The New Heavyweight Champion of the Universe

EDIT: added in another image of star cluster R136

Ladies and gentlemen, let me introduce you, to Hypergiant “blue” R136a1, “The New” Solar Mass Heavyweight Champ! Weighing in at an estimated 265 solar masses, he may very well be the most massive star in our universe! He’s  so big, that scientists are baffled by how he came to be.

Size Comparison for R136a1

You heard it folks, there’s a newly discovered star, that’s so heavy that it disputes current models of how stars may be formed. R136a1 was discovered last year with the findings published in July 2010. It’s found in a star cluster known as R136 that’s 165,000 light-years away.

In 2005 NASA had released an article which suggested that in our current era of the universe, stars cannot exceed 150 solar masses (i.e. 150 times the mass of the sun) otherwise they would violate the Eddington Limit. This limit is where the radiation force outwards of a star is equal to the gradational force pulling inwards. Stars bigger than this would have too much out flowing radiation that they would eject all their gaseous matter into space.

This may be the case for R136a1: scientists speculate it was actually much heavier at its formation and may have lost as much as 50 solar masses through continuous emission of stellar winds in the last million years due to its instability. So, how did R136a1 come to be? Scientists speculate that its ridiculous size may be attributed to several young stars colliding together to form a single object.

Size Comparison for VY Canis Majoris

One thing to keep in mind is that while R136a1 is the heaviest known star, at only 35 solar radii (i.e. 35 times the radius of the sun), it is certainly not the largest. The title of “biggest star” belongs to VY Canis Majoris that is 1800-2,100 solar radii in size! At the same time, it is only 30 times the mass of our sun.

As for its fate, R136a1 is too big to form a black hole and may instead explode as hypernova (an explosion equivalent to over  100 supernovae). Of course, that’s only if it doesn’t blow all of its matter into space before then..

The original article can be found here (#83, “The Biggest Star of All”):  http://discover.coverleaf.com/discovermagazine/201101?pg=76#pg76

NASA’s 2005 article can be found here:  http://www.nasa.gov/home/hqnews/2005/mar/HQ_05071_HST_galaxy.html

For more general information on hypergiant stars, see:  http://en.wikipedia.org/wiki/Hypergiant

Hubble - R136 - Stellar Nursery

Less and Less Baby Polar Bears with Melting Arctic Ice

We all know of the strong correlation between changes in the environment and the polar bears,but a recent study suggests that the population of this species, Ursus maritimus, could be in real danger with the decline of Arctic sea ice specifically in our country’s Hudson Bay.

Source: Flickr

Article published on February 8th, 2011 in Nature Communications outlines a study conducted by Peter K. Molnar et al. from the University of Alberta who used mechanistic models to predict changes in litter size of cub polar bears for pregnant females in the western Hudson Bay population under expected changes in sea ice.

Sea ice is vital for the polar bears because during the winter feeding season they rely on the solid floes to take them near the waters where there are lots of food source – seals. But with temperatures rising and early breakup of the ice sheets, the bears are forced ashore sooner than in the past. Moreover, “on shore, there is no food available for them,” as the lead author of the study puts it. Thus the bears, particularly females of reproductive age, are storing up less energy for the months that they have to hibernate during pregnancy.

The researchers found that ~28% of pregnant females already failed to reproduce for energetic reasons during the 1990s. Using mechanistic models, they predicted that if spring sea ice break-up happens 1 month earlier than during the 1990s – 40-73% of pregnant female polar bears could fail to reproduce, and if the break-up happens 2 month earlier55-100% could fail. On a global perspective, the study states that a similar litter size decline trend may be found in over 1/3 of the polar bear population.

What’s even more discouraging is that “the litter size predictions provided in this study serve as another indicator that the western Hudson Bay population will probably not remain viable under predicted climatic conditions” as the article states.

Heart wenching video that hits home of malnourished  mother polar bear and starving cubs as an example of the conditions that polar bears are and will be facing in the future with current climate change conditions. A Warming Climate Takes its Toll on the Polar Bears of Hudson Bay by Daniel J. Cox

WARNING: NOT FOR THE SENSITIVE SOULS.