Two Rare Star Systems Appropriate for Tatooine Discovered

July 12 () –

Astronomers have identified the second and third examples of a rare type of star system comprising two central stars orbiting each other, surrounded by a remarkable disk of gas and dust.

“If there were a planet in one of these systems, It would be like the planet Tatooine from Star Warssays Michael Poon, a student in the Department of Astronomy and Astrophysics at the University of Toronto, and one of the scientists involved in the discovery.

“You would see two suns in the sky orbiting each other. Also, there is a disk around the stars. Imagine the rings of Saturn but much, much larger, with the stars in the middle.”

Such disks are known as protoplanetary disks because they eventually form families of planets like our solar system. The newly discovered systems are rare because their disks are at an angle to the orbits of their central stars.

“The discovery of objects like these is important to our understanding of planet formation,” says it’s a statement JJ Zanazzi, a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics (CITA) faculty. “The planets are born from them, so the existence of disks around binary stars shows that we are likely to find more planets orbiting binaries.

“They will also help us understand whether life can exist on a planet that orbits a binary star at an angle because of how that orientation affects temperature and other conditions.”

The discovery of new objects, named Bernhard-1 and Bernhard-2described in an article published in The Astrophysical Journal Letters.

Bernhard-1 and Bernhard-2 are so distant that we cannot see their two central stars individually (these pairs of stars are known as binary stars). Instead, we only see a single point of light and measure the total brightness of the binary.

The researchers identified the new objects by analyzing the complex and distinctive brightness variations caused by their unusual geometry. A graph of these variations over time is called a light curve, and the light curves of the new systems match those of the first such system ever discovered, an object called Kearns Herbst 15D (KH 15D).

The light curves of Bernhard-1 and Bernhard-2 dip to a fraction of their maximum brightness, the first for 112 days every 192 days; the latter for 20 days every 62 days. These dips are the signal that one of the stars in each binary is moving behind the disk as seen from Earth. When the star re-emerges, the brightness of the system returns to normal.

Furthermore, when the co-authors compared recent observations with archival data dating back decades, they found that both objects varied in brightness over much longer periods. Previous analysis of KH 15D by Zanazzi’s team, along with the work of other researchers, concluded that this long-term pattern revealed that the disk and stars were at an angle to each other.

Because binary stars and their protoplanetary disks condense from the same huge spinning cloud of material, the disk generally lies in the same plane as the stars’ orbits, as do the orbits of most planets. and moons of our solar system. the same plane. Imagine two figure skaters, holding hands, spinning around each other while other skaters surround the pair; they are all skating in the same plane on the ice surface.

But KH 15D, Bernhard-1, and Bernhard-2 are rare because their circumbinary disks are at an angle to the planes of the orbiting stars. Because of this tilt, the disks wobble like a top, a movement known as precession, as they move between us and the stars, causing the light from the central stars to dim. For KH 15D, that dimming cycle could take anywhere from 60 to 6,000 years.

The two types of brightness variations combine to create the light curve characteristic of KH 15D-like objects.

The discovery of Bernhard-1 and Bernhard-2 was made when Klaus Bernhard, an amateur astronomer and member of the Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne, analyzed data from the Zwicky Transient Facility. The ZTF instrument surveys the entire northern sky every two days, providing data from countless objects over long periods of time.

Combing through the data, Bernhard discovered candidates similar to KH 15D. He then shared his findings with Zanazzi’s team, whose further analysis revealed Bernhard-1 and Bernhard-2.

Now that researchers have found two more of these rare celestial objects, they are optimistic that more discoveries will follow.

“Just this month, Gaia published its most recent dataZanazzi says of the space mission that has been observing a billion stars in the Milky Way since its launch in 2013. “And now that we have this model for these objects, we can be hopeful that we can use it to find more objects to add to the list”.