(Press-News.org) COLUMBUS, Ohio - New research provides the best evidence to date into the timing of how our early Milky Way came together, including the merger with a key satellite galaxy.
Using relatively new methods in astronomy, the researchers were able to identify the most precise ages currently possible for a sample of about a hundred red giant stars in the galaxy.
With this and other data, the researchers were able to show what was happening when the Milky Way merged with an orbiting satellite galaxy, known as Gaia-Enceladus, about 10 billion years ago.
Their results were published today (May 17, 2021) in the journal Nature Astronomy.
"Our evidence suggests that when the merger occurred, the Milky Way had already formed a large population of its own stars," said Fiorenzo Vincenzo, co-author of the study and a fellow in The Ohio State University's Center for Cosmology and Astroparticle Physics.
Many of those "homemade" stars ended up in the thick disc in the middle of the galaxy, while most that were captured from Gaia-Enceladus are in the outer halo of the galaxy.
"The merging event with Gaia-Enceladus is thought to be one of the most important in the Milky Way's history, shaping how we observe it today," said Josefina Montalban, with the School of Physics and Astronomy at the University of Birmingham in the U.K., who led the project.
By calculating the age of the stars, the researchers were able to determine, for the first time, that the stars captured from Gaia-Enceladus have similar or slightly younger ages compared to the majority of stars that were born inside the Milky Way.
A violent merger between two galaxies can't help but shake things up, Vincenzo said. Results showed that the merger changed the orbits of the stars already in the galaxy, making them more eccentric.
Vincenzo compared the stars' movements to a dance, where the stars from the former Gaia-Enceladus move differently than those born within the Milky Way. The stars even "dress" differently, Vincenzo said, with stars from outside showing different chemical compositions from those born inside the Milky Way.
The researchers used several different approaches and data sources to conduct their study.
One way the researchers were able to get such precise ages of the stars was through the use of asteroseismology, a relatively new field that probes the internal structure of stars.
Asteroseismologists study oscillations in stars, which are sound waves that ripple through their interiors, said Mathieu Vrard, a postdoctoral research associate in Ohio State's Department of Astronomy.
"That allows us to get very precise ages for the stars, which are important in determining the chronology of when events happened in the early Milky Way," Vrard said.
The study also used a spectroscopic survey, called APOGEE, which provides the chemical composition of stars - another aid in determining their ages.
"We have shown the great potential of asteroseismology, in combination with spectroscopy, to age-date individual stars," Montalban said.
This study is just the first step, according to the researchers.
"We now intend to apply this approach to larger samples of stars, and to include even more subtle features of the frequency spectra," Vincenzo said.
"This will eventually lead to a much sharper view of the Milky Way's assembly history and evolution, creating a timeline of how our galaxy developed."
INFORMATION:
The work is the result of the collaborative Asterochronometry project, funded by the European Research Council.
Contact: Fiorenzo Vincenzo, Vincenzo.3@osu.edu
Josefina Montalban, josefina.montalban7@gmail.com
Mathieu Vrard, Vrard.1@osu.edu
Patients with both diabetes and heart failure who were treated with sotagliflozin, a novel investigational drug for diabetes, for a median of nine to 16 months experienced reductions of 22% to 43% in the risk of death or worsening heart failure compared with similar patients who were treated with a placebo. The drug was effective in patients with all forms of heart failure, including those whose heart muscle is abnormally stiff (preserved ejection fraction) and for whom there is currently no effective treatment, according to research presented at the American College of Cardiology's 70th Annual Scientific Session.
"Treatment with sotagliflozin robustly and significantly reduced cardiovascular adverse events across the full spectrum of ...
Researchers at the Francis Crick Institute have found out how microscopic structures called lipid droplets may help to prevent a high-fat diet causing kidney damage. The work in fruit flies, published in PLoS Biology opens up a new research avenue for developing better treatments for chronic kidney disease.
Eating foods high in fats can cause inflammation and metabolic stress in the kidneys, leading to chronic disease, which in severe cases requires dialysis or a transplant. And with obesity on the rise globally, it's a growing problem - around 10% of people in the UK are living with chronic kidney ...
The University of Kent's School of Physical Sciences, in collaboration with the Science and Technology Facilities Council (STFC) and the Universities of Cardiff, Durham and Leeds, have developed an algorithm to train computers to analyse signals from subatomic particles embedded in advanced electronic materials.
The particles, called muons, are produced in large particle accelerators and are implanted inside samples of materials in order to investigate their magnetic properties. Muons are uniquely useful as they couple magnetically to individual atoms inside the material and then emit a signal detectable by researchers to obtain information on that magnetism.
This ability to ...
A program designed to improve hospital care for patients with heart failure, the leading cause of hospitalization among adults over age 65, did not bring additional benefits beyond existing hospital quality improvement programs in a randomized controlled trial presented at the American College of Cardiology's 70th Annual Scientific Session.
Heart failure is a condition in which the heart becomes too weak or too stiff to pump blood effectively to the rest of the body. It causes symptoms such as swelling and fluid retention, shortness of breath and coughing.
In the CONNECT-HF study, one group of hospitals received additional auditing and ...
For the first time, Penn State researchers have identified a gene that controls flowering in cacao, a discovery that may help accelerate breeding efforts aimed at improving the disease-ridden plant, they suggested.
Characterizing the Flowering Locus T gene in cacao, responsible for the production of florigen -- a protein that triggers flowering in most plants -- is important, according to study co-author Mark Guiltinan, J. Franklin Styer Professor of Horticultural Botany and professor of plant molecular biology. He expects this advancement to enable scientists to develop disease-resistant trees faster, which is critical because 20% to 30% ...
Some words sound like what they mean. For example, "slurp" sounds like the noise we make when we drink from a cup, and "teeny" sounds like something that is very small. This resemblance between how a word sounds and what it means is known as iconicity.
In her lab at the University of Miami, Lynn Perry, an associate professor in the College of Arts and Sciences Department of Psychology, previously found that children tend to learn words higher in iconicity earlier in development then they do words lower in iconicity. She also found that adults tend to use more iconic words when they speak to children than when they speak to other adults.
"That got us curious about why," said Stephanie Custode, a doctoral student in psychology, who ...
University researchers have carried out the largest systematic review and meta-analysis to date of how people's perceptions of their screen time compare with what they do in practice, finding estimates of usage were only accurate in about five per cent of studies.
The international team say this casts doubt on the validity of research on the impact of screen time on mental health, and its influences on government policy, as the vast majority rely on participants to estimate (self-report) how long they spend on digital devices, rather than logs of actual usage, or tracked time.
"For decades, researchers have relied on estimates of how we use various technologies to study how people use digital ...
A new study led by researchers from the Oxford University Museum of Natural History, University of Oxford and the University of Birmingham for Current Biology has used new methods to analyse the variability of mammal fossils, revealing extraordinary results: it was not dinosaurs, but possibly other mammals, that were the main competitors of modern mammals before and after the mass extinction of dinosaurs.
The study challenges old assumptions about why mammals only seemed to diversify, becoming larger and exploring new diets, locomotion and ways of life, after the extinction of the non-bird dinosaurs. It points to a more complex story of competition between distinct mammal groups. ...
Before undergoing surgery, patients often go through a number of tests: blood work, sometimes a chest X-ray, perhaps tests to measure heart and lung function.
In fact, about half of patients who had one of three common surgical procedures done in Michigan between 2015 and the midway point of 2019 received at least one routine test beforehand.
That's according to new research in JAMA Internal Medicine from a collaboration between the University of Michigan-based Michigan Program on Value Enhancement (MPrOVE) and the Michigan Value Collaborative, a statewide initiative that focuses on improving medical and surgical quality.
Yet plenty of evidence suggests that preoperative testing is often unnecessary ...
The experimental heart failure drug omecamtiv mecarbil reduced heart failure hospitalizations by a greater margin among patients with more severely reduced ejection fraction, a measure indicating severe impairment in the heart's pumping ability, compared with those who had moderately reduced ejection fraction, according to research presented at the American College of Cardiology's 70th Annual Scientific Session.
Omecamtiv mecarbil works by improving the ability for heart muscle cells to contract and operates through a different biological pathway than any of the current heart failure medications. The research ...
