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Wednesday, September 30, 2009

Hubble sees galaxies blowing in the wind

"Newly released images from the Hubble Space Telescope show two galaxies that are moving so fast that gas within the galaxies is being stripped away.
The two galaxies, NGC 4522 and NGC 4402, are located in the Virgo galaxy cluster, about 60 million light years from Earth.
Astronomers estimate that NGC 4522 is moving within the cluster at more than 10 million km/h, or nearly 2,800 kilometres every second.
Because the space within the cluster isn't empty, but filled with a very thin mixture of gases called the intracluster medium, the galaxy's movement is creating drag, in the same way that a rider on a speeding motorcycle will feel wind, even on a calm day.
The drag, or ram pressure, is stripping gases out of the galaxy, leaving a ghostly shadow behind. The Hubble images show new stars forming in bright blue clusters in the cloud of gas being left behind the galaxy."

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Source of image of image of Galaxy NGC 452: (top image)

Source of image of Galaxy 4402 (bottom image):
"GC 4522 is a spectacular example of a spiral galaxy that is currently being stripped of its gas content. Part of the Virgo galaxy cluster, its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. Scientists estimate that the galaxy is moving at more than 10 million kilometres per hour. A number of newly-formed star clusters that developed in the stripped gas can be seen in the Hubble image. The stripped spiral galaxy is located some 60 million light-years away from Earth."

"The second image shows NGC 4402 and highlights some telltale signs of ram pressure stripping such as the curved, or convex, appearance of the disc of gas and dust, a result of the forces exerted by the heated gas. Light being emitted by the disc backlights the swirling dust that is being swept out by the gas. Studying ram pressure stripping helps astronomers better understand the mechanisms that drive the evolution of galaxies, and how the rate of star formation is suppressed in very dense regions of the Universe like clusters."

source of text:

In  physicsram pressure is a pressure exerted on a body which is moving through a fluid medium. It causes a strong  drag force to be exerted on the body.
For example, a meteor traveling through the Earth's atmosphere produces a shock wave generated by the extremely rapid  compression of air in front of the meteoroid. It is primarily this ram pressure (rather than friction) which heats the air which in turn heats the meteoroid as it flows around it.
(source: Plait, Philip (2002), Top 5 Cosmic Myths #4:Meteors are heated by friction as they pass through the atmosphere.

In the case of a galaxy moving through the intergalactic gas, the ram pressure is capable of stripping the galaxy of much of its interstellar gas.

The ram pressure increases when the velocity increases. For example, when you are in a windy place, you feel a force on your body from the wind. The stronger (faster) the wind, the greater the force you feel.
(source: Grebel, Gallagher, Harbeck (2003) The Progenitors of Dwarf Spheroidal Galaxies

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Thoughts worth thinking about

"Our subconscious minds have no sense of humor, play no jokes and cannot tell the difference between reality and an imagined thought or image. What we continually think about eventually will manifest in our lives."-Sidney Madwed

Laws alone can not secure freedom of expression; in order that every woman and man present their views without penalty, there must be spirit of tolerance in the entire population.- Albert Einstein Too often we underestimate the power of a touch, a smile, a kind word, a listening ear, an honest compliment, or the smallest act of caring, all of which have the potential to turn a life around. - Leo Buscaglia

A person's true wealth is the good he or she does in the world. - Mohammed

Our task must be to free ourselves... by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty. -Albert Einstein

The best way to find yourself, is to lose yourself in the service of others. - Ghandi

The unselfish effort to bring cheer to others will be the beginning of a happier life for ourselves. - Helen Keller

Aim for success, not perfection. Never give up your right to be wrong, because then you will lose the ability to learn new things and move forward with your life. Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make yourself a happier and more productive person. - Dr. David M. Burns

Life is as dear to a mute creature as it is to man. Just as one wants happiness and fears pain, just as one wants to live and not die, so do other creatures. -His Holiness The Dalai Lama

Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude towards those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it. -

Milan Kundera, The Unbearable Lightness of Being

The worst sin towards our fellow creatures is not to hate them, but to be indifferent to them. That's the essence of inhumanity. -George Bernard Shaw

Ego's trick is to make us lose sight of our interdependence. That kind of ego-thought gives us a perfect justification to look out only for ourselves. But that is far from the truth. In reality we all depend on each other and we have to help each other. The husband has to help his wife, the wife has to help the husband, the mother has to help her children, and the children are supposed to help the parents too, whether they want to or not.-Gehlek Rinpoche Source: "The Best Buddhist Writing 2005 pg. 165

The hostile attitude of conquering nature ignores the basic interdependence of all things and events---that the world beyond the skin is actually an extension of our own bodies---and will end in destroying the very environment from which we emerge and upon which our whole life depends.