Space.com (August 5, 2009)
"Stars in a distant galaxy move at stunning speeds — greater than 1 million mph, astronomers have revealed.
"These hyperactive stars move at about twice the speed of our sun through the Milky Way, because their host galaxy is very massive, yet strangely compact. The scene, which has theorists baffled, is 11 billion light-years away. It is the first time motions of individual stars have been measured in a galaxy so distant.
"While the stars' swiftness is notable, stars in other galaxies have been observed to travel at similarly high speeds. In those situations, it was usually because they were interlopers from outside, or circling close to a black hole.
"But in this case, the stars' high velocities help astronomers confirm that the galaxy they belong to really is as massive as earlier data suggested.
"The compact nature of this and similar galaxies in the faraway early universe is puzzling to scientists, who don't yet understand why some young, massive galaxies are about five times smaller than their counterparts today...."
The article is a pretty good overview of an intriguing situation in astronomy, physics, and cosmology. Until the latest set of observations were made, there was a somewhat comfortable amount of uncertainty about exactly how massive these galaxies were and how far they are from us. It was possible to assume that the masses were lower than assumed, and the distances less.
That set of assumptions allowed existing theories of how galaxies - and the universe - developed to stand.
That was then, this is now.
"...'It's a bit of a puzzle,' [study leader and Yale University astronomer Pieter] van Dokkum told SPACE.com. 'We think these galaxies must grow through collisions with other galaxies. The weird thing is that these mergers must lead to galaxies that are larger in size but not much more massive. We need a mechanism that grows them in size but not in mass.'..."
I've written before, how it's nice when data confirms an existing theory: but exciting and rewarding when data doesn't fit the mathematical models. (March 23, 2009)
The trick is to come up with a revised, or new, theory - a new mathematical model - and see if that matches the real world.
"How Strange, Small Galaxies Lost Their Stars"
Space.com (August 4, 2009)
"Close encounters of the galactic kind may explain the existence of an unusual type of dwarf galaxy, a new study suggests.
"So-called dwarf spheroidal galaxies are small and very faint, containing few stars relative to their total mass.
"These star-deprived galaxies appear to be made mostly of dark matter — an elusive form of matter detectable only by its gravitational influence. Dark matter outweighs normal matter by a factor of five to one in the universe as a whole.
"Astronomers have found it difficult to explain the origin of dwarf spheroidal galaxies...."
Again: observed data and current mathematical models don't quite agree. I'm enough of an old fogy to think that it's the theories that need to be changed.
This article is a look - quick, but pretty good - of another bit of the cosmological puzzle that researchers are working on today.
Some words about dark matter:
"Dark matter" and "dark energy" are phrases that come up now and then in articles about what astronomers, physicists, and cosmologists are thinking these days. Some of those articles seem to have been written - or edited - by someone who learned science by watching the Star Wars movies.
I like the Star Wars movies, by the way: but they're to physics and astronomy what the Terminator movies are to robotics: 'Any resemblance to real science or technology, off-the-shelf or in development, is purely coincidental.'
Where was I? Dark matter and energy, right.
Turns out, "dark matter" isn't just a way for an astronomer to say, "I can't see it." Dark matter and dark energy are pretty good ways of explaining some observed phenomena. If they exist, they're very odd stuff. Dark matter isn't unlit stuff of the sort that the sun and planets are made of; it isn't antimatter; and it's not black holes. As for what it is - that's a matter of some debate.
I found a fairly clear discussion of dark matter and dark energy on the NASA website.
Right now, some enthusiasts notwithstanding, dark matter and dark energy are convenient mathematical models. The models may describe something that's real, or not.
This wouldn't be the first time that additional research showed that a part of the universe 'discovered' by a theory wasn't really there. I remember phlogiston. That doesn't mean that chemistry and physics are a fraud: Just that we don't know everything there is to know. There may be better models than what we have today, which more accurately reflect the underlying reality.
- "Lemming Tracks: All Betelgeuse, All the Time"
(June 10, 2009) (list of related posts updated as they're written)
- "Colliding Galaxies Leave Debris"
(June 9, 2009)
- "Star Explodes Too Early: Theory May Need Tweaking or Trashing"
(March 23, 2009)
- "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"
(May 29, 2009)
- " 'What's a Supernova?' - a Pretty Good Overview"
(May 4, 2009)
- "Dark Energy, Dark Matter"
Astrophysics, Science, NASA