NASA’s Chandra X-ray Observatory may have witnessed a young planet being destroyed by its star host, a “baby” stellar object caught gorging on the mass of its planetary satellite.
While stars have been known to devour planets before, as reported by the Inquisitr last year and again in 2012, when a red giant was seen munching on its orbiting planet, this is the first direct observation of this kind, stated NASA officials.
According to a report by the space agency, the infant star, dubbed RW Aur A and found some 450 light-years away from our home planet, is currently in the process of assimilating the planetary debris around it — which could have come either from one young planet orbiting the newly-formed star or from two planetary satellites that coalesced from the same molecular cloud of gas and dust as their stellar host.
The Curious Case Of Star RW Aur A
This particular celestial object is part of a binary star system, each about the mass of our sun, located in the Taurus-Auriga Dark Clouds — one of the nearest and most intensely studied star birth regions, notes the Harvard-Smithsonian Center for Astrophysics.
This famous stellar nursery in the Milky Way occupies a wide portion of our spiral arm of the galaxy and houses thousands of very young stars bursting with activity, among which are RW Aur A and its binary companion, RW Aur B.
The star — which is only a few million years old, practically a baby in cosmic terms — was first spotted in 1937 and has baffled astronomers for almost a century with its bizarre and continuous flickering of its optical light.
Telescopes pointed at RW Aur A have seen the star fade for short periods of time and then grow brighter over and over again, with these dimming intervals becoming more frequent and increasingly longer in recent years.
While the initial dips in optical brightness only lasted for about a month and repeated every few decades, in 2011 the star remained dim for six months in a row.
“The star eventually brightened, only to fade again in mid-2014. In November 2016, the star returned to its full brightness, and then in January 2017 it dimmed again,” explained NASA.
Caught Snacking On Planetary Iron
Intrigued by what was going on, astronomers turned to the Chandra X-ray Observatory to unravel the mystery.
Chandra tracked RW Aur A both during its luminous period of 2013 and while the star had faded considerably in 2015 and 2017. The X-ray observations revealed that, during its latest dimming event, the star had become faint because it was obscured by “a thick veil of dust and gas” coming from the collision of two young planetary bodies, NASA revealed.
According to the findings, published yesterday in the Astronomical Journal, one of the two bodies was even large enough to be a planet.
Commenting on the discovery, study lead author Hans Moritz Guenther, from the Massachusetts Institute of Technology (MIT), noted that this could be the first direct observation of the phenomenon.
“Computer simulations have long predicted that planets can fall into a young star, but we have never before observed that. If our interpretation of the data is correct, this would be the first time that we directly observe a young star devouring a planet or planets.”
The latest Chandra observations revealed another interesting detail. After recording a total of nearly 14 hours of X-ray data from the young star, as noted by a news release from MIT, Chandra eventually picked up a decrease in X-ray intensity last year. The changes in the star’s X-ray spectrum helped the team piece together the chemical composition of RW Aur A, which was found to contain 10 times more iron atoms than it did in 2013.
This “is very unusual, because typically stars that are active and hot have less iron than others, whereas this one has more,” said Guenther, who is a scientist at MIT’s Kavli Institute for Astrophysics and Space Research.
One explanation is that all the extra iron was assimilated from the cloud of debris created by the collision of the two planetary bodies, especially if one or both of them were partly made out of iron.
The alternative is that iron particles get caught up in so-called “death zones” of the gas disk still surrounding young stars. If this disk experiences a sudden change in its structure — such as when the star and its binary companion pass close to each other — the iron molecules could be released by the resulting tidal forces, falling into the star.
“If you look at our solar system, we have planets and not a massive disk around the sun,” Guenther says. “These disks last for maybe 5 million to 10 million years, and in Taurus, there are many stars that have already lost their disk, but a few still have them. If you want to know what happens in the end stages of this disk dispersal, Taurus is one of the places to look.”