The Universe’s Most Extreme Black Holes
Black holes, the great gravitational beasts left behind when stars collapse in a supernova, are some of the weirdest and most exotic objects in the universe. But even among these bizarre beasts, some black holes are weirder than others. The youngest black hole ever observed -- just 31 years old -- was announced today, but it's just the latest in a long line of black hole superlatives.
Youngest
The 31-year-old remains of supernova SN 1979c make up the youngest known black hole.
This supernova in the galaxy M100 approximately 50 million light-years from Earth, was discovered by an amateur astronomer in 1979. The star that exploded that year was just on the edge of the theoretical mass limit for forming black holes, about 20 times the mass of the sun. After the supernova, the leftover matter could either have collapsed into a black hole or an extremely dense neutron star.
New observations from the Chandra X-ray Observatory seem to clinch it in favor of the black hole, astronomers announced today. As material falls in to a black hole, it heats up to millions of degrees and spews X-rays. If the object that was SN 1979c was a neutron star, the brightness of the X-rays it emits would tail off with time. But if it was a black hole, the X-rays would stay nearly as bright as the black hole gobbled new material.
Observations show that SN1979c blasted out X-rays at a constant brightness level between 1995 and 2007, definitely tilting the odds in favor of a black hole -- although the object could still be a rapidly spinning neutron star with a powerful wind of high energy particles.
Image: X-ray: NASA/CXC/SAO/D.Patnaude et al, Optical: ESO/VLT, Infrared: NASA/JPL/Caltech
Nearest
The nearest black hole to Earth lies about 24,000 light-years away. A member of a binary system called V4641 Sagitarii, the black hole is slowly devouring its ordinary stellar companion.
This black hole gave away its location when it let loose a violent outburst of X-rays in 1999. Initially, astronomers thought the pair of celestial objects was just 1,600 light-years away, but follow-up observations in 2001 showed it to be 15 times farther away.
Image: NASA/ESA/Felix Mirabel
Farthest
The most distant black hole known is in the galaxy NGC 300, 6 million light-years away. Discovered in January 2010, the black hole is the first found to lurk outside the "Local Group" of galaxies to which the Milky Way belongs.
Like the nearest black hole, the farthest is also feasting on a normal companion star. The black hole is also among the heaviest stellar-mass black holes ever weighed. Black holes that reside at the centers of galaxies can grow to be billions of times more massive than the sun, but the black holes that mark the end of a star's life cycle are rarely more than 20 times the sun's mass. There are only three such black holes known that weigh more than 15 solar masses.
Image: ESO/L. Calçada/M.Kornmesser
Biggest
The most massive black hole in the universe weighs in at 18 billion times the mass of the sun -- six times as massive as the previous record holder and as massive as a small galaxy.
The monster lurks in quasar OJ287 3.5 billion light-years away. Astronomers weighed the behemoth in 2008 by observing the orbit of a smaller black hole -- which itself weighs as much as 100 million suns -- caught in the larger black hole's gravitational field.
Image: NASA/JPL-Caltech
Smallest
The lightest and smallest black hole ever found is just 3.8 times the mass of our sun and only 15 miles across -- just barely longer than the island of Manhattan.
Despite its diminutive size, this black hole -- called XTE J1650-500 -- is still an engine of destruction. Like many other black holes, this little monster showed itself by stealing gas from a companion star and heating it until it glowed in X-rays. The intensity of those X-rays can vary periodically, depending on the black hole's mass. Watching for those small variations allowed astronomers to take the black hole's measurements.
Image: NASA/CXC
Fastest
Black holes don't just sit in space guzzling gas. If the star that formed the black hole was spinning rapidly, the black hole can end up spinning, too. A spinning black hole can hold the disk of matter that surrounds it closer than a black hole that sits still.
The fastest-spinning black hole, called GRS 1915+105, whips around 1,000 times per second. This is almost the theoretical limit for how fast a black hole can spin, which is calculated by how fast stars can spin before they collapse.
Image: NASA/CXC/M Weiss
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