Stars and Planets » Extremely Masive Stars


In the very early times many of the stars were very massive. They consisted almost entirely of hydrogen and helium and traces of lithium and deuterium (which were destroyed very early in the life of the star). They burnt very fast and collapsed in huge supernovae explosions. Some left black holes behind – other underwent an only recently discovered form of explosion called a pair instability super supernova. Although this was known of theoretically for some time it was only very recently that such an event was observed. A star over 200 times the mass of the Sun underwent a supernova explosion known as a pair instability supernava. The gamma radiation was so intense that a reversal of the normal reaction Electron + Positron = gamma radiation occurred. Radiation was creating matter/antimatter pairs. These went on to annihilate to produce more radiation and so on in a feedback reaction which blew the whole star apart. The star Y-155 exploded about 7 billion years ago, when the universe was half its current age. It was discovered in the constellation Cetus (just south of Pisces) with the National Optical Astronomy Observatory's (NOAO) 4-m Blanco telescope in Chile in November of 2007. The entire star exploded. No neutron star, no black hole, nothing was left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space apart.

On 21 July 2010 astronomers announced the discovery of an extremely large star in the Large Megallanic Cloud, a small satellite to our own Milky Way Galaxy. It has shattered the record as the most massive stellar monster ever seen. It has a mass of 265 times the mass of the Sun and may have actually slimmed down since birth, when it may have tipped the scales at 320 times the Sun's mass.

The discovery could rewrite the laws of stellar physics, since it's long been thought that stars beyond a certain mass would be too unstable to survive.

"We are really taken aback, This fast-burning stellar giant, however, may be large enough to actually completely blow itself apart in a titanic explosion without leaving behind any corpse whatsoever, because up until now the astronomical community at large has assumed that the upper size limit for stars would be around 150 times the mass of the Sun. This giant could really revolutionize the way we think about how stars form and die in clusters and galaxies." said Richard Parker an astronomer at Sheffield University in the UK. Parker's team found the stellar monster in images taken by the the European Southern Observatory's Very Large Telescope in Chile. The star is truly massive as the diagram on the right above shows. It will probably undergo a pair instability supernova in less than a million years time. (Image courtesy M. Kornmesser, ESO.)


Somewhere
by
Ray Goodwin


Somewhere there are mountains
Glistening in the snow
Somewhere there are mountains
That we shall never know

Somewhere there are rivers
Flowing fast and free
Somewhere there are rivers
That we can never see

Somewhere there are oceans
And sun drenched island sands
Forests full of creatures
In vastly distant lands

Somewhere there’s a planet
Beneath an alien star
The people watch our tiny sun
And wonder where we are

One day perhaps we’ll find them
Across the void of space
Perhaps through ways as yet unknown
We’ll meet them face to face


The author of this web site Ray Goodwin holds B.Sc. Degrees from London University in Chemistry, Geology and Physiology and an M.Sc. in Biochemistry. He has spent most of his professional life teaching in Colleges of Technology. On his retirement he has entered the fields of astronomy, astrochemistry, astrobiology and space sciences. He has spent a great deal of his retirement in visiting amateur astronomy societies and in attending European Space Agency Symposia in ESTEC in the Netherlands and other scientific conferences in England and Sweden. He regularly attends the yearly European Astrofest in South Kensington London and other meetings in the UK. He has written scientific articles and given a number of lectures on diverse scientific subjects.

Readers of this web site are invited to e-mail the author ( ray@lifeinthecosmos.com) and discuss their opinions of the topics dealt with and suggest any changes which they think may be helpful.

Life in the Cosmos Website
Version 01.00 - April 20, 2015.