Cosmic butterfly or interstellar citizen? This planet-forming disk is the largest ever seen

The largest planetary construction site ever seen, spanning hundreds of billions of kilometers, may well be cast in a huge shadow that accentuates its bizarre appearance. In short, it looks like a cosmic butterfly – and for years it was ignored.

The object, known as IRAS 23077+6707, was originally cataloged by the Infrared Astronomy Satellite (IRAS) in the 1980s as a source of infrared emission. Then in 2016, while conducting an investigation into active galaxies in the region of the constellation Cepheus, astronomer Ciprian Berghea of ​​the US Naval Observatory coincidentally rediscovered it with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS).

Berghea wasn’t sure what it was, but it appeared to have two parallel lobes with a dark orbit between them – typical of a planet-forming disk at the edge. The bright parts in such an object represent light scattered by dust in the upper regions of the disk, while the dark band is the equivalent of our light. solar system‘s ecliptic plane, where most material is concentrated. It is this dense piece of material that blocks and absorbs the light from a system’s central star. The upper and lower faces of the disk spread gradually rather than showing a sharp edge, while two filaments follow the flared portions, which are also flared. All of this makes the arrangement look eerily similar to a butterfly, but in a way, those bright areas separated by a dark lane also give the impression of a hamburger. So, according to his Romanian heritage, growing up near Transylvania, Berghea nicknamed IRAS 23077+6707 Dracula’s Chivito, “a chivito is a hamburger-like sandwich from his native country.

Related: The cosmic ‘sandwich’ theory could explain how smaller planets form

Thanks to observations with the Submillimeter Array (SMA) in Hawaii, astronomers including Berghea have now confirmed that this particular chivito is indeed a planet-forming disk as seen from the edge, but that it is not an ordinary disk. It is the most immense planet-forming disk ever seen.

“What we found was incredible: evidence that this was the largest planet-forming disk ever discovered. It is extremely rich in dust and gas, which we know are the building blocks of planets,” said Kristina Monsch, an astronomer at Harvard University. Smithsonian Center for Astrophysics, in a rack. Monch is the lead author of one of two new papers describing the drive.

To give an idea of ​​the size of this particular world construction site, astronomers assume it is somewhere between 800 and 1,000 meters. light years away based on the fact that it is located in the sky near the star-forming region of Cepheus. If this is correct, the angular size of the disk in our sky corresponds to a radius of thousands astronomical units (AU). To provide more context, one AU is defined as the average distance between Soil and the Sunor 149.6 million kilometers (93 million miles), while the outermost known planet, Neptuneis 30 AU from our sun.

‘Based on the SMA data, we can also weigh the dust and gas in this planetary nursery, which we found contains enough material to form many giant planets – and to distances more than 300 times further away than between the sun and the earth. Jupiter!” said Monsch.

In addition, the disk spins. The SMA measured radio waves emitted by carbon monoxide gas in the disk, and some of these radio waves were redshifted, indicating that they are emitted by gas clouds moving away from us; Meanwhile, the submillimeter radio waves of carbon monoxide in other parts of the disk were blue-shifted, meaning they are moving toward us. This behavior is the hallmark of a rotating system.

“The SMA data gives us compelling evidence that… it orbits a star that is probably two to four times as massive as our own Sun,” Monsch says. It is possible that this star is still growing as disk material. falls in and grows on it.

Besides the gigantic size of the disk, another special aspect is that the western lobe of the disk is noticeably fainter than the other lobe, by a factor of six. Monsch, Berghea and their colleagues aren’t sure why that is, but some possibilities are being considered. One strong candidate is that it is just an illusion that the two halves are uneven in brightness, a geometric effect caused by the disk not being perfectly on its side, so we can see slightly more of the eastern half than of the western half . .

But there is also another explanation, namely that half of the disk is in the shadows.

This assumes that the disk, instead of being pregnant with planetary potential, has already given birth and a giant planet is now plowing through the disk. It could be that this planet is sweeping up resources as it grows, carving out an annular orbit or gap in the disk.

Such a gap would essentially split the disc in half, resulting in instabilities that would warp the inner disc, such as a vinyl record that is bent too much. This misalignment would block some of the light from the central young star, causing the inner disk to cast a shadow on the outer disk. Therefore, the asymmetry in the brightness of the disk studied could be indirect evidence for the presence of a giant planet. It is fitting that IRAS 23077+6707 bears some resemblance to the shape of a butterfly; Just as a caterpillar enters a chrysalis and emerges as a butterfly, the chrysalis of a protoplanetary disk can release gas and dust – the remains of ancient generations of stars – to reform and flourish in the cosmic butterflies of new planets.

Related stories:

—The mystery of how strange cosmic objects called “JuMBOs” went rogue

-Surprise! Baby exoplanets may look more like Smarties candies than spheres

— James Webb Space Telescope catches a glimpse of Earendel, the most distant star known in the universe

And beyond all this, the existence of IRAS 23077+6707 raises a tantalizing question. Computer simulations predict that we should see more planet-forming disks on the edge than we actually do. So are there more super-sized disks that we haven’t recognized yet?

The observations of IRAS 23077+6707 are reported in two papers, one published May 14 in The astrophysical diary lettersAnd another that has been accepted for publication in a future issue of the same journal.

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