star age of 13.2 billion years
we know that age of universe is 13.7 billion years
now , scientists found star of 13.2 billion years
How old are the oldest stars? Using ESO's VLT, astronomers recently measured the age of a star located in our Galaxy. The star, a real fossil, is found to be 13.2 billion years old, not very far from the 13.7 billion years age of the Universe. The star, HE 1523-0901, was clearly born at the dawn of time
This technique is analogous to the carbon-14 dating method that has been so successful in archaeology over time spans of up to a few tens of thousands of years. In astronomy, however, this technique must obviously be applied to vastly longer timescales
the abundance of a radioactive (unstable) isotope decreases all the time. The faster the decay, the less there will be left of the radioactive isotope after a certain time, so the greater will be the abundance difference when compared to a stable isotope, and the more accurate is the resulting age.
Yet, for the clock to remain useful, the radioactive element must not decay too fast - there must still be enough left of it to allow an accurate measurement, even after several billion years.
Large amounts of these elements have been found in the star HE 1523-0901, an old, relatively bright star that was discovered within the Hamburg/ESO survey
The star was then observed with UVES on the Very Large Telescope (VLT) for a total of 7.5 hours
they measure more than a single cosmic clock for a star
use 6 elements
they use vlt to measure radioactive elements
"Actual age measurements are restricted to the very rare objects that display huge amounts of the radioactive elements thorium or uranium "said by anna frebel
Ever since the star was born, these "clocks" have ticked away over the eons, unaffected by the turbulent history of the Milky Way. They now read 13.2 billion years.
The Universe being 13.7 billion years old, this star clearly formed very early in the life of our own Galaxy, which must also formed very soon after the Big Bang.
this resarch was done by
Anna Frebel
McDonald Observatory, Texas
Norbert Christlieb
Department of Astronomy and Space Physics, Uppsala University, Sweden
source
European Organisation
for Astronomical
Research in the
Southern Hemisphere
طبعا اكيد لسه هتظبط المواضيع دي ، يعني حرف ناقص
تربط الجمل ف بعض
كده
بس الموضوع استرفيزكس
موضوع: مجله المنتدي بسرعه الحق حط موضوع وشارك وتميز 
2007-10-22, 10:55 pm
