Astronomers have made a groundbreaking discovery by observing a baby planet, known as AB Aurigae b, forming in real time. This protoplanet, approximately four times the mass of Jupiter, is located about 93 astronomical units from its host star, a distance nearly three times that between the Sun and Neptune. This observation provides a rare glimpse into the chaotic and dynamic process of planetary formation.
Protoplanets are celestial bodies in the process of developing into full-fledged planets, situated within the gas and dust disks that surround young stars. Unlike mature planets, they actively feed on surrounding materials through their own circumplanetary disks. The detection of AB Aurigae b marks a significant moment in astronomy as it allows researchers to witness the direct accretion of material, effectively watching the planet grow.
The international team of astronomers, led by researchers from the Astrobiology Center in Japan, utilized the Very Large Telescope in Chile to gather data on this protoplanet. They detected hydrogen alpha emissions, a specific type of light resulting from hot gas spiraling into the planet as it consumes material from the protoplanetary disk. This observation is unprecedented; it provides direct evidence of a planet actively accumulating mass from its surroundings.
Unique Characteristics of AB Aurigae b
The hydrogen emissions from AB Aurigae b displayed a distinctive pattern known as an “inverse P Cygni profile.” This profile indicates that gas is falling inward toward the planet rather than being expelled. Specifically, the data revealed gas moving towards the observers at approximately 100 kilometers per second, while absorption features indicated material moving away at roughly 75 kilometers per second. This unique combination of emissions underscores the active feeding process of the protoplanet.
Unlike other young planets that orbit in cleared gaps within their disks, AB Aurigae b remains embedded in its birth disk. This position allows astronomers to observe the planet’s formation as it gathers mass. The system is estimated to be around 2 million years old, placing it in the earliest stages of planetary formation, which challenges existing models of how planets develop.
Implications for Planet Formation Theories
The findings regarding AB Aurigae b raise questions about standard models of planet formation. Given its significant distance from its star, the planet likely formed via a process where dense regions of the disk collapsed under their own gravity, differing from the core accretion method responsible for the formation of Jupiter and Saturn. This observation offers crucial insights into the mechanisms by which gas giant planets grow during their formation phase.
The circumplanetary disk surrounding AB Aurigae b serves as a vital feeding mechanism, channeling material from the larger protoplanetary disk onto the developing planet. This discovery marks the beginning of a new era in planetary formation studies. Future observations will be essential to determine how much of the detected emission originates from the planet itself compared to the surrounding disk. Additionally, researchers hope to find similar signatures around other young stars, further expanding our understanding of planetary birth.
The original version of this article was published on Universe Today, highlighting the significance of this discovery in the field of astrophysics and our understanding of the universe.
