“Water Vapor Detected on Rocky Exoplanet GJ 486 b: A Potential Breakthrough in the Search for Habitable Worlds”

SPACE — We could be on the verge of a major breakthrough in the search for other worlds that might support life. Astronomers used NASA’s James Webb Space Telescope (Webb) to observe water vapor found around a distant rocky planet.

Water vapor could indicate the presence of an atmosphere around an exoplanet, or extrasolar planet, a discovery important to the search for habitable worlds outside the solar system. However, the scientists behind the discovery warned that the water vapor could have come from its parent star, not the planet itself.

“Water vapor in the atmosphere of a hot rocky planet would be a major breakthrough for exoplanet science. But we have to be careful and make sure the star isn’t the culprit,” said the principal investigator behind the find, Kevin Stevenson, a researcher at the University’s Applied Physics Laboratory. Johns Hopkins in a statement. The team’s research has been accepted for publication in Astrophysical Journal Letters.

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The exoplanet, which is named GJ 486 b, orbits a red dwarf (small star) located 26 light years away in the constellation Virgo. Despite having three times the mass of Earth, it is less than a third the size of our planet. GJ 486 b takes less than 1.5 Earth days to orbit its star and is probably tidally locked to a red dwarf, meaning it constantly shows the same face to its star.

Red dwarfs like the host star GJ 486 b are the most common star form in the cosmos, meaning statistically, the rocky exoplanet is the most likely to be found orbiting such a stellar object. Red dwarf stars are also cooler than other types of stars, meaning a planet must orbit them tightly to stay warm to accommodate liquid water, a vital element required for life.

However, red dwarfs also usually emit loud and powerful ultraviolet radiation and X-rays when they are young. That would blow up the atmosphere of a planet that gets too close, potentially making the exoplanet extremely inhospitable to life.

That means astronomers are currently interested in finding out whether rocky planets in such harsh environments could still form atmospheres, and survive long enough for life to exist. Typically, planets that harbor life take about a billion years to change.

In an attempt to answer that question, the research team pointed Webb and his Near-Infrared Spectrograph (NIRSpec) instrument toward GJ 486 b. You know, Webb is currently a very powerful mental telescope, capable of even reaching the beginning of the universe. Webb, will observe the planet as it crosses its star. Despite the fact that the planet is very close to its star and has a temperature of 430 degrees Celsius which is unsuitable for liquid water, astronomers have found traces of water vapor nearby.

The fact that GJ 486 b is transmitting its star from our perspective on Earth means it is in front of its star. That is, the red turtle’s light shines through the exoplanet’s atmosphere. Different chemical elements and compounds absorb and emit different wavelengths of light which allows them to be identified.

Seeing the light emitting from a planet during its journey around its host star can reveal its origin, what its potential atmosphere is made of. This search for chemical traces in the light of stars filtered by the atmosphere is called ‘transmission spectroscopy’.

Astronomers observed GJ 486 b with the Webb telescope for two transits, each of which lasted just one hour. They then analyzed the data collected using three remote methods which showed a similar pattern, a flat spectrum with interesting peaks in shortwave infrared light. They found that the most likely cause of the peak was water vapor.

“We saw a signal and it was almost certainly due to water,” said lead author of the study and University of Arizona astronomer Sarah Moran.

“But we can’t say yet whether the water is part of a planet’s atmosphere, meaning it has an atmosphere (?), or whether we are just seeing traces of water coming from a star.”

Water vapor has previously been seen in starspots, namely sunspots. These spots are darker, as cooler regions of the star are brought to their surface. These areas commonly form disturbances such as solar flares or coronal mass ejections (CMEs).

Even though the host star GJ 486 b is cooler than the sun, water vapor can still concentrate in the starspots. If so, it could create a signal that mimics planetary atmospheres, such as ours.

“We see no evidence that the planet crosses any point on the star during the transit. But that doesn’t mean that there aren’t other points on the star,” study co-author Ryan MacDonald said in a statement. The University of Michigan scientist added that it was a physical scenario that could embed water signals into the data and look like a planet’s atmosphere.

If there is an atmosphere around GJ 486 b, radiation from its parent star will constantly erode it. This means that the atmosphere must be replenished by steam from the exoplanet’s interior through volcanic activity.

Astronomers observed GJ 486 b with the Webb telescope for two transits, each of which lasted just one hour. They then analyzed the data collected using three remote methods which showed a similar pattern, a flat spectrum with interesting peaks in shortwave infrared light. They found that the most likely cause of the peak was water vapor. “We saw a signal and it was almost certainly due to water,” said lead author of the study and University of Arizona astronomer Sarah Moran. “But we can’t say yet whether the water is part of the planet’s atmosphere, meaning the planet has an atmosphere (?), or whether we are just seeing traces of water coming from the star.” Water vapor has previously been seen in starspots, i.e. sun. These spots are darker, as cooler regions of the star are brought to their surface. These areas commonly form disturbances such as solar flares or coronal mass ejections (CMEs). Even though the parent star GJ 486 b is cooler than the sun, water vapor can still be concentrated in the starspots. If so, this could create a signal that mimics the atmosphere of a planet, such as ours. “We see no evidence that the planet crosses any point on the star during the transit. But that doesn’t mean that there isn’t another point on the star,” said the study’s co-authors. , Ryan MacDonald in a statement. The University of Michigan scientist added that it was a physical scenario that could embed water signals into the data and look like a planet’s atmosphere. If there was an atmosphere around GJ 486 b, then radiation from its host star would be constantly eroding it. This means that the atmosphere must be replenished by steam from the exoplanet’s interior through volcanic activity. To determine whether the water vapor is coming from the atmosphere around the planet and how much of it is present, astronomers will need to take a closer look at GJ 486 b and its star. To do this, Webb’s Mid-Infrared Instrument (MIRI) will examine the planetary system and focus on its day side, which faces the star permanently.

If GJ 486 b had a thin atmosphere or no atmosphere at all, the hottest region during the day should be just below the red dwarf. However, if this hot spot was offset, it could indicate the presence of an atmosphere thick enough for heat to circulate.

Webb’s continued investigation of this planet will also integrate other instruments at his disposal, namely the Near-Infrared Imager and Slitless Spectrograph (NIRISS). “It incorporates several instruments that will actually determine whether or not this planet has an atmosphere,” Stevenson said. Source: Space.com