Extrasolar Planets Archives

November 11, 2024November 12, 2024 by Matt Williams

Project Hyperion is Seeking Ideas for Building Humanity’s First Generation Ship

Project Hyperion is the first design competition for a generation ship. Credit: Maciej Rebisz/Michel Lamontagne

The dream of traversing the depths of space and planting the seed of human civilization on another planet has existed for generations. For long as we’ve known that most stars in the Universe are likely to have their own system of planets, there have been those who advocated that we explore them (and even settle on them). With the dawn of the Space Age, this idea was no longer just the stuff of science fiction and became a matter of scientific study. Unfortunately, the challenges of venturing beyond Earth and reaching another star system are myriad.

When it comes down to it, there are only two ways to send crewed missions to exoplanets. The first is to develop advanced propulsion systems that can achieve relativistic speeds (a fraction of the speed of light). The second involves building spacecraft that can sustain crews for generations – aka. a Generation Ship (or Worldship). On November 1st, 2024, Project Hyperion launched a design competition for crewed interstellar travel via generation ships that would rely on current and near-future technologies. The competition is open to the public and will award a total of $10,000 (USD) for innovative concepts.

October 17, 2024October 19, 2024 by Matt Williams

Establishing a New Habitability Metric for Future Astrobiology Surveys

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

The search for exoplanets has grown immensely in recent decades thanks to next-generation observatories and instruments. The current census is 5,766 confirmed exoplanets in 4,310 systems, with thousands more awaiting confirmation. With so many planets available for study, exoplanet studies and astrobiology are transitioning from the discovery process to characterization. Essentially, this means that astronomers are reaching the point where they can directly image exoplanets and determine the chemical composition of their atmospheres.

As always, the ultimate goal is to find terrestrial (rocky) exoplanets that are “habitable,” meaning they could support life. However, our notions of habitability have been primarily focused on comparisons to modern-day Earth (i.e., “Earth-like“), which has come to be challenged in recent years. In a recent study, a team of astrobiologists considered how Earth has changed over time, giving rise to different biosignatures. Their findings could inform future exoplanet searches using next-generation telescopes like the Habitable Worlds Observatory (HWO), destined for space by the 2040s.

October 12, 2024October 14, 2024 by Matt Williams

A Possible Exomoon Could be Volcanic, like Jupiter’s Moon Io

New NASA-led research suggests a sodium cloud seen around the exoplanet WASP-49 b might be created by a volcanic moon, which is depicted in this artist’s concept. Jupiter’s fiery moon Io produces a similar cloud. Credit: NASA/JPL-Caltech

In 2012, astronomers detected a gas giant transiting in front of WASP-49A, a G-type star located about 635 light-years from Earth. The data obtained by the WASP survey indicated that this exoplanet (WASP-49 b) is a gas giant roughly the same size as Jupiter and 37% as massive. In 2017, WASP-49 b was found to have an extensive cloud of sodium, which was confounding to scientists. Further observations in 2019 using the Hubble Space Telescope detected the presence of other minerals, including magnesium and iron, which appeared to be magnetically bound to the gas giant.

WASP-49 b and its star are predominantly composed of hydrogen and helium, with only trace amounts of sodium – not enough to account for this cloud. In addition, there was no indication of how this sodium cloud was ejected into space. In our Solar System, gas emissions from Jupiter’s volcanic moon Io create a similar phenomenon. In a recent study, an international team led by scientists from NASA’s Jet Propulsion Laboratory found potential evidence of a rocky, volcanic moon orbiting WASP-49 b. While not yet confirmed, the presence of a volcanic exomoon around this gas giant could explain the presence of this sodium cloud.

October 10, 2024October 10, 2024 by Matt Williams

Exoplanet Discovered in a Binary System Could Explain Why Red Dwarfs Form Massive Planets

This artist's concept illustrates a red dwarf star surrounded by exoplanets. Credit: NASA/JPL-Caltech

In recent years, the number of known extrasolar planets (aka. exoplanets) has grown exponentially. To date, 5,799 exoplanets have been confirmed in 4,310 star systems, with thousands more candidates awaiting confirmation. What has been particularly interesting to astronomers is how M-type (red dwarf) stars appear to be very good at forming rocky planets. In particular, astronomers have detected many gas giants and planets that are several times the mass of Earth (Super-Earths) orbiting these low-mass, cooler stars.

Consider TOI-6383A, a cool dwarf star less than half the mass of the Sun that orbits with an even smaller, cooler companion – the red dwarf star TOI-6383B. In a recent study, an international team of astronomers with the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey detected a giant planet transiting in front of the primary star, designated TOI-6383Ab. This planet is similar in size and mass to the system’s companion star, which raises questions about the formation of giant planets in red dwarf star systems.

October 1, 2024October 2, 2024 by Matt Williams

An Earth-like Planet Around a Dead Sun Provides Some Reassurance About the Future of Earth

Astronomers have discovered a distant white dwarf with an Earth-like planet in an orbit just beyond where Mars is in our solar system. Earth could end up in such an orbit circling a white dwarf in about 8 billion years, if, like this exoplanet, it can survive the sun's red giant phase on its way to becoming a white dwarf. Credit: Adam Makarenko

In about five billion years, our Sun will exit its main sequence phase and transition to its red giant phase. At this point, the Sun will expand and consume the planets of the inner Solar System, including Mercury and Venus. What will become of Earth when this happens has been the subject of debate for many decades. But with the recent explosion in exoplanet discoveries, 5,759 confirmed in 4,305 systems so far, astronomers hope to learn more about how planets fare as their stars near the end of their life cycle.

Using the 10-meter telescope at the Keck Observatory in Hawaii, an international team of astronomers discovered an Earth-like planet orbiting a white dwarf star 4,000 light-years from Earth. This planet orbits its star, about half the mass of our Sun, at a distance roughly twice that of the Earth today. The system resembles what is expected to become of our system once the Sun has exhausted the last of its fuel and sheds its outer layers. It also offers some assurances that Earth will survive the Sun becoming a red giant and exploding in a supernova.

September 17, 2024September 17, 2024 by Matt Williams

Astronomers Have Found a Star with a Hot Jupiter and a Cold Super Jupiter in Orbit

Artist's vision of a cold super-Jupiter in the HD 118203 system. It is an extremely massive gas planet orbiting its star in an orbit six times that of Earth. Credit: NCU/ Maciejewski, G. et al (2024)

Located in the constellation Ursa Major, roughly 300 light-years from Earth, is the Sun-like star HD 118203 (Liesma). In 2006, astronomers detected an exoplanet (HD 118203 b) similar in size and twice as massive as Jupiter that orbits very closely to Liesma (7% of the distance between Earth and the Sun), making it a “Hot Jupiter.” In a recent study, an international team of astronomers announced the detection of a second exoplanet in this system: a Super Jupiter with a wide orbit around its star. In short, they discovered a “Cold Super-Jupiter” in the outskirts of this system.

August 6, 2024August 6, 2024 by Matt Williams

Elliptical Orbits Could be Essential to the Habitability of Rocky Planets

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle) — This is Kepler 186f, an exoplanet in the habitable zone around a red dwarf. We've found many planets in their stars' habitable zones where they could potentially have surface water. But it's a fairly crude understanding of true habitability. Image Credit: NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

A seismic shift occurred in astronomy during the Scientific Revolution, beginning with 16th-century polymath Copernicus and his proposal that the Earth revolved around the Sun. By the 17th century, famed engineer and astronomer Galileo Galilei refined Copernicus’ heliocentric model using observations made with telescopes he built himself. However, it was not until Kepler’s observations that the planets followed elliptical orbits around the Sun (rather than circular orbits) that astronomical models matched observations of the heavens completely.

As it turns out, this very quirk of orbital mechanics may be essential to the emergence of life on planets like Earth. That was the hypothesis put forth in a recent study by a team of astronomers led by the University of Leeds. According to their work, orbital eccentricity (how much a planet’s orbit deviates from a circle) can influence a planet’s climate response, which could have a profound effect on its potential habitability. These findings could be significant for exoplanet researchers as they continue to search for Earth-like planets that could support life.

August 5, 2024August 5, 2024 by Matt Williams

Habitable Planet’s Orbiting Red Dwarf Suns Could at Risk from Far-Ultraviolet Radiation

Artist's depiction of red-dwarf-flare. Image credit: Casey Reed/NASA

The question of whether or not red dwarf stars can support habitable planets has been subject to debate for decades. With the explosion in exoplanet discoveries in the past two decades, the debate has become all the more significant. For starters, M-type (red dwarf) stars are the most common in the Universe, accounting for 75% of the stars in our galaxy. Additionally, exoplanet surveys indicate that red dwarfs are particularly good at forming Earth-like rocky planets that orbit within their circumsolar habitable zones (CHZs).

Unfortunately, a considerable body of research has shown that planets orbiting red dwarf suns would be subject to lots of flare activity – including some so powerful they’re known as “superflares.” In a recent study led by the University of Hawai’i, a team of astrophysicists revealed that red dwarf stars can produce stellar flares with significantly more far-ultraviolet radiation than previously expected. Their findings could have drastic implications for exoplanet studies and the search for extraterrestrial life on nearby rocky planets.

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.