A study published today (Wednesday) reports that the mass of the Milky Way galaxy is four to five times less than previously thought, results that overturn what is known to date about the galaxy that contains the planet Earth.

As astronomer François Hamer, co-author of the study published by the journal “Astronomy and Astrophysics,” explained to Agence France-Presse, the result is “the result of the Gaia revolution.” Gaia, a satellite dedicated to mapping the Milky Way galaxy, revealed the positions and motions of 1.8 billion stars in its latest data in 2022.

It represents a small fraction of the total contents of our spiral galaxy, a disk about 100,000 light-years in diameter and consisting of four large arms, one of which includes our Solar System, all of which extend around a very luminous core. .

The authors of the study report that by studying the Gaia data they were able to calculate the rotation curve of the Milky Way with unprecedented precision. The task is to determine the speed at which celestial bodies rotate around the center of the galaxy.

Observations of spiral galaxies have previously concluded that this curve is “flattening”, meaning that once a certain distance from the center is reached, the rate of rotation is constant.

But “this is the first time we find that the curve descends outside its disk,” according to Francois Hamer, “as if there wasn’t a lot of matter” in the galaxy between 50 and 80 thousand years from the center.

As a result, “the mass of our Milky Way Galaxy has been revised to very low values,” about 200 billion times the mass of the Sun, five times less than previous estimates.

“Bold Decisions”

The study, conducted by an international team and led by astronomers from the Paris Observatory and the National Center for Scientific Research in France, has a second major conclusion, as it questions “the relationship between luminous matter and dark matter.” Astronomer.

This hypothesis is also called thematic theme because it is so far invisible and undetectable. It is thought to provide the mass necessary for the coalescence of galaxies, and represents about six times the mass of luminous matter that contains stars and gas clouds. For the Milky Way, the study calculates that this ratio is much lower, with three times as much dark matter as bright matter.

But astronomer François Combes, a colleague of François Hammer at the Paris Observatory, told Agence France-Presse that the results were “a bit bold” or “perhaps not well founded.”

This is significant because this study focuses on low galactic radii, while astronomers typically calculate galactic masses by taking greater distances into account.

However, apart from gas, globular clusters, dwarf galaxies or the Magellanic Cloud, “up to this distance we have a lot of dark matter,” notes Francois Combe, a senior expert on galaxy evolution.

But the Gombe galaxy, about 80,000 light-years away from the center of the galaxy, welcomes “very precise work that will improve our knowledge of the stars and their rotation”.

François Hammer’s team defends this work by talking about the uniqueness of our galaxy. Unlike most spiral galaxies, which saw violent collisions between galaxies six billion years ago, the Milky Way “evolved very quietly for nine billion years,” Hamer says.

Also, the difference between the Milky Way and other spiral galaxies can be justified by the observational method, which relies on stars in the former and gas clouds in the latter.

Meanwhile, Françoise Combe believes the Milky Way galaxy is “not exceptional,” but in terms of dark matter, “it’s like the others.”

After 3 years of suffering from the corona virus and its variants, the severity of the virus decreased and the virus began to recover from the effects of the terrible epidemic, scientists began to warn about the “nipa” virus, which is transmitted by bats. , pigs and animals.

Although it has not started spreading, some virologists in Russia have warned about the danger of the “Nipah” virus, which has already started spreading in India, and it is said to be likely to cause a new epidemic in the world.

Russian scientists have said that if the Nipah virus undergoes genetic changes it could become a pandemic.

A Russian scientist said Nipah virus is a viral disease originating from bats and is currently spreading in India, Bangladesh and some countries in Southeast Asia.

We advise virologists not to travel to countries where infections with this virus have been reported, as the virus is not widespread and infections are few and far between in India and Southeast Asia.

Virologists advised to wash fruits and vegetables thoroughly, wash hands and wear masks, because there is currently no vaccine against this virus, and there are no drugs against it.

The disease is spread from animals to humans, from an infected person to others, through contaminated food and respiratory droplets.

The disease may show no symptoms, or may be accompanied by mild or severe respiratory infection or encephalitis, in the latter case it can lead to coma and death.

According to the Wall Street Journal, the outbreak has so far occurred in the city of Kozhikode in the Indian state of Kerala.

The Nipah virus was discovered in 1998 among pig farmers living in the Nipah River in Malaysia, hence its name.

By Reem Abdel Hamid

Tuesday, September 26, 2023 03:36 PM

According to the Associated Press, many Americans joke about how bad they are at math, and their already poor scores on standardized math tests continue to decline.

Employers say America needs math geniuses like animated movies need superheroes. They believe America’s poor performance in math is no laughing matter, but a threat to national security and global economic competitiveness.

Jim Stigler, a professor of psychology at the University of California who studies the teaching and learning process in subjects including mathematics, believes that the technological advances that will lead the world in the next fifty years will come from other countries. Capital that America does not have.

The U.S. Department of Defense has called for a major effort to support education in science, technology, education and math, or “STEM” for short. The number of graduates in these categories in China is eight times that of their counterparts in the United States, and the number of engineers in Russia is four times that of those in the United States, he said.

For his part, Aspen Research Institute Vice President Josh Weiner says the matter is not just an academic issue. Last July, he warned that other countries, particularly China, were challenging America’s technological dominance. He explained that mathematics is needed to solve the fundamental challenges faced in the present era.

On the other hand, the number of jobs in mathematical occupations, i.e. jobs that use the dream of arithmetic and use advanced methods to perform calculations, analyze data, and solve problems, will increase by more than 30,000 per year. In the current decade, that’s the fastest rate compared to any other type of job, according to the U.S. Bureau of Labor Statistics.