At Least a Quarter of All Sun-Like Stars Are Known to Have Consumed One of Their Own Planets

Artist's impression of an exoplanet orbiting a binary star. (Lynette Cook/NASA)

Saturn – or Kronos – may have a dreadful reputation for filial cannibalism in mythology, but it turns out that Sun-like stars have a lot to answer for when it comes to cosmic giants eating their own children.

According to recent research, at least a quarter of all stars, including the Sun, have devoured one of their own planets at some point during their lives.

This doesn't mean we'll throw them in a star prison for crimes against their kind, but it does reveal that many planetary systems are dynamically unstable, which distinguishes the Solar System - a finding that could have ramifications for our quest for Earth-like worlds.

"The fact that planetary systems can be highly distinct from one another suggests that their dynamical histories were also very diverse, most likely because to a high sensitivity to the beginning conditions. Planetary orbits may have been destabilised by dynamical processes in the most chaotic systems, driving them to crash into the host star "a group of researchers stated in a new report published in Nature Astronomy.

Planet engulfment evidence and knowledge of their occurrence in Sun-like stars would give information on the evolutionary routes of planetary systems, demonstrating how many of them have gone through intricate phases of highly dynamical reconfiguration.

Our weird Sun

Our Sun, believe it or not, is a rare sight in the Milky Way. Around 75% of the stars in our galaxy are M-type stars, or red dwarfs, which are tiny, cool, and have a long life span. Our Sun is a G-type star, also known as a yellow dwarf; G-type stars make up only 7% of the Milky Way's stars.

In addition, the Sun is a solitary figure. Most stars, according to astronomers, are born in star systems with one or more siblings; indeed, most stars in the Milky Way have at least one additional companion in a binary system. (And yes, it's possible that the Sun has a long-lost twin someplace out there.)

This is how it works. The beginning of a star, or protostar, is formed when a compact knot in a cloud of molecular gas in space collapses under its own gravity and begins spinning. The protostar's gas condenses into a disc, which feeds the expanding star. The disc may fragment during this process, resulting in the formation of a second protostar.

After the stars have formed, the remaining material in the disc creates planets, asteroid belts, and comets, as well as everything else that makes up a planetary system. These objects can have varying ratios of the substance that was in the initial cloud depending on where they originate in the disc.

Because they were produced from the same clump of material, the twin stars should have chemical compositions and masses that are quite similar.

However, this isn't always the case. As a result, a group of astronomers led by Lorenzo Spina of the Astronomical Observatory of Padua in Italy and Monash University in Australia decided to investigate binary systems in greater depth. They analysed the chemical attributes of 107 pairs of stars with identical temperatures and surface gravities.

Surprisingly, they discovered that many of the binaries had incompatible chemistry.

Despite the fact that binary stars should have the same chemical pattern, the stellar components of 33 pairings in our sample have iron abundances that are abnormally varied at the 2-sigma level. This means that any Sun-like star has a 20-35 percent chance of devouring its planets.

They discovered that when the temperature of the pair rises, the chances of finding such a chemically abnormal binary rise. This is unlikely to be the result of inhomogeneities within the protostellar cloud; rather, planetary material dropping onto the star and polluting the convective zone - the layer where material is moved via heat fluxes - according to modelling.

When planetary debris approaches the star and pollutes its convective zone, the stellar atmosphere alters in a way that matches the makeup of rocky planets, the researchers noted, with refractory elements [metals and silicates] being more numerous than volatiles. 

As a result, stars that have absorbed planetary material should have higher refractories to volatiles abundance ratios than stars of similar ages and metallicities.

Read The Original Article Here.