Planets beyond our solar system
Hycean worlds are planets covered in oceans that also have thick hydrogen atmospheres. There are no confirmed Hycean worlds—also called ocean worlds—but many candidates. Even though they're only candidates so far, researchers are curious about their habitability. New research examines the role tidal heating plays in their potential habitability.
The early Solar System was filled with both hydrogen and oxygen that can chemically bond into water. But did we create all the water, or was some of it inherited from the earlier times, already present in the protostellar nebula? Astronomers have used the James Webb Space Telescope to study a newly-forming protoplanetary system called L1527 IRS, which will eventually become a star like our Sun. They found evidence that water from interstellar space is preserved when it becomes part of a new star system.
Astronomers have used JWST to study a fascinating planetary system that's only 16.7 million years old, with two bizarre giant exoplanets. Designated YSES-1, its closer planet, YSES-1b seems to be surrounded by a disk of material that could be the birthplace of moons, similar to what might have happened at Jupiter billions of years ago. The other, YSES-1c, has a layer of silicate particles in its upper atmosphere—clouds of sand.
Astronomers have discovered the site of a newly forming exoplanet, probably with several times the mass of Jupiter. The image was captured by ESO's Very Large Telescope, seeing the young star system 2MASS 1612 in infrared light. The disk extends about 130 astronomical units from the star, but you can see a bright ring followed by a gap at about 50 AU. It's believed there's a new planet forming in that gap, pulling in material from the disk of gas and dust around it.
Most exoplanets have been detected indirectly through the transit or radial velocity method. But here's an image of the exoplanet 14 Herculis c captured by Webb. It has been described as a "chaotic" and "abnormal" planetary system and is about 7 Jupiter masses, but with a surface temperature of only -3°C. The discovery offers new insights into how planetary systems can develop in dramatically different ways from our own Solar System.
As astronomers found more and more exoplanets in recent years, they've discovered an unusual gap in the population. It's called the Neptunian Desert, a curious scarcity of Neptune-sized exoplanets orbiting close to their stars. Researchers just discovered an exoplanet in the Neptunian Desert around a Sun-like star. Can it help explain the Desert?
The discovery of a Saturn-sized gas giant orbiting a small red dwarf is urging astronomers to reconsider their theories of planet formation. Core accretion theory is the most widely accepted explanation for planetary formation. It describes how planet formation begins with tiny dust grains gathering together and forming planetary cores that grow larger through accretion. It explains much of what we see in our Solar System and others. This discovery introduces some doubt.
Astronomers have found another super-Earth. It's about 10 times more massive than Earth, and orbits in the habitable zone of a Sun-like star about 2475 light-years away. These massive Earth-like planets hold key information about how planets form and evolve.
The challenge in the search for habitable worlds is clear. We need to be able to identify habitable worlds and distinguish between biotic and abiotic processes. Ideally, scientists would do this on entire populations of exoplanets rather than on a case-by-case basis. Exoplanets' natural thermostats might provide a way of doing this.
A team of geophysicists from the University of Chicago showed how clouds on exoplanets could enhance the search for biosignatures. Their findings could have significant implications for the Habitable Worlds Observatory (HWO) and other next-generation telescopes that will study exoplanets via direct imaging.
Tracking exoplanets via orbital mechanics isn't easy. Plenty of variables could affect how a planet moves around its star, and determining which ones affect any given exoplanet requires a lot of data and a lot of modeling. A recent paper from researchers led by Kaviya Parthasarathy from National Tsing Hua University in Taiwan tries to break through the noise and determine what is causing the Transit Timing Variations (TTVs) of HAT-P-12b, more commonly known as Puli.
NASA's Transiting Exoplanet Survey Satellite (TESS) has already uncovered hundreds of exoplanets of all sizes. Now, a team of astronomers is pushing the search even further—this time, looking for signs of planetary rings. Scanning 308 TESS planet candidates, they zeroed in on large, fast-orbiting worlds circling bright, nearby stars. Out of those, six showed subtle hints that rings might be present. But despite the tantalising clues, none offered definitive evidence of ring systems—at least not yet.
The idea that our Solar System is representative of other solar systems hasn't survived the age of exoplanet discovery. Kepler and TESS have shown us that our system doesn't even contain the most common type of planet: sub-Neptunes. These planets pose a mystery to planetary scientists, and the JWST is helping unravel the mystery.
What can exozodiacal dust, also called exozodi, teach astronomers about identifying Earth-like exoplanets? This is what a recently submitted NASA white paper—which highlights key findings from the annual Architecture Concept Review—hopes to address as a team of researchers discussed how exozodi orbiting within a star's habitable zone (HZ) could interfere with detecting Earth-like exoplanets. This study has the potential to help scientists better understand observational constraints of observing Earth-like exoplanets and what improvements could be made for future telescopes and instruments to overcome these constraints.
The habitable zone is where planets could have liquid water on their surfaces, but not if they're actually habitable. In a new paper, astronomers propose a new way to map the inner edge of habitable zones by searching for sulfur dioxide (SO?) in the atmospheres of exoplanets. If there's SO?, this indicates that the planet doesn't have liquid water on its surface. Telescopes like Webb could scan planets for SO?, creating a more accurate map of habitable zones.
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