Herschel telescope shows galactic star formation is slowing (Update)

May 06, 2010
The Herschel telescope is the biggest ever sent into space. New star formations in spiral galaxies such as the Milky Way have declined five-fold in the last three billion light years, according to the first findings of the European Space Agency's Herschel telescope.

The formation of new stars in galaxies like the Milky Way has declined five-fold in the last three billion years, initial findings of the European Space Agency's Herschel telescope showed Thursday.

While scientists already knew that star formation was more prolific billions of years ago, the Herschel telescope has for the first time been able to start measuring the rate of decline, scientist Steve Eales said at the launch.

Three billion years ago "galaxies were forming stars at ... five times the rate we know today," he told AFP at the agency's offices in Noordwijk in the western Netherlands.

Eales said the Herschel telescope's infrared technology allowed scientists to see galaxies, mainly spiral ones like the Milky Way, that were previously hidden from scientists' view by cosmic dust clouds.

The telescope, launched a year ago to study star formation, is the biggest ever sent into space, orbiting at a distance of 1.5 million kilometres (932,000 miles) from the Earth.

Scientists already knew that 10 billion years ago "there were these galaxies that were forming stars really fast," said Eales, but previous telescopes were unable to see up to a distance of 10 billion light years.

"We haven't been able to fill that gap until today.

"What Herschel has been able to do because of the wave length it is observing at, it can suddenly see lots of galaxies in the nearby universe, up to about the last three or four billion light years. It can fill the gap in cosmic history," Eales said.

The findings suggested, he said, that "at some point stars will stop forming" altogether, unless solar conditions changed.

Scientists did not know the reasons for the decline.

Researchers also told the launch that Herschel had managed to spot an embryonic "massive star" -- a celestial object more than eight times the size of our sun.

"Massive stars are rare and short-lived," said an ESA statement. "To catch one during formation presents a golden opportunity to solve a long-standing paradox in astronomy."

Scientist Annie Zavagno said that radiation emitted by massive stars should destroy them at some point -- instead they continue to grow.

According to accepted scientific principles, stars should not be able to become more than eight times bigger than our sun.

Understanding how these "impossible" stars were formed was critical because they "control the dynamical and chemical evolution of galaxies," said Zavagno.

The ESA's director of science and robotic exploration, David Southwood, said "a new universe" was emerging from Herschel's findings.

"We can look at the complex chemistry that goes on in space that ultimately has created the things that we are made of," he said.

Explore further: Astronomers release most detailed catalogue ever made of the visible Milky Way

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User comments : 15

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Chase_O_
5 / 5 (2) May 06, 2010
"star formation was more prolific billions of light years ago"

How does a writer for a science journal not know that a "light year" is a measurement of distance? And there isn't any kind of editing or screening process over at Physorg ?
Mesafina
2.3 / 5 (3) May 06, 2010
"star formation was more prolific billions of light years ago"

How does a writer for a science journal not know that a "light year" is a measurement of distance? And there isn't any kind of editing or screening process over at Physorg ?


A light year is also a unit of time as well as a unit of spatial measurement. While it's odd to say light-years over just years as they mean the same thing at that point, it isn't itself inaccurate.
franl
5 / 5 (2) May 06, 2010
@Chase_O_ is spot on. Especially, since the article also includes this: "The telescope, launched a year ago, [...]". Didn't the author notice the contrast between "light years ago" and "a year ago"? I also seriously doubt a scientist with the ESA would say "light years ago". Did the author tweak the scientist's quotes to change "years" to "light years"?
franl
5 / 5 (4) May 06, 2010
@Mesafina a light year is NOT a unit of time. The universe is a little over 13 billion years old, but the visible part of the universe is over 40 billion light years in diameter. See http://www.atlaso...ift.html
Mayday
5 / 5 (2) May 06, 2010
Yeah, yeah, yeah. Bad writing + bad speaking = bad science. The editors should delete this article from the site.

"...previous telescopes could not actually see that many galaxies between now and 10 billion light years ago." Huh? Really? Maybe start over, you're having a bad day.
CSharpner
5 / 5 (2) May 06, 2010
Mesafina, a light year is NOT a measure of time. It's ONLY a measure of distance... the distance light travels in a year... which is about 5,865,696,000,000 miles. It's NEVER been a measure of time and anyone who uses it as a measure of time doesn't know what they're talking about.
eachus
5 / 5 (1) May 06, 2010
"The findings suggested, he said, that "at some point stars will stop forming" altogether, unless solar conditions changed."

Unless SOLAR conditions changed? Who knew that the sun controlled star formation universe-wide? ;-)
astrotim
not rated yet May 06, 2010
Phew, they changed the light years reference.
Oliver_k_Manuel
1 / 5 (1) May 06, 2010
Neutron repulsion is the power source, i am right and everyone else is wrong hic!
PhysicsLver21
5 / 5 (2) May 06, 2010
"star formation was more prolific billions of light years ago"

How does a writer for a science journal not know that a "light year" is a measurement of distance? And there isn't any kind of editing or screening process over at Physorg ?


A light year is also a unit of time as well as a unit of spatial measurement. While it's odd to say light-years over just years as they mean the same thing at that point, it isn't itself inaccurate.


Mesafina you have absolutely no idea what your talking about. Who ever edited this article totally butchered it haha but back to my main point... CSharpner has got it spot on, a light year is NOT a unit of time but a unit of measurement that describes the distance light travels in one year ~5.8 trillion.. so it is both redundant and grammatically wrong to state that something is 10 billion years ago... gotta love the physorg editors
Szkeptik
3 / 5 (2) May 07, 2010
Since it takes exactly one year for light to travel a light year, an object we see from one light year away is how it looked one year ago. Looking at something that's 1 billion LY away is how it looked 1 billion years ago.
LY is not a unit of time itself, but can be used to specify how far we go back in time when we look at said object.
in7x
5 / 5 (2) May 07, 2010
1) v=d/t
2) t=d/v
3) d=v*t
4) s*t=f/u
CSharpner
5 / 5 (2) May 07, 2010
A light year is ONLY a measure of distance. Of course, by simple and direct logical derivation, you can say that if you see something that's 100 LY away, it's correct to say what you're looking at is as it was 100 years ago, but you can NEVER say, "It's X light years ago." That's equivalent to saying, "It's N miles ago."
Au-Pu
not rated yet May 09, 2010
Szkeptik is correct. Whilst a light year is by standard use a measure of distance it is a measure of distance over time and therefore also measures time. So whilst the method of expression is not common it is technically not incorrect.
If a galaxy were to form out of masses of cosmic gas it would be reasonable to expect star formation to be more prolific when there was more gas and it would be reasonable to expect star formation to slow as the volume of available free gas diminished.
The observations only go to prove what one should reasonably expect.
Graeme
not rated yet May 14, 2010
I wonder how the bias of the brighter galaxies being easier to see is removed. Galaxies at 3 Giga ly will not be very bright, so the average ones may be missed, and only the brightest with active star forming going on analyzed in this study.