Big stars are born near Milky Way's black hole

Reuters on Yahoo ^ | 10/13/05 | Deborah Zabarenko - Reuters

[NormsRevenge]

WASHINGTON (Reuters) - Dozens of massive stars, destined for a short but brilliant life, were born less than a light-year away from the Milky Way's central black hole, one of the most hostile environments in our galaxy, astronomers reported on Thursday.

On Earth, this might be a bit like setting up a maternity ward on the side of an active volcano. But researchers using the Chandra X-ray Observatory and other instruments believe there is a safe zone around black holes, a big dust ring where stars can form.

Black holes, including the one at the center of our galaxy, are monstrous matter-sucking drains in space, with gravitational pull so strong that nothing, not even light, can escape once it comes within the hole's grasp.

These young stars, however, are just far enough away to be held in orbit around the hole much as planets are kept in orbit around the sun, according to Sergei Nayakshin of the University of Leicester, United Kingdom.

At less than a light-year's distance, the 50 or 100 massive young stars are quite close to the black hole, but not close enough to be drawn in, Nayakshin said in a telephone interview.

A light-year is about 6 trillion miles, the distance light travels in a year. By comparison, Earth is about 26,000 light-years from the galactic center where the black hole lies.

LIVE FAST, DIE YOUNG

The dusty zone in which these big stars thrive makes them impossible to see with optical telescopes, but the orbiting Chandra detected them by the X-rays they emit. Some smaller stars were also detected.

The massive stars buried in the cosmic murk are each between 30 and 50 times the mass of the sun, Nayakshin said.

The more massive the star, the brighter it shines, so that a star with 50 solar masses would be five orders of magnitude brighter than the sun; it would shine with the brilliance of 100,000 suns, Nayakshin said.

Over the course of perhaps 5 million years or so -- a mere blink of an eye in astronomical time -- these high mass stars would likely lose 80 percent of their mass and explode as supernovae, transforming into smaller black holes around the supermassive black hole in the center of our galaxy.

Unlike the sun, which burns its fuel slowly, these massive stars live fast and die young.

"These stars live a short life because they're so luminous, they just use up all of their energy too quickly," Nayakshin said. He is co-author of a study to be published in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.

These findings also contradict theorists who believe massive stars form elsewhere in the galaxy and migrate toward the black hole, he said. And this research may shed some light on how such big, rare stars are created.

[NormsRevenge]

This light-year mosaic of several observatory images of the central region of our Milky Way galaxy reveals hundreds of white dwarf stars, neutron stars, and black holes bathed in an incandescent fog of multimillion-degree gas. A supermassive black hole at the center of the Galaxy is located inside the bright white patch in the center of the image. Dozens of massive stars, destined for a short but brilliant life, were born less than a light-year away from the Milky Way's central black hole, one of the most hostile environments in our galaxy, astronomers reported on Thursday. REUTERS/NASA

[NormsRevenge]

http://chandra.harvard.edu/photo/2005/sgra/

Chandra's image of the Galactic Center (left) has provided evidence for a new and unexpected way for stars to form. A combination of infrared and X-ray observations indicates that a surplus of massive stars has formed from a large disk of gas around Sagittarius A*, the Milky Way's central black hole (illustration on right).

[manwiththehands]

Live fast. Die young. "James Dean" stars?

[stevem]

This is likely utterly naive, but if I understand the "communication" of gravity, it is instantaneous whether objects are juxtaposed or separated by a universe. Wouldn't black holes that are a light year apart tend to fall into one another over some astronomically short period of time?

If I understand the "elegant universe" correctly, we live in some weird curved structure. Never-the-less, I have always wondered what exactly is on the other side of the boundary of the universe?

[linear]

I echo your question - wouldn't the smaller black holes be absorbed by the central hole?

[tamalejoe]

WASHINGTON (Reuters) - Dozens of massive stars, destined for a short but brilliant life, were born less than a light-year away from the Milky Way's central black hole, one of the most hostile environments in our galaxy, astronomers reported on Thursday.

I hate to disillusion people, but they have images of the galactic center now, and there isn't any sort of a "black hole" there. What IS there is a radio arc and it seems obvious enough to me that you'd not see the radio arc if there was any sort of a black hole there:

[possible]

I've said this before. Here's how the creation of these stars works:

Black holes don't just collect matter (as a result of their enormous gravity), they also radiate energy (see Hawking).

Think of this energy radiation as similar to lightning. Once a path opens up (in lightning through dialectric breakdown) a large amout of energy flows. In the case of black holes, this huge flow of energy to one location creates a new star.

You heard it here first. (Unless you read my earlier post on a different thread.)

Possible

[jwh_Denver]

tend to fall into one another over some astronomically short period of time?

Not if the orbiting speed was fast enough.

I have always wondered what exactly is on the other side of the boundary of the universe?

The Scriptures say there is water:

Gen 1:6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.

Gen 1:7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.

Gen 1:8 And God called the firmament Heaven. And the evening and the morning were the second day.

[Moral Hazard]

"This is likely utterly naive, but if I understand the "communication" of gravity, it is instantaneous whether objects are juxtaposed or separated by a universe."

Actually this is incorrect. The effect of gravity actually moves at the speed of light according to Einstein's general theory of relativity.

As the article described, the force of gravity causes these stars to orbit around the black hole at the center of the galaxy. The size of the orbit depends on the velocity of the orbiting star (the slower the velocity, the smaller the orbit).

[Yossarian]

if I understand the "communication" of gravity, it is instantaneous

Actually, no - gravity travels at the speed of light. Imagine our Solar system as a trampoline. The Sun is a large bowling ball in the middle, pulling down the trampoline, and there are 9 marbles that swirl around the trampoline's now cone-like shape.

If you suddenly snatch the bowling ball off of the trampoline, it would take time for the shape of the trampoline to become flat. The shape would look like a ripple, like when you throw a pebble into the pond.

That ripple takes some time - not much, but some - before it reaches the orbiting marbles - and the speed of the ripple can't be faster than the speed of light. (As to whether the ripple travels at the speed of light itself, I don't know - maybe there's some dampening action in the "mechanics" of the model.)

[Yossarian]

Ah, I didn't see your reply when composing mine.....

[RightWhale]

In the illustration at the right there is a monstrous black marble in the center of the galactic disk. Does that represent the actual relative size of the central black hole?

[TheyConvictedOglethorpe]

Big stars are born near Milky Way's black hole

I thought they formed in Memphis in the early Seventies.

</rock snob joke>

[VadeRetro]

You might as well say there wouldn't be a galaxy if it had a black hole in the middle. You can be near a galaxy's central black hole. You just have to be whipping around very fast indeed or you fall in.

[Moral Hazard]

"Black holes don't just collect matter (as a result of their enormous gravity), they also radiate energy (see Hawking)."

Wouldn't the temperature of a black hole the size of the one at the center of our galaxy be far less then that of the cosmic background?

I know the temperature drops as a black hole gets bigger, and for one the size of the sun it would be 60 nanokelvins, while the cosmic background temperature is 2.725 kelvin. Given that the black hole in the center of the galaxy is roughly 1 billion solar masses, the radiation would be on the order of 10^-47 degrees kelvin.

Not exactly the stuff new stars are made of.