Found: The Fastest-Approaching Object in the Universe
A giant black hole may have hurled a star cluster toward us at record speed
GARGANTUAN GALAXY: M87's central black hole may be shooting out more than just the blue jet seen here.
Hubble Space Telescope.
NASA and the Hubble Heritage Team (STScI/AURA)
Most of the universe is rushing away from us.
It's not that we're particularly repellent; it's just that the universe is expanding, pushing most other galaxies away.
Now astronomers have accidentally discovered the greatest blueshift ever seen, in a star cluster that a giant black hole may have catapulted our way.
Over small distances gravity has reversed the universe's expansion, so modest blueshifts are common.
Not even the Local Group —the collection of approximately 75 galaxies that includes the Milky Way—expands.
In fact, the Local Group's largest member, the Andromeda Galaxy, is moving toward us : it has a blueshift of 300 kilometers per second.
Yet astronomers have spotted an object far beyond the Local Group's borders with a blueshift of 1,026 kilometers per second, far surpassing the previous record of 780 kps set by a star in the Andromeda Galaxy.
"It's always fun to be at the extreme," says Nelson Caldwell, an astronomer at the Harvard–Smithsonian Center for Astrophysics who made not just this discovery but the earlier one as well.
Caldwell and his colleagues were measuring Doppler shifts of star clusters around M87, a giant elliptical galaxy located at the heart of the Virgo Cluster, 54 million light-years from Earth.
Unlike the Local Group, which holds only two giant galaxies—Andromeda and our own Milky Way—the Virgo cluster has dozens of large galaxies.
According to an idea proposed two decades earlier , when a binary star system skirts close enough to a black hole, one star falls in, losing a large amount of energy; in order to conserve energy, the other star shoots away at high speed.
If M87's black hole actually consists of two black holes orbiting each other, they could fling away a star cluster that strayed too near.
When its central black hole was still two separate supermassive black holes, it could have hurled the star cluster away.
http://www.scientificamerican.com/article/found-the-fastest-approaching-object-in-the-universe/?WT.mc_id=SA_Facebook
A giant black hole may have hurled a star cluster toward us at record speed
GARGANTUAN GALAXY: M87's central black hole may be shooting out more than just the blue jet seen here.
Hubble Space Telescope.
NASA and the Hubble Heritage Team (STScI/AURA)
Most of the universe is rushing away from us.
It's not that we're particularly repellent; it's just that the universe is expanding, pushing most other galaxies away.
Now astronomers have accidentally discovered the greatest blueshift ever seen, in a star cluster that a giant black hole may have catapulted our way.
Over small distances gravity has reversed the universe's expansion, so modest blueshifts are common.
Not even the Local Group —the collection of approximately 75 galaxies that includes the Milky Way—expands.
In fact, the Local Group's largest member, the Andromeda Galaxy, is moving toward us : it has a blueshift of 300 kilometers per second.
Yet astronomers have spotted an object far beyond the Local Group's borders with a blueshift of 1,026 kilometers per second, far surpassing the previous record of 780 kps set by a star in the Andromeda Galaxy.
"It's always fun to be at the extreme," says Nelson Caldwell, an astronomer at the Harvard–Smithsonian Center for Astrophysics who made not just this discovery but the earlier one as well.
Caldwell and his colleagues were measuring Doppler shifts of star clusters around M87, a giant elliptical galaxy located at the heart of the Virgo Cluster, 54 million light-years from Earth.
Unlike the Local Group, which holds only two giant galaxies—Andromeda and our own Milky Way—the Virgo cluster has dozens of large galaxies.
According to an idea proposed two decades earlier , when a binary star system skirts close enough to a black hole, one star falls in, losing a large amount of energy; in order to conserve energy, the other star shoots away at high speed.
If M87's black hole actually consists of two black holes orbiting each other, they could fling away a star cluster that strayed too near.
When its central black hole was still two separate supermassive black holes, it could have hurled the star cluster away.
http://www.scientificamerican.com/article/found-the-fastest-approaching-object-in-the-universe/?WT.mc_id=SA_Facebook
