Thibault Roger/NCCR PlanetS
The orbits of six planets orbiting a star called HD110067 draw a geometric pattern due to resonance.
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Astronomers have used two different exoplanet-detecting satellites to unravel the mysteries of the universe, revealing an unusual family of six planets about 100 light-years from Earth. This discovery could help scientists uncover the secrets of planet formation.
The six exoplanets orbit a bright Sun-like star called HD110067, located in the constellation Coma in the northern sky. Larger than Earth and smaller than Neptune, these planets belong to a little-understood class called sub-Neptunes, which are commonly found around sun-like stars in the Milky Way. The planets, labeled b through g, then rotate around the star in a celestial dance known as orbital resonance.
Research published Wednesday shows that there are discernible patterns as the planets orbit each other and exert their gravitational forces on each other. journal nature. For every planet b, the closest planet to the star, completes her six orbits, the outermost planet g completes one of her orbits.
If planet c orbits the star three times, planet d will orbit the star twice, and if planet e orbits the star four times, planet f will orbit the star three times.
This harmonic rhythm creates a resonance chain in which all six planets align every few orbits.
What makes this planetary system a rare discovery is that it has remained largely unchanged since it formed more than a billion years ago, a revelation that sheds light on the planet’s evolution and prevalent sub-Neptunian origins. This means that there is a possibility that in our home galaxy.
Researchers first noticed this system in 2020 when NASA’s Transiting Exoplanet Survey Satellite (TESS) detected a decrease in HD110067’s brightness. Drops in starlight often suggest the presence of a planet that passes between the host star and an observing satellite as it moves along its orbit. Detecting these dips in luminosity, known as transit methods, is one of the main strategies scientists use to identify exoplanets with ground-based and space-based telescopes.
From that 2020 data, astronomers determined the orbital periods of the two planets around the star. Two years later, TESS observed the star again, and the evidence suggested that the orbital periods of these planets were different.
When the datasets didn’t match, astronomer and study lead author Rafael Luque and several colleagues decided to take another look at the star using a different satellite. Features of the European Space Agency’s ExOPlanet satellite, or Cheops. TESS is used to observe parts of the night sky in short observations, while Cheops observes her one star at a time.
ESA/ATG Media Lab
This artist’s illustration shows King Khufu exploring exoplanets in orbit around Earth.
“We went looking for signals among all the possible periods these planets could have,” said Luque, a postdoctoral fellow in the University of Chicago’s Department of Astronomy and Astrophysics.
The data collected by Cheops helped the team solve the “detective story” initiated by TESS, he said. Kufps was able to confirm the existence of his third planet in the system. This was important to confirm the orbital periods of his two other planets and their rhythmic resonances.
When the researchers matched the remaining unresolved TESS data with observations of Khupus, they discovered three other planets orbiting the star. Follow-up observations with ground-based telescopes confirmed the existence of the planet.
The time Khufus spent observing the star helped astronomers unravel the mixed signals from TESS data and determine the number of planets passing in front of the star and the resonance of their orbits.
“Cheops has given us this resonance configuration that allows us to predict all other periods. Without Cheops’ discovery, that would not have been possible,” Luque said.
The closest planet takes just over 9 Earth days to orbit the star, and the most distant planet takes about 55 days. All planets orbit their stars faster than Mercury, which takes 88 days to orbit the sun once.
Given how close they are to HD110067, the average temperature of these planets could range from 332 degrees Fahrenheit to 980 degrees Fahrenheit (167 degrees Celsius to 527 degrees Celsius), similar to Mercury and Venus.
Like our solar system, the formation of planetary systems can be a violent process. Astronomers believe that planets initially tend to form in resonance around stars, but then due to the gravitational influence of giant planets, grazing with passing stars, or collisions with other celestial bodies. , the harmonic balance may be disrupted.
Most planetary systems are not in resonance, and planetary systems in which multiple planets preserve their initial rhythmic orbits are rare. That’s why astronomers want to study HD110067 and its planet in detail as a “rare fossil,” Luque said.
“We believe that only about 1% of all systems are in resonance,” Luque said in a statement. “It shows the primitive configuration of a planetary system that has survived untouched.”
This discovery marks the second time Kufus has contributed to the elucidation of planetary systems with orbital resonance.The first one is known as TOI-178, announced in 2021.
“As our science team says, Cheops is making outstanding discoveries that seem trivial. Of only three known six-planet resonance systems, this one was made by Cheops in just three years. “This is the second system to be discovered in operation,” ESA Cheops project scientist Maximilian Günther said in a statement.
The system can also be used to study how sub-Neptune forms, the study authors said.
Subneptunes are common in the Milky Way, but they are absent from our solar system. And there is little agreement among astronomers about how these planets form or what they are made of. So the entire system of stars smaller than Neptune could help scientists further understand the origins of planets, Luque said.
Many exoplanets have been discovered orbiting small dwarf stars that are much cooler than the Sun. The famous TRAPPIST-1 system and its seven planetsThe TRAPPIST-1 system also has a resonance chain, but it is difficult to observe because the host star is dark.
But with 80% the mass of the Sun, HD110067 is the brightest known star with four or more planets in orbit, making the system much easier to observe.
Initial detections of the planets’ masses suggest that some of them have swollen hydrogen-rich atmospheres, making them ideal study targets for the James Webb Space Telescope. As starlight passes through the planet’s atmosphere, the web can be used to determine the composition of each world.
“Neptune’s subplanets in the HD110067 system appear to be low-mass, suggesting they may be rich in gas or water. In the future, we will be able to study the atmospheres of these planets using, for example, the James Webb Space Telescope. “Observations of the planet could reveal whether the planet’s internal structure is rocky or water-rich,” said study co-author Jo Ann Egger, a doctoral student in astrophysics at the University of Bern in Switzerland. Ta. In a statement.