How planets form depends on the size of their star, astronomers find

Images of massive stars and their swirling disks of dust and gas where planets can form (Gemini International Observatory/NOIRLab/NSF/AURA/E. Rich (University of Michigan))

Images of massive stars and their swirling disks of dust and gas where planets can form (Gemini International Observatory/NOIRLab/NSF/AURA/E. Rich (University of Michigan))

How planets form, or if they form at all, can depend on the mass of their star.

That’s the main finding of new research presented Wednesday at the 240th Meeting of the American Astronomical Society, where researchers trained the Gemini telescope in Chile on 44 young, massive stars, most of which were at the center of swirling disks of dust and gas. . Planets are known to form from these protoplanetary disks around young stars. .

But the new findings suggest that the shape and behavior of protoplanetary disks is largely dependent on the size of the star at their center. For stars just a little more massive than our Sun, the disks break up into dusty rings, while the disks of more massive stars are not ringed.

“Systems with small rings of dust grains are only found around stars with masses less than three times the mass of the Sun,” said Evan Rich, a postdoctoral researcher in astronomy at the University of Michigan and lead author of the new study, in a statement study. “This is important because forming planets are thought to create the ring structure, and our findings suggest that the process of planet formation may be different for stars larger than three times the mass of the Sun.”

The study, called Gemini-Large Imaging with GPI Herbig/T-Tauri Survey, or Gemini Lights, looked at 44 target stars of two different classes, T-Tauri stars and Herbig Ae/Be stars.

T-Tauri stars are variable stars, meaning their brightness varies when viewed from Earth, less than 10 million years old and three times the mass of our Sun or smaller. Herbig Ae/Be stars are also less than 10 million years old, but have different chemical signatures in their light than T-Tauri stars and can be two to eight times the mass of the Sun.

The study found that 80% of the stars surveyed had protoplanetary disks, but only nine had ringed disks. Four of the target stars had disks structured in spiral arms, four were large, irregularly shaped disks, and 12 were undetermined due to limitations in observations. A continuous disk with no gap or hole in the center was seen around 11 target stars, and there was some overlap between the types, with one of the spiral-armed disks also qualifying as a continuous disk.

The study also discovered a new exoplanet candidate around V1295 Aquilae, a star about 278 light-years away from Earth in the constellation Aquila, and a new candidate brown dwarf star.

Some theories of planet formation hold that forming planets are responsible for the gaps in the protoplanetary disks around some stars, which generate the rings, and that the mass of a planet needed to open a gap and create a ring is proportional. to the mass of your planet. star, Dr. Rich and his co-authors write in a preprint of their study published on the Arxiv server. Their findings seem to fit this hypothesis, but they caution that the association between lower-mass stars and manipulated disks could be due to the greater difficulty of visualizing larger stars.

“The detectability of rings around more massive systems is complicated because the central stars are also more luminous, increasing the brightness of the outer disk,” the researchers write. “Future work needs to verify these findings and look for massive systems that host ring and apertured structures.”

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