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Most Precise Map to Date of Milky Way Reveals Warped, Twisted Galaxy

The researchers on Thursday unveiled a three-dimensional map of the Milky Way — home to more than 100 billion stars

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Map, Milky Way, Galaxy
The warped shape of the stellar disk of the Milky Way is seen over the Warsaw University Telescope at Las Campanas Observatory, Chile, in an artist's rendition, Aug. 1, 2019. (Jan Skowron/University of Warsaw). VOA

Astronomers have created the most precise map to date of the Milky Way by tracking thousands of big pulsating stars spread throughout the galaxy, demonstrating that its disk of myriad stars is not flat but dramatically warped and twisted in shape.

The researchers on Thursday unveiled a three-dimensional map of the Milky Way — home to more than 100 billion stars including our sun — providing a comprehensive chart of its structure: a stellar disk comprised of four major spiral arms and a bar-shaped core region.

“For the first time, our whole galaxy — from edge to edge of the disk — was mapped using real, precise distances,” said University of Warsaw astronomer Andrzej Udalski, co-author of the study published in the journal Science.

Until now, the understanding of the galaxy’s shape had been based upon indirect measurements of celestial landmarks within the Milky Way and inferences from structures observed in other galaxies populating the universe. The new map was formulated using precise measurements of the distance from the sun to 2,400 stars called “Cepheid variables” scattered throughout the galaxy.

Map, Milky Way, Galaxy
Astronomers have created the most precise map to date of the Milky Way by tracking thousands of big pulsating stars spread throughout the galaxy. Pixabay

“Cepheids are ideal to study the Milky Way for several reasons,” added University of Warsaw astronomer and study co-author Dorota Skowron. “Cepheid variables are bright supergiant stars and they are 100 to 10,000 times more luminous than the sun, so we can detect them on the outskirts of our galaxy. They are relatively young — younger than 400 million years — so we can find them near their birthplaces.”

The astronomers tracked the Cepheids using the Warsaw Telescope located in the Chilean Andes. These stars pulsate at regular intervals and can be seen through the galaxy’s immense clouds of interstellar dust that can make dimmer stellar bodies hard to spot.

The map showed that the galaxy’s disk, far from flat, is significantly warped and varies in thickness from place to place, with increasing thickness measured further from the galactic center. The disk boasts a diameter of about 140,00 light years. Each light year is about 6 trillion miles (9 trillion km).

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The Milky Way began to form relatively soon after the Big Bang explosion that marked the beginning of the universe some 13.8 billion years ago. The sun, located roughly 26,000 light years from the supermassive black hole residing at the center of the galaxy, formed about 4.5 billion years ago. (VOA)

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Chinese Researchers Spot Monster Black Hole Bigger Than Sun

Chinese team spots monster black hole which is 70 times bigger than Sun

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Black Hole
A team of Chinese scientists spotted a black hole that is 70 times larger than the sun. (Representational Image Only). Wikimedia Commons

A team led by Chinese researchers has spotted a monster black hole with a mass 70 times greater than Sun — toppling the earlier assumption that the mass of an individual black hole in our Galaxy is no more than 20 times that of Sun.

Our Milky Way Galaxy is estimated to contain 100 million stellar black holes — cosmic bodies formed by the collapse of massive stars and so dense even light can’t escape.

The team, headed by Professor LIU Jifeng of the National Astronomical Observatory of China of the Chinese Academy of Sciences (NAOC), spotted a stellar black hole with a mass 70 times greater than the Sun.

The monster black hole is located 15 thousand light-years from Earth and has been named “LB-1” by the researchers in a paper reported in the journal Nature.

“Black holes of such mass should not even exist in our Galaxy, according to most of the current models of stellar evolution,” said LIU.

“We thought that very massive stars with the chemical composition typical of our Galaxy must shed most of their gas in powerful stellar winds, as they approach the end of their life. Therefore, they should not leave behind such a massive remnant,” he explained.

Spotting black hole
The monster black hole is located 15 thousand light-years from Earth. (Representational Image Only). Wikimedia Commons

Until just a few years ago, stellar black holes could only be discovered when they gobbled up gas from a companion star.

The vast majority of stellar black holes in our Galaxy are not engaged in a cosmic banquet, though, and thus don’t emit revealing X-rays.

As a result, only about two dozen Galactic stellar black holes have been well identified and measured.

To counter this limitation, LIU and collaborators surveyed the sky with China’s Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).

After the initial discovery, the world’s largest optical telescopes – Spain’s 10.4-m Gran Telescopio Canarias and the 10-m Keck I telescope in the US – were used to determine the system’s physical parameters.
The results were nothing short of fantastic: a star eight times heavier than the Sun was seen orbiting a 70-solar-mass black hole, every 79 days.

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The direct sighting of LB-1 proves that this population of over-massive stellar black holes exists even in our own backyard.

“This discovery forces us to re-examine our models of how stellar-mass black holes form,” said LIGO Director Professor David Reitze from University of Florida in the US. (IANS)