Latest news with #Kepler-725c
Yahoo
2 days 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.
The Irish Sun
4 days ago
- General
- The Irish Sun
Super Earth in ‘Goldilocks zone' discovered with new alien-hunting tool – now it will search for more habitable planets
SCIENTISTS have stumbled across a new Super-Earth that orbits inside its star's habitable zone with a new alien-hunting tool. Searching for Earth-like planets - and Earth-like life - is the ultimate goal for planetary science. Advertisement 3 Located in the Lyra constellation, the Super Earth planet completes an orbit of its nearby star every 207.5 days Credit: Alamy 3 An artist's impression of Kepler-725b, a gas giant planet in the same system And finding planets that lie in the Goldilocks zone of their sun-like stars – where the conditions are 'just right' to possibly host life – is key to that mission. An international team of scientists, led by the Yunnan Observatories of the Chinese Academy of Sciences (CAS), have used a new technique to find these potentially habitable worlds. It's called the Transit Timing Variation (TTV) technique - which looks for changes in the predicted transit times of an exoplanet. If the time changes, it could indicate the presence of other unseen planets in the system that are gravitationally influencing the transiting planet. Advertisement READ MORE ON SPACE The technique is a good way to detect smaller planets that would otherwise be difficult to find By analysing the TTV signals of Kepler-725b, a gas giant planet in the same system, the team were able to find its hidden sister planet Kepler-725c, according to a new study in Nature Astronomy . Researchers said the technique offers a promising alternative in the hunt for "Earth 2.0." Kepler-725c has 10 times the mass of Earth and is located in the habitable zone of the sun-like star Kepler-725. Advertisement Most read in Science Breaking It receives roughly 1.4 times the solar radiation than Earth does. Best-ever sign of ALIEN life found on distant planet as scientists '99.7% sure of astounding biological activity signal' Located in the Lyra constellation, the Super Earth planet completes an orbit of its nearby star every 207.5 days. During part of this orbit, the planet enters its star's habitable zone - meaning it could host alien life. Little else is known about the planet so far. Advertisement It is the first time it has been used to discover a Astronomers have relied on alternative techniques to find exoplanets for decades. Like the transit method, where astronomers track how the light from a host star dims when a planet passes in front of it. Or through radial velocity (RV) observations, which is when scientists watch the slight wobble of a star as it interacts with the gravitational pull of an orbiting planet. Advertisement However, both of these techniques have their flaws and make it difficult to detect planets with long orbital periods. The transit approach, for example, requires a planet's orbit to align exactly with our line of sight from Earth. Whereas the RV method requires extremely high-precision measurements, which makes it harder to find smaller planets. 3 An artist's impression of the Kepler-725 system - the small planet in the lower right is the newly discovered Super-Earth in the habitable zone Credit: Gu Shenghong Advertisement All you need to know about planets in our solar system Our solar system is made up of nine planets with Earth the third closest to the Sun. But each planet has its own quirks, so find out more about them all... How old is How many moons does What colour is How far away is How big is How many moons does Does How many moons does How big is How hot is the
