Can you photograph Jupiter without any noticeable clouds or haze? It’s not easy because the occasional cloud bands of Jupiter and its great red point are distinct visual features in our solar system. These features are due to upward and downward gases, mostly ammonia. After Saturn’s rings, the shapes of Jupiter’s cloud are perhaps the most distinctive feature of the solar system.
Now astronomers with the Center for Astrophysics | Harvard and Smithsonian University (CfA) found a planet similar in mass to Jupiter, but with an atmosphere free of clouds.
These planets are rare, and astronomers believe that only about 7% of exoplanets are like this. The discovery allows scientists to study how it formed. With no clouds en route, a clearer view awaits.
The team of astronomers responsible for this discovery published their findings in The Astrophysical Journal Letters. the address is «Evidence of an apparent atmosphere for the WASP-62b: the only transient gas giant known in the JWST continuous viewing area. The lead author of the study is Menaza Alam, a CfA graduate student.
WASP-62b is the closest planet to WASP-62, which is a main sequence star 600 light years from Earth. 62b is the only planet in the system. It is just over half the mass of Jupiter, and orbits WASP-62 in about 4.5 days. It is 1.4 times the size of Jupiter. It falls directly into the category of hot Jupiter planets, with an average temperature of about 1,330 K (1057 ° C; 1934 ° F).
Characteristics of a planet’s temperature, size, and density are not rare. What is rare is the serenity of the atmosphere. The atmosphere of an exoplanet is of particular interest to lead the author. at Press releaseA scientist said, «For my mission, I have been working on characterizing exoplanets. I take the discovered planets, and follow them to find out their atmospheres.»
WASP-62b was discovered using WASP, but Alam and her colleagues used Hubble to study it more closely. “I’ll admit it at the start, I wasn’t very excited about this planet,” Alam said. «But once I started looking at the data, I got excited.»
Using spectroscopy, they closely observed the planet passing in front of its star three times, looking for potassium and sodium. As starlight passed through the planet’s atmosphere, they determined the full spectral signature of sodium, but no potassium. The sodium signature told them it was clear.
«This is strong evidence that we are witnessing a clear atmosphere,» Alam said.
In an email with Universe Today, Allam explained the team’s spectral findings and what they mean.
The concentration of potassium and sodium depends on two things. First of all, its spectra are easily observable in optical light. “Sodium and potassium are two types that can be easily observed in the atmospheric observations of exoplanets taken at optical wavelengths, and their presence or absence can help us conclude whether there are clouds or haze in the atmosphere of an exoplanet,” Alam said.
Sodium and potassium also play a role in exoplanet atmospheres, although the details are unclear. A scientist explained, «Sodium and potassium are two elements that play an interesting — but poorly understood — role in atmospheric physics and exoplanet chemistry.» It also reported that sodium was the first identified absorption feature in an exoplanet’s atmosphere.
The discovery of the full spectral footprint of sodium tells astronomers that the atmosphere is clear, even if there is no way to see the atmosphere. Allam explained that «the clouds in the planet’s atmosphere will hide or obscure parts of the absorption line.» “In the absence of clouds, we can resolve the complete sodium footprint — which has a tent-like shape with a peak at the core of the absorbent characteristic and wide linear wings. For our observations of the WASP-62b, this is the second time that we have observed the full sodium feature (for example, With its linear wings) in an exoplanet and the first time that we do this from space. «
But the full sodium signature does more than just tell us that an exoplanet’s atmosphere is clear of clouds. It can help explain how much sodium is present and indicate other elements in the atmosphere.
“Not only does it tell us that the atmosphere is clear, it can also help us restrict the minute amounts (amounts) of sodium — as well as other elements in the planet’s atmosphere,” said Elm. «This abundance is useful in measuring key quantities that can help us trace the origins and evolution of this planet.»
Obviously, something different happens when a planet without a cloud forms. Since there are very few of them, astronomers are only at the beginning of their studies. The only other exoplanet devoid of clouds that we know is the hot planet Saturn called WASP-96b. Found in 2018.
It would be up to the James Webb Space Telescope to closely examine this exoplanet’s atmosphere. Its clear skies also make this possibility even more exciting. Webb’s advanced monitoring capabilities mean it should be able to identify more chemical components in WASP-62b’s atmosphere.
Due to JWST’s direction and location in space, it will have two Continuous Viewing Zones (CVZ). They are centered on each pole of the ecliptic. Fortune smiles at the Alam and other exoplanet scientists because the WASP-62b is in one of Webb’s CVZs.
The team of researchers even predicted what JWST might find in its 62b atmosphere. They write in their paper, “We expect that JWST observations of WASP-62b, within the scope of the ERS program, could conclusively detect Na (12.1).?), H2O (35.6?), FeH (22.5?), SiH (6.3?), New Hampshire3 (11.1?), CO (8.1?), CO2 (9.7?) And CH4 (3.6?). They also say that the planet Earth theory could present subtle limits to the abundance of chemicals in the atmosphere.
In their conclusion, the authors made their case to follow up on WASP-62b’s observations with JWST.
“In preparation for JWST, cloud-free / fog-free target designation is critical to mobilizing community efforts to monitor the best planets for detailed atmospheric tracking. Although alternative targets have been proposed since then, the WASP-62 is the only star in the JWST CVZ. With a known transient giant planet bright enough for high-quality characterization of the atmosphere via transient spectroscopy. «
The James Webb Space Telescope is scheduled to launch at the end of October 2021.