exoplanets Archives

July 25, 2024July 25, 2024 by Matt Williams

Planetary Habitability Depends on its Star’s Magnetic Field

Earth's magnetosphere is the region defined by our planet's magnetic field. Image Credit: NASA

The extrasolar planet census recently passed a major milestone, with 5500 confirmed candidates in 4,243 solar systems. With so many exoplanets available for study, astronomers have learned a great deal about the types of planets that exist in our galaxy and have been rethinking several preconceived notions. These include the notion of “habitability” and whether Earth is the standard by which this should be measured – i.e., could there be “super habitable” exoplanets out there? – and the very concept of the circumsolar habitable zone (CHZ).

Traditionally, astronomers have defined habitable zones based on the type of star and the orbital distance where a planet would be warm enough to maintain liquid water on its surface. But in recent years, other factors have been considered, including the presence of planetary magnetic fields and whether they get enough ultraviolet light. In a recent study, a team from Rice University extended the definition of a CHZ to include a star’s magnetic field. Their findings could have significant implications in the search for life on other planets (aka. astrobiology).

July 23, 2024July 23, 2024 by Matt Williams

The Ultraviolet Habitable Zone Sets a Time Limit on the Formation of Life

Artist's impression of the range of habitable zones for different types of stars. Credit: NASA/Kepler Mission/Dana Berry

The field of extrasolar planet studies has grown exponentially in the past twenty years. Thanks to missions like Kepler, the Transiting Exoplanet Survey Satellite (TESS), and other dedicated observatories, astronomers have confirmed 5,690 exoplanets in 4,243 star systems. With so many planets and systems available for study, scientists have been forced to reconsider many previously-held notions about planet formation and evolution and what conditions are necessary for life. In the latter case, scientists have been rethinking the concept of the Circumsolar Habitable Zone (CHZ).

By definition, a CHZ is the region around a star where an orbiting planet would be warm enough to maintain liquid water on its surface. As stars evolve with time, their radiance and heat will increase or decrease depending on their mass, altering the boundaries of the CHZ. In a recent study, a team of astronomers from the Italian National Institute of Astrophysics (INAF) considered how the evolution of stars affects their ultraviolet emissions. Since UV light seems important for the emergence of life as we know it, they considered how the evolution of a star’s Ultraviolet Habitable Zone (UHZ) and its CHZ could be intertwined.

June 28, 2024June 28, 2024 by Evan Gough

Take a Look at These Stunning New Exoplanet Infographics

"Icy and Rocky Worlds" is a new exoplanet infographic from Martin Vargic, an artist and space enthusiast from Slovakia. It's available as a wall poster on his website. Image Credit and Copyright: Martin Vargic.

Martin Vargic is a space enthusiast, author, and graphic artist from Slovakia. He created two new infographic posters that show almost 1600 exoplanets of different types and sizes. One is called Icy and Rocky Worlds, and the other is called The Exoplanet Zoo.

June 28, 2024June 28, 2024 by Evan Gough

Could We Detect an Alien Civilization Trying to Warm Their Planet?

This artist's illustration shows a hypothetical Earth-like inhabited planet being terraformed with artificial greenhouse gases. We could detect these chemicals with infrared spectroscopy. Image Credit: Sohail Wasif, UC Riverside/Schwieterman et al. 2024

Humanity is facing an atmospheric threat of our own device, and our internecine squabbles are hampering our ability to neutralize that threat. But if we last long enough, the reverse situation will arise. Our climate will cool, and we’ll need to figure out how to warm it up. If that day ever arises, we should be organized enough to meet the challenge.

If there are other civilizations out there in the galaxy, one may already be facing a cooling climate or an ice age. Could we detect the greenhouse chemicals they would be purposefully emitting into their atmosphere in an attempt to warm their planet?

June 17, 2024June 17, 2024 by Andy Tomaswick

Which Stars are Lethal to their Planets?

Many years ago, there was a viral YouTube video called “History of the entire world, i guess,” which has been an endless source of internet memes since its release. One of the most prominent is also scientifically accurate—when describing why animals couldn’t start living on land, the video’s creator, Bill Wurtz, intones, “The Sun is a deadly laser.”

June 9, 2024June 9, 2024 by Matt Williams

Instead of Losing its Atmosphere, an Exoplanet Puffed Up and Held Onto it

Artist's impression of the "hot Neptune" Phoenix orbiting its red giant star. Credit: Credit: Roberto Molar Candanosa/JHU

To date, astronomers have confirmed the existence of 5638 extrasolar planets in 4,199 star systems. In the process, scientists have found many worlds that have defied expectations. This is certainly the case regarding “hot Neptunes,” planets that are similar to the “ice giants” of the outer Solar System but orbit much closer to their stars. But when a Johns Hopkins University-led team of astronomers discovered TIC365102760 b (aka. Pheonix), they observed something entirely unexpected: a Neptune-sized planet that retained its atmosphere by puffing up.

June 3, 2024June 3, 2024 by Andy Tomaswick

Suppressing Starlight: How to Find Other Earths

One underappreciated aspect of the current flood of exoplanet discoveries is the technical marvels that enable it. Scientists and engineers must capture and detect minute signals from stars and planets light years away. With the technologies of even a few decades ago, that would have been impossible – now it seems commonplace. However, there are still some technical hurdles to overcome before finding the “holy grail” of exoplanet hunting – an Earth analog. To help that discussion, a team of researchers led by Bertrand Mennesson at NASA’s Jet Propulsion Laboratory has released a paper detailing the current experimental and theoretical work around one of the most critical technical aspects of researching exoplanet atmospheres – starshades.

May 29, 2024May 29, 2024 by Andy Tomaswick

A Mini-Neptune in the Habitable Zone in a Binary Star System

Sometimes, it seems like habitable worlds can pop up almost anywhere in the universe. A recent paper from a team of citizen scientists led by researchers at the Flatiron Institute might have found an excellent candidate to look for one – on a moon orbiting a mini-Neptune orbiting a star that is also orbited by another star.

May 23, 2024May 23, 2024 by Andy Tomaswick

A New Venus-Sized World Found in the Habitable Zone of its Star

The parade of interesting new exoplanets continues. Today, NASA issued a press release announcing the discovery of a new exoplanet in the Gliese 12 system, sized somewhere between Earth and Venus and inside the host star’s habitable zone. Two papers detail the discovery, but both teams think that the planet is an excellent candidate for follow-up with the James Webb Space Telescope (JWST) to try to tease out whether it has an atmosphere and, if so, what that atmosphere is made of.

May 18, 2024May 18, 2024 by Matt Williams

Astronomers Discover the Second-Lightest “Cotton Candy” Exoplanet to Date.

A NASA illustration of the giant planet WASP-193b and its star. Credit: NASA/ESA/CSA)

The hunt for extrasolar planets has revealed some truly interesting candidates, not the least of which are planets known as “Hot Jupiters.” This refers to a particular class of gas giants comparable in size to Jupiter but which orbit very closely to their suns. Strangely, there are some gas giants out there that have very low densities, raising questions about their formation and evolution. This is certainly true of the Kepler 51 system, which contains no less than three “super puff” planets similar in size to Jupiter but is about one hundred times less dense.

These planets also go by the moniker “cotton candy” giants because their density is comparable to this staple confection. In a recent study, an international team of astronomers spotted another massive planet, WASP-193b, a fluffy gas giant orbiting a Sun-like star 1,232 light-years away. While this planet is roughly one and a half times the size of Jupiter, it is only about 14% as massive. This makes WASP-193b the second-lightest exoplanet observed to date. Studying this and other “cotton candy” exoplanets could provide valuable insight into how these mysterious giants form.