Astronomers studying this photo, taken by the Chandra X-ray Observatory, determined that sound waves emitted by explosive venting around the black hole are heating the surrounding area and inhibiting star growth some , light-years away. Black holes are points in space that are so dense they create deep gravity sinks. Beyond a certain region, not even light can escape the powerful tug of a black hole's gravity.
And anything that ventures too close—be it star, planet, or spacecraft—will be stretched and compressed like putty in a theoretical process aptly known as spaghettification. There are four types of black holes : stellar, intermediate, supermassive, and miniature.
The most commonly known way a black hole forms is by stellar death. As stars reach the ends of their lives, most will inflate, lose mass, and then cool to form white dwarfs. But the largest of these fiery bodies, those at least 10 to 20 times as massive as our own sun, are destined to become either super-dense neutron stars or so-called stellar-mass black holes.
In their final stages, enormous stars go out with a bang in massive explosions known as supernovae. Such a burst flings star matter out into space but leaves behind the stellar core. While the star was alive, nuclear fusion created a constant outward push that balanced the inward pull of gravity from the star's own mass.
In the stellar remnants of a supernova, however, there are no longer forces to oppose that gravity, so the star core begins to collapse in on itself. If its mass collapses into an infinitely small point, a black hole is born. Packing all of that bulk—many times the mass of our own sun—into such a tiny point gives black holes their powerful gravitational pull.
Thousands of these stellar-mass black holes may lurk within our own Milky Way galaxy. Supermassive black holes, predicted by Einstein's general theory of relativity, can have masses equal to billions of suns; these cosmic monsters likely hide at the centers of most galaxies. The tiniest members of the black hole family are, so far, theoretical. The light emitted from such accretion disks makes it possible for scientists to find these otherwise invisible objects.
Astronomers also spot black holes by noticing how they affect other objects, including stars. With these methods, scientists have found many black hole candidates over the years, including the smallest known black hole located in a binary system called GRO J The visible companion star in this system is dumping gas onto the black hole, generating enough energy to power a microquasar. Quasars develop in extremely luminous active galactic nuclei, which are the centers of galaxies hosting a supermassive black hole that is surrounded by a bright and energetic accretion disk.
The black hole in GRO J is estimated to weigh about 5. By studying microquasars such as this, astronomers hope to better understand the possible link between the monsters lurking in galactic cores and smaller, accreting black holes spread throughout galaxies. In , scientists believed they had found an even smaller black hole, but the mass was later corrected by the same team.
Any smaller black holes would likely be due to the merger of two neutron stars rather than the collapse of a dying star. The Laser Interferometer Gravitational-Wave Observatory detected gravitational waves from a possible neutron star merger in , just two years after detecting gravitational waves for the first time. Gravitational waves emitted during mergers provide a new way for scientists to identify black holes within million light-years of Earth. On the other end of the spectrum, the size of a stellar-mass black hole depends on how massive the original star was.
The most massive star found to date is Ra1 and weighs in at times the mass of the Sun. If it stayed at its current mass, the resulting black hole from its inevitable collapse would have a radius of some miles. Although large compared to the smallest known black holes, even this hefty stellar-mass black hole pales in comparison to its supermassive cousins.
RO J in blue is the second so-called 'microquasar' discovered in our galaxy. How big are intermediate-mass black holes? Only a few intermediate-mass black hole candidates have been found to date, including one found by the Hubble Space Telescope earlier this year.
The recent black hole Hubble found is over 50, times the mass of the Sun. And while significantly big, intermediate-mass black holes only range from about to , solar masses. Meanwhile, supermassive black holes can reach up to billions of times the mass of the Sun. Ask Astro : Can a black hole form without a parent star? How doomed matter reveals the inner secrets of black holes. The basic structure of a black hole consists of a singularity hidden by an event horizon.
Within the event horizon, the escape speed v esc exceeds the speed of light c and an object is trapped forever. The existence of such objects was first suggested as far back as the late s. However, it was Karl Schwarzschild , a German astronomer, who basically developed the modern idea for a black hole.
The limit of this region is called the event horizon, a name which signifies that it is impossible to observe any event taking place inside it since information is unable to get out. For a non-rotating black hole, the radius of the event horizon is known as the Schwarzschild radius , and marks the point at which the escape velocity from the black hole equals the speed of light. In theory, any mass can be compressed sufficiently to form a black hole. But this supermassive black hole, as large as it is, could still fit within our solar system with plenty of room to spare.
So we have to look at one of the most massive of all supermassive black holes. It has a diameter of about 78 billion miles. And it's estimated to be about 21 billion times the mass of our sun. So there you have it, black holes can be millions of times larger than suns and planets or as small as a city. It all depends on how much mass is inside. Turns out, when it comes to the cosmos, size isn't the only thing that matters.
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