Have you ever wondered?

csb (Craig) · #1 13-09-2007, 02:02 AM

I often wonder that we cannot get a larger and more detailed view of a star, considering that we can image galaxies that are so, so much further away.

You would think that a star would be able to be seen as more than just a point when imaged through a telescope (especially Hubble).

Obviously galaxies are so huge that even being millions of light years away we can see detail in them. But stars are relatively so very tiny, in comparison to the distances involved (and in comparison to galaxies) that even a star "only" 4 ly away cannot be resolved to anything greater than a dot.

Stargazing really helps me appreciate that the size of the universe, and celestial objects in it, are beyond human comprehension. The size of the Earth I cannot even comprehend, although units of time do help just a little bit.

I love wondering about the distances to the things out there in space.

The nightsky objects are so awesome!!

OneOfOne (Trevor) · #2 13-09-2007, 07:40 AM

As I recall Antares has been imaged at a scale larger than a single pixel. It showed what appeared to be a huge coronal mass ejection, but unlike our Sun's CMEs this was imense! Maybe millions of kilometres in size. I think the image I saw was in a book or magazine somewhere, about a year ago? The caption said something like "the only other star to be imaged".

You could probably google it or look on Sky & Tel and come up with something.

I am always impressed when I look at Alpha Centauri AB and realise that I am looking at a distance comparable to the Sun to Neptune separation. This is my favourite "public viewing" target.

csb (Craig) · #3 13-09-2007, 01:33 PM

Thanks for that suggestion.

I did a google and it came up with some stars that have been imaged. These images seem to have been zoomed as the pixels are large.

These are recent technologies, less than 15 years perhaps.

I was actually referring to glass/mirror lensed telescopes. Even amateur telescopes with a camera can image a galaxy but can't get a good sized image of a star.

I suppose some maths would be able to show why we can't see stars as more than just points of light.

Anyway, just something that I have wondered about.

Thanks

Terry B · #4 13-09-2007, 02:22 PM

The angular size is very small but optical interferomerty can measure stellar diameters. See http://www.physics.usyd.edu.au/astron/susi/

xelasnave · #5 13-09-2007, 06:55 PM

Try standing closer when you take your photo
alex

CoombellKid · #6 13-09-2007, 07:19 PM

Quote:

Originally Posted by xelasnave

Try standing closer when you take your photo
alex

The problem is once you get to lightyears in distance things start to
become a hell of a long way away for creatures like us to look at.
However I would love to park myself up close to Antares with my
pst, and a couple of beers of course

regards,CS

ballaratdragons (Ken) · #7 13-09-2007, 10:56 PM

Antares through my ED80 at last Astro Camp. A little dot it ain't!!!
Steve (Janoskiss) freaked when he saw me imaging this

taminga16 (Greg) · #8 13-09-2007, 11:13 PM

Quote:

Originally Posted by xelasnave

Try standing closer when you take your photo
alex

I have done that Alex, but the excitment caused me to shake.

xelasnave · #9 14-09-2007, 02:11 AM

Well it is agreed

... I propose a mission to each region where there is another star to build platforms upon which people can take their photos.

You know there is a way to get true size images of any object in the Universe if you would like to know

..it is a big camera I invented but it will work

... I think it would work but it would cost a bit

...

But the concept that I think could be developed is to build a long array of chips on am arm such to replicate a scanner action as opposed to a camera action... think about it.. a scanner calibrated to scan in real size gets over all the problems but creates some no doubt as the only allowable incoming light would have to be all parallel... are you with me so far?? guiding it would be real hard enormous challenges but a full size scan would be something

..we could see into a back yard light years away

...in theory

..opps bad word for that mmm is it ... should the hideous cost of the idea stop it from being a theory

...
alex

Dujon · #10 14-09-2007, 10:04 AM

Pity I flogged my focal plane shutter SLR so many years ago, Alex. Then again, photographing a motor car travelling at well over the speed limit with exposures of 1/1000th of a second and panning at the same time could be a little different from your hypothetical astronomical model.

csb (Craig) · #11 14-09-2007, 11:29 AM

Ballarat, I question whether your claim for that Antares image is correct.

Is it perhaps the brightness of the star washing out the image so as to appear as a disc?

Quote:

Originally Posted by xelasnave

Well it is agreed

... I propose a mission ....

Was it agreed? The centuries have dulled your thinking but not your humour? Hilarious, thanks Mr X.

Outbackmanyep · #12 14-09-2007, 03:56 PM

Quote:

Originally Posted by CoombellKid

However I would love to park myself up close to Antares with my
pst, and a couple of beers of course

regards,CS

Dont forget the zinc cream and sunscreen!

xelasnave · #13 16-09-2007, 01:20 PM

Quote:

Originally Posted by csb

Ballarat, I question whether your claim for that Antares image is correct.

Is it perhaps the brightness of the star washing out the image so as to appear as a disc?

Was it agreed? The centuries have dulled your thinking but not your humour? Hilarious, thanks Mr X.

You have the honor of being the first person to ever pick up my tactic... usually folk are happy that agreement has been reached on something and from that point go along with whatever idea comes next

...

Try it sometime I have found one can get away with stuff your opponent had earlier been at odds with

And one other thing who told you my real age????

alex

seeker372011 (Narayan) · #14 16-09-2007, 01:50 PM

Quote:

Originally Posted by xelasnave

And one other thing who told you my real age????

alex

he's realised that Lazarus Long in Heinlein's books and alex may have something in common

but back to the thread

The first image of a star was only in 1996-Betelgeuse by the Hubble Space Telescope...which incidentally was also the first star whose diameter was calculated using interferometry (by Michelson in 1920)

and yes CCD images sometimes show stars as discs-would that it were not so

csb (Craig) · #15 16-09-2007, 06:24 PM

Thanks for that prompt, Seeker. The Lazarus Effect (?) was a great read. Quite chilling in some ways. And I also read the sequel (I seem to remember it being just about as good).

Actually, Exelasnave, I am sure that I have seen someone with your likeness in the background of a Van Gogh painting. It wouldn't surprise me if you two particular individuals were aquaintanced?

Back on topic: So is Ballarat just teasing? (I ask this sincerely)

ballaratdragons (Ken) · #16 16-09-2007, 08:59 PM

Quote:

Originally Posted by csb

Back on topic: So is Ballarat just teasing? (I ask this sincerely)

No, not teasing, but yes, it is just the immense amount of light from Antares washing out the surrounding pixels on the Toucam sensor chip.

If I take a very short exposure it still forms a very small disc shape. Waaayyy smaller, but still larger than the surrounding stars. Even observing Antares at very high power it is more than an orange dot. But no, nothing like looking at the sun.

csb (Craig) · #17 17-09-2007, 06:26 PM

Ok, thanks for clarifying.