Astronomers find evidence of a volcanic exomoon

Date:
Sun, 13 Oct 2024 03:38:56 +0000

Description:
Astronomers have found evidence for a volcanic moon orbiting an exoplanet 635 light-years from Earth. The post Astronomers find evidence of a volcanic exomoon appeared first on NASASpaceFlight.com .

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Astronomers have found evidence for a volcanic moon orbiting an exoplanet 635 light-years from Earth. No moons have been confirmed to orbit planets outside our solar system, but a sodium cloud hints at the existence of one around exoplanet WASP-49 b.

Moons orbiting planets outside our solar system also known as exomoons are hard to detect, as they are too small and too dim to be picked up by telescopes. Astronomers have found multiple candidates for exoplanets with moons, but none have been confirmed.

However, volcanically active exomoons could be detected through the material they spew into space. A similar phenomenon occurs in our solar system, as volcanic activity on Jupiters moon Io creates gigantic clouds of volcanic gasses around the planet. These clouds are many times the size of Jupiter, up to 1,000 times the planets radius. A similar cloud has now been detected around WASP-49 b.



The evidence is very compelling that something other than the planet and star are [sic] producing this cloud, said co-author Rosaly Lopes of NASAs Jet Propulsion Laboratory (JPL). Detecting an exomoon would be quite extraordinary, and because of Io, we know that a volcanic exomoon is
possible.

WASP-49 b is a planet with roughly the mass of Saturn, orbiting a Sun-like star. At only 10 percent of the distance between the Sun and Mercury, this planet completes a revolution in only 2.8 days. The sodium cloud around this exoplanet was first found in 2017. Io surrounded by a cloud of volcanic gas.
A plume of gas from the volcano Prometheus reflects sunlight. This image was captured by NASAs Galileo spacecraft using clear, green, and yellow filters. (Credit: NASA/JPL)

Astronomers study exoplanets like WASP-49 b by measuring their effect on the light emitted by their host stars. When the exoplanet transits its star,
which means it passes between its star and Earth, it slightly changes the stars light signal. Studying how the starlight is absorbed by whatever passes in front of the star, helps scientists learn more about exoplanets or their potential moons. See Also Astronomy & Planetary Science Space Science Section Click here to join L2

For this study, the team used data from the European Southern Observatorys (ESO) Very Large Telescope (VLT) in northern Chile. VLT observed the transiting exoplanet on Dec. 16, 2020, using its Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) instrument. The astronomers also reanalyzed the observations from the 2017 study, which observed WASP-49 b for three days in late 2015 and early 2016 using ESOs 3.6
m telescope.

The team found that the sodium cloud was located well within the zone around the exoplanet where moons can physically exist. That zone is defined by the planets Hill sphere, within which a moons orbit can be stable in the long term, and the Roche limit, wherein moons break up under immense tidal forces.

Moreover, the sodium cloud also seemed to move faster than WASP-49 b. The astronomers measured the clouds Doppler shift, which is a change in the light signals frequency resulting from the object moving toward or away from its observer. Using this method, they found that the cloud was moving in a way that had never been observed at exoplanets but was similar to the movement of Ios sodium cloud around Jupiter.

We think this is a really critical piece of evidence, said study lead Apurva Oza of the California Institute of Technology (Caltech). The cloud is moving in the opposite direction that physics tells us it should be going if it were part of the planets atmosphere.



Having ruled out the exoplanet itself as the source of the observed sodium, the astronomers had to exclude all other possible sources. They found that it was unlikely to originate from the star. Additionally, the signal varied too much between the analyzed observations for it to be interstellar sodium, located between WASP-49 b and Earth.

The team even analyzed historical weather records to ensure the observations were likely not distorted by atmospheric conditions on Earth.

To gain even more confidence that the sodium cloud originated from a volcanic exomoon, the astronomers created a computer model. That model showed that the observed fluctuations in the position of the sodium cloud could be explained by an exomoon orbiting WASP-49 b every eight hours.

While the new study has shown that a volcanic exomoon is very likely to orbit WASP-49 b, it has not provided definitive evidence. The team has only been able to analyze a few transits and believes that observing more transits
would help determine a moons orbit. Additionally, upcoming telescopes can
help find traces of other materials that are expected in volcanic clouds,
such as potassium.

If there is a moon at WASP-49 b and if it is anything like Io, its volcanism is likely caused by the exoplanets gravity. The tidal forces distort the
moons shape, heating its interior. Eventually, this process might cause the moon to break up.

If there really is a moon there, it will have a very destructive ending, said Oza.

Oza et al.s study was published in The Astrophysical Journal Letters
journal.

(Lead image: Artists concept WASP-49 b, its parent star, and a potential volcanic exomoon surrounded by a cloud of sodium. Credit: NASA/JPL-Caltech)

The post Astronomers find evidence of a volcanic exomoon appeared first on NASASpaceFlight.com .



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Link to news story:
https://www.nasaspaceflight.com/2024/10/wasp-49b-exomoon/


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