Wednesday, December 10, 2008

Bright Cluster, Dark Centre

From the European Southern Observatory in La Silla, Chile. Omega Centauri is 17,000 light years away in the constellation Centaurus. This is the most massive of the globular clusters surrounding our Milky Way. The cluster is 150 light-years across and contains about 10 million stars. In our southern sky it appears nearly as big as the full Moon.

Recent observations with the Hubble Space Telescope and Gemini Observatory indicate that the Omega Centauri contains a Black Hole with the mass of 40,000 suns. The cluster is thought to be 12 billion years old. Astronomers have long wondered how globular clusters could have formed before the galaxy's oldest stars had formed. The Black Hole provides an answer. The cluster could have been seeded by a Black Hole like a pearl forming around a grain of sand.

Below is Globular Cluster M13 as imaged by the Hubble Space Telescope. Early formation of massive Black Holes is one more indication that the speed of light was once much higher.

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Blogger qraal said...

Hi Louise

Your changing c theory - how will c change in the future? How will that affect the Sun? I'm guessing the luminosity will decrease, but so will the available energy from fusion. I'm wondering what the net result on the Sun's lifetime will be, and just how slow c will get. Does your theory have any answers to that question? Is there an end point to c's evolution?

12:43 PM  
Blogger L. Riofrio said...

Hello qraal: According to old theories, the Sun is slowly getting brighter so someday Earth's oceans will boil. We would then be fortunate to live in a time between freezing and boiling, just as Earth is centre of the Universe.

With c change added, solar luminosity is approximately constant. Earth's temperature has therefore been comfortable for billions of years, allowing life to evolve. It is better to live in a Universe of changing c.

The speed of light decreases asymptotically, so it will never slow to zero. Therefore the time we live in is not special, just part of a continuing process of expansion and slowing.

7:27 AM  
Blogger qraal said...

Hi Louise

If c is decreasing the energy from fusion also decreases doesn't it? Modelling that process in the evolving Sun will be difficult - the Sun is supported by how much fusion occurs per unit volume within the solar core. As the helium fraction goes up, the energy release decreases and the core contracts due to the cooling - but this also ups the overall fusion rate as more of the surrounding material is heated up by the contracting core. A lower c might mean a more rapid evolution towards the Red Giant stage, as less "bang" is yielded by the same mass of hydrogen over time!

Yikes! Or have I missed something?

2:51 PM  

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