Astrophysics speaker lectures on black holes

Chronicle Staff

Andrea Ghez, a professor of astrophysics at UCLA, gave a presentation to students about her research that shows a massive black hole exists in the center of the Milky Way.

Ghez, a leading female scientist in astrophysics, came to  the Upper School at the request of physics teacher Dr. Antonio Nassar on Nov 26.

To prove the existence of a black hole in the middle of our galaxy, she needed to find a great amount of mass in an extremely small volume. She theorized this from observing other galaxies that emitted huge amounts of energy from their centers.

She wondered why we would not have a black hole in the center of the Milky Way, when all of the other galaxies she had studied did have them.

Since the earth is relatively close to the center of the galaxy, Ghez realized she was in a prime spot to study the center of the Milky Way in order to determine whether or not a black hole exists. 

However, dust in space and the atmosphere only allowed one billionth of the light to reach her telescope.

Ghez then devised a new, more detailed method of observing stars. She called it “taking the twinkle out of the stars.” 

After she used her new observation technique, she was able to study stars hidden by the glare emited from nearby  stars, Ghez said.

By studying the orbit and speed of the stars at the center of the Milky Way, she was able to approximate the mass of the center of orbit and then realized that the closer the stars were to the center of the galaxy, the faster they moved. 

If there were no black holes pulling on the stars, they would all travel at the same speed, she explained.  She also saw that stars were extremely close together.

Ghez thereby proved the existence of a super massive black hole in the Milky Way.