. 24/7 Space News .
EXO WORLDS
Puzzling six-exoplanet system with rhythmic movement challenges theories of how planets form
by Staff Writers
Munich, Germany (SPX) Jan 26, 2021

stock illustration only

Using a combination of telescopes, including the Very Large Telescope of the European Southern Observatory (ESO's VLT), astronomers have revealed a system consisting of six exoplanets, five of which are locked in a rare rhythm around their central star. The researchers believe the system could provide important clues about how planets, including those in the Solar System, form and evolve.

The first time the team observed TOI-178, a star some 200 light-years away in the constellation of Sculptor, they thought they had spotted two planets going around it in the same orbit. However, a closer look revealed something entirely different. "Through further observations we realised that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration," says Adrien Leleu from the Universite de Geneve and the University of Bern, Switzerland, who led a new study of the system published in Astronomy and Astrophysics.

The new research has revealed that the system boasts six exoplanets and that all but the one closest to the star are locked in a rhythmic dance as they move in their orbits. In other words, they are in resonance. This means that there are patterns that repeat themselves as the planets go around the star, with some planets aligning every few orbits. A similar resonance is observed in the orbits of three of Jupiter's moons: Io, Europa and Ganymede. Io, the closest of the three to Jupiter, completes four full orbits around Jupiter for every orbit that Ganymede, the furthest away, makes, and two full orbits for every orbit Europa makes.

The five outer exoplanets of the TOI-178 system follow a much more complex chain of resonance, one of the longest yet discovered in a system of planets. While the three Jupiter moons are in a 4:2:1 resonance, the five outer planets in the TOI-178 system follow a 18:9:6:4:3 chain: while the second planet from the star (the first in the resonance chain) completes 18 orbits, the third planet from the star (second in the chain) completes 9 orbits, and so on. In fact, the scientists initially only found five planets in the system, but by following this resonant rhythm they calculated where in its orbit an additional planet would be when they next had a window to observe the system.

More than just an orbital curiosity, this dance of resonant planets provides clues about the system's past. "The orbits in this system are very well ordered, which tells us that this system has evolved quite gently since its birth," explains co-author Yann Alibert from the University of Bern. If the system had been significantly disturbed earlier in its life, for example by a giant impact, this fragile configuration of orbits would not have survived.

Disorder in the rhythmic system
But even if the arrangement of the orbits is neat and well-ordered, the densities of the planets "are much more disorderly," says Nathan Hara from the Universite de Geneve, Switzerland, who was also involved in the study. "It appears there is a planet as dense as the Earth right next to a very fluffy planet with half the density of Neptune, followed by a planet with the density of Neptune. It is not what we are used to." In our Solar System, for example, the planets are neatly arranged, with the rocky, denser planets closer to the central star and the fluffy, low-density gas planets farther out.

"This contrast between the rhythmic harmony of the orbital motion and the disorderly densities certainly challenges our understanding of the formation and evolution of planetary systems," says Leleu.

Combining techniques
To investigate the system's unusual architecture, the team used data from the European Space Agency's CHEOPS satellite, alongside the ground-based ESPRESSO instrument on ESO's VLT and the NGTS and SPECULOOS, both sited at ESO's Paranal Observatory in Chile. Since exoplanets are extremely tricky to spot directly with telescopes, astronomers must instead rely on other techniques to detect them.

The main methods used are imaging transits - observing the light emitted by the central star, which dims as an exoplanet passes in front of it when observed from the Earth - and radial velocities - observing the star's light spectrum for small signs of wobbles which happen as the exoplanets move in their orbits. The team used both methods to observe the system: CHEOPS, NGTS and SPECULOOS for transits and ESPRESSO for radial velocities.

By combining the two techniques, astronomers were able to gather key information about the system and its planets, which orbit their central star much closer and much faster than the Earth orbits the Sun. The fastest (the innermost planet) completes an orbit in just a couple of days, while the slowest takes about ten times longer.

The six planets have sizes ranging from about one to about three times the size of Earth, while their masses are 1.5 to 30 times the mass of Earth. Some of the planets are rocky, but larger than Earth - these planets are known as Super-Earths. Others are gas planets, like the outer planets in our Solar System, but they are much smaller - these are nicknamed Mini-Neptunes.

Although none of the six exoplanets found lies in the star's habitable zone, the researchers suggest that, by continuing the resonance chain, they might find additional planets that could exist in or very close to this zone. ESO's Extremely Large Telescope (ELT), which is set to begin operating this decade, will be able to directly image rocky exoplanets in a star's habitable zone and even characterise their atmospheres, presenting an opportunity to get to know systems like TOI-178 in even greater detail.

Research Report: "Six transiting planets and a chain of Laplace resonances in TOI-178"


Related Links
ESO
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


EXO WORLDS
A 'super-puff' planet like no other
Montreal, Canada (SPX) Jan 19, 2021
The core mass of the giant exoplanet WASP-107b is much lower than what was thought necessary to build up the immense gas envelope surrounding giant planets like Jupiter and Saturn, astronomers at Universite de Montreal have found. This intriguing discovery by Ph.D. student Caroline Piaulet of UdeM's Institute for Research on Exoplanets (iREx) suggests that gas-giant planets form a lot more easily than previously believed. Piaulet is part of the groundbreaking research team of UdeM astrophysi ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

EXO WORLDS
Tourism on track in the world's largest cave

Bridenstine leaves NASA, calls for unity in space, science efforts

NASA may limit its presence in Russia over shrinking cooperation on ISS

Pandemic drags German admin out of the 1980s

EXO WORLDS
Framework agreement facilitates future slot bookings by ESA

SpaceX rocket deploys record-setting cargo

SpaceX launches first Starlink satellite mission of 2021

Florida's Space Coast the Number 1 Launch Site in the World in 2020

EXO WORLDS
Mystery of Martian glaciers revealed

Analyzing different solid states of water on other planets and moons

Crater study offers window on temperatures 3.5 billion years ago

New Mars rover may collect first sounds recorded on another planet

EXO WORLDS
China's space tracking ship completes satellite launch monitoring

Key modules for China's next space station ready for launch

China's space station core module, cargo craft pass factory review

Major space station components cleared for operations

EXO WORLDS
China launches new mobile telecommunication satellite

OneWeb secures investment from Softbank and Hughes Network Systems

Astronauts to boost European connectivity

Statement on Satellite Constellations by German Astronomical Society

EXO WORLDS
3D printing to pave the way for Moon colonization

NASA's Deep Space Network welcomes a new dish to the family

Keep this surface dirty

European team to collaborate in optical communication

EXO WORLDS
Holding the system of HR 8799 together

The seven rocky planets of TRAPPIST-1 seem to have very similar compositions

The 7 rocky TRAPPIST-1 planets may be made of similar stuff

Astronomers discover first cloudless, Jupiter-like planet

EXO WORLDS
A Hot Spot on Jupiter

The 15th Anniversary of New Horizons Leaving Earth

Juno mission expands into the future

Dark Storm on Neptune reverses direction, possibly shedding a fragment









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.