Posted on 12/24/2004 6:07:04 PM PST by neverdem
Fourteen billion years after the Big Bang started it all, there is still life in the old cosmos.
Astronomers announced yesterday that they had discovered three dozen baby galaxies in what passes for nearby space in the universe - two billion to four billion light-years distant. The galaxies, which are blossoming with new stars at a prodigious rate, resemble the infant Milky Way 10 billion years ago, the astronomers said.
Studying these new galaxies could give cosmologists new insights into the processes by which galaxies and stars first formed out of clouds of primordial gas and dust at the beginning of time.
"It's like looking out your window and seeing a dinosaur walk by," said Dr. Tim Heckman of Johns Hopkins University, who led a team using a NASA satellite, the Galaxy Evolution Explorer, or Galex, to pinpoint the newborns. Dr. Heckman spoke in Pasadena, Calif., at a news conference at the Jet Propulsion Laboratory, which manages the satellite. A paper describing the results has been submitted to The Astrophysical Journal.
The babies were a pleasant surprise.
Like the parents of a woman of a certain age who long ago gave up hope of grandchildren, astronomers had given up hope that the universe was still producing galaxies that could grow up to be the size of the Milky Way. The heyday of making stars, the active ingredients of galaxies, was five billion to eight billion years ago. Perhaps only dwarf galaxies were being born today.
"We didn't know if there were any newborns still around or if this phase of cosmic creation is over," Dr. Heckman explained.
The baby galaxies appear as bluish blobs of light about 10,000 light-years across in images sent back by the Galex satellite, which was launched in 2003 on a 29-month mission to survey the sky for ultraviolet emissions.
Ultraviolet light, which has a shorter wavelength than visible light, is produced by the hottest, most massive stars, like those of the Pleiades cluster, which shines in the sky above Orion these frigid crystalline nights. Because such stars do not last very long, they are also among the youngest stars in the sky.
As a result, young galaxies stand out in ultraviolet light, said Dr. Chris Martin of the Jet Propulsion Laboratory, the principal investigator for the Galex project. "Ultraviolet traces star formation," Dr. Martin said.
The hitch for astronomers hoping to study the recent evolution of stars and galaxies is that the atmosphere blocks ultraviolet rays from reaching Earth. So ultraviolet astronomy can be pursued only in space, with instruments like the Hubble Space Telescope and Galex.
Galex is designed to spot the ultraviolet glows of young stars and galaxies and thus help fill in the history of star formation and cosmic evolution over the last 10 billion years. It has a specially designed 20-inch-diameter telescope with a field of view four times as big as a full moon.
The new babies are only the first results of the project, and the astronomers said they expected to find more, although not many.
While they are not nearly the size of mature galaxies like the Milky Way, which is about 100,000 light-years across and has about 200 billion stars, the newborn galaxies outshine them in ultraviolet by a factor of 100 or so, which means they are producing stars "at a prodigious rate," in the words of Dr. Martin.
Dr. Alice Shapley, a theorist at the University of California, described them as "stragglers" of the great wave of galaxy formation that peaked when the universe was half its present age.
It is important, Dr. Shapley said, to try to find out what is finally causing these galaxies to form now. Are they accreting fresh star material from outside, for example? Indeed, she said, astronomers still do not know for sure whether these are really new galaxies, or whether perhaps they are old galaxies, hiding old stars inside them, that are undergoing a new burst of star formation.
These would be ideal objects to study with the Hubble Space Telescope, she added.
What will happen to these newborns is another mystery, Dr. Heckman said.
The infant Milky Way coalesced out of the murk 10 billion years ago, when the universe was more crowded and baby galaxies could bang into one another, merge and grow. "It's less clear what will happen in the future," Dr Heckman said.
The universe is now a more diffuse place, and the baby galaxies may have been born into loneliness. If so, they will never grow up.
Let me guess: you live near a city? ;-)
A very Merry Christmas to you and yours....
"Let me guess: you live near a city? ;-)"
Yes. How did you know that?
the Galex satellite, which was launched in 2003
And a merry one back to you !
33 - "I alway wondered why they call it the Milky Way. "
If you wish to have a real treat, purposely go to a mountain in the desert (low water vapor), far from any civilization (lights), or ocean (clouds) and do some star gazing.
The night sky in such a place is simply amazing, and totally awe inspiring. And the 'milky way' (the area of the sky looking into the massive amount of stars which make up our galaxy, is readily apparent.
It is sad that you 'wonder' why, because that means, like most on earth, you haven't had the opportunity to observe the 'real' night sky, unclouded, unfogged, unsmogged, un-backlit. As much as I love my home areas on the Gulf and Atlantic, I do miss the spectacular night skys of the desert (no telescope necessary).
On a mountain in Saudi Arabia, I have even read a newspaper by starlight. It is simply amazing - like something out of 'Startrek', but there it is, real, right before your very eyes.
To give an astute, astronomical observation:
WOW !
Well, if it were up to me I'd hire Slartibartfast to head up the design team. He does some really nice fjords.
Thanks for the pic. I assume it's an illustration. Merry Christmas!
Same here -- except it was through a surveyor's transit (but, like you, in the '60's...)
Petuniasevan, APOD's poster, stopped posting just after the November election. I was on the ping list for APOD. Do you have any idea what happened?
I've had APOD on my favorites bar for a l-o-n-g while, so I seldom followed the APOD threads here. I have no idea as to what transpired with Petuniaseven -- sorry...
"It is sad that you 'wonder' why, because that means, like most on earth, you haven't had the opportunity to observe the 'real' night sky, unclouded, unfogged, unsmogged, un-backlit."
Thanks.
You bring back a lot of memories.
I was asking why they call it the Milky Way and now I know. I really know. I have experienced what you describe above in my younger days in Europe - ie, Sardinia, Sicily and Malta. I go back about 50 years. But not here on the East Coast.
Merry Christmas.
Here's to clear skies tonight and a big scope..
Click here to see large pic.
COBE image of the Milky Way: (Courtesy of Ned Wright, click here for related images)
http://map.gsfc.nasa.gov/m_uni/uni_101mw.html
The Galaxy has three major components:
A thin disk consisting of young and intermediate age stars - this disk also contains gas and is actively forming new stars. Dust in the disk makes it appear orange in the picture. Dust absorbs blue light more than red light and thus makes stars appear reddish. Our Galaxy has spiral arms in its disk - these spiral arms are regions of active star formation.
A bar of older stars (white in the COBE picture).
An extended dark halo whose composition is unknown. Since the matter in the halo does not consist of luminous stars, it does not show up in the COBE image. The existence of the dark halo is inferred from its gravitational pull on the visible matter.
I thought I'd share this. It may not be Hubble quality, but it's mine.
This is my most recent image of M-42 Nebula in Orion that was taken on 11/13/04.
This image was prime focus, 3 minute exposure film format, 20 minute exposure, and was processed with Adobe Photoshop, as the raw image had slight light pollution fogging, was slightly out of focus and there were some tracking problems. For those that are interested
At at distance of about 1600 light years from earth, the Orion Nebula owes its appearance to a grouping of four young, hot stars known as the Trapezium. The brightest member produces enough radiation to cause the surrounding shell of hydrogen gas to glow so brightly that we can see it from a distance of 1,600 light-years.
The gas clouds are actually a stellar nursery where new stars are being formed. The bright part of the nebula is the glow of many luminous, newborn stars shining on the surrounding gas cloud. The nebula and the brighter stars are very young by astronomical standards, at about 30,000 years old. Compare this to our own Sun, which is a middle-aged star at over four billion years!
And Merry Christmas and Happy New Year to you and all.
Only galaxies driving under the influence collide with each other.
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