Technology A New Map For The Milky Way, Most Detailed Yet
Thousands of Black Holes May Lurk at the Galaxy's Center
The discovery could help scientists better understand the space-time ripples called gravitational waves.For years, scientists have known that a monster black hole sits in the middle of the galaxy. Called Sagittarius A* (Sgr A*), the compact object is more than four million times as massive as our sun, but it's packed into a region of space no bigger than the distance between Earth and the sun.
The European Space Agency released the second batch of data from its Gaia mission Wednesday, which identifies the location of almost 1.7 billion stars in the Milky Way and beyond, making it the most detailed map of stars we currently have. The data also include precise information on the movement of asteroids with the solar system.
The data relate to observations made over 22 months — between July 25, 2014, and May 23, 2016. Gaia, a space observatory launched in 2013 to measure the position and distance of stars, had observed about two million stars in its first data set that was released in 2016. The data in this new release are a lot more precise — the brightest stars were tracked with accuracy similar to an observer on Earth being able to spot a quarter coin on the moon’s surface.
Milky Way core may harbour thousands of black holes: study
Astrophysicists have detected a dozen black holes at the centre of our Milky Way galaxy, and said Wednesday there could be as many as 10,000. The find provides the first evidence for a long-held theory that the massive black hole at the core of every large galaxy should be surrounded by thousands of smaller ones, they wrote in the science journal Nature."We observed a dozen black holes" around Sagittarius A, the black hole at the centre of the Milky Way, said study co-author Chuck Hailey, an astrophysicist at New York's Columbia University."But this is the tip of the iceberg," he told AFP.
This level of precision allowed astronomers to track the true movement of stars, instead of relying on an approximation using the parallax method — the apparent shift seen in object’s position in the sky, as Earth orbits the sun.
Along with stars’ positions, the data also reveal their brightness and colors, and in the case of about half a million stars, also how those two have changed over time. For about 100 million stars, the data include their surface temperatures and for 87 million or so stars, the effect that interstellar dust has on them.
“The sheer number of stars alone, with their positions and motions, would make Gaia’s new catalogue already quite astonishing. But there is more: this unique scientific catalogue includes many other data types, with information about the properties of the stars and other celestial objects, making this release truly exceptional,” Anthony Brown of Leiden University in the Netherlands, who chairs of the Gaia Data Processing and Analysis Consortium Executive, said inWednesday.
Stellar 'DNA' Survey Could Reveal Sun's Lost Siblings
The Galactic Archaeology survey was launched in a bid to provide new insights into the formation and evolution of the Milky Way. In total, GALAH will investigate more than one million stars using the HERMES spectrograph—an instrument at the Australian Astronomical Observatory’s 3.9-meter Anglo-Australian Telescope in New South Wales. HERMES measures the different colors of light coming from stars in order to determine the proportions of chemical elements that they contain.
For instance, the database has information on the positions of over 14,000 asteroids in the solar system that were already known, allowing astronomers to plot their precise orbits. It also includes the locations of 500,000 quasars, the first time their coordinates have been made available in optical wavelengths.
Gaia also observed the motion of stars inside globular clusters in the Milky Way’s halo, as well as those in nearby galaxies — the Small and Large Magellanic Clouds. Using that data, astronomers could plot the orbits of 75 globular clusters in our galaxy’s halo and of 12 dwarf galaxies orbiting our own. This would allow them to study the evolution of the Milky Way and the distribution of dark matter in it.
Highlights from the second release of Gaia data were presented in Berlin, and a series of scientific papers, discussing various aspects of that large volume of data, are scheduled to be published in a special edition of the journal Astronomy & Astrophysics.
Scientists release most detailed star chart of the Milky Way
The European Space Agency released the most accurate census yet of stars in the Milky Way and neighboring galaxies.The high-precision measurements about the distance, motion, brightness and color of almost 1.7 billion stars were collected by the space agency's Gaia probe between July 2014 and May 2016.
In an unrelated study, also about the Milky Way, researchers used a theoretical model to suggest our home galaxy has several supermassive black holes in it. Typically, most large galaxies have a supermassive black hole in their centers, not several.
According topublished Tuesday in the Astrophysical Journal Letters, a team of researchers suggest that galaxies as massive as our own should contain several supermassive black holes, likely a result of a smaller galaxy merging into a larger one, and bringing with it its own supermassive black hole in the process. This second supermassive black hole would be at the center of the smaller galaxy, but following the merger, could wander throughout the now-larger galaxy.
However, given their predicted locations — far from galactic centers and even outside the galactic disks — these wandering supermassive black holes would be unlikely to accrete any material. And since they are black holes, the lack of accretion would render them effectively invisible.
“We are currently working to better quantify how we might be able to infer their presence indirectly,” Michael Tremmel, a postdoctoral fellow at the Yale Center for Astronomy and Astrophysics, and lead author of the study, said in.
But if there are supermassive black holes darting around the galaxy, does that forebode impending doom for Earth? No, says Tremmel.
“It is extremely unlikely that any wandering supermassive black hole will come close enough to our Sun to have any impact on our solar system. We estimate that a close approach of one of these wanderers that is able to affect our solar system should occur every 100 billion years or so, or nearly 10 times the age of the universe,” he said.
An astronomer's stunning photo of the Milky Way shows our galaxy through a crystal ball .
Astronomer Juan Carlos Muñoz-Mateos took a photo of the Milky Way through a crystal ball. A stunning new photo of the Milky Way (shown above) came about because of a flea-market purchase, a late night on a Chilean mountain range, and a dash of inspiration.
Laniakea: Our home supercluster
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