Photo by David Shankbone, CC BY-SA 3.0, http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Liberal comedian Bill Maher has always been one of Donald Trump’s biggest critics in the media.…

The three-body problem is one of Nature’s thorniest problems. The gravitational interactions and resulting movements of three bodies are notoriously difficult to predict because of instability. A planet orbiting two stars is an example of the three-body problem, but it’s sometimes called a “restricted three-body problem.” In that case, there are some potential stable orbits for a planet. A new study shows that the nearby Alpha Centauri AB pair could host a Super Jupiter in a stable orbit. The research is “Stability of the Potential Super Jupiter in Alpha Centauri System.” It’s available on the preprint site arxiv.org. The sole author is Tinglong Feng, an undergraduate at Xi’an Jiaotong University in China. “The three-body problem, which seeks stable orbit configurations among gravitating bodies, is a longstanding challenge in celestial mechanics,” Feng writes. Feng examines ? Centauri AB, our nearest binary neighbour, to understand if the system could host a super Jupiter and what orbit the giant planet could follow. Feng isn’t the first astronomer to tackle the problem. “As the closest triple stellar system to Earth, Alpha Centauri system has attracted diverse studies in astronomy, including exoplanet stability,” Feng writes. Though the entire Alpha Centauri system is a triple star system, ? Centauri AB are far enough from the third star that they comprise a binary system. Size comparisons for the Alpha Centauri A and B, Proxima Centauri, and the Sun. Image Credit: Planetary Habitability Lab/UPR Arecibo There are some solutions to the three-body problem if one of the bodies has a negligible mass compared to the other two. ? Centauri AB is a pair of Sun-like stars. ? Centauri A is a class G star a little more massive than the Sun, and ? Centauri B is a class K star a little less massive than the Sun. The study compares the ? Centauri AB system with a similar star system named GJ65AB (Gliese 65). It’s a binary pair known to host a Neptune-mass exoplanet. Though Gliese 65 is a pair of M-dwarfs, the comparison is still valuable because it “shares similar mass ratios and orbital eccentricities,” Feng writes. Gliese 65 is also close at only about 8.8 light-years from Earth. Feng also performed simulations of the ? Centauri AB system to test the idea of it hosting an exoplanet. “The similarities between GJ65AB and Alpha Centauri AB, together with the newly detected stable super Neptune in the GJ65 system, suggest the stability of the corresponding potential super Jupiter in Alpha Centauri AB,” Feng writes. The Gliese 65 and the Alpha Centauri AB systems have nearly identical mass ratios and eccentricities. If GJ65 can host a planet in a stable orbit, can ? Centauri AB also host one? Feng used the Mean Exponential Growth factor of Nearby Orbits (MEGNO) method to test the potential stability of a super Jupiter at ? Centauri AB. First, he used it to simulate the GJ65AB system and the newly discovered planet to verify the planet’s orbital stability. Then, he did the same with ? Centauri AB. “For this simulation, we restricted the semimajor axis of the planet to range from 0.1 to 5.0 au, and eccentricities less than 0.5,” Feng writes. The MEGNO simulations for Gliese 65 showed that the newly discovered Neptune mass planet should be stable. This figure from the research shows MEGNO results for Gliese 65. Dynamically stable regions of e (orbital eccentricity) and a (astronomical units) are shown in green, and the results show that the planet discovered around GJ65 should be stable. We identified the stable zone spanning from 0.1 to ~ 0.35au, which contains all the stable orbits for ? ranging from 0 to 0.5 to ~0.35 au, which contains all the stable orbits for ? ranging from 0 to 0.5,” Feng explains. Image Credit: Feng 2024. The next step was to find stable orbits for a planet orbiting ? Centauri AB. To do that, Feng used ? Centauri A as the primary star and injected a 350 Earth-mass planet at a distance of 23.336 AU. All of the other parameters were similar to GJ65 but scaled to ? Centauri AB. “We figured out the stable zone with ?spanning from 0.1 to ~ 2.2 au, and ? ranges from 0 to 0.5,” Feng writes. Feng says that the “potentially stable planet” should have ? about equal to 1.189 and ? about equal to 0.33. Those numbers place the planet in the stable zone in MEGNO results. This figure from the study is a stability map based on MEGNO values for a Jupiter-mass planet in Alpha Centauri AB. Dynamically stable regions are coloured in green. For a stable planet around ? Centauri AB to “mimic” the stability of the newly discovered Neptune planet around GJ65, the planet would have ? about equal to 1.189 and ? about equal to 0.33, which places it right in the green stability zone. Image Credit: Feng 2024. Of course, none of this means there is a planet there. It just shows that a potential stable orbit is available. Feng’s work proposes that exoplanets in binary systems with nearly identical mass ratios and eccentricities can exhibit similar stability properties. “From this hypothesis, together with the newly detected Neptune-mass planet in the GJ65 system, which is similar to Alpha Centauri AB, we assume the existence of a potential Jupiter-mass planet with corresponding orbital parameters in Alpha Centauri AB should also be possible,” Feng writes. No planets have been detected around ? Centauri AB, but that doesn’t mean there isn’t one there. Our planet-hunting methods are far from absolute, and there are bound to be many planets in nearby systems that we haven’t been able to detect yet. There are many proposals for missions to the region or for telescopes designed to probe the system more deeply. Their neighbour, Proxima Centauri, has two confirmed exoplanets. And there’ve been tantalizing hints that Alpha Centauri A hosts a planet, but it remains only a candidate. A true detection or emphatic non-detection may be years or decades away. Who knows? But at least Feng’s work shows that there could be a stable orbital home for a super Jupiter in the system. The post Alpha Centauri Could Have a Super Jupiter in Orbit appeared first on Universe Today.

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Politics Biden Replacement Theory Gains Steam with First Elected Democrat’s Endorsement State of the Union: Texas Rep. Lloyd Doggett became the first elected Democrat to publicly call for President Joe Biden to step down as the Democratic Party’s presumptive nominee for president. He may not be the last. On Tuesday, Rep. Lloyd Doggett (D-TX) became the first elected Democrat to publicly call for President Joe Biden to step down as the Democratic Party’s presumptive nominee for president. “My decision to make these strong reservations public is not done lightly nor does it in any way diminish my respect for all that President Biden has achieved,” Doggett said in a statement. “Recognizing that, unlike Trump, President Biden’s first commitment has always been to our country, not himself, I am hopeful that he will make the painful and difficult decision to withdraw. I respectfully call on him to do so.” Doggett is the first elected lawmaker to pile on to the calls  from liberals in the media and activist class for Biden to step aside after the president appeared to cognitively struggle in the first presidential debate with former President Donald Trump. The Texas representative said Biden failed to “effectively defend his many accomplishments.” “I represent the heart of a congressional district once represented by Lyndon Johnson,” Doggett added. “Under very different circumstances, he made the painful decision to withdraw. President Biden should do the same.” Doggett may be the first Democratic lawmaker to come out in favor of replacing Biden as the nominee, but he may not be the last. Just before Doggett’s statement, Rep. Nancy Pelosi (D-CA), formerly the speaker of the house, told MSNBC that she believes, “it is a legitimate question,” whether or not Biden’s debate performance was just “an episode or is this a condition.” “When people ask that question, it’s legitimate — of both candidates,” Pelosi added. Rep. Jim Clyburn (D-SC), a major Biden ally in the 2020 election cycle that helped Biden win South Carolina on his way to the nomination, told MSNBC that he “will support” Vice President Kamala Harris if Biden “were to step aside.” Rep. Jaime Raskin (D-MD) told the same network that, “whether he’s the candidate or someone else is the candidate, he is going to be the keynote speaker at our convention.” “He will be the figure that we rally around to move forward,” Raskin added. The post “Biden Replacement Theory” Gains Steam with First Elected Democrat’s Defection appeared first on The American Conservative.

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