Theoretically a neutron star could have less mass than a white dwarf. If these light neutron stars exist, we might detect them through the gravitational waves they emit during a cataclysmic merger with another star.
Continue reading
A current mystery in astronomy is how supermassive black holes gained so much heft so early in the Universe. Black holes have been seen in the first billion years after the Big Bang with hundreds of millions of solar masses, defying current models of their growth. Now, astronomers have a clue. They observed a bright jet coming from a type of supermassive black hole called a blazar, which interacts with surrounding gas, helping to drive it into the maw of the black hole.
Continue reading
Many of the black holes astronomers observe are the result of mergers from less massive black holes. Using gravitational waves, we can observe two black holes coming together and their combined remnant. But can astronomers observe a black hole and work out the masses of the objects that came together? Can we build a black hole's family tree? In a new paper, researchers propose that the nearby environment puts limits on the kinds of black holes that can merge.
Continue reading
Astronomers have already discovered many stars orbiting the supermassive black hole at the heart of the Milky Way, Sgr A*. Now, researchers have announced they've found a binary star system in the vicinity too. This is surprising since Sgr A* tears at nearby stars with its ferocious tidal forces, and you'd expect binary stars to be separated from one another after too many close flybys. Well, there they are, still a pair after millions of years.
Continue reading
Don Pettit is one of the astronauts currently on board the International Space Station. He's also a serious shutterbug and amateur astronomer. To take advantage of his current lofty perspective, he rigged up a special star tracking mount that he could use to take long-exposure astrophotos from the ISS. The homemade orbital sidereal tracker rotates at a 90-minute period to match the pitch rate of the ISS, allowing him to take 30-second exposures.
Continue reading
Astronomers have used JWST to weigh a galaxy in the early Universe, finding that it has roughly the same mass as the Milky Way should have had at the same time in the Universe's history. The galaxy was seen in a gravitational lens and contains a collection of star clusters, so astronomers have nicknamed it the "Firefly Sparkle Galaxy." The galaxy also contains companion dwarf galaxies, similar to the Milky Way's Magellanic Clouds, which probably merged with it.
Continue reading
When a massive star dies as a supernova, it can leave behind a pulsar, a rapidly spinning neutron star. The fastest pulsars can spin upwards of 700 times a second, blasting out regular pulses of energy. In a new paper, researchers propose that the fastest-spinning pulsars could contain quark matter in their cores. This would be even denser matter than neutrons and help explain how surprisingly massive neutron stars can spin so rapidly, maybe reaching 1,000 Hz.
Continue reading
When the Earth was struck by a Mars-sized planet in its early history, it ejected a debris cloud that led to the formation of the Moon. In the beginning, the Moon was extremely close to the Earth, but then conservation of angular momentum led to the Moon drifting away from the Earth - it's still doing it today. Because the Earth was covered in oceans of magma, researchers think the Moon moved quickly away from the Earth, getting to 25 Earth radii within 100,000 years.
Continue reading