Black Hole | Eating Asteroids and Gas Clouds

Our Milky Way galaxy has been know for several years to have a black hole at the center. It has a mass of several million times our Sun. The giant black hole may be vaporizing and devouring asteroids according to astronomers using data from NASA’s Chandra X-ray Observatory. For several years, x-ray flares have been observed about once a day from the region. The flare ups have also been observed in the infrared by the European Space Agency Very Large Telescope in Chile. The flares last a few hours and have a brightness of a few, to nearly a hundred, times the normal brightness of the region near the black hole.

Chandra X-ray Observatory

Kastytis Zubovas of the University of Leicester in the United Kingdom is lead author of the report appearing in the Monthly Notices of the Royal Astronomical Society. The report suggests that stars which passed near the black hole would have planets, comets, and asteroids stripped from them. If the stripped debris passed within 100 million miles of the black hole, tidal forces would tear them apart. That distance is closer than the Earth-Sun distance. The cloud of debris contains trillions of pieces.

As the asteroid chunks orbit the black hole, they collide and interact with each other, getting knocked on a course taking them toward a path of no return at the black hole. On their journey, they encounter a disk shaped cloud of gas and dust surrounding the black hole. In passing through at enormous velocities, they are heated and vaporized much the same way that meteors do in entering the atmosphere of Earth. But the scale is enormous compared to meteors that are often tiny bits or rock or dust. The chunks of asteroids larger than 6 miles in radius would need to be involved in order to produce the flares seen by Chandra illustrated by the following video. The chunks accelerate toward the black hole and get heated by the friction of the passing gas and dust. Then, it vaporizes emitting a flare of x-rays seen by the telescope.

Gas Cloud Near The Black Hole

Astronomers at the European Southern Observatory reported a huge gas cloud was headed toward an encounter with the black hole in the Milky Way.

European Southern Observatory

The telescopes at the ESO have been involved in a 20 yr study of the movements of the stars in the near vicinity of the black hole.

Over the last seven years, the speed of this object has nearly doubled, reaching more than 8 million km/h. It is on a very elongated orbit and in mid-2013 it will pass at a distance of only about 40 billion kilometres from the event horizon of the black hole, a distance of about 36 light-hours. This is an extremely close encounter with a supermassive black hole in astronomical terms.This object is much cooler than the surrounding stars (only about 280˚ Celsius), and is composed mostly of hydrogen and helium. It is a dusty, ionized gas cloud with a mass roughly three times that of the Earth. The cloud is glowing under the strong ultraviolet radiation from the hot stars around it in the crowded heart of the Milky Way.

The current density of the cloud is much higher than the hot gas surrounding the black hole. But as the cloud gets ever closer to the hungry beast, increasing external pressure will compress the cloud. At the same time the huge gravitational pull from the black hole will continue to accelerate the inward motion and stretch the cloud out along its orbit.

The cloud is now interacting with the black hole and is expected to be very disrupted over the next few years. It is likely to get much hotter during the encounter and give off x-rays. This video is ©European Space Agency.

Star Movements Near the Black Hole

The 20 yr study of star movements near the black hole has yielded some interesting results. Sharply curved orbit segments have been traced. One star, S2,  has even been followed for a complete orbit of just over 15 yr.

European Southern Observatory

The following two videos illustrate these findings. First, the results of the 20 yr study.

Second, how the orbits would look if projected 200 years into the future.

Kepler’s 3^rd Law of Planetary Motion allow astronomers to calculate the mass of a central body if the period and average radius of orbit can be determined for an orbiting body. Watching and measuring these orbiting stars allows for the calculation of the mass of the black hole in the Milky Way at 4.1 million solar masses.