About 1,000 light-years away, a vast disk of gas and dust is offering astronomers a peek at how planets are born. What you think it looks like might depend on where you stand. Some might look at the curved expanses of the body and see a cosmic butterfly. Then again, others may see the layers as more closely resembling a sandwich. U.S. Naval Observatory astronomer Ciprian Berghea first spotted the disk in 2016. Inspired by the name of a similar disk, “Gomez’s Hamburger,” Berghea decided to continue with the sandwich theme. Based on a suggestion from his Uruguayan colleague Ana Mosquera, he named it “Dracula’s Chivito” after the South American country’s national dish, a meat-packed sandwich, as well as after the iconic character based on a historical figure from his own homeland, Romania’s Transylvania region.

Whether you call it a butterfly or a sandwich, though, researchers have now confirmed the nature of this intriguing spot in space. Technically known as IRAS 23077+6707, the body is a planet-forming disk.

Protoplanetary disks, as experts call them, are rotating masses of dense gas and dust moving around a young star. Berghea and colleagues proposed that IRAS 23077 is such a mass in a paper released earlier this year. Now, a team of researchers from the Smithsonian Astrophysical Observatory and colleagues have confirmed that what Berghea informally dubbed “Dracula’s Chivito” may be the largest protoplanetary disk yet found.

The new research, recently published in the Astrophysical Journal Letters, began when Berghea reached out to astrophysicist Kristina Monsch of the observatory, also a postdoctoral fellow at the Harvard & Smithsonian Center for Astrophysics. “He was looking for advice on how to interpret this very odd object he had found,” Monsch says, which started her on a search for already-published data that might help determine the body’s identity. Researchers had previously identified the protoplanetary disk known as “Gomez’s Hamburger,” which had been studied with radio telescopes in Hawaii called the Submillimeter Array, or SMA. If the SMA had revealed the nature of the cosmic sandwich, perhaps it could reveal critical details of Berghea’s find.

Monsch didn’t have to wait very long to get a chance to look into the disk. At a conference in Japan, Monsch recalls, she chatted about her research with colleague Joshua Lovell, SMA fellow at the center. “I told him about IRAS 23077 and asked him if he could help me get some SMA observations myself,” Monsch says. Lovell began the process to observe IRAS 23077 the same day, with approval for observations coming within two weeks and the first data shortly after.

Cosmic Butterfly, a Planet-Forming Disk
The center of this composite image shows IRAS 23077, likely the largest planet-forming disk ever seen, which looks like a giant cosmic butterfly. Radio: SAO/ASIAA/SMA/K. Monsch et al; Optical: Pan-STARRS

Even at such a vast distance from us, the SMA was able to detect important details of what IRAS 23077 is actually made of. “The SMA allows us to observe the small dust grains, about millimeter-sized pebbles, and carbon monoxide gas,” Monsch says, both of which are telltale components of protoplanetary disks. The data revealed that IRAS 23077 contains vast amounts of both, suggesting an immense reservoir of gas and dust within the disk. The volume of gas and dust could allow the protoplanetary disk to create numerous giant planets over a wide span of space. Monsch notes that the huge size of IRAS 23077 is what allowed her and her colleagues to get such good data on the object’s makeup, as other protoplanetary disks appear much smaller in the sky.

“The large size of the IRAS 23077 disk makes it special,” says Carnegie Institution for Science astrochemist Dana Anderson, who was not involved in the new study. “Many disks are so small that even our best radio telescope arrays have difficulty spatially resolving them,” she says. Not only is IRAS 23077 so large that its makeup can be detected, Anderson notes, but its edge-on orientation toward the Earth allows researchers a rare view of what’s going on inside. “We get a nearly unobstructed view of the side of the disk,” Anderson says, allowing experts to see planet-forming expanses of the disk that would otherwise be obscured.

It’s possible that planets have already begun forming within IRAS 23077. Curious asymmetries occur in the shadows and brightness along the “wings”—or “buns”—of the body. “We think that one of these shadows could hint at an embedded planet that has already formed,” Monsch says. A planet within the disk would carve a path through it, causing parts of the disk to warp and tilt, casting shadows. It’s also possible that two suns exist within the disk, creating a similar effect, with Monsch noting that additional data from the SMA, James Webb Space Telescope or other scientific instruments will be needed to be sure.

Such planet-forming disks are popular subjects for study at telescope facilities, Anderson says, and she expects IRAS 23077 will become another. The object may well become a new favorite for observation, she expects, and notes that “the fact that it was discovered recently also presents the exciting possibility that there are other fascinating targets we have yet to find.”

SMA in Hawaii
The Submillimeter Array's eight dishes act together as a single telescope. It has been part of the Event Horizon Telescope that took images of the black holes at the center of our galaxy and of galaxy M87. Alanna Garay

Monsch and colleagues are already beginning to find those additional points of interest. The effort to identify IRAS 23077 allowed Monsch and colleagues to search for other protoplanetary disks among the expanses of space. “Using the properties we measured for IRAS 23077, we already went on the hunt for similar objects, and indeed it seems we have already found some more,” Monsch says. Studies on these new disks are expected to be published soon.

Each of the newly identified disks will inform our understanding of how planetary systems form. Even though something as fundamental as the formation of planets might appear to be well understood, relatively little is known about how such processes actually play out. There seems to be a disconnect between theoretical models of how planetary systems should coalesce and the different forms of planetary systems experts can see in space. Studying protoplanetary disks will help experts better understand the different ways that planets form. “By characterizing the composition and structure of these outlier disks where we know that they must have the potential to form multiple gas giants because of their size, we have to gain insights into various pathways of planet formation,” Monsch says.

Identifying IRAS 23077 is only the beginning. Now that experts know what the disk is, and some of its makeup, they can begin to tease apart the elusive story of how planets come together and make so much of our universe what it is. Astronomical beginnings are playing out at various points we can see from our own spot in space, part of the cosmic backstory we can’t travel back to but may be able to reconstruct from what’s transpiring light-years away.

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