(Press-News.org)
The first stars illuminated the Universe during the Cosmic Dawn and put an end to the cosmic "dark ages" that followed the Big Bang. However, the distribution of their mass is one of the great unsolved mysteries of the cosmos.
Numerical simulations of the formation of the first stars estimate that the mass of the first stars reached up to several hundred solar masses. Among them, the first stars with masses between 140 and 260 solar masses ended up as pair-instability supernovae (PISNe). PISNe are quite different from ordinary supernovae (i.e., Type II and Type Ia supernovae) and would have imprinted a unique chemical signature in the atmosphere of the next-generation stars. However, no such signature has been found.
A new study led by Prof. ZHAO Gang from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has identified a chemically peculiar star (LAMOST J1010+2358) in the Galactic halo as clear evidence of the existence of PISNe from very massive first stars in the early Universe, based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey and follow-up high-resolution spectra observation by Subaru Telescope. It has been confirmed that this star was formed in the gas cloud dominated by the yields of a PISN with 260 solar masses.
The team also includes the researchers from Yunnan Observatories of CAS, National Astronomical Observatory of Japan and Monash University, Australia.
This study was published online in Nature on June 7th.
The research team has performed follow-up high-resolution spectroscopic observation for J1010+2358 with the Subaru telescope and derived abundances for more than ten elements. The most significant feature of this star is its extremely low sodium and cobalt abundances. Its sodium-to-iron ratio is lower than 1/100 of the solar value. This star also exhibits a very large abundance variance between the odd and even charge number elements, such as sodium/magnesium and cobalt/nickel.
"The peculiar odd-even variance, along with deficiencies of sodium and α-elements in this star, are consistent with the prediction of primordial PISN from first-generation stars with 260 solar masses," said Dr. XING Qianfan, first author of the study.
The discovery of J1010+2358 is direct evidence of the hydrodynamical instability due to electron–positron pair production in the theory of very massive star evolution. The creation of electron–positron pairs reduces thermal pressure inside the core of a very massive star and leads to a partial collapse.
"It provides an essential clue to constraining the initial mass function in the early universe," said Prof. ZHAO Gang, corresponding author of the study. "Before this study, no evidence of supernovae from such massive stars has been found in the metal-poor stars."
Moreover, the iron abundance of LAMOST J1010+2358 ([Fe/H] = -2.42) is much higher than the most metal-poor stars in the Galactic halo, suggesting that the second-generation stars formed in the PISN-dominated gas may be more metal-rich than expected.
"One of the holy grails of searching for metal-poor stars is to find evidence for these early pair-instability supernovae," said Prof. Avi Loeb, former chair of the Astronomy Department at Harvard University.
Prof. Timothy Beers, the provost's chair of astrophysics at Notre Dame University, commented on the results: "This paper presents what is, to my knowledge, the first definitive association of a Galactic halo star with an abundance pattern originating from a PISN."
END
TORONTO, CANADA –A new study followed more than 7000 middle aged and older Canadians for approximately three years to understand whether higher rates of social participation were associated with successful aging in later life. They found that those who participated in volunteer work and those participating in recreational activities were more likely to maintain excellent health across the subsequent 3-year study period and less likely to develop physical, cognitive, mental, or emotional problems.
The researchers defined successful aging as freedom from any serious physical, cognitive, mental, or emotional conditions ...
Certain crops, like greenhouse tomatoes, eggplant, peppers, and blueberries, rely on bumblebees for a style of pollination that only bumblebees can perform. Among growers, the preference can be for bigger-bodied bumblebees because they’re thought to be more efficient pollinators.
Enabled by a $750,000 grant from the National Institute of Food and Agriculture, the research team will investigate factors suspected of influencing bumblebee biology and body size, including climate change, wildfires, and the ...
PHILADELPHIA – First-line ibrutinib (Imbruvica) plus venetoclax (Venclexta) led to high response and survival rates in patients with chronic lymphocytic leukemia (CLL) whether or not their cancer harbored high-risk genetic features typically associated with poor outcomes, according to results published in Clinical Cancer Research, a journal of the American Association for Cancer Research (AACR).
Patients with high-risk CLL, defined by deletion of 17p, mutated TP53, and/or unmutated immunoglobulin ...
IOP Publishing (IOPP) is expanding its open access (OA) Environmental Research portfolio to address the urgent need for sustainable food solutions globally. Environmental Research: Food Systems, which supports the United Nation’s Sustainability Development Goals (SDGs), is an interdisciplinary forum for researchers working to achieve sustainable global food security.
Scientific innovations are key to transforming the global food system. Efficient and effective food supply enables the world to achieve progress on all 17 of the SDGs, from eliminating poverty ...
A research team led by the Complexity Science Hub Vienna and the Medical University of Vienna has analysed the actual prevalence of Type 2 diabetes in Austria for the first time as part of a study. In addition to identifying clear regional differences, an alarming and previously unknown figure came to light: one in three people suddenly stop treatment and go without medication and/or medical check-ups for at least a year. And, as the study also showed, this group had a higher mortality rate than patients with diabetes who regularly access the care available to them. The results have ...
Cerebral Palsy has been linked to a condition called cryptorchidism in males—when one or both of the testicles are not present in the scrotum. A new study in Developmental Medicine & Child Neurology found that spasticity in the lower extremities was linked to a higher likelihood of receiving surgery for cryptorchidism in boys with cerebral palsy.
The study included 44,561 male patients with cerebral palsy in the Pediatric Health Information System, a comparative administrative database involving multiple US children’s hospitals.
In addition to finding an overall association between lower extremity spasticity and cryptorchidism ...
Speech and voice disorders are common in individuals with Parkinson’s disease. New research published in the International Journal of Language & Communication Disorders found that a tele-rehabilitation program that combines conventional speech therapy and singing may help improve patients’ voice problems.
For the study, 33 people with Parkinson’s disease were randomly assigned to receive the combination therapy, conventional speech therapy, or a singing intervention. Each patient participated in 12 tele-rehabilitation sessions over four weeks. Voice-related ...
New research reveals that the level of fat within the body’s muscle—or muscle adiposity—may indicate a person’s likelihood of experiencing cognitive decline as they age. In the study published in the Journal of the American Geriatrics Society, 5-year increase in fat stored in the thigh muscle was a risk factor for cognitive decline. This risk was independent of total weight, other fat deposits, and muscle characteristics (such as muscle strength or mass) and also independent of traditional dementia risk factors.
Investigators assessed muscle fat in 1,634 adults 69–79 years of age at years 1 and 6 and evaluated their cognitive function ...
The quality of recovery a person experiences on a given evening after work may impact their mood when they start their job again the next day, according to new research published in the Journal of Occupational and Organizational Psychology.
The study, which was based on diary entries by 124 employees on 887 days, found that people who had higher quality recovery during the evening than usual had higher levels of wakefulness, calmness, and pleasantness when they started work the next day. However, people’s wakefulness and calmness tended to decline more strongly during the workday after evenings with higher ...
At least 237,000 people died in organised violence in 2022. A new report from Uppsala Conflict Data Program (UCDP) at Uppsala University shows that this is a 97 per cent increase compared with the previous year, and the highest number since the Rwandan genocide in 1994.
“We see this increase despite considerable de-escalation in the two deadliest conflicts of 2021; Yemen and Afghanistan. Instead, violence in Ethiopia and Ukraine escalated drastically,” says Shawn Davies, Senior Analyst at UCDP.
Together, the wars in Ethiopia and Ukraine resulted in at least 180,000 battle-related deaths in 2022. This is a low estimate as information from these ...
