A newfound cluster of young stars (blue star) sits on the periphery of the Milky Way. These stars probably formed from material originating from neighboring dwarf galaxies called the Magellanic Clouds. Credit: D. Nidever; NASA
The outskirts of the Milky Way are home to the galaxy’s oldest stars. But astronomers have spotted something unexpected in this celestial retirement community: a flock of young stars.
More surprising still, spectral analysis suggests that the infant stars have an extragalactic origin. The stars seemingly formed not from material from the Milky Way, but from two nearby dwarf galaxies known as the Magellanic Clouds. Those galaxies are on a collision course with our own. The discovery suggests that a stream of gas extending from the galaxies is about half as far from crashing into the Milky Way as previously thought.
“This is a puny cluster of stars—less than a few thousand in total—but it has big implications beyond its local area of the Milky Way,” says primary discoverer Adrian Price-Whelan, a research fellow at the Flatiron Institute’s Center for Computational Astrophysics in New York City. (The cluster also bears his name: Price-Whelan 1.)
The newfound stars could reveal new insights into the Milky Way’s history; they might, for example, tell if the Magellanic Clouds collided with our galaxy in the past.
Astronomers have spotted a group of young stars (blue) on the outskirts of the Milky Way. The scientists propose that these stars formed from material from two dwarf galaxies known as the Magellanic Clouds. Credit: A. Price-Whelan
Identifying clusters of stars is tricky because our galaxy is chock-full of the radiant orbs. Some stars may appear to be close together in the sky but actually sit at drastically different distances from Earth. Other stars may temporarily neighbor one another but move on in opposite directions. Determining which stars are actually clustered together requires many precise measurements over time.
Price-Whelan started with the latest data collected by the Gaia spacecraft, which has measured and cataloged the distances and motions of 1.7 billion stars. He searched the Gaia dataset for very blue stars, which are rare in the universe, and identified clumps of stars moving alongside them. After cross-matching with and removing known clusters, one remained.
The newfound cluster is relatively young at 117 million years old and is on the far outskirts of the Milky Way. “It’s really, really far away,” Price-Whelan says. “It’s further than any known young stars in the Milky Way, which are typically in the disk. So right away, I was like, ‘Holy smokes, what is this?'”
The cluster inhabits a region near a river of gas, dubbed the Magellanic Stream, that forms the outmost edge of the Large and Small Magellanic Clouds and reaches toward the Milky Way. Gas in the stream doesn’t contain much metal, unlike gases in the outer reaches of the Milky Way. David Nidever, assistant professor of physics at Montana State University in Bozeman, led an analysis of the metal content of the 27 brightest stars in the cluster. Just like the Magellanic Stream, the stars contain meager levels of metal.
A visualization of the position of the newfound Price-Whelan 1 star cluster (blue points) relative to the Milky Way (white points). The star cluster probably formed from material from the Large and Small Magellanic Clouds (purple points). The vertical green line shows the location of the Sun. Credit: A. Price-Whelan; Simulation by J. Hunt
The researchers propose that the cluster formed as gas from the Magellanic Stream passed through the gases surrounding the Milky Way. This pass-through created a drag force that compressed the Magellanic Stream gas. This drag, along with tidal forces from the Milky Way’s gravitational tug, condensed the gas enough to trigger star formation. Over time, the stars zoomed ahead of the surrounding gas and joined the Milky Way.
The stars’ presence presents a unique opportunity. Gauging the distance of gas from Earth is tricky and imprecise, so astronomers weren’t sure how far the Magellanic Stream was from reaching the Milky Way. The distance of stars, on the other hand, is comparatively trivial. Using the current positions and movements of stars in the cluster, the researchers predict that the edge of the Magellanic Stream is 90,000 light-years away from the Milky Way. That’s roughly half the distance previously predicted.
“If the Magellanic Stream is closer, especially the leading arm closest to our galaxy, then it’s likely to be incorporated into the Milky Way sooner than the current model predicts,” Nidever says. “Eventually, that gas will turn into new stars in the Milky Way’s disk. Right now, our galaxy is using up gas faster than its being replenished. This extra gas coming in will help us replenish that reservoir and make sure that our galaxy continues to thrive and form new stars.”
The updated distance to the Magellanic Stream will improve models of where the Magellanic Clouds have been and where they’re going, Price-Whelan says. The improved numbers could even settle a debate over whether the Magellanic Clouds have crossed through the Milky Way before. Finding an answer to that question will help astronomers better understand the history and properties of our galaxy.
More information:
Adrian M. Price-Whelan et al, Discovery of a Disrupting Open Cluster Far into the Milky Way Halo: A Recent Star Formation Event in the Leading Arm of the Magellanic Stream?, The Astrophysical Journal (2019). DOI: 10.3847/1538-4357/ab4bdd
David L. Nidever et al. Spectroscopy of the Young Stellar Association Price-Whelan 1: Origin in the Magellanic Leading Arm and Constraints on the Milky Way Hot Halo, The Astrophysical Journal (2019). DOI: 10.3847/1538-4357/ab52fc
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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.
