Space & Cosmos

Planets can form even in the harshest conditions

An artist’s concept of planet formation occurring in a harsh stellar environment. Credit: AUI/NSF NRAO/S.Dagnello

According to the most widely held astronomical model (the nebular hypothesis), new stars are born from giant clouds of dust and gas (also known as nebulae) that undergo gravitational collapse. The remaining dust and gas forms a protoplanetary disk surrounding the new star and slowly accretes to form planetary systems.

For the past decade, astronomers have used Chile’s Atacama Large Millimeter/Submillimeter Array (ALMA) to study young stars and their disks to learn more about how this process occurs.

In a recent study, an international team of astronomers used ALMA to take high-resolution images of eight protoplanetary disks in the Sigma Orionis cluster, a group of stars in the constellation Orion. During their observations, the researchers found evidence of gaps and rings in most of the disks. These findings indicate the possibility that giant planets are forming.

This was surprising given how these disks are illuminated by intense ultraviolet (UV) radiation from the massive stars in the cluster. Their findings suggest that planet formation can occur in environments previously thought to be inhospitable.

The research was led by Jane Huang, an assistant professor in Columbia University’s astronomy department. She was joined by Shangjia Zhang, a NASA Sagan Fellow from Columbia University and the Nevada Center for Astrophysics, and Feng Long, also a NASA Sagan Fellow, from the Lunar and Planetary Laboratory (LPL). The team also included researchers from Munich’s Ludwig Maximilian University (LMU), the University of St. Andrews, the University of Hawaii at Manoa, and NASA Headquarters. Their research was recently published in The Astrophysical Journal.

Planets can form even in the harshest conditions

Images taken with ALMA’s most extended antenna configuration reveal a surprisingly rich array of disk structures within the Sigma Ori cluster. Credit: ALMA (ESO/JAO/National Astronomical Observatory of Japan/NRAO), J. Huang et al.

The research team used the most extended configuration of ALMA’s 12-meter antenna. This created a zoom lens effect and allowed us to achieve a resolution of about 8 astronomical units (eight times the distance between the Sun and the Earth). This allowed them to resolve multiple gaps and rings in the five disk images. This is comparable to what astronomers have observed in other star systems where giant planets are forming. The most impressive of these was the disk known as SO 1274, which featured five gaps that could be planetary systems in the making.

Previous studies have focused on disks in regions with low ultraviolet light, but this study provides ALMA’s highest-resolution observations of disks in more extreme environments. Although stars are typically born in much harsher ultraviolet environments, astronomers’ understanding of their substructure is based primarily on observations of nearby star-forming regions in milder ultraviolet environments. These discoveries could impact our understanding of how the solar system formed and evolved in a similar high-radiation environment. Huang said in the NRAO press release.

“We had expected that the high levels of radiation in this cluster would inhibit planet formation in the outer regions of these disks. But instead, planets would form at distances of tens of astronomical units from their stars. We are seeing signs that it may be forming. We observed it in less harsh environments.

“These observations suggest that the processes that drive planet formation are very robust and can function even under difficult conditions. “This gives us even more confidence that planets may be forming in even more places throughout the galaxy.”

However, the research team acknowledges that these structures could also result from interactions between the forming planet and the disk’s material. Their findings therefore demonstrate the need and potential for tracking studies of disks in even more extreme stellar environments. It also demonstrates ALMA’s ability to explore protoplanetary disks in diverse environments throughout the galaxy.

Further information: Jane Huang et al, High-resolution ALMA Observations of Richly Structured Protoplanetary Disks in σ Orionis, The Astrophysical Journal (2024). DOI: 10.3847/1538-4357/ad84df

Provided by Universe Today

Citation: Planets Can Form Even in the Harshest Conditions (January 13, 2025) Retrieved January 14, 2025 from https://phys.org/news/2025-01-planets-harshest-conditions.html

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