Friday, June 8, 2007

A fascinating discovery to report !!!

The most massive star known in the universe has been discovered and "weighed," astronomers have announced !!!

The star, part of a binary system, topped the scales at 114 times the mass of the sun !!!

Though astronomers suspected that stars with masses up to 150 times the mass of the sun must exist, this discovery marks the first time a star has broken the 100-solar-mass barrier. The previous record holder was only a measly 83 solar masses.

The newly weighed star, known simply as A1, is the brightest hot star at the heart of a giant, but dense, young star cluster called NGC 3603, which lies 20,000 light-years from Earth. The star's companion has a mass 84 times that of the sun.


Now
to add in my own comments here:

Stars of high mass die young. In case of massive stars su
ch as this, its life would only be, and my best guess is, around 200-300 million years only.

That's because the fuel needed to overcome the tremendous gravitation keeping it from collapsing on itself is considerably higher than medium weight stars such as our Sun. These massive stars die very young (200-300 Million years is like comparing around 300 minutes out of a total earth day of 1440 minutes - if my calculation are right !) - That's quite puny by comparison..isn't it ?

To also put that into perspective: Medium weight stars such as our SUN have a life-span of around 10 billion years.

To put that even further into perspective - The oldest star found till date is
13.2 billion years old !!. This is 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.

And when massive stars such as these die, they die in a spectacular...mind-boggling explosion !!!!!! These explosion are called Supernovas.

This star wouldn't explode though ! There is a more sinister future in store for it ! The explanation is give later.


Supernovas (the definition from wikipedia)- A supernova (plural: supernovae or supernovas) is a stellar explosion that creates an extremely luminous object that is initially made of plasma—an ionized form of matter. A supernova may briefly out-shine its entire host galaxy before fading from view over several weeks or months. During this brief period of time, the supernova radiates as much energy as the Sun would emit over about 10 billion years.

(Can you even begin to even grasp the energy output that we are talking about here !!!!)


The explosion expels much or all of a star's material
at a velocity of up to a tenth the speed of light, driving a shock wave into the surrounding interstellar gas. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.

The photo on the side is a M
ultiwavelength X-ray image of the remnant of Kepler's Supernova, SN 1604. (Chandra X-ray Observatory)

I sure do hope that my future generations would be lucky enough to witness this explosion in the near future. In Astronomical time scales, it should be happening tomorrow :)

By the way - What will remain out of a stellar explosion would depend on the mass of the star we talk of (the mass of stars is not measures in Kilos or tonnes but in our own Sun weight multiples. The star reported, if you had noticed, has a mass of 114 times the mass of our Sun. Difficult to imagine right ???)

My guess is that star this massive would collapse directly into a blackhole rather than go through the tedious and complex process of a Supernova explosion.

Why do I say this ? Well, I don't have the balls to make a prediction but here's what scientists say
:

When the progenitor star is below about 20 solar masses (depending on the strength of the explosion and the amount of material that falls back), the degenerate remnant of a core collapse is a neutron star.

Above this mass the remnant collapses to form a black hole. (This type of collapse is one of many candidate explanations for gamma ray bursts—producing a large burst of gamma rayshypernova explosion.) The theoretical limiting mass for this type of core collapse scenario is about 40–50 solar masses.
through a still theoretical

Above 50 solar masses (such as this star), most stars are believed to collapse directly into a black hole without forming a supernova explosion, although uncertainties in models of supernova collapse make calculation of these limits uncertain.

In the range of about 140–250 solar masses , it is hypothesized that low-metallicity stars may explode in pair-instability supernovae without leaving behind a black hole remnant. This rare type of supernova is formed by an alternate mechanism that does not require an iron core.

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