The Sun likely contains
nearly three times more neon than previously thought, according to a new study.
The finding, if shown to be
accurate, solves a theoretical problem regarding how stars in general work.
The question of the Sun's
neon abundance has been a sensitive topic among astronomers in recent years.
"Understanding the way
the Sun works is the bottom rung in a ladder to understanding how the rest of
the universe works," said Jeremy Drake of the Harvard-Smithsonian Center
for Astrophysics.
In the past, astrophysicists
based their solar model on data collected from studies that measured the way
pressure waves propagate throughout the Sun.
The model was put into
question, however, when their value for the neon abundance in the Sun differed
from those calculated using other techniques.
One of these techniques
involved capturing particles from the solar wind, a stream of charged particles
that continuously streams from the Sun, and tallying up the total number and
type of atoms present from each element.
Another involved X-rays;
neon does not appear in the visible spectrum of light but it shines brightly in
X-rays.
Based on these techniques,
astronomers came up with a value for the Sun's neon concentration that differed
from the value used in the astrophysicist's model by a factor of three.
"When astrophysicists
plugged in these new values, their model broke," Drake said.
Drake said the disagreement
about the concentration of neon may have been due to problems with both the
solar wind technique and the X-ray method.
In the case of the solar
wind, the Sun accelerates a particle differently depending on its mass and
charge -- things that vary from element to element.
With X-rays, the problem is
one of distance. Because Earth is so close to the Sun, relatively speaking,
scientists can't look at the solar furnace in its entirety, and must instead
settle for examining different parts separately.
When viewed from such a
close distance, different elements appear in different concentrations in
different parts of the Sun, Drake explained, and it is difficult to say which
area, if any, is an accurate representation of the Sun's chemical makeup.
Drake and his colleague
Paola Testa from the Massachusetts Institute of Technology got around these
problems by measuring the neon abundance of 21 nearby Sun-like stars using
NASA's Chandra X-ray Observatory.
By stepping back, they
measured the average X-ray emission from the stars.
What the researchers found
was that the nearby stars contained three times more neon than was calculated
for the Sun.
The implication was clear.
"Either the Sun is a freak in its stellar neighborhood, or it contains a
lot more neon than we think," said Paola Testa from Massachusetts
Institute of Technology and another study team member.
Drake said the same
technique could be used on our own Sun, if not for one problem: the detectors
on Chandra's instruments would fry because of the heat.
The study is detailed in the
July 28 issue of the journal Nature.
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