Sunday, June 28, 2009

Betelgeuse Shrinking

No, not the Michael Keeton character, but the star, the massive star (5.5 AUs wide) in Orion. Betelgeuse has shrunk 15% since 1993, and astronomers are puzzled as to why:

"To see this change is very striking," said Charles Townes, a UC Berkeley professor emeritus of physics. "We will be watching it carefully over the next few years to see if it will keep contracting or will go back up in size." (Townes won the 1964 Nobel Prize in physics for inventing the laser and the maser, a microwave laser.)

Though the star is shrinking, its visible brightness has not dimmed significantly over the past 15 years, the researchers say.

"But we do not know why the star is shrinking," said Edward Wishnow, a research physicist at UC Berkeley's Space Sciences Laboratory. "Considering all that we know about galaxies and the distant universe, there are still lots of things we don't know about stars, including what happens as red giants near the ends of their lives."

The really sad part of studying such items for an astronomer is the massive timescales involved. Stars live billions of years, so the amount of time we have in our lifetimes to study them is a microscopic portion of the total.


Al said...

In the linked article it refers to the popularity of Betelgeuse to amateur astronomers.

I think what is really true here is that the Orion nebula is one, if not the, most popular amateur astronomer objects.

parakeet said...

Since you're interested in red stars, you'll probably like this clip about blue stars:

“Our understanding of the evolution of massive stars before their final explosions as supernovae is incomplete, from both an observational and a theoretical standpoint.” --

"The progenitor of supernova SN 2005gl was proposed to be an extremely luminous object, but the association was not robustly established (it was not even clear that the putative progenitor was a single luminous star). Here we report that the previously proposed object was indeed the progenitor star of SN 2005gl. This very massive star was likely a luminous blue variable that standard stellar evolution predicts should not have exploded in that state."
“This might mean that we are fundamentally wrong about the evolution of massive stars, and that theories need revising.” “The unexpected explosion could mean other stars may behave in ways not previously expected,” “We may be missing something very basic in understanding how a superluminous star goes through mass loss.”