Saturday, January 10, 2009

Black Holes Everywhere


UPDATE: From a previous trip to Long Beach, something else Big and Black. The Queen Mary 2 (seen from the deck of Queen Mary 1) has a mass of about 10^8 kg, that of a small Black Hole. Despite our close proximity, QM2 is not about to suck us up gravitationally. The allure of travel draws us to her anyway!

The American Astronomical Society (AAS) meeting in Long Beach this week was full of holes. Astronomer Elizabeth Humphreys and her team reported the stars can form near our galaxy's core and its supermassive Black Hole. Using the Very Large Array of radio telescopes, the team found stars in the act of forming just 7-10 light-years from the galactic centre. Astronomers once thought it impossible that stars could form amid the massive tidal forces here. They thought that stars must form elsewhere and migrate toward the core. Elizabeth's work shows that the stars form in place, through a process that old science can't explain.

Chris Carilli of the National Radio Astronomy Obesrvatory reported that supermassive Black Holes formed before the galaxies that contained them. Astronomers have long known that central Black Holes weigh a nearly constant percentage of a galaxy's mass, about 1 in 1000. Why this ratio exists in many galaxies has been a mystery. The new evidence suggests that giant Black Holes formed first and the galaxies, including our Milky Way, formed around them. NRAO Press Release

Evidence is mounting that supermassive Black Holes are primordial, formed soon after the Big Bang. Size of early Black Holes is limited by a "horizon distance." This is the distance within range of gravity, proportional to the speed of light. Once scientists thought that early Black Holes were tiny because c has been constant. Formation of supermassive Black Holes soon after the Big Bang is one more sign that the speed of light was once much faster.

Separately, beautiful physicist Katie Freese of University of Michigan has been promoting "dark matter stars." There are many holes in present theories of star formation. Katie believes that stars may have formed around cores of dark matter. If DM turns out to be Black Holes then stars could have them at their centres. If so, that would explain how stars can form so close to the galactic centre. Someday humans may realise that a Black Hole could exist in the second last place they expect, rising in front of our faces each morning. We think of that while watching the sun rise from the lanai.

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2 Comments:

Blogger Paul said...

Believe it or not, my purpose in life is not to disagree with you about the GRT/tonnage/weight/mass of the QM2. She weighs ~76000 tons, that is the weight of the water she displaces.

76000 tons = 76000*2000/2.2 = ~7*10^7 kg which is close enough to 10^8 kg for me, assuming weight and mass are equivalent in this context.

More fun for both of us to actually sail on her. I've had that pleasure a few times and I recommend it to you. The food and service are better than anything a black hole of any size has to offer.

4:29 PM  
Blogger L. Riofrio said...

Nice to hear from you, Paul. Because of your and Michael's input, I've put QM2's mass as "about 10^8 kg." This is a good opportunity to remember Archimedes' Law, that the mass of a ship equals the mass of water she displaces. I share your enjoyment of cruising (including the food) and hope you are enjoying the posts.

3:24 AM  

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