Astronomers may have for the first time detected evidence that a distant planet had its atmosphere partially blown away by a giant impact, according to a new study.
Scientists think newborn planetary systems generally experience severe growing pains as infant planets-in-the-making, known as protoplanets, slam together and fuse to form more giant planets.
In our solar system, the Earth and moon are thought to be products of this type of enormous impact.
According to the words of the study’s lead author, Tajana Schneiderman, an astronomer at the Massachusetts Institute of Technology (MIT), during her talk with Space.com.
“Our solar system shows abundant evidence of giant impacts,” Astronomers conjecture that such smashups should be commonplace in early systems, but they have been challenging to observe around other stars.
What is unique about this? And how do the astronomers explain the phenomenon?
This is the first-ever time such a phenomenon has been directly observed, as confirmed by the Massachusetts Institute of Technology astronomers.
Following the phenomenon’s discovery, now astronomers at MIT, Cambridge University, the National University of Ireland Galway, and elsewhere have discovered evidence of a giant impact in a nearby star system, just 95 light-years from Earth.
The star, named HD 172555, is about 23 million years old, and scientists have suspected that its dust bears traces of a recent collision. The MIT-led team has discovered further evidence of a giant impact around the star.
They determined that the crash likely occurred between a roughly Earth-sized terrestrial planet and a smaller impactor at least 200,000 years ago, at speeds of 10 kilometres per second or more than 22,000 miles per hour.
Along with that discovery, they also detected gas, which indicated that such a high-speed impact likely blew away part of the giant planet’s atmosphere. This dramatic event would explain the observed gas and dust around the star. The findings, appearing today in Nature, represent the first detection of its kind.
Tajana Schneiderman confirmed this by stating that this was the first time we’ve detected this phenomenon of a stripped protoplanetary atmosphere in a giant impact. Tajana Schneiderman is a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences.
She added that everyone is interested in observing a giant impact because they expect them to be shared, but we don’t have evidence in many systems for it. And now we have additional insight into these dynamics based on the stripped protoplanetary atmosphere in a giant impact.
What is the aftermath of the phenomenon?
After a careful reanalysis, the MIT team detected the abundance of carbon monoxide around the star. After measuring it, they found the gas amounted to 20 per cent of the carbon monoxide found in Venus’ atmosphere.
They also observed that the gas circled in large amounts, surprisingly close to the star, at about ten astronomical units, or ten times the distance between the Earth and the sun.
According to Schneiderman, the presence of carbon monoxide this close to the star must be examined and explained.
Because carbon monoxide is characteristically vulnerable to photodissociation, a process in which a star’s photons break down and destroy the molecule.
So, there would generally be very little carbon monoxide at close range at such closeness to a star. To understand more on this, the group tested various scenarios to explain the gas’s abundant, close-in appearance.
They immediately did rule out a scenario in which the gas arose from the debris of a newly formed star and one in which a close-in belt of icy asteroids produced the gas. After considering and evaluating different scenarios, the team’s last idea was that the gas was a remnant of a giant impact.
As per Schneiderman, out of all the scenarios, that is the only one that could explain all the data features. According to them, the only plausible process that could produce carbon monoxide in this system in this context is a giant impact.
The team estimates that the gas was released from a giant impact that occurred at least 200,000 years ago — recent enough that the star would not have had time to destroy the gas. Based on the gas’ abundance, the impact was likely massive, involving two proto-planets, likely comparable in size to the Earth.
The effect was so significant that it probably blew off part of one planet’s atmosphere in the form of the gas that the team observed today. And, the discovery opens up the possibility for future works beyond this system, according to Tajana.
