How planets form, or if they do, may 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 in the center of disks. dust and gas gyratory. 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 depends largely on the size of the star at their center. For stars somewhat 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 report. release. statement. “This is important because forming planets are thought to create the ringed structure, and our findings suggest that the planet formation process might be different for stars more than three times the mass of the Sun.”
The study, called the Gemini-Large Imaging with GPI Herbig/T-Tauri Survey, or Gemini Lights, looked at 44 target stars from two different classes, T-Tauri stars and Herbig Ae/Be stars.
T-Tauri stars are variable stars, meaning their brightness varies as seen from Earth, they are less than 10 million years old, and three times the mass of our Sun or less. 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 as massive as the Sun.
The study found that 80% of the stars surveyed possessed protoplanetary disks, but only nine had ringed disks. Four of the target stars had spiral arm-structured disks, four were large, irregularly shaped disks, and 12 were not determined due to observational limitations. A continuous disk without a gap or hole in the center was seen around 11 target stars, and there was some overlap between types, with one of the spiral arm disks also qualifying as a continuous disk.
The study also discovered a new candidate exoplanet around V1295 Aquilae, a star about 278 light-years from Earth in the constellation Aquila, and a new candidate brown dwarf star.
Some theories of planet formation hold that the 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 his star, Dr. Rich and his co-authors write in a preliminary version of their study published on the Arxiv server. Their findings appear to fit that hypothesis, but they caution that the association between lower-mass stars and paired disks could be because larger stars are more difficult to image.
“The detectability of rings around more massive systems is complicated because the central stars are also more luminous, which increases the brightness of the outer disk,” the researchers write. “Future work should verify these findings and look for massive systems that harbor ringed and open structures.”