But maybe you know me without thinking you know me.

Just curious, regarding blue stragglers, and the hypothesis that they’re lower mass stars that have collided: has anyone ever observed a stellar collision?

Hey, guess what I just stumbled upon online? This :

http://www.sciencenews.org/view/generic/id/71387/title/Two_stars_caught_fusing_into_one

Purely by rather awesome co-incidence about five minutes ago!

http://stars.astro.illinois.edu/sow/sheliak.html

for more on Sheliak (Beta Lyrae) one of the stars mentioned above and archetypal very close binary system via Kaler’s superb website.

See :

http://en.wikipedia.org/wiki/Contact_binary

for contact binaries via Wikipedia and see :

http://en.wikipedia.org/wiki/Blue_straggler

for the blue straggler entry on Wikipedia.

We have however seen stars in various stages of merging –

1. Extremely close spectroscopic binaries such as Spica (Alpha Virginis) and Sheliak. (Beta Lyrae)

2. Contact Binaries where the stars are actually touching and starting to fuse together.

& finally

3. Single very rapidly rotating stars – FK Comae Berenices variables.

Ken Croswell had a good article on this “Dance of the Double Sun” about ER Vulpeculae – two sunlike stars that will one day merge into one Sirius-like star – in the July 1993 issue of Astronomy magazine if you can somehow find a copy of that.

@31. Joseph G :

@MTU: Er, I think that “politics” and “factual” don’t really belong in the same sentence.

Very true.

In any case, he’s certainly opinionated, he just doesn’t go in for unverifiable fringe ideas (that is, conspiracy theories).
Maybe that’s why I can’t seem to stop having some fondness for the guy despite disagreeing with a bunch of his views, or his religious blind spot. He sorta reminds me of my dad, I think
(My dad’s also somewhat conservative and can be grouchy, but he’s intelligent and a skeptic all the same)

Take II :

http://kencroswell.com/YoungestGlobular.html

Hopefully that’ll work now.

Otherwise search : Ken Croswell articles + Whiting 1 /globular clusters.

BTW. Totally off topic, but anyone else following the Cricket World Cup might like to know Australia is now 132 for 4 versus Pakistan in the 33rd over . Fortunately, Mike Hussey is batting!

@ Phil – OFF TOPIC Look Phil! O’Reilly can be skeptical too!

Actually, many on the Right Wing of politics think Bill O’Reilly is too pro-Obama & almost too centrist in his approach – see :

http://www.youtube.com/watch?v=imqMBTtKGIM&feature=related

&

http://www.youtube.com/user/billoreilly#p/u/22/-aukp2pUuu0

&

http://www.youtube.com/watch?v=XGQU0EutLsU

That is the view of many right wing folks anyhow whether folks agree with it or not.

Personally, I know of O’ Reilly only by reputation from what others have posted about him – haven’t seen his show or enough of him to be able to judge fairly for myself. Although his Moon comments noted in the “Bill O’Reilly: tidal bore” post by the BA here (posted
January 31st, 2011 11:09 AM) were pretty stupid.

OTOH, Bill O’Reilly came over as fairly reasonable in one interview I did see of him on ‘Letterman’ (TV Late Show there with) and on some of his other Youtube videos so, again, too little to tell. His views on astronomy are clearly bad but them his views on politics which is more his field of expertise may be more factually based, perhaps?

http://en.wikipedia.org/wiki/RR_Lyrae_variable

&

http://en.wikipedia.org/wiki/Subdwarf_star

&

http://kencroswell.com/YoungestGlobular.htmlhttp://kencroswell.com/YoungestGlobular.html

for an odd youthful globular named for a type of fish. (Okay,not really! )

@12. Jamie : Hmmm … still not quite getting it although I am now hearing it in Yoda’s voice!

@16. Thameron : Nice . I like that one.

Please, Bad Astronomer, can you tell us which spectral types – and luminosity classes – each star colour corresponds to in this image? Are the blue stars type B, type F, type G, or what?

Was I right earlier thinking these stars are all metal poor sub-dwarfs or am I mistaken about that?

I don’t think I know you.

(Head explodes in an infinite improbability vortex).

Maybe Phil meant radius rather than diameter. That would make the diameter of the galaxy 120,000 light-years, which fits nicely in your range.

Whew, the large image is almost enough to make me dizzy – so many stars!

Incidentally, there’s some pretty convincing evidence for the hypothesis of radiation hormesis, but again, dosage is everything. People who don’t know what a “therapeutic index” is shouldn’t be telling people to expose themselves to anything dangerous (be it herbs, minerals, or ionizing radiation).

…or he can continue to be a paid propaganda tool of the oil industry…

EDIT : Hang on, the BA did write “blue is blue” So, hmm… interesting.

Not sure what spectral class these blue stars are but suspect they’re NOT O-B or even A but maybe F-G types?

Also there are the odd blue stragglers that form later than the rest via stellar mergers to consider.

Plus the lower metallicity – assuming it is low metallicity in this Glob – could be making these stars low metal sub-dwarfs which have somewhat different characteristics to the higher metallicity stars we’re used to.

Eg. Compare RR Lyrae “cluster variables” usuallyfound in oler regions such as globular clusters with the “Classical Cepheid variables” as found in the disk & spiral arms. Population I versus Pop’n II star types.

Please can you elaborate on that though Phil – it is rather curious.