Discussion at Sion on 20th June 2007

Last Wednesday at Sion, we discussed about two recent discoveries. One is about the newly found oldest star which is 13.2 billion years old. Todays accepted age of the universe is 13.7 billion years. And another discussion was on the heaviest star found which is about 114 solar masses.



The oldest star named as HE 1523 is dated by the method of Radioactive decay. The star contains very rare radioactive elements like Uranium and Thorium which have very high half life period for the decay. Scientists photographed high resolution spectrum of the star through which they found out the ratio of these two elements and calculated the age. The radioactive substances are thought to be introduced in it by the nearby nebula at its birth.

The second topic of discussion was on the 114 solar masses star. This star named as A1 is found in ngc 3603 and has a companion star of 84 solar masses. There is an upper limit on the mass of a stable star called as Eddington limit and is of 120 Solar masses. Though A1 is below the limit it is an exceptional star as no other star was found to exceed 90+ solar mass.

Aniket Sule and Sukhada Palav gave the information of these two discoveries. There were 15-20 people present.
Aniket Sule has given following 3 topics for the coming Wednesdays:
1 Comparison of Different Stellar Populations (for next wed.)
2 Initial Mass Function
3 Stellar Occultations By Small Kuiper Belt Objects