Astronomers uncover the stunning purpose for a star’s disappearance

The regular beam of a star twice the scale of the solar performed a trick on astronomers a couple of yr in the past: It vanished. 

Then some 9 months later, it reappeared within the constellation Monoceros, about 3,200 light-years away in house.

Now researchers assume they’ve solved the thriller of one of many longest star-dimming occasions ever recorded. The star, known as ASASSN-24fw, might have disappeared behind a large planet with an unlimited system of rings, in accordance with new analysis, blocking most of its gentle from reaching Earth for 9 months. 

The study, which seems in Monthly Notices of the Royal Astronomical Society, serves as a reminder that worlds round different stars can have ring programs far bigger and extra complicated than something in our personal photo voltaic system.

“Long-lasting dimming events like this are exceptionally uncommon as they require very perfect line-ups,” stated Sarang Shah, lead writer on the Inter-University Centre for Astronomy and Astrophysics in India, in a statement. “The dimming began gradually because the outer parts of the rings are thin, and only became obvious when the denser regions passed in front of the star.”

Near the tip of 2024, astronomers seen the star immediately grew faint. Rather than brighten in days or even weeks like most dimming occasions, ASASSN-24fw pale for practically 200 days. The star’s cheeky identify comes from the All Sky Automated Survey for Supernovae, a robotic telescope based mostly in Hawaii nicknamed “Assassin.” 

After making an attempt varied laptop fashions to clarify the occasion, the crew concluded the wrongdoer was both a brown dwarf or a super-Jupiter planet, each massive objects which can be smaller than stars however larger than most worlds. Experts generally seek advice from brown dwarfs as failed stars as a result of they are not fairly large sufficient to generate their very own nuclear energy. 

Researchers imagine a brown dwarf or super-Jupiter blocking ASASSN-24fw shaped a virtually opaque saucer protecting the star, via which solely a tiny quantity of its gentle may escape.
Credit: S. Shah et al. / DOI: 10.1093/mnras/staf2251 illustration

The crew’s prime rationalization entails a brown dwarf surrounded by humongous rings, comparable in form to Saturn’s however vastly bigger, eclipsing the star. In this case, the rings are estimated to stretch about 15.8 million miles from the brown dwarf, about half the gap between the solar and Mercury.

As the ring system moved in entrance of the star, it blocked about 97 p.c of ASASSN-24fw’s gentle. By learning modifications within the star’s brightness and light-weight patterns — strategies astronomers use to deduce mass and movement — the crew estimates the hidden object weighs greater than 3 times as a lot as Jupiter.

The information additionally counsel the star itself has leftover materials shut by, probably particles from previous or ongoing planetary collisions. That is uncommon for a star believed to be greater than a billion years previous.

Researchers assume the brown dwarf or large planet that eclipsed the star had a hoop system just like Saturn’s, seen right here, although vastly bigger.
Credit: NASA / JPL-Caltech / Space Science Institute

“Large ring systems are expected around massive objects, but they are very difficult to observe directly to determine their characteristics,” stated Jonathan Marshall, a coauthor affiliated with Academia Sinica in Taiwan, in an announcement. 

The researchers now wish to measure the star’s temperature, make-up, age, and life stage. They plan to collect extra information utilizing highly effective observatories, together with the Very Large Telescope in Chile and the James Webb Space Telescope, NASA‘s main infrared observatory.

They count on the star to dim once more in roughly 42 years, when the ringed object returns, providing one other likelihood to check this uncommon system, stated Marshall, whose experience is in circumstellar materials and particles disks.

“This rare event allows us to study such a complex system in remarkable detail,” he stated. “In fact, while studying this dimming, we also serendipitously discovered that ASASSN-24fw also has a red dwarf star in its vicinity.”