(C) Daily Kos This story was originally published by Daily Kos and is unaltered. . . . . . . . . . . Top Comments: Planetary Resonance Found in an Exoplanetary System [1] ['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.'] Date: 2024-12-08 Here at Top Comments we welcome longtime as well as brand new Daily Kos readers to join us at 10pm Eastern. We strive to nourish community by rounding up some of the site's best, funniest, most mojo'd & most informative commentary, and we depend on your help!! If you see a comment by another Kossack that deserves wider recognition, please send it either to topcomments at gmail or to the Top Comments group mailbox by 9:30pm Eastern. Please include a few words about why you sent it in as well as your user name (even if you think we know it already :-), so we can credit you with the find! A recent paper published in Nature presents analysis of brightness patterns of the star HD110067, located 100 light years from Earth in the constellation Coma Berenices, which reveals that the star is the center of a planetary system consisting of six planets. What’s particularly interesting about this planetary system is that the ratios of orbital periods for various pairs of planets in the system are whole-number ratios. (Most of the information in what follows comes not from the Nature paper, but from an article on the topic from CNN.) The data on this system were obtained from two different probes designed to investigate systems of relatively nearby exoplanets. Researchers first took notice of the star system in 2020 when NASA’s Transiting Exoplanet Survey Satellite, or TESS, detected dips in the brightness of HD110067. A dip in starlight often suggests the presence of a planet that’s passing between its host star and an observing satellite as the planet travels along its orbital path. Detecting these dips in luminosity, known as the transit method, is one of the main strategies used by scientists to identify exoplanets via ground and space-based telescopes. Astronomers determined the orbital periods of two planets around the star from that 2020 data. Two years later, TESS observed the star again, and the evidence suggested different orbital periods for those planets. When the data sets didn’t add up, astronomer and lead study author Rafael Luque and some of his colleagues decided to take another look at the star using a different satellite — the European Space Agency’s CHaracterising ExOPlanet Satellite, or Cheops. While TESS is used to observe fractions of the night sky for short observations, Cheops observes one star at a time. “We went fishing for signals among all the potential periods that those planets could have,” said Luque, a postdoctoral scholar in the University of Chicago’s department of astronomy and astrophysics. The data collected by Cheops helped the team solve the “detective story” started by TESS, he said. Cheops was able to determine the presence of a third planet in the system, which was crucial to confirming the orbital periods of the other two planets, as well as their rhythmic resonance. As the team matched up the rest of the unexplained TESS data with the Cheops observations, they discovered the other three planets orbiting the star. Follow-up observations with ground-based telescopes confirmed the presence of the planets. The star HD110067 is about 80 % the size of the Sun, but other aspects of this solar system are quite different from our solar system. First, all of the planets orbiting HD110067 are in a class of planets called “sub-Neptunes” because they are smaller than the planet Neptune, the smallest of the gas giants, but larger than the rocky inner planets of our system (Mercury, Venus, Earth & Mars). Apparently, a survey of exoplanets shows that this class of planets is most common in exoplanetary systems, but our Solar System has no sub-Neptunes. Hence, we know nothing about what they’re made of or of the process of their formation. The second big difference between HD110067’s system and ours is that these planets are all very close to the star, which makes the orbital periods of the planets very short. The six planets have been labeled using the letters b through g, and the observed periods for each planet are: b—9.11 days; c—13.7 days; d—20.5 days; e—30.8 days; f—41.0 days; g—54.8 days. The short distances from the star would also make the surface temperatures of these planets very hot, like the planet Mercury, or hotter. Now, about the resonances. If you take the ratios of the orbital periods for c/b, d/c, and e/d, you get about 1.5, or 3/2. The ratio of periods f/e and g/f are approximately 4/3.* Other resonances are highlighted in the video embedded below. These small-whole-number ratios are what causes resonance. According to the article, when planetary systems develop, they emerge having orbits with resonances to the orbital periods of other planets in the system, but over time, through gravitational perturbations caused by the larger planets, or gravitational disturbances from massive objects passing close to the system, the resonances are destroyed. (This was news to me.) The planets in our Solar System have no resonances, for example. However, HD110067’s has somehow preserved its original resonances over the billions of years since the system developed. Back in graduate school, I learned that resonances in a planetary system was a bad thing, as they enable orbital energy transfer to occur between planets, which could result in a planet either falling into the star, or being flung out of the system entirely. As such, I’m surprised that a planetary system with resonances would be stable over such a long period of time. x YouTube Video *Corrected according to BMScott’s comment below. Comments are below the fold. Top Comments (December 7-8, 2024): No nominations or highlights for the past two days. Top Mojo (December 6, 2024): Top Mojo is courtesy of mik! Click here for more on how Top Mojo works. Top Mojo (December 6, 2024): [END] --- [1] Url: https://www.dailykos.com/stories/2024/12/8/2289600/-Top-Comments-Planetary-Resonance-Found-in-an-Exoplanetary-System?pm_campaign=front_page&pm_source=latest_community&pm_medium=web Published and (C) by Daily Kos Content appears here under this condition or license: Site content may be used for any purpose without permission unless otherwise specified. via Magical.Fish Gopher News Feeds: gopher://magical.fish/1/feeds/news/dailykos/