- The Blackhole in the center of our Galaxy may be flaring up soon. Astronomers have found a giant gas cloud that is heading right towards it and it is picking up speed.
- Our Blackhole is been quiet as far as galaxy Blackholes go. We are located in one of the four spiral arms in the Milky Way 26,000 lightyears from the center. You can see where the Blackhole sits at the center from your backyard. Look to the southern night sky at the Constellation Sagittarius the Archer. The shape of the constellation is better described as the “ teapot”. The had bow and arrows but they did not have teapots at the time the Constellations were first named. This Blackhole is named “Sagittarius A star”. It is located right at the top of the teapot where the steam comes out.
- The Blackhole is massive, 4,000,000 Solar Mass. It is compresses into a volume less than 26,000,000 miles across. This would be a sphere about have the radius of the orbit of the planet Mercury.
- Blackholes discovered to date appear to come in two sizes , big and enormously big.
Solar Blackholes are created from an single massive star and are about 10 Solar Mass. The Blackholes at the center of galaxies weigh millions and billions of Solar Mass.
- 10 Solar Mass Blackholes have enormous gravity and relatively small event horizons. As a consequence in falling material experiences tremendous tidal forces once it crosses the Event Horizon. These forces tear the material to pieces as it falls to the center.
- On the other hand billion Solar Mass Blackholes have a much larger spherical Event Horizon. Crossing it Event Horizon would be a big mistake but you would hardly notice any difference. You could not call home because radio waves could never leave the Blackhole. Neither could you. Science is not sure what happens next?
- If you are outside the Blackhole looking at what is happening the picture is much different. Outside means you are in a different “ reference frame” in the Gravity’s distortion of space-time. To the outsider the material falling into the Blackhole appears to “ freeze” as time slows and eventually stops as it hit’s the Event Horizon. At the Event Horizon the material appears to hang motionless forever.
- The Chandra X-ray telescope has detected weak X-ray flares being emitted at the Blackhole’s Event Horizon. These flares are most likely coming form high-speed atoms spiraling inward until they cross the Horizon.
- Huge lobes of ultra-hot gas is streaming away on opposite sides of the Blackhole. these lobes extend out dozens of lightyears and are likely the result of massive explosions ad emissions that have occurred over the past 10,000 years. There also X-ray filaments that result from rapidly spinning Neutron Stars creating magnetic fields with streams of high-energy electrons.
- Astronomers have been tracking 28 stars that are orbiting close to the Blackhole. Some have passed within 10 lighthours of the center. One has been tracked for nearly a complete orbit, circling the center in 15.6 years. It passes within 17 lighthours of the center ( This is about 3 times the orbit of Pluto.) Measuring these orbits is how astronomers have estimated the mass of the Blackhole to be 4,000,000 Solar Mass.
- As mentioned earlier, our Blackhole is relatively quiet compared with other galaxies. The X-rays from the Blackhole is only one of some 2,000 X-ray sources that have been detected in the region. It appears that very little of the solar winds form the orbiting stars is being pulled into the Blackhole. Less than 0.01% of the solar winds are fueling Sagittarius A* at this time.
- To explain this astronomers theorize the particles in the hot inner region close to the Horizon collide and transfer energy through convection to particles in the cooler outer region. This is in turn creates an outward pressure pushing as away from the Blackhole.
- But, things are about to change. Astronomers have spotted a cool cloud of hydrogen and helium that is 3 times the mass of the Earth heading directly for Sagittarius A*. The gas is moving 5,257,000 miles per hour. Its speed has doubled in the last 7 years. By 2013 it will begin being sucked in to the Event Horizon and fireworks will flare up.
- The massive cloud will be within 250 AU, 250 times the Earth-Sun distance. Unlike stars that could whisk by at enormous speeds, clouds of gas get shredded by the tidal forces and break apart. They will then spiral inward towards the Blackhole. Rapid heating of the in falling gas will create blasts of X-ray hundreds or thousands of times their normal intensity. The period of quiescence is about to change. Astronomers are anxiously awaiting the fireworks. An announcement will be made shortly, stay tuned.
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Other reviews available:
(1) 1350 - Blackholes can get bit and bright, Cygnus X-1
(2) 1244 - Blackholes explained
(3) 1105 - How small can Blackholes get, plus a more complete index of Blackhole reviews.
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707-536-3272, Sunday, December 18, 2011
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