I thought we were colliding with Andromeda in 5 billion years….was it refined to 1-2 billion years recently?

Pssst dude! It’s all cause of galactic warming!

…

“Our Galaxy’s date with destruction” by Abraham Loeb & T.J. Cox, Pages 28-33, Astronomy magazine June 2008.

They include a simulation showing the collision between the Milky Way and Andromeda starting in 2 billion years time and concluding in 5.5 billion years time. Its a long drawn out collision beginning with approach and interaction and ending up in a fusion of the two spiral galaxies into a single “Milkomeda” elliptical galaxy.

…. SCR : There have been images taken of the red supergiant Betelgeux (Alpha Orionis – the 10th brightest star as seen from our skies) although they used a special technique called interferometry to capture the image. So yes. Again, check on Kaler’s website & is shown in his books and some other astronomical texts.

…I’d think if it was an out of focus issue then it’d look more out of focus & you may expect more smearing and lack of sharpness? Pretty sure that light is lost within some telescope designs (esp. reflectors) but more than that …?

“I thought we were colliding with Andromeda in 5 billion years….was it refined to 1-2 billion years recently?”

There’s an article – the cover article actually – on this topic in the june 2008 issue of Astronomy magazine :

“Our Galaxy’s date with destruction” by Abraham Loeb & T.J. Cox, Pages 28-33.

“Very nice, Phil! This has to be a Basic Astronomy 101 type question, but I hope you may be able to provide an explanation. In images such as this one, we always see many stars, with a wide range of diameters. Are these images of larger-diameter stars really just nearby stars (in our own galaxy) that are out of focus? Do any of our telescopes have enough resolution to image the true diameters of stars in our galaxy? Or are we really seeing images in which the apparent star diameters are just representative of either inappropriate focus (for those particular objects) or light scattering within the optics of the telescopes, or some other type of “aliasing”?

I did try to search the site for an answer but was not successful. Party on, BA!”

If you happen to see this : try checking out James B. Kaler’s awesome Stars website :

http://www.astro.uiuc.edu/~kaler/sow/sowlist.html

Yes, several stars have had thediameters measured and at least one – Betelgeux – has even been photographed. Check Hamal (Alpha Arietis) and one other star which have had limb darkening I think it was detected for them ..

I’ll try and answer your questions here :

1) Are these images of larger-diameter stars really just nearby stars (in our own galaxy) that are out of focus?

SCR (me) : I think so usually yes – But what you’re seeing with the stars in the image here isn’t actually diameter but instead just the relative brightness or apparent magnitude of the individual star – I think.

Although some of these “stars” esp. the fuzziest looking ones – may actually be distant background galaxies : Eg. notably galaxies present in an image of the Helix Nebula in Aquarius! (NGC 7293)

2) Do any of our telescopes have enough resolution to image the true diameters of stars in our galaxy?

SCR : There have been images taken of the red supergiant Betelgeux (aLpjha Orionis – the 10th brightest star as seen from our skies) although they used a specialtechnique called interferometry to capture the image. So yes. Again, check on Kaler’s website & is shown in his books and some other astronomical texts.

3) Or are we really seeing images in which the apparent star diameters are just representative of either inappropriate focus (for those particular objects) or light scattering within the optics of the telescopes, or some other type of “aliasing”?

SCR : Hmm .. Not quite sure what you are meaning here tobe quite honest but very probably yes. I think it has a lot to do with how the light (photons) build up quicker from brighter stars on photographic film and CCD chips but I’m not quite sure. Maybe somebody else can clarify further? I’d think if itwasan out offocus issue then it’d look more out of focus & you may expect more smearing and lack of sharpness? pretty sure that light is lost within some telescope designs (esp. reflectors) but more than that …? Well I’d have to do more research on that …

***

“If you put three grains of sand inside a vast cathedral, that cathedral will be more densely packed with grains of sand than stars are found apart in the space.”

***

By Sir James Jeans, British astronomer, quoted on page 28, ‘Skywatching’, David H. Levy, Ken Fin Books, 1995.

… & that must surely be a top three contender for this years best photos / images.

____________________________________________

“Yet here we are with our eyes and our minds and our curiosity, six billion passengers aboard a tiny blue boat, bobbing and wheeling our way around one vast Catherine wheel among many.”
- P.246, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

At the very least, any aliens in those galaxies, if not the very
galaxies themselves, will know we are a really cool species.

“…the first steps of a dance that will take 100 million years to complete.”

So in “present day” terms this collision is almost over.

Anybody modeled it digitally?

See the Galaxy Crash reference above. Its not Arp271, but it will give you a good idea of what happens. Visit the Case Western web site, and you probably could model it with their software.

Enterprise when they get hit by a Klingon disruptor beam and
aren’t wearing any seatbelts! This will be accompanied by
dramatic orchestral music to set the mood.

Yeah, but I want the scene to be set to O Fortuna!
http://www.youtube.com/watch?v=xuERh0jBjh8

Beware the concussion!

Entertain the thought, just for a moment, that galaxies are
living beings in a manner and on a scale we puny little creatures
are not used to.

Would their mergers be a form of reproduction? Or actual
cannibalism as astronomers call it? Or just a really long version
of our one night stands?

These two galaxies are clearly getting it on.

Maybe we should let them have their privacy, rather than
post the pictures of their sordid intergalactic love affair
all over the Internet.

First Britney Spears and now Arp 271. Is there no deceny,
no shame left in the Cosmos?

What? no intergalactic porn? Sheesh! Some of us like seein’ galaxies get it on!

Thanks for taking a stab. Actually, I’m not referring to the other distant galaxies or the star clusters or nebulae in the image. Surely, some of those dots are stars, and they have many different diameters in the image. I’m just trying to learn whether the diameters of the stars in the image are real properties of those stars or just artifacts that have more to do with how the image was taken.

I know the BA could explain it, if he has time.

Maybe we should let them have their privacy, rather than
post the pictures of their sordid intergalactic love affair
all over the Internet.

First Britney Spears and now Arp 271. Is there no deceny,
no shame left in the Cosmos?