February 18, 2013

Supermassive Black Holes! (Need We Say More?)

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A galactic center is characterized by a supermassive black hole, where gravity is so strong not even light particles can escape. But if light cannot escape, how do we know what is there? Although we cannot see into a black hole, we can still observe the way matter behaves around it. By calculating orbits of galactic material, astronomers can pinpoint the locations and the sizes of black holes.

Ryan Lau grad researches the supermassive black hole in the center of our galaxy, approximately 26,000 light-years away from Earth, which is located on the outer edges of the galaxy. Lau studies the luminous ring that is located about 4.5 light-years away from the supermassive black hole in the galactic center. Lau can observe this ring using the giant telescope onboard NASA’s Stratospheric Observatory for Infrared Astronomy. One of the main advantages of SOFIA is that it can fly above the clouds that obscure most light in the mid-infrared range of the electromagnetic spectrum. Using a massive 2.5-meter telescope, the observatory has a high resolution within the mid-infrared range of the light spectrum. This allows astronomers to look at objects in space from thousands of light-years away.

Lau and other astronomers theorize that the gravity of the black hole pulls the ring, which is made up of galactic dust, toward it until the ring becomes very dense.

At that point, “there is a huge burst of star formation,” Lau said. The ring then blows outward and the cycle continues until the next time the ring is dense enough for star formation.

“If we had observed this ring a million years from now, we would see something entirely different,” Lau said. Although a million years may sound like a long time, our planet’s sun is about 4.5 billion years old, so one million years on a galactic time-frame is quite short.

Other than studying the ring around the supermassive black hole at the center of our galaxy, Lau also studies the quintuplet cluster, “a massive cluster of stars that formed four millions years ago” found in the inner 100 light years of the galactic center.

The types of massive stars found around this cluster are quite rare due to their short lifespan and are typically found at the galactic center. In fact, these stars are so rare, that only 12 are known in the galaxy. The phase in which Lau and his colleagues discovered these stars, known as the luminous blue variable phase, only occurs for approximately 3,000 to 10,000 years, and it is  rare to catch of glimpse of them in this form.

“Distinguishing characteristics of the luminous blue variable phase are that the stars are very unstable and luminous, over a million times the brightness of the sun,” Lau said.

Lau and his colleagues hope to learn enough about our galactic center to be able to transfer the information to other galaxies and discover more about the wonders of our universe.

Original Author: Amit Blumfield