Perseus double cluster

[Caz]

I've been trying to get this beauty for a few days now, and has evaded me.....until tonight, I've spotted the [removed word].....   And what a corker it is...   The more I studied it, the more detail I could make out, and what really got me intrigued was the red star smack bang in the middle.   I checked out the astro software just to see if I wasn't seeing things, and theres another 5 or 6 of them!  What are they? 

Oh yes the Little Dumbell Nebula, am I able to spot this with my 8" scope....?

[FLO]

I've been trying to get this beauty for a few days now, and has evaded me.....until tonight, I've spotted the [removed word].....   And what a corker it is...   The more I studied it, the more detail I could make out, and what really got me intrigued was the red star smack bang in the middle.   I checked out the astro software just to see if I wasn't seeing things, and theres another 5 or 6 of them!  What are they? 

Caz,

I thought you'd like it

Astroman excels at questions like this (you've not met him yet ) but until then, I can at least say that warm coloured stars are normally older stars; young stars tend to burn bright blue/white. 

Hope that helps,

Steve

[Astroman]

Funny, I've always seen bunches of red stars around the double cluster! The prominent one smack between the two though is FZ Perseii, a semiregular variable. Coxellis is spot on, too. It's an older star between us and the cluster. Pretty much all the red stars you see toward PDC are not associated with it, since the DC is two "brand new" open clusters, (only millions of years) while the red ones are billions of years along the HR chart.

Hope that helps.

[Astroman]

So if they are older stars, does that mean that they would become a supernova??

Not necessarily. It depends on how much mass they have. Most of the variable stars of this type are not massive enough to go supernova. They need to be a lot more massive. Stars like Betelgeuse, VV Cephei and Mu Cephei are massive enough, but not old enough to worry much about. These last stars are also a different type of variable, too, so they're not a good example, but mass-wise, they are. Hope that's not too confusing.

BTW, the other stars I saw in Coxellis' excellent image are K-type stars-just about as red as they get. :-)

[Astroman]

Coxellis is right again, but there's something about red stars that explains the effect better. It's called the Purkinje effect. It's a physiological phenomenon inside the eye when dark adapted. As you know, after the lights go down, you detect light with the rods in your eye instead of the color sensitive cones. After full dark adaptation, 35 to 45 minutes, chemicals in the eye allow even more sensitive vision. With the Purkinje effect, the eye is even more sensitive to red light, and the eye starts to act almost like a CCD camera-collecting red light and "saving" it with more persistance than shorter wavelength light. This makes red objects appear brighter than blue objects-stars for instance-or even the same red object when stared at. They warn about this effect in the user's guide to the AAVSO, (American Association of Variable Star Observers). It's also described in the book by David Levy, Observing Variable Stars, A Guide For The Beginner. Brian Skiff has also given many talks on this subject and those related to it.

I did wonder why they didn't twinkle like the others.

Hi, as far as 'twinkling' is concerned, there should be no discernable difference. The effect can be caused by two factors only - atmospheric disturbance and occultation (i.e., objects like asteroids passing in front) both of which (in stellar terms) are very local phenomena. So the closer ones should twinkle as much. For that matter, water (the main disruptive influence in our atmosphere) absorbs more red light than blue, so from atmospheric effect they would be less visible and appear to twinkle more.

As at that relative distance, all could be considered point sources, it's interesting to note that you consider them to twinkle less, though there must be a more 'human' explanation.

Andy