super-Earth planets Archives

July 16, 2023July 16, 2023 by Brian Koberlein

Liquid Water on Rocky Planets Could be 100 Times More Likely

Artist’s impression, frozen world with sub-surface ocean. Credit: Bryce Troncone

It’s easy to think of Earth as a water world, with its vast oceans and beautiful lakes, but compared to many worlds, Earth is particularly wet. Even the icy moons of Jupiter and Saturn have far more liquid water than Earth. Earth is unusual not because it has liquid water, but because it has liquid water in the warm habitable zone of the Sun. And as a new study in Nature Communications shows, Earth could be even more unusual than we thought.

February 16, 2023February 16, 2023 by Evan Gough

What Would Happen if the Solar System Gained a Super-Earth?

This illustration shows the super-Earth exoplanet 55 Cancri e with its star. What would our Solar System be like if it was home to a super-Earth like this one? Credit: NASA/JPL

In this era of exoplanet discovery, astronomers have found over 5,000 confirmed exoplanets, with thousands more awaiting confirmation and many billions more waiting to be discovered. These exoplanets exist in a bewildering spectrum of sizes, compositions, orbital periods, and just about every other characteristic that can be measured.

Learning about them has also shed light on our Solar System. We used to think of it as an archetypal arrangement of planets since it’s all we had to go on. But now we know we might be the outlier because we have no Super-Earth.

December 9, 2022December 9, 2022 by Evan Gough

This Hellish Planet Orbits its Star Every 18 Hours. How Did it Get There?

An artist’s impression of the planet 55 Cnc e (smaller, dark orange circle) blocking the light from its rotating host star. Image Credit: Maggie Chiang/Simons Foundation

Astronomers discovered 55 Cancri e in 2004. That was five years before NASA’s Kepler planet-hunting spacecraft was launched, and exoplanet science has come a long way in the intervening years. Astronomers discovered the planet with the radial velocity method rather than Kepler’s transit method. 55 Cancri e was the first super-Earth found around a main-sequence star. The 55 Cancri system was also the first star discovered with four, and then five, planets.

The discovery was big news then; over the years, follow-up work has revealed more details, including that 55 Cancri e is extremely close to its star and has a molten surface.

But one question remained unanswered: How did it get there?

November 9, 2022November 9, 2022 by Matt Williams

The Case of the “Missing Exoplanets”

An illustration of the variations among the more than 5,000 known exoplanets discovered since the 1990s. Could their stars' metallicity play a role in making them habitable to life? Credit: NASA/JPL-Caltech

Today, the number of confirmed exoplanets stands at 5,197 in 3,888 planetary systems, with another 8,992 candidates awaiting confirmation. The majority have been particularly massive planets, ranging from Jupiter and Neptune-sized gas giants, which have radii about 2.5 times that of Earth. Another statistically significant population has been rocky planets that measure about 1.4 Earth radii (aka. “Super-Earths”). This presents a mystery to astronomers, especially where the exoplanets discovered by the venerable Kepler Space Telescope are concerned.

Of the more than 2,600 planets Kepler discovered, there’s an apparent rarity of exoplanets with a radius of about 1.8 times that of Earth – which they refer to as the “radius valley.” A second mystery, known as “peas in a pod,” refers to neighboring planets of similar size found in hundreds of planetary systems with harmonious orbits. In a study led by the Cycles of Life-Essential Volatile Elements in Rocky Planets (CLEVER) project at Rice University, an international team of astrophysicists provide a new model that accounts for the interplay of forces acting on newborn planets that could explain these two mysteries.

September 27, 2022September 27, 2022 by Matt Williams

TESS Finds a Super-Earth and two Mini-Neptunes in a Single System

An artist’s rendition of the Transiting Exoplanet Survey Satellite (TESS). Credit: NASA's Goddard Space Flight Center

The field of extrasolar planet studies continues to grow by leaps and bounds. Currently, 5,090 exoplanets have been confirmed in 3,816 systems, and another 8,933 candidates are awaiting confirmation. The majority of these have been Neptune-like gas giants (1,779), gas giants comparable to Jupiter or Saturn (1,536), and rocky planets many times the size of Earth (1,582). The most effective means for finding exoplanets has been the Transit Method (aka. Transit Photometry), where periodic dips in a star’s brightness are seen as an indication of a planet passing in front of its star (transiting) relative to the observer.

Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a three-planet system orbiting a Sun-like star (HD 22946, or TOI 11) located about 205.5 light-years. Based on size estimates yielded from their transits, the team theorizes that these exoplanets consist of a rocky planet several times the size of Earth (a Super-Earth) and two gas giants smaller than Neptune. Given its proximity, this system could be ideal for follow-up studies and characterization with the James Webb Space Telescope (JWST).

June 16, 2022June 16, 2022 by Evan Gough

Two New Rocky Planets Discovered Close to the Solar System

An artist's illustration of two newly-discovered super-Earths. They're only 33 light years away and they orbit a red dwarf named HD 260655. Image Credit: NASA/JPL-Caltech

TESS has struck paydirt again. NASA’s planet-hunting spacecraft has found two new super-Earths orbiting a star only 33 light-years away. These are two of the closest rocky planets ever found.

March 7, 2022March 7, 2022 by Evan Gough

What’s it Like Inside a Super-Earth?

This artist’s impression shows the planet orbiting the Sun-like star HD 85512 in the southern constellation of Vela (The Sail). This planet is one of sixteen super-Earths discovered by the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory. This planet is about 3.6 times as massive as the Earth lis at the edge of the habitable zone around the star, where liquid water, and perhaps even life, could potentially exist. Credit: ESO

We know a ton about the inside of Earth. We know it has both an inner core and an outer core and that the churning and rotation create a protective magnetosphere that shields life from the Sun’s radiative power. It has a mantle, primarily solid but also home to magma. We know it has a crust, where we live, and plate tectonics that moves the continents around like playthings.

But what about Super-Earths? We know they’re out there; we’ve found them. What do we know about their insides? Earth’s structure, and its ability to support life, are shaped by the extreme pressure and density in its interior. The pressure and temperature inside Super-Earths are even more powerful. How does it shape these planets and affect their habitability?

October 15, 2021October 15, 2021 by Matt Williams

Rocky Planets Might Need to be the Right age to Support Life

Extrasolar planets are being discovered at a rapid rate, with 4,531 planets in 3,363 systems (with another 7,798 candidates awaiting confirmation). Of these, 166 have been identified as rocky planets (aka. “Earth-like”), while another 1,389 have been rocky planets that are several times the size of Earth (“Super-Earths). As more and more discoveries are made, the focus is shifting from the discovery process towards characterization.

In order to place tighter constraints on whether any of these exoplanets are habitable, astronomers and astrobiologists are looking for ways to detect biomarkers and other signs of biological processes. According to a new study, astronomers and astrobiologists should look for indications of a carbon-silicate cycle. On Earth, this cycle ensures that our climate remains stable for eons and could be the key to finding life on other planets.

October 3, 2021October 3, 2021 by Matt Williams

Astronomers Look at Super-Earths That had Their Atmospheres Stripped Away by Their Stars

Figure 1: Artist’s conceptual image showing the sizes of the planets observed in this study. The radius of TOI-1634 is 1.5 times larger than Earth’s radius and TOI-1685 is 1.8 times larger. The planets would appear red, due to the light from the red dwarf stars they orbit. (Credit: Astrobiology Center, NINS)

As the planets of our Solar System demonstrate, understanding the solar dynamics of a system is a crucial aspect of determining habitability. Because of its protective magnetic field, Earth has maintained a fluffy atmosphere for billions of years, ensuring a stable climate for life to evolve. In contrast, other rocky planets that orbit our Sun are either airless, have super-dense (Venus), or have very thin atmospheres (Mars) due to their interactions with the Sun.

In recent years, astronomers have been on the lookout for this same process when studying extrasolar planets. For instance, an international team of astronomers led by the National Astronomical Observatory of Japan (NAOJ) recently conducted follow-up observations of two Super-Earths that orbit very closely to their respective stars. These planets, which have no thick primordial atmospheres, represent a chance to investigate the evolution of atmospheres on hot rocky planets.

September 4, 2021September 4, 2021 by Matt Williams

Ocean Worlds With Hydrogen-Rich Atmospheres Could be the Perfect Spots for Life

Artist's impression of the surface of a "Hycean" world. Credit: University of Cambridge

The search for planets beyond our Solar System (extrasolar planets) has grown by leaps and bounds in the past decade. A total of 4,514 exoplanets have been confirmed in 3,346 planetary systems, with another 7,721 candidates awaiting confirmation. At present, astrobiologists are largely focused on the “low hanging fruit” approach of looking for exoplanets that are similar in size, mass, and atmospheric composition to Earth (aka. “Earth-like.”)

However, astrobiologists are also interested in finding examples of “exotic life,” the kind that emerged under conditions that are not “Earth-like.” For example, a team of astronomers from the University of Cambridge recently conducted a study that showed how life could emerge on ocean-covered planets with hydrogen-rich atmospheres (aka. “Hycean” planets). These findings could have significant implications for exoplanet studies and the field of astrobiology.