Black holes are confounding objects that stretch physics to its limits. The most massive ones lurk in the centers of large galaxies like ours. They dominate the galactic center, and when a star gets too close, the black hole’s powerful gravitational force tears the star apart as they feed on it. Not even the most massive stars can resist.
But supermassive black holes (SMBHs) didn’t start out that massive. They attained their gargantuan mass by accreting material over vast spans of time and by merging with other black holes.
There are large voids in our understanding of how SMBHs grow and evolve, and one way astrophysicists fill those voids is by watching black holes as they consume stars.
Black holes are gluttonous behemoths that lurk in the center of galaxies. Almost everybody knows that nothing can escape them, not even light. So when anything made of simple matter gets too close, whether a planet, a star or a gas cloud, it’s doomed.
But the black hole doesn’t eat it at once. It plays with its food like a fussy kid. Sometimes, it spews out light.
When the black hole is not only at the center of a galaxy but the center of a cluster of galaxies, these burps and jets carve massive cavities out of the hot gas at the center of the cluster called radio bubbles.
In 1961 astronomers discovered a powerful x-ray source coming from the constellation Cygnus. Not knowing what it was, they named the source Cygnus X-1. It’s one of the strongest x-ray sources in the sky, and we now know it is powered by a stellar-mass black hole. Since it is only about 7,000 light-years away, it also gives astronomers an excellent view of how stellar-mass black holes behave. Even after six decades of study, it continues to teach us a few things, as a recent study in Science shows.
From a distance, supernovae explosions are fascinating. A star more massive than our Sun runs out of hydrogen and becomes unstable. Eventually, it explodes and releases so much energy it can outshine its host galaxy for months.
But space is vast and largely empty, and supernovae are relatively rare. And most planets don’t support life, so most supernovae probably explode without affecting living things.
But a new study shows how one type of supernova has a more extended reach than thought. And it could have consequences for planets like ours.
Why is there so much antimatter in the Universe? Ordinary matter is far more plentiful than antimatter, but scientists keep detecting more and more antimatter in the form of positrons. More positrons reach Earth than standard models predict. Where do they come from?
Scientists think pulsars are one source, and a new study strengthens that idea.
When two neutron stars collide, it creates a kilonova. The event causes both gravitational waves and emissions of electromagnetic energy. In 2017 the LIGO-Virgo gravitational-wave observatories detected a merger of two neutron stars about 130 million light-years away in the galaxy NGC 4993. The merger is called GW170817, and it remains the only cosmic event observed in both gravitational waves and electromagnetic radiation.
Astronomers have watched the expanding debris cloud from the kilonova for years. A clearer picture of what happens in the aftermath is emerging.
The planets in our Solar System all rotate on axes that roughly match the Sun’s rotational axis. This agreement between the axes of rotation is the typical arrangement in any system in space where smaller objects orbit a larger one.
But in one distant binary system, the large central object has an axis of rotation tilted about 40 degrees compared to its smaller satellite. This situation is even more strange because the main body isn’t a star but a black hole.
Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find.
Astronomers have spotted an intermediate-mass black hole destroying a star that got too close. They’ve learned a lot from their observations and hope to find even more of these black holes. Observing more of them may lead to understanding how SMBHs got so massive.
Astronomers have found a supermassive black hole (SMBH) with an unusually regular feeding schedule. The behemoth is an active galactic nucleus (AGN) at the heart of the Seyfert 2 galaxy GSN 069. The AGN is about 250 million light years from Earth, and contains about 400,000 times the mass of the Sun.
In the coming years, thousands of satellites, several next-generation space telescopes and even a few space habitats are expected to be launched into orbit. Beyond Earth, multiple missions are planned to be sent to the lunar surface, to Mars, and beyond. As humanity’s presence in space increases, the volume of data that is regularly being back sent to Earth is reaching the limits of what radio communications can handle.
For this reason, NASA and other space agencies are looking for new methods for sending information back and forth across space. Already, optical communications (which rely on lasers to encode and transmit information) are being developed, but other more radical concepts are also being investigating. These include X-ray communications, which NASA is gearing up to test in space using their XCOM technology demonstrator.