This is an artist’s impression of a white dwarf (burned-out) star
accreting rocky debris left behind by the star’s surviving planetary
system. It was observed by Hubble in the Hyades star cluster. At lower
right, an asteroid can be seen falling toward a Saturn-like disk of dust
that is encircling the dead star. Infalling asteroids pollute the white
dwarf’s atmosphere with silicon. Credit: NASA, ESA, and G. Bacon
(STScI)
› Larger image
› Larger image
Hubble Tells a Tale of Galactic Collisions
05.10.13
Credit: ESA/Hubble & NASA.
Acknowledgement: Luca Limatola
› Larger image
› Larger image
When we look into the distant cosmos, the great majority of the objects
we see are galaxies: immense gatherings of stars, planets, gas, dust,
and dark matter, showing up in all kind of shapes. This Hubble picture
registers several, but the galaxy catalogued as 2MASX J05210136-2521450
stands out at a glance due to its interesting shape.
This object is an ultraluminous infrared galaxy which emits a tremendous amount of light at infrared wavelengths. Scientists connect this to intense star formation activity, triggered by a collision between two interacting galaxies.
The merging process has left its signs: 2MASX J05210136-2521450 presents a single, bright nucleus and a spectacular outer structure that consists of a one-sided extension of the inner arms, with a tidal tail heading in the opposite direction, formed from material ripped out from the merging galaxies by gravitational forces.
The image is a combination of exposures taken by Hubble’s Advanced Camera for Surveys, using near-infrared and visible light.
This object is an ultraluminous infrared galaxy which emits a tremendous amount of light at infrared wavelengths. Scientists connect this to intense star formation activity, triggered by a collision between two interacting galaxies.
The merging process has left its signs: 2MASX J05210136-2521450 presents a single, bright nucleus and a spectacular outer structure that consists of a one-sided extension of the inner arms, with a tidal tail heading in the opposite direction, formed from material ripped out from the merging galaxies by gravitational forces.
The image is a combination of exposures taken by Hubble’s Advanced Camera for Surveys, using near-infrared and visible light.
European Space Agency/NASA Hubble
NASA'S Hubble Space Telescope Finds Dead Stars 'Polluted' With Planet Debris
WASHINGTON
-- NASA's Hubble Space Telescope has found the building blocks for
Earth-sized planets in an unlikely place-- the atmospheres of a pair of
burned-out stars called white dwarfs.
These dead stars are located 150 light-years from Earth in a relatively young star cluster, Hyades, in the constellation Taurus. The star cluster is only 625 million years old. The white dwarfs are being polluted by asteroid-like debris falling onto them.
Hubble's Cosmic Origins Spectrograph observed silicon and only low levels of carbon in the white dwarfs' atmospheres. Silicon is a major ingredient of the rocky material that constitutes Earth and other solid planets in our solar system. Carbon, which helps determine properties and origin of planetary debris, generally is depleted or absent in rocky, Earth-like material.
"We have identified chemical evidence for the building blocks of rocky planets," said Jay Farihi of the University of Cambridge in England. He is lead author of a new study appearing in the Monthly Notices of the Royal Astronomical Society. "When these stars were born, they built planets, and there's a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system."
This discovery suggests rocky planet assembly is common around stars, and it offers insight into what will happen in our own solar system when our sun burns out 5 billion years from now.
Farihi's research suggests asteroids less than 100 miles (160 kilometers) wide probably were torn apart by the white dwarfs' strong gravitational forces. Asteroids are thought to consist of the same materials that form terrestrial planets, and seeing evidence of asteroids points to the possibility of Earth-sized planets in the same system.
The pulverized material may have been pulled into a ring around the stars and eventually funneled onto the dead stars. The silicon may have come from asteroids that were shredded by the white dwarfs' gravity when they veered too close to the dead stars.
"It's difficult to imagine another mechanism than gravity that causes material to get close enough to rain down onto the star," Farihi said.
By the same token, when our sun burns out, the balance of gravitational forces between the sun and Jupiter will change, disrupting the main asteroid belt. Asteroids that veer too close to the sun will be broken up, and the debris could be pulled into a ring around the dead sun.
According to Farihi, using Hubble to analyze the atmospheres of white dwarfs is the best method for finding the signatures of solid planet chemistry and determining their composition.
"Normally, white dwarfs are like blank pieces of paper, containing only the light elements hydrogen and helium,"Farihi said. "Heavy elements like silicon and carbon sink to the core. The one thing the white dwarf pollution technique gives us that we just won't get with any other planet-detection technique is the chemistry of solid planets."
The two "polluted" Hyades white dwarfs are part of the team's search of planetary debris around more than 100 white dwarfs, led by Boris Gansicke of the University of Warwick in England. Team member Detlev Koester of the University of Kiel in Germany is using sophisticated computer models of white dwarf atmospheres to determine the abundances of various elements that can be traced to planets in the Hubble spectrograph data.
Farihi's team plans to analyze more white dwarfs using the same technique to identify not only the rocks' composition, but also their parent bodies.
For more information about NASA's Hubble Space Telescope, visit:
These dead stars are located 150 light-years from Earth in a relatively young star cluster, Hyades, in the constellation Taurus. The star cluster is only 625 million years old. The white dwarfs are being polluted by asteroid-like debris falling onto them.
Hubble's Cosmic Origins Spectrograph observed silicon and only low levels of carbon in the white dwarfs' atmospheres. Silicon is a major ingredient of the rocky material that constitutes Earth and other solid planets in our solar system. Carbon, which helps determine properties and origin of planetary debris, generally is depleted or absent in rocky, Earth-like material.
"We have identified chemical evidence for the building blocks of rocky planets," said Jay Farihi of the University of Cambridge in England. He is lead author of a new study appearing in the Monthly Notices of the Royal Astronomical Society. "When these stars were born, they built planets, and there's a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system."
This discovery suggests rocky planet assembly is common around stars, and it offers insight into what will happen in our own solar system when our sun burns out 5 billion years from now.
Farihi's research suggests asteroids less than 100 miles (160 kilometers) wide probably were torn apart by the white dwarfs' strong gravitational forces. Asteroids are thought to consist of the same materials that form terrestrial planets, and seeing evidence of asteroids points to the possibility of Earth-sized planets in the same system.
The pulverized material may have been pulled into a ring around the stars and eventually funneled onto the dead stars. The silicon may have come from asteroids that were shredded by the white dwarfs' gravity when they veered too close to the dead stars.
"It's difficult to imagine another mechanism than gravity that causes material to get close enough to rain down onto the star," Farihi said.
By the same token, when our sun burns out, the balance of gravitational forces between the sun and Jupiter will change, disrupting the main asteroid belt. Asteroids that veer too close to the sun will be broken up, and the debris could be pulled into a ring around the dead sun.
According to Farihi, using Hubble to analyze the atmospheres of white dwarfs is the best method for finding the signatures of solid planet chemistry and determining their composition.
"Normally, white dwarfs are like blank pieces of paper, containing only the light elements hydrogen and helium,"Farihi said. "Heavy elements like silicon and carbon sink to the core. The one thing the white dwarf pollution technique gives us that we just won't get with any other planet-detection technique is the chemistry of solid planets."
The two "polluted" Hyades white dwarfs are part of the team's search of planetary debris around more than 100 white dwarfs, led by Boris Gansicke of the University of Warwick in England. Team member Detlev Koester of the University of Kiel in Germany is using sophisticated computer models of white dwarf atmospheres to determine the abundances of various elements that can be traced to planets in the Hubble spectrograph data.
Farihi's team plans to analyze more white dwarfs using the same technique to identify not only the rocks' composition, but also their parent bodies.
For more information about NASA's Hubble Space Telescope, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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