Steamy Space Mystery: Webb telescope finds water vapor, but from a rocky planet or its star?

Steamy Area Thriller: Webb telescope finds water vapor, however from a rocky planet or its star?

This artists’ idea represents the rocky exoplanet GJ 486 b, which orbits a purple dwarf star situated simply 26 light-years away within the constellation Virgo. Observing the passage of GJ 486 b in entrance of its star, astronomers seemed for indicators of an environment. They detected hints of water vapor. Nevertheless, they warning that whereas this could possibly be an indication of a planetary ambiance, the water could possibly be within the star itself particularly, in cool starspots relatively than the planet.
GJ 486 b is about 30% bigger than Earth and weighs 3 times as a lot. It orbits its star in lower than 1.5 days.
Credit: NASA, ESA, CSA, Joseph Olmsted (STScI), Leah Hustak (STScI)

Extra observations shall be wanted to find out whether or not exoplanet GJ 486 b has an environment.

GJ 486 b is about 30% bigger than Earth and 3 times as huge, that means it’s a rocky world with stronger gravity than Earth. It orbits a purple dwarf star in lower than 1.5 Earth days. It’s too near its star to be inside the liveable zone, with a floor temperature of about 800 levels

The Fahrenheit scale is a temperature scale, named after the German physicist Daniel Gabriel Fahrenheit and based mostly on one he proposed in 1724. On the Fahrenheit temperature scale, the freezing level of water is 32 F and water boils at 212 F, a 180 F separation, as outlined at sea degree and normal atmospheric strain.

“data-gt-translate-attributes=”[{” attribute=””>Fahrenheit. And yet, Webb observations show hints of water vapor.

The water vapor could be from an atmosphere enveloping the planet, in which case it would need to be continually replenished due to losses from stellar irradiation. But an equally likely possibility is that the water vapor is actually from the outer layer of the planets cool host star. Additional Webb observations will help answer the question: Can a rocky planet maintain, or reestablish, an atmosphere in the harsh environment near a red dwarf star?

Exoplanet GJ 486 b (Webb Transmission Spectrum)

This graphic shows the transmission spectrum obtained by Webb observations of rocky exoplanet GJ 486 b. The science teams analysis shows hints of water vapor; however, computer models show that the signal could be from a water-rich planetary atmosphere (indicated by the blue line) or from starspots from the red dwarf host star (indicated by the yellow line). The two models diverge noticeably at shorter infrared wavelengths, indicating that additional observations with other Webb instruments will be needed to constrain the source of the water signal.
Credit: NASA, ESA, CSA, Joseph Olmsted (STScI), Sarah E. Moran (University of Arizona), Kevin B. Stevenson (APL), Ryan MacDonald (University of Michigan), Jacob A. Lustig-Yaeger (APL)

Webb Space Telescope Finds Water Vapor, But From a Rocky Planet or Its Star?

The most common stars in the universe are red dwarf stars, which means that rocky exoplanets are most likely to be found orbiting such a star. Red dwarf stars are cool, so a planet has to hug it in a tight orbit to stay warm enough to potentially host liquid water (meaning it lies in the habitable zone). Such stars are also active, particularly when they are young, releasing ultraviolet and X-ray radiation that could destroy planetary atmospheres. As a result, one important open question in astronomy is whether a rocky planet could maintain, or reestablish, an atmosphere in such a harsh environment.

To help answer that question, astronomers used NASAs James Webb Space Telescope to study a rocky

We see a signal and its almost certainly due to water. But we cant tell yet if that water is part of the planets atmosphere, meaning the planet has an atmosphere, or if were just seeing a water signature coming from the star, said Sarah Moran of the University of Arizona in Tucson, lead author of the study.

Water vapor in an atmosphere on a hot rocky planet would represent a major breakthrough for exoplanet science. But we must be careful and make sure that the star is not the culprit, added Kevin Stevenson of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, principal investigator on the program.

GJ 486 b is about 30% larger than the Earth and three times as massive, which means it is a rocky world with stronger gravity than Earth. It orbits a red dwarf star in just under 1.5 Earth days. It is expected to be tidally locked, with a permanent day side and a permanent night side.

GJ 486 b transits its star, crossing in front of the star from our point of view. If it has an atmosphere, then when it transits starlight would filter through those gasses, imprinting fingerprints in the light that allow astronomers to decode its composition through a technique called transmission spectroscopy.

The team observed two transits, each lasting about an hour. They then used three different methods to analyze the resulting data. The results from all three are consistent in that they show a mostly flat spectrum with an intriguing rise at the shortest infrared wavelengths. The team ran computer models considering a number of different molecules, and concluded that the most likely source of the signal was water vapor.

While the water vapor could potentially indicate the presence of an atmosphere on GJ 486 b, an equally plausible explanation is water vapor from the star. Surprisingly, even in our own Sun, water vapor can sometimes exist in sunspots because these spots are very cool compared to the surrounding surface of the star. GJ 486 bs host star is much cooler than the Sun, so even more water vapor would concentrate within its starspots. As a result, it could create a signal that mimics a planetary atmosphere.

We didnt observe evidence of the planet crossing any starspots during the transits. But that doesnt mean that there arent spots elsewhere on the star. And thats exactly the physical scenario that would imprint this water signal into the data and could wind up looking like a planetary atmosphere, explained Ryan MacDonald of the University of Michigan in Ann Arbor, one of the studys co-authors.

A water vapor atmosphere would be expected to gradually erode due to stellar heating and irradiation. As a result, if an atmosphere is present, it would likely have to be constantly replenished by volcanoes ejecting steam from the planets interior. If the water is indeed in the planets atmosphere, additional observations are needed to narrow down how much water is present.

Future Webb observations may shed more light on this system. An upcoming Webb program will use the Mid-Infrared Instrument (MIRI) to observe the planets day side. If the planet has no atmosphere, or only a thin atmosphere, then the hottest part of the day side is expected to be directly under the star. However, if the hottest point is shifted, that would indicate an atmosphere that can circulate heat.

Ultimately, observations at shorter infrared wavelengths by another Webb instrument, the Near-Infrared Imager and Slitless Spectrograph (NIRISS), will be needed to differentiate between the planetary atmosphere and starspot scenarios.

Its joining multiple instruments together that will really pin down whether or not this planet has an atmosphere, said Stevenson.

The study is accepted for publication in The


Leave a Reply

Your email address will not be published. Required fields are marked *