Latest news with #GraduateUniversityforAdvancedStudiesinJapan
Time of India
07-06-2025
- Science
- Time of India
What's TOI-6894b that just showed up around a dwarf star only 2.5 times its size; here's why that's weird
Astronomers have made a discovery that challenges long-standing beliefs about how planets form. A gas giant planet , roughly the size of Saturn, has been found orbiting an unusually small red dwarf star . This rare pairing defies current models, which say small stars don't have enough material in their surrounding disks to form such large planets. Named TOI-6894b, the planet was found about 241 light-years from Earth in the constellation Leo. TOI-6894b is about 1.07 times the diameter of Saturn but has just over half its mass. This makes the planet very low in density, similar to that of a beach ball. Despite its large size, the planet orbits extremely close to its host star, completing a full revolution in just under three Earth days. Also Read: Sun will die in 5 billion years but life could survive on Jupiter's moon Europa; here's how by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Elegant New Scooters For Seniors In 2024: The Prices May Surprise You Mobility Scooter | Search Ads Learn More Undo The star it orbits, TOI-6894, is a red dwarf with only about 21% the mass of the Sun and roughly 250 times dimmer. In terms of physical size, the star is just 2.5 times wider than the planet itself, a remarkable size ratio rarely seen in planetary systems. Live Events Why This Is a Big Deal The formation of such a large planet around such a small star has puzzled astronomers. According to the well-accepted 'core accretion' model, large planets are thought to grow from small rocky cores that gradually gather gas from the star's surrounding protoplanetary disk. But small, dim stars like red dwarfs are believed to have disks too thin and short-lived to form massive planets before the gas disappears. Dr. Teruyuki Hirano, the lead researcher from the Graduate University for Advanced Studies in Japan, noted that this planetary system 'is completely inconsistent with what we thought we knew.' He said the discovery 'forces us to question our assumptions about planet formation .' Detected by TESS, Confirmed by Ground Telescopes The planet was first flagged by NASA 's Transiting Exoplanet Survey Satellite (TESS), which detects periodic dips in starlight caused by planets passing in front of their stars. Follow-up observations using the European Southern Observatory's Very Large Telescope (VLT) confirmed the planet's mass and orbit. Also Read: Rare superorganism 'wormnadoes' caught on camera for the first time; what is it exactly? More data will be needed to determine how TOI-6894b formed. Future observations by the James Webb Space Telescope could reveal more about its atmosphere and structure, including how much of it is made up of hydrogen and helium and whether it has a large core. Red dwarfs are the most common type of star in the Milky Way, making up about 75% of the stellar population. They're also seen as good candidates for hosting habitable planets due to their long lifespans. Discoveries like TOI-6894b suggest there's still much to learn about the diversity of planetary systems these stars may host. Though this is not the first time a massive planet has been found orbiting a small star, it is one of the most extreme examples yet.
The Independent
11-04-2025
- Science
- The Independent
Ancient jawbone found on seafloor belongs to mysterious group of human ancestors
Scientists have identified an ancient jawbone discovered in Taiwan as belonging to the Denisovans, an elusive group of early human relatives. Denisovans, who co-existed with Neanderthals and Homo sapiens, remain a poorly understood group. "Denisovan fossils are very scarce," noted Takumi Tsutaya of the Graduate University for Advanced Studies in Japan, highlighting the significance of the find. To date, confirmed Denisovan fossils are limited to fragmented remains, including jawbones, teeth, and a finger bone, primarily found in Siberian and Tibetan caves. Some researchers suggest that fossils discovered in a cave in Laos may also be attributed to Denisovans. The probable identification of the jawbone from Taiwan as Denisovan expands the region where scientists know these ancient people once lived, said Tsutaya. The partial jawbone was first recovered when a fishing operation dredged the seafloor in the Penghu Channel near the Taiwan Strait. After it was sold to an antique shop, a collector spotted it and purchased it in 2008, then later donated it to Taiwan's National Museum of Natural Science. Based on the composition of marine invertebrates found attached to it, the fossil was dated to the Pleistocene era. But exactly which species of early human ancestor it belonged to remained a mystery. The condition of the fossil made it impossible to study ancient DNA. But recently, scientists in Taiwan, Japan and Denmark were able to extract some protein sequences from the incomplete jawbone. An analysis showed some protein sequences resembled those contained in the genome of a Denisovan fossil recovered in Siberia. The findings were published in the journal Science. While the new research is promising, Rick Potts, director of the Smithsonian Institution's Human Origins Project, said he would like to see further data before confirming the Taiwan fossil as Denisovan. Potts, who was not involved in the new research, praised the study for 'a fantastic job of recovering some proteins.' But he added, such a small sliver of material may not give a full picture. At one time, at least three human ancestor groups — Denisovans, Neanderthals and Homo sapiens — coexisted in Eurasia and sometimes interbred, researchers say. 'We can identity Neanderthal elements and Denisovan elements" in the DNA of some people alive today, said Tsutaya.
Yahoo
10-04-2025
- Science
- Yahoo
First Denisovan Fossil Discovered in Taiwan Reveals Secrets of Our Ancient Relatives
Analysis of a perfect jawbone found in Taiwan has given us new clues to the Denisovans, an enigmatic people with whom our ancestors had relations. Once upon a time, Homo sapiens wasn't the only human species walking the planet. We shared this world with multiple long-lost relatives, a history of intermingling written in our genomes. The most famous and well-known of these are the Neanderthals. But, further to the east, another, smaller relative once made their home. These were the Denisovans, who we know very little about, due to the scarcity of their remains. Named Penghu 1 by archaeologists, the jawbone is the most intact Denisovan fossil of the less than 15 identified to date, and the first discovered in Taiwan. Denisovan remains have been found in Siberia, in Denisova Cave for which they are named; in China, in Baishiya Cave on the Tibetan Plateau; and one possible Denisovan tooth in a cave in Laos, although that one may be Neanderthal. Most of these remains are either bone fragments or teeth. A complete Denisovan skeleton has never been identified. While genetic analysis suggests they diverged from Neanderthals a few hundred thousand years ago, the precise timing of their migration across Asia or their eventual demise isn't clear. Dating of sediment layers in Denisova Cave suggests that the Denisovans occupied the space between 300,000 and 50,000 years ago. That's the best information we have so far. We also know, based on the remnants of Denisovan DNA in modern humans, that they were probably significantly more widespread than their remains suggest. Despite being hauled from the ocean some 25 kilometers (15 miles) off Taiwan's western coast over a decade ago, Penghu 1's story has been as murky as the sediment it lay in for thousands of years. Beyond belonging to a member of the hominid family, a more precise identity remained elusive, with an attempt to recover DNA unsuccessful. Now, a team of scientists led by the Graduate University for Advanced Studies in Japan and the University of Copenhagen have taken another crack at it… and cracked the mystery wide open. Their research was based on, not DNA, but a series of techniques collectively called ancient protein analysis, or paleoproteomics. This process involves extracting proteins from the bone and tooth enamel of ancient remains, subjecting them to techniques such as mass spectrometry, and using them to build a profile of the individual in question. After removing likely contaminants and potentially biasing factors, the team was left with 22 proteins that provided 2,218 amino acid residues that could be used to put the fossil in context with Denisovans, Neanderthals, ourselves, and other great apes. Comparison confirmed that the jawbone is indeed of hominid origin… and two amino acid sequence variants of the thousands sampled were exclusive to Denisovans. They also found proteins specific to the male sex, revealing that Penghu 1 belonged to a male Denisovan who lived tens of thousands of years ago – some 4,000 kilometers southeast of Denisova Cave, and 2,000 kilometers southeast of Baishiya Cave. We don't know exactly when Penghu 1 lived; so far, attempts to date the mandible have returned a wide range of between 10,000 and 190,000 years old. What the bone does tell us is that Denisovans had larger molars and more robust jawbones than Neanderthals, a difference that likely emerged after the two groups diverged between 300,000 and 400,000 years ago. "The identification of Penghu 1 as a Denisovan mandible confirms the inference from modern human genomic studies that Denisovans were widely distributed in eastern Asia," the researchers write in their paper. "It is now clear that two contrasting hominin groups – small-toothed Neanderthals with tall but gracile mandibles and large-toothed Denisovans with low but robust mandibles (as a population or as a male character) – coexisted during the late Middle to early Late Pleistocene of Eurasia." We may never truly have a comprehensive picture of who the Denisovans were and how they lived, but this is a spectacular discovery that takes us just a little bit closer to understanding this enigmatic piece of the human puzzle. The research has been published in Science. Could Stonehenge Be a Copy of This Even More Ancient Monument? This Bronze-Age Tablet Is The Oldest Customer Complaint on Record 23andMe Is Bankrupt. Here's What That Means For Your Genetic Data.
