Search found 304 matches

by astro_uk
Mon Nov 12, 2007 9:07 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Largest structure (APOD 07 Nov 2007)
Replies: 1
Views: 1486

I don't think that anyone has a particular one in mind, but the largest bound structure is probably a large galaxy cluster. I don't know which cluster has the most mass of those that have had theirs estimated, though.
by astro_uk
Mon Nov 12, 2007 9:04 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Cosmic Rays from Galactic Centers: protons? (APOD 12 Nov 07)
Replies: 2
Views: 1610

I think it means heavier atomic nuclei, like a fully or partially ionised Iron atom for example. At the high energies being talked about it is entirely possible to strip all or most of the electrons from heavier nuclei. What it seems to be getting at is that such heavily ionised nuclei would feel a ...
by astro_uk
Fri Nov 02, 2007 12:11 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Where are ANY of the impactors?
Replies: 145
Views: 34609

Nereid - Although I am but a novice in this new field of discovery, what amazes me the most is your apparent lack of ability to do your own research. Some research is not beyond us sidekickbobcat/Craterchains. To reply to your point: the fact is that while Nereid and most of the other people on the...
by astro_uk
Fri Nov 02, 2007 11:39 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Peculiar Arp87 - tidal effect, peculiar redshift? (1Nov2007)
Replies: 9
Views: 3400

Which ones exactly do you mean? There are some objects that are probably just red stars in the milky way, there is one small very red spiral that is visible between the two galaxies, this is probably just an S0 galaxy, a spiral which has stopped forming young blue stars and now only has the old red ...
by astro_uk
Thu Oct 25, 2007 11:07 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: hubble
Replies: 65
Views: 14376

Yup, makes you wonder why he doesn't get either bored or frustrated.

Perhaps he is just one of those "intelligent" codes, designed to mimic human conversations by giving a standard response to any reply.

:D
by astro_uk
Thu Oct 25, 2007 11:04 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Kilometers?
Replies: 11
Views: 3201

Dutchman nailed it, its simply because when you do astronomy at least of the quantitative kind you work in SI units generally. Its a lot simpler to do calculations all within the SI framework you don't have to worry about units or conversion factors that way. Some people writing APOD blurbs will go ...
by astro_uk
Wed Oct 17, 2007 10:51 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Aging Galaxy (APOD 17 Oct 2007)
Replies: 18
Views: 6589

Some of the objects are stars in the Milky Way, and some are background galaxies or star clusters. But some are actually individual (or chance allignments of two) stars in the target galaxy. The HST is just about capable of resolving individual stars at this distance, but only if they are bright eno...
by astro_uk
Tue Oct 09, 2007 12:48 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Bang or No Bang
Replies: 284
Views: 29238

For instance, let us say that in this scenario, the universe existed prior to the BB, it contained matter, and when the 'event' that created the microwave background radiation that we see occured some 13.7 billion light years ago, it reorganized matter and space profoundly, likely by recycling matt...
by astro_uk
Mon Oct 08, 2007 12:20 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Multiple planes of space
Replies: 12
Views: 3424

Some galaxies do appear to "tumble" the case I know about is NGC 524, is obvious when you look at it it is a face on S0, essentially a dead spiral galaxy, you can see the residual spiral structure. However when you measure the velocity of different parts of the galaxy (as the SAURON collab...
by astro_uk
Mon Oct 08, 2007 12:14 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Bang or No Bang
Replies: 284
Views: 29238

To me it is more plausible that as a result of a BB energy was dispersed through pre-existing matter along with inflation of space. You seem to be suggesting that the Universe existed before the BB, that the BB then spread material through it, and caused space to expand. But if the BB caused the ex...
by astro_uk
Wed Aug 15, 2007 1:32 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Milky Way Galaxy
Replies: 53
Views: 13922

The bad astronomer had a decent post up a few week debunking the idea that the Sun formed in the Sagitarius dwarf.

You can find links here:

http://www.badastronomy.com/bablog/2007 ... -followup/
by astro_uk
Thu Aug 02, 2007 8:45 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: The Black Eye (APOD 02 August 2007)
Replies: 9
Views: 3845

Counter rotation is actually quite common in early type galaxies, the SAURON http://www.strw.leidenuniv.nl/sauron/ team has found many such cases, though the counter rotation is usually confined to the very inner region. My understanding is that the system remains fairly stable, there would be littl...
by astro_uk
Sat Jul 21, 2007 4:34 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Hercules Cluster (APOD 19 July 2007)
Replies: 6
Views: 3566

If I'm reading your question correctly I think you're asking about whether or not the Universe is homogeneous? I think the point is that on the very largest scales the Universe is fairly homogeneous, but clearly a galaxy is very far above the average density of the Universe. This is just because of ...
by astro_uk
Fri Jul 20, 2007 2:54 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Hercules Cluster (APOD 19 July 2007)
Replies: 6
Views: 3566

We're not presently part of any cluster, though over time our own little group will probably get swallowed up by something larger, perhaps the Virgo cluster, though I believe that may be too far away. The number of red and blue galaxies per cluster is not a sure sign of the clusters age, because som...
by astro_uk
Thu Jul 19, 2007 4:41 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Hercules Cluster (APOD 19 July 2007)
Replies: 6
Views: 3566

The Hercules cluster is probably younger, the Coma cluster is fairly old and settled, their has been time for interactions to convert the spirals into S0s and ellipticals. The Hercules cluster will probably look pretty similar a few billion years from now, when things have settled down.
by astro_uk
Tue Jul 10, 2007 2:29 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Radiometric dating
Replies: 23
Views: 6586

Considering radiometric dating and the methods used (and calibration of such equipment and experiments) to gain "knowledge" of said science remains dependent on a theory of time spans to begin with. Well not really, I can sit in a lab and watch a certain fraction of a radioactive material...
by astro_uk
Tue Jul 10, 2007 2:26 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: A Modest Proposal from a fan...
Replies: 2
Views: 1564

There is another reason why images are presented in certain resolutions. That is simply the size of the image produced by the instrument, the ACS on Hubble for instance produces images of around 4000 x 4000 pixels, there simply isn't any point changing this as it doesn't add any information. Most ot...
by astro_uk
Thu Jun 28, 2007 11:35 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: A Vist from Atlantis (APOD 28 June 2007)
Replies: 7
Views: 3048

According to google its 769 641.295 cubits.

Just type "190 nautical miles in cubits" into google. It can convert almost anything.
by astro_uk
Thu Jun 14, 2007 4:43 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Origins of the UNIVERSE
Replies: 829
Views: 141880

Hi Nico

Just out of curiousity whats with the fascination about the ether? You don't have objections to say relativity as well do you?
by astro_uk
Thu Jun 14, 2007 4:38 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Question re the field of stars
Replies: 3
Views: 1492

In images of fields of stars all the stars are essentially the same size, no size in fact, they are all point sources. We can't resolve individual stars with normal optics, though you can do it with large interferometers. (This page has some details. http://isi.ssl.berkeley.edu/research.htm ) The st...
by astro_uk
Wed Jun 13, 2007 3:58 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Origins of the UNIVERSE
Replies: 829
Views: 141880

I think the point cosmo is trying to make is this: We see ellipical galaxies in the nearby Universe, close enough for some that we know a great deal about them. It doesn't matter how far into space you look you still see Elliptical galaxies, there are elliptical galaxies observed at redshifts compar...
by astro_uk
Tue Jun 12, 2007 12:03 pm
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Origins of the UNIVERSE
Replies: 829
Views: 141880

To amplify cosmos question. The normal boring galaxies he looks at can be examined spectroscopically. When you do that you always find that their ages are consistent with the age of the universe, in other words, if you see them as they were 7Gyr ago, because they are at a redshift of one, they alway...
by astro_uk
Mon Jun 11, 2007 8:27 am
Forum: The Asterisk Café: Discuss Anything Astronomy Related
Topic: Origins of the UNIVERSE
Replies: 829
Views: 141880

cosmos not a moderator, that would be me. With regard to arps claims of correlations betwen quasars and foreground galaxies, these have been shown to be nothing more that random alignments, I'm afraid I don't have the references here, but if you check out the BadAstronomy and Universe Today discussi...
by astro_uk
Fri Jun 08, 2007 8:45 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Markarian's Eyes and material torn out (APOD 08 June 2007)
Replies: 6
Views: 3219

Indeed in clusters you get quite a lot of stars that float between the galaxies, not bound to any particular galaxy. They form what is known as the intracluster light. Some of the stars in the cluster may even have formed out there, but most probably have been thrown out of galaxies during mergers s...
by astro_uk
Fri May 18, 2007 3:58 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: Dark Matter Ring (APOD 16 May 2007)
Replies: 26
Views: 9723

Actually I see a whole bunch of bluish colored galaxys smeared in the arc shape characteristic of gravitational lensing. Is it possible that this amount of 'lensing' may be accounted for by the gravitational field of the central cluster of galaxys? It is not possible for only the luminous matter to...