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J0045+41 in M31 Animations

Correction: A follow-up paper by Barth & Stern (2018) has shown that the evidence for periodic light variations presented in Dorn-Wallenstein et al. (2017) and publicized in this press release is not, in fact, significant. Although a supermassive black hole behind M31 has been discovered, the claim that a pair of supermassive black holes was detected can no longer be made.

Editor's Note: Honest errors such as this are part of the scientific process, especially on the frontiers of discovery. To quote Nobel laureate Frank Wilczek, "If you don't make mistakes, you're not working on hard enough problems. And that's a big mistake."


A. J. Barth & D. Stern, 2018, ApJ, 858, 10

T. Dorn-Wallenstein, E. M. Levesque & J. J. Ruan, 2017, ApJ, 850, 86

A Tour of J0045+41 in M31
(Credit: NASA/CXC/A. Hobart)
[Runtime: 02:39]

The term "photobomb" means for someone or something to unexpectedly appear in an image. While this is generally used for pictures of celebrities or selfies with friends, it turns out that the universe can have photobombs as well.

A new result using data from NASA's Chandra X-ray Observatory and ground-based optical telescopes reveals a photobomb in the nearby Andromeda galaxy. While looking for other types of objects, a team of researchers from the University of Washington noticed one particularly unusual source in this sister spiral galaxy to the Milky Way. While previous scientists had classified this object, known as J0045+41, as a pair of orbiting stars within Andromeda, the researchers decided to take a closer look.

They discovered that J0045+41 was not in Andromeda at all. Instead, J0045+41 was about a thousand times farther away at a distance of some 2.6 billion light years from Earth. They also used the X-ray and optical data to uncover that this was not a pair of stars, but may instead be a duo of supermassive black holes. The researchers estimated that these black holes together contain about 200 million times the mass of the Sun, yet were separated by less than one hundredth of one light year. By comparison, the nearest star to the Sun is over four light years away.

They might take cameras bigger than your smartphone's and instruments that are in space, but the photobombs from the cosmos can be just as entertaining — and even informative.

A Quick Look at J0045+41 in M31
(Credit: NASA/CXC/A. Hobart)
[Runtime: 01:08]

Astronomers have discovered a cosmic photobomb in the Andromeda galaxy.

Scientists previously thought this source was in Andromeda, but now they know it is not.

This object is actually 1,000 times farther away than Andromeda at a distance of about 2.6 billion light years.

Not only is it much more distant, it may contain two giant black holes in very close orbit around one another.

Scientists used data from NASA's Chandra X-ray Observatory and optical telescopes on the ground to identify this unexpected member in Andromeda's images.

This distant black hole pair could have formed when two galaxies, each containing a supermassive black hole, merged billions of years ago.

Return to J0045+41 in M31 (November 30, 2017)