Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Planets like earth may have formed around other stars

20.08.2007
The chemical fingerprint of a burned-out star indicates that Earth-like planets may not be rare in the universe and could give clues to what our solar system will look like when our sun dies and becomes a white dwarf star some five billion years from now.

Astronomers from UCLA report that a white dwarf star known as GD 362, which is surrounded by dusty rings similar to those of Saturn, has been contaminated by a large asteroid that left more than a dozen observable chemical elements in the white dwarf’s atmosphere. Such an observation is unprecedented in astronomy. Was there some kind of violent interaction between the star and the asteroid"

The UCLA astronomers think that after about a billion years orbiting the white dwarf as part of an ancient planetary system, an asteroid got close enough to the star to be torn apart by its very strong gravitational force field. An Earth-sized but exceedingly dense white dwarf is the standard end state for most stars. This particular white dwarf, which is under investigation by the W.M. Keck Observatory in Hawaii, is located in the constellation Hercules, approximately 150 light-years, or 1,000 trillion miles, from Earth.

The asteroid broke apart into dust particles that orbited the white dwarf and over time “polluted the white dwarf’s atmosphere,” said Benjamin Zuckerman, UCLA professor of physics and astronomy and lead author of the research, which has been accepted for publication in an upcoming issue of the Astrophysical Journal, the premier journal of astronomy.

The astronomers note that the spectroscopic observations they are reporting constitute the first detailed assessment of the elemental composition of an object in an extrasolar planetary system.

“The relative abundance of the elements in the white dwarf’s atmosphere, polluted by the asteroid, appears similar to those in our Earth-Moon system,” Zuckerman said.

“What we have here is a composition of the white dwarf that is fairly similar to that of the inner planets of our solar system,” said Michael Jura, UCLA professor of physics and astronomy and co-author of the research. “Are there other terrestrial planets like Earth in other solar systems" This white dwarf’s fingerprint is a significant advance in demonstrating that something like terrestrial planet formation occurred around this other star and probably occurred around other stars as well, because it suggests the Earth’s composition is not unique.

“The asteroid that is being shredded is very iron-rich and abundant in calcium and other elements, and low in carbon, like a sturdy rock,” Jura added.

The research implies that the forces that made the Earth and our inner solar system seem to have occurred in this system as well, and probably around other white dwarfs too, Jura said.

Zuckerman said the research result does not rule out the possibility that two planets in this ancient planetary system collided and the orbiting dust and detected elements are from a piece of one of the colliding planets rather than from a more conventional asteroid.

“Something dramatic and violent probably happened,” he said.

What knocked the asteroid out of its original orbit" It probably was deflected by the gravitational field of a large planet, Zuckerman said.

Our own planetary system looks very stable, Zuckerman said, but billions of years from now, when the sun starts to expand in size and lose mass rapidly, the planets and asteroids will spiral away, and the planets closest to the sun, like Mercury and Venus, will be engulfed by the sun and destroyed.

“But other planets, probably including the Earth and the asteroid belt between Mars and Jupiter will spiral out, and their orbits then will make our stable system much less stable,” he said.

A third UCLA author on the paper, physics and astronomy associate professor Brad Hansen, said, “In our solar system, objects rich in iron formed closer to the sun than the objects rich in carbon and ice, which formed farther away, where it is colder. This research tells us about the origin of the asteroid, its temperature when it formed and its chemistry — conditions similar to the Earth’s.”

The group of astronomers, which also includes of UCLA graduate student Carl Melis and Detlev Koester at Germany’s University of Kiel, detected 17 elements in the atmosphere of the white dwarf that probably came from a large asteroid; the asteroid may have once been part of a larger body, perhaps like one of the inner planets of our solar system. Many of the elements have never before been detected in the atmosphere of a white dwarf, including the rare elements strontium and scandium.

The gravitational field of the white dwarf is so strong that all elements heavier than the lightest elements — hydrogen and helium — quickly sink into the white dwarf’s interior, Hansen said.

The asteroid likely broke up more than 100,000 years ago, and perhaps as long as a million years ago, the astronomers said. The star became a very hot white dwarf approximately 1 billion years ago and since then has been steadily cooling off.

Unlike GD 362, most white dwarfs are pristine in their composition.

“You wouldn’t notice another skyscraper in New York, but the same skyscraper in Nebraska would stick out like a sore thumb,” Hansen said. “That’s the case here. A little change in the atmosphere of a white dwarf is very obvious.”

The astronomers used the HIRES spectrometer on the Keck I Telescope to take optical spectra of the white dwarf, spanning the ultraviolet to the full visible range of light. Each element can be identified by its own characteristic spectrum.

The researchers said they find it quite remarkable that even at a distance of 1,000 trillion miles, the Keck HIRES measurements enable them to determine minute details of the bulk composition of a relatively tiny object — as astronomical sizes go — like an asteroid. Currently, no other known observational technique exists that allows for such compositional information to be obtained.

The remains of a white dwarf cool slowly over many billions of years as the dying ember makes its slow journey into oblivion.

Stuart Wolpert | EurekAlert!
Further information:
http://www.ucla.edu

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>