Many are concerned about the devastation an asteroid would have on life on Earth, but astronomers have discovered the first evidence that a ‘giant impact’ in deep space ‘stripped’ away part of a planet’s atmosphere.
A group of astronomers, led by those at MIT, have found evidence that the HD 172555 planetary system had a collision between an Earth-sized terrestrial planet and an impactor roughly 200,000 years ago.
The collision in the planetary system – 95 light-years away – occurred at more than 22,000 miles per hour and it may have caused part of the planet’s atmosphere to blow away, as evidenced by the carbon monoxide and dust that surround the HD 172555 star.
Astronomers discovered the first evidence that a ‘giant impact’ in deep space ‘stripped’ part of a planet’s atmosphere. The HD 172555 planetary system (pictured) had a collision roughly 200,000 years ago
The researchers found that carbon monoxide was circling close to HD 172555, roughly 10 astronomical units, or approximately 930 million miles.
A heavy presence of the gas so close to the star suggests it emanated from a collision.
It’s likely that the impact was ‘massive’ and may have involved two proto-planets, similar in size to the Earth.
‘This is the first time we’ve detected this phenomenon, of a stripped protoplanetary atmosphere in a giant impact,’ said the study’s lead author, Tajana Schneiderman, in a statement.
‘Everyone is interested in observing a giant impact because we expect them to be common, but we don’t have evidence in a lot of systems for it.
‘Now we have additional insight into these dynamics.’
The star is known to have dust that contains minerals unusual for a star, as well as carbon monoxide gas that suggests the giant impact.
‘Because of these two factors, HD 172555 has been thought to be this weird system,’ Schneiderman explained.
The researchers found evidence of carbon monoxide and dust roughly 10 astronomical units, or 930 million miles, from the HD 172555 star
The impact may have involved two proto-planets, similar in size to the Earth, with the collision occurring at more than 22,000 miles per hour
The star HD 172555 has been an intrigue for some time to scientists.
In 2009, NASA’s Spitzer Space Telescope found evidence that a high-speed collision occurred around the star during the early stages of planet formation.
However, the telescope did not detect any evidence at the time the planet’s atmosphere was partially stripped away.
The group of researchers used data from the Atacama Large Millimeter Array in Chile and sifted through signs of carbon monoxide around nearby stars to come up with their findings.
A heavy presence of carbon monoxide so close to the star suggests it emanated from a collision
‘When people want to study gas in debris disks, carbon monoxide is typically the brightest, and thus the easiest to find,’ Schneiderman said.
‘So, we looked at the carbon monoxide data for HD 172555 again because it was an interesting system.’
‘The presence of carbon monoxide this close requires some explanation,’ Schneiderman added.
Carbon monoxide is vulnerable to a process known as photodissociation, or when star’s photons break down and destroy the molecule.
However, a heavy presence of the gas so close to the star suggests it emanated from a collision.
‘Of all the scenarios, it’s the only one that can explain all the features of the data,’ Schneiderman said.
‘In systems of this age, we expect there to be giant impacts, and we expect giant impacts to be really quite common. The timescales work out, the age works out, and the morphological and compositional constraints work out.
‘The only plausible process that could produce carbon monoxide in this system in this context is a giant impact.’
The estimate that the impact occurred 200,000 years ago is a short amount of time — in terms of the universe — that the star has not yet destroyed the carbon monoxide.
The study was published in the scientific journal Nature.