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 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 ~ 0.35
au, 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.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
