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[RobbW]

Hey fellow CAers! I'm hosting a small session near my house tomorrow evening and could use some pointers on specific night-sky objects. During my session, I plan to talk about the color of stars and what it can tell us about their age. An idea/suggestion proffered by our own Papa Joe. Other than Spica and Arcturus, as mentioned by Joe, anyone have other suggestions for stars that are great examples of color and age? I'd especially enjoy any ideas for double stars that exhibit different colors due to their ages. Makes it easier to compare and contrast two stars in the same EP rather than slewing to different stars.

Thanks for any help!

[Paulie pchris00]

Color tells more about mass for main sequence stars, although the big blue ones don't live long, so that's probably where age comes into play. Albireo is probably the best double to show color, but it will be low in the east, if it's up at all when you're out. Larry from Michigan City once showed me a double star at the Dunes where the color contrast showed one of the stars as green, but I forgot where it was. Might have been in Ophiuchus, but I really don't remember. I'm not big on doubles, but I'm kicking myself for not remembering that one.

I'll take a quick look through my star atlas to see if I can find any doubles of different spectral types that will be well placed tomorrow.

[Paulie pchris00]

Delta and Eta Corvus, the northeast corner of Corvus, are spectral types A and F, respectively. Might not be enough contrast of colors, though.

Algieba, Gamma Leo, in the Sickle, is an F and K double. Might be worth a look.

Regulus has a faint companion.

The Big Bear's forepaws each has a wide pair of stars of different spectral classes. With low power, they might fit in the field of view together, and the dimmest is only 3rd magnitude. The front paw, Nu and Xi Ursa Major are a 2nd magnitude K star, and 3rd magnitude G star. Again, maybe not enough to show color difference, but high overhead, and out of distortion. A better bet for color difference is the other forepaw, Gamma and Mu Ursa Major, though they have a slightly wider separation. Both are 2nd magnitude, Gamma being A, and Mu being at the red end (my atlas lists spectral types M,N,R,S as the same).

Pi Hercules, the shoulder opposite M13, is a 2nd magnitude K star, with a dimmer nearby A star.

Those are the best I can come up with right now. If I get a chance later, I'll have a look at each of them and try to rank them for visual and color effect.

[RobbW]

Paulie rocks! Thanks, bro!

[Paulie pchris00]

No problem. I'll take some time tonight for comparisons, see if Bill knows of any others in his cranial repository of all things astronomical, and post my findings in the morning.

[Paulie pchris00]

Three words: go with Albireo.

It will be low, but it will be up.

Regulus is good color contrast, but the difference in magnitude weakens the effect.

I forgot the one in Hercules, but the rest failed.

[RobbW]

Thanks, Paulie. I will add those to my observing list and use them as examples for star color/age. Albierio may be just a little on the low side, but I'll give it a shot if possible. I'm just afraid it will be in the muck of the orange Chicago sky glow.

Do you or anyone else have a recommendation for a website that does a really great job of explaining star color/age? I'm scouring the inter-webs to gain more knowledge, but if anyone has a personal favorite site that's really good at explaining in language that is understandable to the masses, I'd appreciate it.

Ideas for great double stars that will be high and pretty by around 9:30pm?

[-=CROMAN=-]

answers.yahoo.com/question/index?qid=20080715051013AAE0ExZ

[Vinod Kumar]

Great information, Thanks for share it.