars we have in the sky and to give people something to look at while the moon is out drowning all the DSOs in its glorious (debatable) light.
We'll be looking at visual doubles, multiples and binaries of course so no special equipment (which is probably beyond us all anyhow) has to be used, just your telescope. I am hoping to do this on a monthly or bi-monthly basis depending on when I can get out doing constellation each month including 5-10 doubles drawing information from my own knowledge, various websites and a program called cartes du ciel.

Definition: I could have put this in my own words, but alas I am to lazy... so here is an excerpt from the Eagle Creek Observatory site in their doubles section...
Anyhow, enough dribble lets do some observing! :D

This months constellation is our very own Southern Cross (aka crux). Nestled between Centaurus and Musca (the fly) it is our great southern lands best known constellation and it holds a number of really nice double stars.
**note, colours mentioned are how they appeared to me and not necessarily their true colour**

1-Alpha Crux: well... if the cross was up the right way it would be the bottom star. This star is actually a multiple consisting of 3 parts, 2 bright stars close together and one dimmer star out from the rest. All 3 stars show as blue in my 8" newt. Stars A and B are mag1.25 and 1.55 and are 3.9” apart star C is mag 4.8

2-HJ 4524: a great little double near the edge of NGC 4439 (open cluster) consisting of a white star (A) and a yellow star (B). Star A is mag 8.05 and star B is 9.93 and separation is 30.3”. quite pretty next the the cluster really…

3-HJ 4547: marked on the map for your convenience  a double of white and what looked like blue in my 8” scope. The 2 near stars could be mistaken for part of the double and look nice next to it. A is mag 4.72 and B is considerable dimmer at 10.24 but the split is easy due to the 28.1” separation.

4-Dun 117: It’s a triplet! Yup 3 stars in one. This group contains t whites and one dimmer blue. A and B are 7.40 and 7.83 respectively, C is 10.24 mag. Seperation of A and B is 27.7” its another easy split… I didn’t do any hard ones ;)

5-BSO 8: put your hand up if you love yellow stars! We have to lovely yellow stars of similar magnitude here right next to NGC 4337. Their magnitudes are 7.84 and 7.98 with a separation of 5.2”… A lovely sight by any standards.

6-Gama Crux: did you know that 3 of the 4 points are doubles/multiples? Well Gama Crux is one of them. Three stars in this one and they are very purdy. A is white and 1.8 mag, B is blue and 6.45 mag, the bonus star C is 9.25 mag. This is practically for binos (except C is bit dim).

7- Beta Crux: another triple system and one I did not conquer, so I thought I’d put this in as an added bonus because of the blood red carbon star near by. A is 1.25 mag and B is 11.4 mag. Although the aren’t close (42.3”) the dimness of B makes it very hard to see… but hey, check out the carbon star anyway :D

Now get out there and search for them :D
Please feel free to reply here with any feedback, pics or reports of these objects… I want to know how you go :thumbsup:
also tell if you want more of these and any changes to the format you could suggest.

and heres a map to help yas.

http://img.photobucket.com/albums/v46/ving68/th_map-crux.jpg (http://img.photobucket.com/albums/v46/ving68/map-crux.jpg)

[davidpretorius]

this is excellent. I noticed my favourite coming up the other morning gamma2delphinus.

I for one am jumping on board. Images go here too???

Thanks vingo, top effort!

[ving]

yup images are all the go, tanks dave :)
just trying to give something back to the forum that has stopped me from working for the last 2 yrs :P

[vespine]

This is fantastic! I'm looking forward to the next clear night to check them all out, thank you so much. Guides like this is really great for beginners like me! :thumbsup: With all the thousands of objects out there I still get so caught up trying to figure out what to do with myself! :)

[Miaplacidus]

Very nice, David. Very tasty. Nothing like some yummy doubles. Thanks.

[Rodstar]

Nice one Vingstar!

I'll check those ones out tonight if the kids ever go to bed.

Which one is your favourite?

[Dennis]

Hi Ving

Here are 4 multiple stars I captured with my Vixen ED102mm f9 refractor, TeleVue x5 PowerMate, Vixen x2 Barlow using the Meade LPI CMOS digital camera.

Images were taken back in 2004.

Rigil Kentaurus and Acrux were captured using Vixen x2 Barlow.
Theta 1 Ori was captured using Televue x5 PowerMate.
Antares was captured using Televue x5 PowerMate and Vixen x2 Barlow stacked. The bright orange ring around Antares is the first diffraction ring resulting from the extremely high magnification used to capture the image.

Cheers

Dennis

[33South]

thanks ving, great contribution. :thumbsup:

Ill be checking them out with my new toys tonight hopefully, Im intrigued by number 7 - top of my list.

[matt]

Nice one Ving. Some great targets fairly close together. Makes life more easy not having to slew too far.

Nice work too Dennis. Is that nebulosity in Theti 1 Ori??

[Dennis]

Hi Matt

Nebulosity - I wish! The Meade LPI max exposure is 16 secs, so what you are seeing there is.....poor seeing blobs, due to the relatively high magnification and longish (multi-second) exposures to help record the stars.

Cheers

Dennis

[matt]

That's still good work Dennis. Especially with the LPI. It's not really intended for that purpose, is it?

[Dennis]

Hi Matt

Yes, you're right there, it's more for the Moon, Planets and Sunspots (with the necessary solar filters) although I have seen some fairly decent DSO's (Deep Sky Objects) posted by users with large aperture, fast dob's before Meade introduced the DSI for DSO's.

Cheers

Dennis

[ausastronomer]

I posted this reply to a thread on eyepieces but it really is a lot more appropriate here so I have duplicated it.



David/Matt

Not sure if you guys were here when we had the "Monthly Observing Challenge". The files are still available and I have posted a link to them. I selected the double stars and did the write ups for them. If you haven't observed these doubles before they are all really nice. Several have a lovely colour contrast. If you're interested in Double/Multiple stars, these are worth observing now and in the coming months and suited to smaller/medium apertures. Here they all are with a link to the page contining the write ups:-

May 2005 - X Velorum (Dunlop 95) in Vela (http://www.iceinspace.com.au/index.php?id=69,198,0,0,1,0)

June 2005 - 24 Comae in Coma Berenices (http://www.iceinspace.com.au/index.php?id=69,207,0,0,1,0)

July 2005 - HN40 at the heart of the Trifid Nebula in Sagittarius (http://www.iceinspace.com.au/index.php?id=69,217,0,0,1,0)

August 2005 - Gamma Delphinus (http://www.iceinspace.com.au/index.php?id=69,224,0,0,1,0)

September 2005 - h5003 in Sagittarius (http://www.iceinspace.com.au/index.php?id=69,226,0,0,1,0)

October 2005 - Rho Ophiuchus in Ophiuchus (http://www.iceinspace.com.au/index.php?id=69,241,0,0,1,0)
BTW Mike is the one who spells "Ophiuchus" incorrectly in the Challenge notes, com'on Mike learn to speeellll thats an easy one :)

November 2005 - Theta Eridanus (Acamar) in Eridanus (http://www.iceinspace.com.au/index.php?id=69,251,0,0,1,0)

December 2005 - Sigma Orionis in Orion (http://www.iceinspace.com.au/index.php?id=69,258,0,0,1,0)

Another very nice double worth taking a look at which is currently nicely placed early evening is h3945 in Canis Major. This is a really nice bright yellow/blue double and not too dissimilar visually to X Velorum only it's not quite as bright being about Mag 4.5. It is about 2 degrees south of a nice open cluster in NGC 2362.

There are also 4 or 5 nice orange/blue doubles within about 3 degrees of X Velorum. Not as bright but still nice and easily separated at about 60X to 80 X with medium aperture. Not sure of their names (I think 1 is Dunlop 89) but they are easy to find by just panning in a line between Eta Carina and the Gem Cluster

CS-John B

[matt]

That's very much appreciated John.

Cheers

[davidpretorius]

thanks john, a busy month ahead!

[Rodstar]

Ving,

I spent some time last night checking out doubles in Crux. I didn't have your list handy; I was working from the list produced by Eagle Creek Observatory (ECO), but there were some overlaps.

In relation to your list and commments:

Beta Crux: ECO just note there to be a double, but my notes read: "two candidates for secondary, 1 orange and 1 grey". I think I saw the triplet you refer to.

Gacrux: I saw the primary as yellow-white, and the secondary as blue-white. According to ECO, separation is 111", they are certainly a long way apart!

Dun117: I only saw primary and secondary, both a dull grey, not worth revisiting IMHO.

HJ4524: I agree it is in a lovely location near the OC. I saw the primary as white and the secondary as grey.

There are some other nice doubles in Crux also worth checking out that did not make it to your list:

Mu Crux: is a beautiful bright double, sep 34"

HIP 60557: located near OC NGC4337, this close double (sep 5.3") looks rather like two eye protruding from the OC, like eyes of an alligator, the OC being the body of said 'gator!

CP 12 (SAO 251919): A great test for seeing, your sight, and your scope, this is a faint double, with 1.9" separation. I managed a clean split with magnification at 450x, elongated at half that magnification.

COO 140: a close pair (4.9" separation), pale yellowish primary. Split easily at 135x.

BTW, I recommend any doubles fans to also check out delta Bootes. I would interested in what colours you see. It is a bit low on the northern horizon for me to be really confident on its constituent colours, but I see a yellow primary and a bluish secondary.

[ving]

hi Rod, HIP 60557 is a different name for bso-8 in my list, I liked this one too :)
I wonder which contellation i should do next...
dun-117. I probably had less moon that you, so maybe thats why i saw the third star? It helped that I knew where it was in relation to A and B too (via cartes).

thanks for the input everyone :)

[Rodstar]

Thanks for clarifying that, Ving. What was your source for the list of doubles?

[ving]

i used cartes du ceil mainly. it has a huge doubles database. this is also where i got the star names from. i also used WCO and s33, but that was after i had finished, it was meare coincidence that i picked doubles that were on thier lists. I used them just to see if there were any major doubles that i could have put in. I was pretty happy with what i found :)

[astroron]

Good reports guys, I do doubles sometime when thje sky is getting a bit brighter towards moonrise, and a bit bright for DSO's, it is quite an enjoyable interlude. By the way Rod and others did you join the Webb Society?:thumbsup:

[ving]

lol, no ron... far too lazy. :P

[dennislowe]

David,
I spent a little time on your list, from home. I do not have the best southern aspect due to trees. So far I have managed 6 and 7 off your list with certanty. Your 1 (Acrux) I have resolved in the past.
This has got me a little more interested in doubles, but I have no gear to measure PA or separation. Do you do any measurments.
Dennis.

[ving]

hi dennis, glad to hear you doing the list :)
I get my measurements from cartes du ciel. I do plan on getting an eyepiece that will help me measure separation and PA soon :)
thanks for the interest.

[janoskiss]

good stuff Vingo! Never got into doubles, but I'm looking forward to hunting these down.

[ving]

hey dennis, try number 5 on my list... quite pretty :)

[ausastronomer]

Doubles are good fun because in most cases they look just as good in smaller apertures and you're not significantly affected by mild light pollution.

CS-John B

[iceman]

I overlooked this thread for too long, glad I just took the time to read it. Nice challenge Vingo, and a great way to get people out there and observing.

[ving]

yeah, not all my post are spam ;)

would you be opposed to this on a monthly or bimonthly basis mike? I hae started my second one already, it was fun to do :)

[janoskiss]

I was wondering about that. It will give me something to observe besides the Moon and planets from my light polluted back yard.

I think Mike and all other IIS members would be strongly opposed! :P

[ving]

fer a moderator you sure are a strange bloke steve :P

[iceman]

It'd be great, Vingo.

Post them on this forum for now.. when I get some more time i'll re-ignite the monthly observing challenges and the "doubles" section can be an article on their own, with your contributions. It can be a collaborative effort with contributions from Rod, John or any others that might be interested.

Good stuff!

[janoskiss]

Sorry, Ving! :P Of course this sort of thing once a month or whenever you can find the time would be great. :) Observing guides to doubles are particularly handy because it's hard to pick the observable ones from sky charts (either printed or software). One of the reasons I had neglected them.

[ving]

no probs then mike. sounds er... sound :thumbsup:

steve, taken tongue in cheek. no worries ;)

[vespine]

hey if you still want any feed back on constellations to do next, how about Scorpio?? I'm a bit of a newb so I don't know if there are any really good doubles there but I just love that constellation at the moment, still have to wait a little after dusk to get it in good position but it's really magnificent, I'm keen to explore it some more. :)

[ving]

I'll keep that in mind for not the next one but the one after if you like... i have the next one half written already. ;)

[ausastronomer]

Hi,

Scorpius has some very nice doubles in it. Some like Antares and Nu Scorpii require good conditions and optics but all are very "splittable". Off the top of my head, some are:-

Alpha Scorpii (Antares)
Beta Scorpii
Nu Scorpii
Sigma Scorpii
Xi Scorpii (which is attached to another double Struve 1999)

All worth chasing

CS-John B

[dennislowe]

Sorry David, not able to get into your stuff tonight due to some high altitude Ice.
Just a thought, looking at some of the posts, one gets the feeling that looking at multiple star systems is something to do when the moon gets in the way of faint nebule. All I can say is, try a few of these systems at optimum viewing time. They can blow you away.
Dennis.:eyepop:

[ving]

indeed dennis. best viewing for anything is on a new moon :) (except the moon that is :P).
high altitude ice?

[ThunderChild]

Hi Ving,
Thanks for that - all I need now is for this cloud to go away - which seems to have settled in for the long haul! :(

One newbie question : You mention the difference between true binaries and optical doubles - could you classify which category each of these fall into?
I became interested in binaries a month or so ago and would look forward to more of these lists - but I'd love it if any future lists could show which ones are 'real' binaries. They seem much more interesting to me (just my opinion).

[ving]

i can do that starting the next lot if you like. :) its not hard to do.

[chunkylad]

Great work Ving. Thank you.

Can't waitfor future installments.

Dave

[Rodstar]

I must confess, Ron, the answer is not yet. I am still interested, but it is all a matter of $$$, and the many demands on finite resources. Sometime very soon hopefully!:P

[ving]

join the ving society its cheaper :P

[janoskiss]

I went after the Ving doubles tonight. :) I couldn't find 3 & 4, because I could not see 4547 or 117 anywhere on the chart. Now I see they are labelled 1-7 :doh: I could not see it on the printout. Ah well. Two left for next time.

That carbon star looked really cool Ving! Gamma Crux looked very yellow to me, not white. :shrug:

Had some great seeing over here for a couple of hours or so. Now how about something a bit harder for the next one? I looked for some others in Crux marked on the Sky 2000.0 as doubles, but they were too hard. :(

Thanks for putting this together, Ving! It's good fun. One gets to know the constellation a lot better too doing a double hunt.

[ving]

yeah you are right steve, i didnt know there were so many open clusters in crux till i did this. it was an eye opener for me too.

I'll have to recheck gama crux :) thnx for the heads up :)

[ausastronomer]

If any of you guys are interested in chasing down some RED "Carbon Stars", let me know and I will put an observing list of these together.

The Red one that you guys have been observing near Beta Crucis is known as EB 365 or "Ruby Crucis" and it is one of the best visual carbon stars in the sky.

CS-John B

[ving]

which would you say is the best john?

[ausastronomer]

David,

Apologies for the delay in replying.

There are several nice ones. Ruby Crucis is one of the best. All Carbon stars appear redest when they are dimmest, it depends on what aspect you find appealing. I like some of the brighter ones which are not as red as some of the dimmer ones. But I also like a couple of the dim variables which are blood red when at their dimmest.

Some nice ones include:-

R Fornacis, which has scientific significance in that it is also a Mira (Omicron Ceti) type variable. It's magnitude varies from about 7.5 to 13.0 over a period of about 450 days. This is not visible at this time of year.

X Cancri. Quite bright at about Mag 6 but presently only visible early evening.

U Antliae. Another reasonably bright one at about mag 6 with about 1 mag of variability. Currently well placed for observation.

R Centuari. Is another nice 1 and again is a mira type varibale. Currently perfectly placed for observation.

R Leporus. This is also known as Hind's Crimson star. It is also a mira type variable and is at its redest when it is dimmest, which is only 1 month every 14. It is currently just west of Sirius and only visible very early evening from Sydney. It is arguably the redest star in the sky, when dimmest.

CS-John B

[ving]

didnt realise you had replied!
thanks john. if i get a chance i'll hunt them down :)

[robagar]

.. another one in the northern sky at the moment: Y Canes Venaciti, AKA "La Superba". Can't be too bad :)

[janoskiss]

Checked out the rest of them night before last. I also revisited the rest this time with the 12". The carbon star looks even more impressive in the 12". The seeing was not very good, and the star looked like an orange core surrounded by an unsteady deep red glow.

John, I'm looking forward to checking out your list of C stars. Thanks!