Andrew Yee[_1_]
February 7th 07, 02:54 AM
ESA News
http://www.esa.int
6 February 2007
Universe contains more calcium than expected
The universe contains one and a half times more calcium than previously
assumed. This conclusion was drawn by astronomers of the SRON Netherlands
Institute for Space Research, after observations with ESA's XMM-Newton X-ray
observatory.
This research offers scientists new insights in the formation history of the
elemental building blocks of the cosmos in which supernovae play a crucial
role.
The iron in our blood, the oxygen we breathe, the calcium in our bones, the
silicon in the sand box, all the atoms we are made of are released during
the violent final moments of massive stars in the act of dying. These
so-called supernova explosions eject newly made chemical elements into space
where they become the building blocks for new stars, planets, or even life.
However, many questions concerning the very formation of elements and the
way they get distributed across the universe still remain open.
According to Jelle de Plaa, space researcher at SRON, many answers can be
found in distant clusters of galaxies. "Clusters are in many ways the big
cities of the universe," he says.
"They consist of hundreds of galaxies, each containing thousands of millions
of stars. The galaxies are embedded in a gigantic cloud of hot gas that
fills this cluster like a smog. Due to their enormous size and numbers,
clusters contain a large fraction of the total amount of matter in the
universe. During the past thousand-millions of years supernova explosions
have enriched the surrounding hot gas with heavier elements, like oxygen,
silicon and iron."
Using XMM-Newton, De Plaa determined the abundances of oxygen, neon,
silicon, sulphur, argon, calcium, iron and nickel in 22 clusters of
galaxies. In total he saw the 'pollution' produced by about 100 thousand
million supernovae. When he compared the measured amounts of elements in the
clusters with theoretical models of supernovae, the calcium abundance
measured thanks to XMM-Newton appeared to be one and a half times higher
than theoreticians previously assumed.
Dance of death
De Plaa and his colleagues also found that many supernovae in clusters are
the result of a dance of death between two stars that revolve around each
other. A very compact white dwarf withdraws matter from its unfortunate
companion star. The matter forms a layer on the surface of the white dwarf.
When the dwarf reaches a certain mass, its core cannot any longer support
the weight of the matter and explodes as a supernova.
"Roughly half of the number of supernovae that ever exploded in clusters
appear to have exploded this way," says De Plaa. "This is much more than the
fraction of this kind of supernovae in our own galaxy, which we estimate to
be 15 percent."
The results will be valuable for the scientists who make supernova models.
"Until now, supernova experts had to make educated guesses about how a
supernova exactly explodes," continues De Plaa. "Because we measure the
remains of 100 thousand million supernovae at once, we find more accurate
averages than before. This will help the supernova community to learn how
white dwarfs die."
Note for editors
These findings will be published in the scientific journal Astronomy &
Astrophysics, in the article titled: "Constraining supernova models using
the hot gas in clusters of galaxies", by J. de Plaa, N. Werner, J. A.M.
Bleeker, J. S. Kaastra, M. Mendez, and J.Vink
(http://www.aanda.org/index.php?option=forthcoming&Itemid=18, DOI:
10.1051/0004-6361:20066382).
The findings also appear on line at Astro-ph in the article titled:
"Constraining supernova models using the hot gas in clusters of Galaxies",
by J. de Plaa, N. Werner, J.A.M. Bleeker, J. Vink, J.S. Kaastra, M. Mendez
(astro-ph/0701553).
This research is the result of a cooperation between SRON Netherlands
Institute for Space Research and the University of Utrecht, the Netherlands.
For more information:
Jelle de Plaa, SRON
Email: j.de.plaa @ sron.nl
Norbert Schartel, ESA XMM-Newton Project Scientist
Email: norbert.schartel @ sciops.esa.int
[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/esaCP/SEMMMC4ENXE_index_1.html ]
http://www.esa.int
6 February 2007
Universe contains more calcium than expected
The universe contains one and a half times more calcium than previously
assumed. This conclusion was drawn by astronomers of the SRON Netherlands
Institute for Space Research, after observations with ESA's XMM-Newton X-ray
observatory.
This research offers scientists new insights in the formation history of the
elemental building blocks of the cosmos in which supernovae play a crucial
role.
The iron in our blood, the oxygen we breathe, the calcium in our bones, the
silicon in the sand box, all the atoms we are made of are released during
the violent final moments of massive stars in the act of dying. These
so-called supernova explosions eject newly made chemical elements into space
where they become the building blocks for new stars, planets, or even life.
However, many questions concerning the very formation of elements and the
way they get distributed across the universe still remain open.
According to Jelle de Plaa, space researcher at SRON, many answers can be
found in distant clusters of galaxies. "Clusters are in many ways the big
cities of the universe," he says.
"They consist of hundreds of galaxies, each containing thousands of millions
of stars. The galaxies are embedded in a gigantic cloud of hot gas that
fills this cluster like a smog. Due to their enormous size and numbers,
clusters contain a large fraction of the total amount of matter in the
universe. During the past thousand-millions of years supernova explosions
have enriched the surrounding hot gas with heavier elements, like oxygen,
silicon and iron."
Using XMM-Newton, De Plaa determined the abundances of oxygen, neon,
silicon, sulphur, argon, calcium, iron and nickel in 22 clusters of
galaxies. In total he saw the 'pollution' produced by about 100 thousand
million supernovae. When he compared the measured amounts of elements in the
clusters with theoretical models of supernovae, the calcium abundance
measured thanks to XMM-Newton appeared to be one and a half times higher
than theoreticians previously assumed.
Dance of death
De Plaa and his colleagues also found that many supernovae in clusters are
the result of a dance of death between two stars that revolve around each
other. A very compact white dwarf withdraws matter from its unfortunate
companion star. The matter forms a layer on the surface of the white dwarf.
When the dwarf reaches a certain mass, its core cannot any longer support
the weight of the matter and explodes as a supernova.
"Roughly half of the number of supernovae that ever exploded in clusters
appear to have exploded this way," says De Plaa. "This is much more than the
fraction of this kind of supernovae in our own galaxy, which we estimate to
be 15 percent."
The results will be valuable for the scientists who make supernova models.
"Until now, supernova experts had to make educated guesses about how a
supernova exactly explodes," continues De Plaa. "Because we measure the
remains of 100 thousand million supernovae at once, we find more accurate
averages than before. This will help the supernova community to learn how
white dwarfs die."
Note for editors
These findings will be published in the scientific journal Astronomy &
Astrophysics, in the article titled: "Constraining supernova models using
the hot gas in clusters of galaxies", by J. de Plaa, N. Werner, J. A.M.
Bleeker, J. S. Kaastra, M. Mendez, and J.Vink
(http://www.aanda.org/index.php?option=forthcoming&Itemid=18, DOI:
10.1051/0004-6361:20066382).
The findings also appear on line at Astro-ph in the article titled:
"Constraining supernova models using the hot gas in clusters of Galaxies",
by J. de Plaa, N. Werner, J.A.M. Bleeker, J. Vink, J.S. Kaastra, M. Mendez
(astro-ph/0701553).
This research is the result of a cooperation between SRON Netherlands
Institute for Space Research and the University of Utrecht, the Netherlands.
For more information:
Jelle de Plaa, SRON
Email: j.de.plaa @ sron.nl
Norbert Schartel, ESA XMM-Newton Project Scientist
Email: norbert.schartel @ sciops.esa.int
[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/esaCP/SEMMMC4ENXE_index_1.html ]