Jacques van Oene
July 27th 05, 07:58 PM
Erica Hupp
Headquarters, Washington July 27, 2005
(Phone: 202/358-1234)
Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)
RELEASE: 05-196
NASA'S CHANDRA NEON DISCOVERY SOLVES SOLAR PARADOX
NASA's Chandra X-ray Observatory survey of nearby sun-like stars
suggests there is nearly three times more neon in the sun and local universe
than previously believed. If true, this would solve a critical problem with
understanding how the sun works.
"We use the sun to test how well we understand stars and, to some extent,
the rest of the universe," said Jeremy Drake of the Harvard-Smithsonian
Center for Astrophysics in Cambridge, Mass. "But in order to understand the
sun, we need to know exactly what it is made of," he added.
It is not well known how much neon the sun contains. This is critical
information for creating theoretical models of the sun. Neon atoms, along
with carbon, oxygen and nitrogen, play an important role in how quickly
energy flows from nuclear reactions in the sun's core to its edge, where it
then radiates into space.
The rate of this energy flow determines the location and size of a crucial
stellar region called the convection zone. The zone extends from near the
sun's surface inward approximately 125,000 miles. The zone is where the gas
undergoes a rolling, convective motion much like the unstable air in a
thunderstorm.
"This turbulent gas has an extremely important job, because nearly all of
the energy emitted at the surface of the sun is transported there by
convection," Drake said.
The accepted amount of neon in the sun has led to a paradox. The predicted
location and size of the solar convection zone disagree with those deduced
from solar oscillations. Solar oscillations is a technique astronomers
previously relied on to probe the sun's interior. Several scientists have
noted the problem could be fixed if the abundance of neon is in fact about
three times larger than currently accepted.
Attempts to measure the precise amount of neon in the sun have been
frustrated by a quirk of nature; neon atoms give off no signatures in
visible light. However, in a gas heated to millions of degrees, neon shines
brightly in X-rays. Stars like the sun are covered in this super-heated gas
that is betrayed by the white corona around them during solar eclipses.
However, observations of the sun's corona are very difficult to analyze.
To probe the neon content, Drake and his colleague Paola Testa of the
Massachusetts Institute of Technology in Cambridge, Mass., observed 21
sun-like stars within a distance of 400 light years from Earth. These local
stars and the sun should contain about the same amount of neon when compared
to oxygen.
However, these close stellar kin were found to contain on average almost
three times more neon than is believed for the sun. "Either the sun is a
freak in its stellar neighborhood, or it contains a lot more neon than we
think," Testa said.
These Chandra results reassured astronomers the detailed physical theory
behind the solar model is secure. Scientists use the model of the sun as a
basis for understanding the structure and evolution of other stars, as well
as many other areas of astrophysics.
"If the higher neon abundance measured by Drake and Testa is right, then it
is a simultaneous triumph for Chandra and for the theory of how stars
shine," said John Bahcall of the Institute for Advanced Study, Princeton,
N.J. Bahcall is an expert in the field who was not involved in the Chandra
study. Drake is lead author of the study published in this week's issue of
the journal Nature.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra
program for the agency's Science Mission Directorate. The Smithsonian
Astrophysical Observatory controls science and flight operations from the
Chandra X-ray Center in Cambridge, Mass.
For additional information and Chandra images on the Web, visit:
http://chandra.harvard.edu
http://chandra.nasa.gov
--
--------------
Jacques :-)
www.spacepatches.info
Headquarters, Washington July 27, 2005
(Phone: 202/358-1234)
Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)
RELEASE: 05-196
NASA'S CHANDRA NEON DISCOVERY SOLVES SOLAR PARADOX
NASA's Chandra X-ray Observatory survey of nearby sun-like stars
suggests there is nearly three times more neon in the sun and local universe
than previously believed. If true, this would solve a critical problem with
understanding how the sun works.
"We use the sun to test how well we understand stars and, to some extent,
the rest of the universe," said Jeremy Drake of the Harvard-Smithsonian
Center for Astrophysics in Cambridge, Mass. "But in order to understand the
sun, we need to know exactly what it is made of," he added.
It is not well known how much neon the sun contains. This is critical
information for creating theoretical models of the sun. Neon atoms, along
with carbon, oxygen and nitrogen, play an important role in how quickly
energy flows from nuclear reactions in the sun's core to its edge, where it
then radiates into space.
The rate of this energy flow determines the location and size of a crucial
stellar region called the convection zone. The zone extends from near the
sun's surface inward approximately 125,000 miles. The zone is where the gas
undergoes a rolling, convective motion much like the unstable air in a
thunderstorm.
"This turbulent gas has an extremely important job, because nearly all of
the energy emitted at the surface of the sun is transported there by
convection," Drake said.
The accepted amount of neon in the sun has led to a paradox. The predicted
location and size of the solar convection zone disagree with those deduced
from solar oscillations. Solar oscillations is a technique astronomers
previously relied on to probe the sun's interior. Several scientists have
noted the problem could be fixed if the abundance of neon is in fact about
three times larger than currently accepted.
Attempts to measure the precise amount of neon in the sun have been
frustrated by a quirk of nature; neon atoms give off no signatures in
visible light. However, in a gas heated to millions of degrees, neon shines
brightly in X-rays. Stars like the sun are covered in this super-heated gas
that is betrayed by the white corona around them during solar eclipses.
However, observations of the sun's corona are very difficult to analyze.
To probe the neon content, Drake and his colleague Paola Testa of the
Massachusetts Institute of Technology in Cambridge, Mass., observed 21
sun-like stars within a distance of 400 light years from Earth. These local
stars and the sun should contain about the same amount of neon when compared
to oxygen.
However, these close stellar kin were found to contain on average almost
three times more neon than is believed for the sun. "Either the sun is a
freak in its stellar neighborhood, or it contains a lot more neon than we
think," Testa said.
These Chandra results reassured astronomers the detailed physical theory
behind the solar model is secure. Scientists use the model of the sun as a
basis for understanding the structure and evolution of other stars, as well
as many other areas of astrophysics.
"If the higher neon abundance measured by Drake and Testa is right, then it
is a simultaneous triumph for Chandra and for the theory of how stars
shine," said John Bahcall of the Institute for Advanced Study, Princeton,
N.J. Bahcall is an expert in the field who was not involved in the Chandra
study. Drake is lead author of the study published in this week's issue of
the journal Nature.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra
program for the agency's Science Mission Directorate. The Smithsonian
Astrophysical Observatory controls science and flight operations from the
Chandra X-ray Center in Cambridge, Mass.
For additional information and Chandra images on the Web, visit:
http://chandra.harvard.edu
http://chandra.nasa.gov
--
--------------
Jacques :-)
www.spacepatches.info