Galaxies’ Playmates: Solar System’s Unique Growth | TechNews

The figure below compares 31 “baby” star systems at birth. Every forming star is surrounded by a protoplanetary disk of gas and dust. Quite a few of these systems did not form alone like the sun, but grew together with other celestial bodies in the early stages of their birth. The latest research points out that the sources around young stars that can reshape the structure of protoplanetary disks are not necessarily planets. Brown dwarfs and low-mass stellar companions may also play a key role.

（Source：ESA）

In order to clarify the real reason for the structure of the protoplanetary disk, astronomers combined observation data from the European Space Agency’s Gaia space telescope and the Atacama Large Millimeter and Submillimeter Array (ALMA) to analyze 98 young star systems that are still in the early stages of formation. There are 31 systems with extremely subtle swings in star position, indicating that there are companion stars around them that have not yet been directly imaged. Through these nearly imperceptible wobbles, astronomers were able to dynamically and directly identify the source of intra-disk disturbances for the first time in a star system still surrounded by a dust disk.

The protoplanetary disk is shown in orange and purple. The image comes from ALMA’s cold dust observations in the millimeter band, depicting the shape and extent of the disk; the position marked in cyan represents the possible position of the companion calculated by Gaia based on the star’s wobble. These cyan marks are not actual captured images, but dynamic clues left by gravity. The analysis shows that seven of the 31 systems have system disturbances consistent with planetary mass objects, eight are closer to brown dwarfs, and the remaining 16 systems are most likely to have low-mass stellar companions.

The lower right corner shows the “baby” appearance of the solar system when the model estimates it to be about 1 million years old. The sun is at the center of the system, and the cyan circle is the orbital position of Jupiter, allowing the distances of other young system companions to be directly compared with the orbits of the solar system planets. The comparison reminds us that single star systems without stellar companions like our own are not the only way stars look. The Gaia data will continue to be updated, and the companion stars hidden in the dust are expected to be further tracked and observed by instruments such as the James Webb Space Telescope, gradually piecing together a complete picture of the birth of the planetary system.

(This article is reprinted with permission from the Taipei Planetarium; first image source: Freepik)