Some stars are stuck in bad binary relationships. A massive primary star feeds on its smaller companion, sucking gas from the companion and adding it to its own mass while diminishing its unfortunate partner. These vampire stars are called Be stars, and up until now, astronomers thought they existed in binary relationships.
But new research shows that these stars are only able to feed on their diminutive neighbour because of a third star present in the system.
In September 2022, an automated sky survey detected what seemed to be a supernova explosion about one billion light-years away. The Zwicky Transient Facility (ZTF) spotted it and gave it the name AT2022tsd. But something was different about this supernova. Supernovae explode and shine brightly for months, while AT2022tsd exploded brightly and then faded within days.
What happens just before a massive star explodes as a supernova? To figure that out, astronomers need to look at very “young” supernovae across multiple wavelengths of light. That’s what happened when SN 2023ixf occurred in May 2023. It turns out its aging progenitor star blew off a solar mass worth of material just before it died. Now, the big question is: why?
Planetary nebulae were first discovered in the 1700s. Legend tells us that through the small telescopes of the time, they looked rather planet-like, hence the name. Real history is a bit more fuzzy, and early objects categorized as planetary nebulae included things such as galaxies. But the term stuck when applied to circular emission nebulae centered around a dying star. As new observations show, planetary nebulae have a structure that is both simple and complex.
Imagine a living star with a magnetic field at least 100,000 times stronger than Earth’s field. That’s the strange stellar object HD 45166. Its field is an incredible 43,000 Gauss. That makes it a new type of object: a massive magnetic helium star. In a million years, it’s going to get even stranger when it collapses and becomes a type of neutron star called a “magnetar”.
Nuclear fusion is at the center of stellar evolution. Most of a star’s life is a battle between gravity and nuclear power. While we understand this process on a broad scale, many of the details still elude us. We can’t dive into a star to see its nuclear furnace, so we rely on complex computer simulations. A recent study has made a big step forward by modeling the entire fusion cycle of a single element.
What do you get when a hot young world orbits a wildly unstable young red dwarf? For AU Microsopii b, the answer is: flares from the star tearing away the atmosphere. That catastrophic loss happens in fits and starts, “hiccuping” out its atmosphere at one point and then losing practically none the next.
Twinkle, twinkle little star, I wonder just how old you are.
It isn’t an easy question to answer. Stars are notoriously difficult to age. We know the age of the Sun because we happen to live on one of its orbiting rocks, and we know very well how old the rock is. Without that information, things become a bit more fuzzy. But that could change thanks to a new study.
The cosmic zoo has strange beasts that astronomers stumble across in the most fascinating ways. Not long ago a team in Australia found a highly unusual magnetar, one of the weirder denizens of the starry zoo. It’s called GPM J1839-10 and it lies some 15,000 light-years away in the direction of the constellation Scutum.