Latest news with #TRAPPIST-1
Yahoo
17 hours ago
- Science
- Yahoo
A hidden 'super-Earth' exoplanet is dipping in and out of its habitable zone
When you buy through links on our articles, Future and its syndication partners may earn a commission. A huge "super-Earth" with an extreme climate that results in it being habitable for only part of its orbit has been discovered orbiting a star 2,472 light years away. And the most remarkable thing is, it was discovered without even being directly detected. The discovery of the exoplanet, a super-Earth called Kepler-735c, is all down to something called transit timing variations, or TTVs for short. Let's set the scene. One of the primary ways of discovering exoplanets is by looking for when they transit, or pass in front of, their star. As they do so, they block a small fraction of that star's light, and, based on the size of this dip in stellar brightness, we can determine how large the transiting planet must be. Indeed, this was how the most successful exoplanet hunter so far, NASA's Kepler space telescope, discovered over 3,300 confirmed exoplanets and thousands more candidates. There are downsides to detecting exoplanets via transits, however. One is that the technique is biased toward planets on short orbits close to their star, which means they transit more often and are easier to see. Transits also require a precise alignment between the orbital plane of a planetary system and our line of sight. Even a small tilt might mean we cannot see planets on wider orbits transiting. Those unseen planets on wider orbits can still make their presence felt, however, in the form of TTVs. Ordinarily, transits are as regular as clockwork, but in some cases astronomers have noticed that a planet's transit can be delayed, or occur ahead of schedule, and that this is being caused by the gravity of other planets tugging on the transiting world. Sometimes we can see those other planets transiting as well — the seven-planet TRAPPIST-1 system is a great example. Often, though, we can't see the planet that is causing the variations, but the size and frequency of the TTVs can tell us about the orbital period and mass of these hidden worlds. One such planet that has been found to experience TTVs is Kepler-725b. It's a gas giant planet orbiting a yellow sun-like star that was discovered by the now-defunct Kepler spacecraft. "By analyzing the TTV signals of Kepler-725b, a gas giant planet with a 39.64-day period in the same system, the team has successfully inferred the mass and orbital parameters of the hidden planet Kepler-725c," Sun Leilei, of the Yunnan Observatories of the Chinese Academy of Sciences, said in a statement. Sun is the lead author of a new study revealing the existence of this hidden world. Kepler-725c's mass is quite significant — 10 times greater than the mass of Earth. This places it in the upper echelons of a type of planet called super-Earths — giant, probably rocky worlds. We don't have an example of a super-Earth in our solar system, so we don't really know what such planets are like. Planetary scientists are still grappling with theoretical models that attempt to describe the properties of super-Earth worlds. Would they be wrapped in a dense atmosphere? Could they maintain plate tectonics? How would their higher surface gravity affect the evolution of life? Definitive answers to these questions have not yet been forthcoming. Meanwhile, the planet's orbit is unusual to say the least. It is highly elliptical, with an eccentricity of 0.44. For comparison, Earth's orbit has an eccentricity of 0.0167 and is therefore close to circular; at the other extreme, an orbital eccentricity of 1 would be parabolic. Kepler-7825c's orbit is oval-shaped, meaning that at some points in its orbit it is much closer to its star than at other times. While overall Kepler-725c receives 1.4 times as much heat from its star as Earth does from the sun, this is just the average over the course of its orbit, and at times it is receiving less. If Kepler-725c has an atmosphere, then the difference in solar heating at different times in its orbit could wreak havoc on its climate. In fact, the high orbital eccentricity actually means that the exoplanet only spends part of its orbit in the habitable zone, which is a circular zone around the star at a distance where temperatures are suitable for liquid water on a planet's surface. Related Stories: — Exoplanets: Everything you need to know about the worlds beyond our solar system — Scientists discover super-Earth exoplanets are more common in the universe than we thought — Does exoplanet K2-18b host alien life or not? Here's why the debate continues Does this mean that Kepler-725c is only habitable for part of its 207.5-Earth-day year? What would happen to any life that might exist on the planet during the periods that it is outside of the habitable zone? Again, these are theoretical problems that scientists have been wrestling with, but now the existence of Kepler-725c suddenly makes them very real problems. However, because we do not see Kepler-725c transit, it will not be possible to probe its atmosphere with the James Webb Space Telescope, which uses sunlight filtered through a planet's atmosphere to make deductions about the properties and composition of that atmosphere. Fortunately, there may be more such worlds out there to study. It is expected that when the European Space Agency's PLATO (PLAnetary Transits and Oscillations of stars) spacecraft launches in 2026 as our most sensitive exoplanet-detecting mission yet, it will be able to find many more worlds through TTVs. And, unlike radial velocity and transit measurements, which tend to be biased toward finding short-period exoplanets, TTVs open a window onto planets on wider orbits that are not seen to transit. "[Kepler-725c's discovery] demonstrates the potential of the TTV technique to detect low-mass planets in habitable zones of sun-like stars," said Sun. By doing so, the TTV method will help further the search for life in the universe, if only in providing more statistics as to the numbers of habitable zone planets that are out there. The discovery of Kepler-725c was reported on Tuesday (June 3) in the journal Nature Astronomy.
Yahoo
19-05-2025
- Science
- Yahoo
TRAPPIST-1 Planets Could Be Swimming in Water, Study Shows
A seven-planet system some 40 light-years from Earth could be swimming in water, new research shows. In February 2017 scientists announced the discovery of several exoplanets orbiting the red dwarf star TRAPPIST-1, and ever since astronomers have keenly monitored the system for potential signs of life (aka biosignatures). According to recent findings, these planets may have an abundance of one of the most crucial elements for life: water. Since the discovery, scientists have gone back and forth on whether any planets in the TRAPPIST-1 system could be habitable. Much like the Proxima Centauri system and its Earth-like planet (Proxima b), the debate has centered on their parent stars: M-type (red dwarf) stars. These stars are smaller and cooler than our Sun and are noted for the way they are prone to flare activity. Another major question is the availability of water in this system. Previous findings have indicated that planets orbiting red dwarfs may have an overabundance of water, but they may not hold onto it for long. These findings are supported by other research that has revealed that these planets experience high rates of water lost to space, caused by the intense ultraviolet (UV) radiation from their host star. In a new study, a team of researchers led by astrobiologist Trent Thomas from the University of Washington addressed recent findings by the JWST. Recent observations by JWST of TRAPPIST-1 c ruled out a thick carbon dioxide atmosphere, indicating that the planet is not as "Venus-like" as previously thought. However, these observations did not rule out the presence of water vapor or oxygen produced by its chemical dissociation. As the team explained in their paper, "the maintenance of atmospheric water vapor would require a present-day water source, such as volcanic outgassing." To investigate this possibility and estimate plausible outgassing rates on the TRAPPIST-1 planets, the team developed a theoretical outgassing model based on the rocky planets of the Solar System ( Mercury, Venus, Earth, and Mars). They then applied filters based on observations of the system and what is known about its geochemistry to constrain plausible scenarios. Their findings indicated that the outgassing rates of all seven planets would be between 0.03 and eight times that of Earth. However, they also found that magma emplacement rates (the speed at which magma moves through a planet) were similar to those of Mars. While there are indications that Mars still has magma beneath its surface, it is considered 'volcanically dead'. The same may be true of the TRAPPIST-1 planets. "Our model results for magma emplacement rates also indicate that the TRAPPIST-1 planets are currently more likely to have low-to-no volcanic activity," the researchers write in their paper. "Our results indicate that the water outgassing rates on the TRAPPIST-1 planets are more likely to be lower than Earth's, but the plausible range also includes outgassing rates that are an order of magnitude higher than Earth's." Their results further indicated that the TRAPPIST-1 planets may have relatively dry Earth-like mantles. But as they emphasized, it is possible that water could make up to 1 percent of their mass fractions. "Our results indicate that drier mantles are preferred within the broader explored range of mantle water content," the team explains. "This arises due to our assumption that the TRAPPIST-1 planets have terrestrial interiors with mantle water contents that remain below 1 percent by weight upper limit throughout the 5.4 billion-year age of the TRAPPIST-1 system. The preference for lower mantle H2O values is more consistent with Earth's mantle water content." This is especially interesting considering that while water covers about 71 percent of Earth's surface, it constitutes only about 0.02 percent of its total mass. This could mean that planets orbiting within TRAPPIST-1's habitable zone are volcanically inactive and have varying degrees of water, ranging from potential 'water worlds' and barren rocky worlds to Earth-like planets covered in oceans. These results reinforce the idea that the TRAPPIST-1 system has no shortage of water. Unfortunately, many questions remain about its habitability. Fortunately, Webb's observations of TRAPPIST-1 (and other red dwarf systems) are still in their infancy. Additional observations will allow astronomers to constrain the potential habitability of this system. Their findings were reported in a preprint available on arXiv. Unknown Species of Bacteria Discovered in China's Space Station NASA Mission Captures Eerie New View of The Moon And Sun Mysteriously Perfect Sphere Spotted in Space by Astronomers
Yahoo
25-02-2025
- Science
- Yahoo
Exoplanetary parade: What would the night sky look like on alien worlds? (op-ed)
When you buy through links on our articles, Future and its syndication partners may earn a commission. If you have a clear view of the night sky at the end of February, you'll be able to see all the planets in the solar system with the naked eye, lined up in a "planetary parade." But what would these planetary alignments look like if you could stargaze from extraterrestrial worlds? Right now, six of the seven planets — not including Earth — are visible to the naked eye. If you can get away from the city lights and if it's not too cloudy, tonight you will be able to look up and see Venus, Mars, Jupiter, Saturn, Uranus and Neptune. You can add Mercury — the smallest of all the planets in our solar system — to that bucket list later this month. All the planets revolve around the sun in the same plane, which astronomers call the ecliptic. As they speed through their orbits in concert, the distances between each pair of planets grow and shrink. When we look up at the night sky, how bright the planets appear depends on how close they are at that precise moment in time. At the end of February, all the planets will be close enough to Earth to be visible with the naked eye. Because they all orbit in the ecliptic plane, we see them in a magnificent arc across the night sky — the great parade. Related: Planetary parade February 2025: When, where and how to see it There is an abundance of rocky worlds throughout our solar system, from the rocky planets to the moons around our gas and ice giants. Europa is one of the closest moons of the gas giant Jupiter. Scientists believe that there is a subsurface ocean beneath Europa's icy shell that contains more water than all of Earth's oceans combined. What views of the night sky would we have if we had evolved on Europa instead of on Earth? Unfortunately, we would never get to see all the planets in alignment; in fact, we would never get an unaided view of Mercury. However, any planetary alignment seen from Europa — any view of the night sky at all, for that matter — would look nothing like what we are used to looking up and seeing here on Earth. The size of a celestial object in the night sky depends on both its physical size and — just as importantly — its distance from the observer. Stargazing from Europa, Jupiter would look 20 times larger than the size of the moon we see in our own night sky. The Great Red Spot alone would be bigger than the sun! Bizarre as it seems, the sun would only appear as a faint orange glow, five times smaller than for us here on Earth. We have discovered thousands of planets orbiting stars outside of our own solar system. Taking our hypothetical stargazing scenario a step further, what if we could look at the night sky from one of these extrasolar worlds? An exquisite seven-planet system orbits around the star TRAPPIST-1. TRAPPIST-1 is a red dwarf; as the name suggests, it's much smaller and redder than the sun. The orbits of all seven planets would fit inside the orbit of Mercury around our own sun. Because they orbit so close, each planet revolves around TRAPPIST-1 much faster than the amount of time it takes Earth to revolve around the sun. If we had evolved on TRAPPIST-1 b — the closest planet in the system — you would be able to step outside and see planetary parades of the other six TRAPPIST planets every few days. But these alignments would be far more breathtaking than any views we get here on Earth. You'd have a dazzling backdrop of the red dwarf TRAPPIST-1, seeing it 10 times larger than the sun looks to us. You'd also be able to watch planets vanish behind the red dwarf and then grow larger than the moon every few days. You could sit back and enjoy an ever-changing planetary menagerie. Related stories: — The brightest planets in February's night sky: How to see them (and when) — Night sky, February 2025: What you can see tonight [maps] — Best telescopes for beginners 2025: Start your stargazing journey with our pick of the best beginner-friendly telescopes. So, where is the best place from which to stargaze? Maybe Earth is special. It just so happens that life evolved on a planet where we can look up at the night sky and every so often see all the other planets in our solar system. I think I would rather look up close at Jupiter every night.
