WASHINGTON: The one-way journey from the heart of a galaxy into the oblivion of a black hole probably takes about 200,000 years, astronomers said on Monday.

By tracking the death spiral of cosmic gas at the center of a galaxy called NGC1097, scientists figured that material moving at 177,000 kilometres an hour would still take eons to cross into a black hole.

Black holes are drains in space that have gravitational pull so strong that nothing, not even light, can escape. Huge ones are believed to lurk at the centers of many galaxies including the Milky Way, which contains the Sun.

"It would take 200,000 years for gas to travel the last leg of its one-way journey," Kambiz Fathi of Rochester Institute of Technology told reporters at a meeting of the American Astronomical Society.

No one has ever seen a black hole, but astronomers study the way matter and energy behave around them.

An international team led by Fathi studied the black hole at the middle of NGC1097, a behemoth with 100 million times the mass of the Sun.

The team managed to observe behavior 10 times closer to the black hole than ever before, Fathi said, seeing clouds of material within 10 light-years of the galactic core, where the black hole is believed to reside.

Milky Way is warped

The Milky Way is warped like a bowl, a saddle or the brim of a fedora hat, depending on when you look and a pair of interloping galaxies may be to blame, astronomers said.

The Earth is in a fairly non-warped neighbourhood, because it lies relatively close to the centre of the Milky Way's disk, said Leo Blitz of the University of California, Berkeley.

But the far-flung reaches of the galaxy could be caught up in a warp of as much as 20,000 light-years.

To figure out what causes the warp, Blitz and his colleagues analyzed hydrogen gas emissions in the warp area, and found that not only is the galactic disk bending, but it is vibrating like a drum-head, in three distinct ways.

One mode is like a bowl, with the galactic plane bending up all around; another is like a saddle, and the third is like the brim of a fedora hat, bent up in the back and down in the front, Blitz said at a briefing.

The various modes of warping correlate closely with the orbit of two satellite galaxies, known as the Large and Small Magellanic Clouds, that make a looping orbit around the Milky Way. As they go, they plough through a halo of dark matter that encircles the Milky Way, scientists said at the meeting of the American Astronomical Society.

Why is it warped?

Scientists have known about the Milky Way's warped nature for half a century, but they never knew the cause. The Magellanic Clouds were previously dismissed as suspects because they lacked the mass to influence our galaxy in their 1.5 billion year trip around it.

While the Magellanic Clouds' mass is small, they pass through the dark matter like ships going through an ocean, creating a cosmic wake powerful enough to make our galaxy bend and flap, Blitz said.

Source: China Daily