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Posts Tagged ‘Andromeda Galaxy’

Hubble Finds Massive Halo Around The Andromeda Galaxy


University of Notre Dame astrophysicist Nicolas Lehner has led a team of scientists who have used NASA’s Hubble Space Telescope to identify an immense halo of gas surrounding the Andromeda Galaxy, the nearest major galaxy to Earth. The halo stretches about a million light-years from Andromeda, halfway to the Milky Way. The discovery will tell astronomers more about the evolution and structure of giant spiral galaxies such as the Milky Way and Andromeda.

“Halos are the gaseous atmospheres of galaxies,” said Lehner, the lead investigator. “The properties of these gaseous halos control the rate at which stars form in galaxies.” The gargantuan halo is estimated to contain at least as much mass in its diffuse gas as half of the stars in the Andromeda Galaxy.

The Andromeda Galaxy, also known as Messier 31 or M31, is the most massive galaxy in the Local Group of galaxies that also includes the Milky Way and about 45 other known galaxies. M31 contains one trillion stars, about double the number of stars in the Milky Way. It is estimated to be about 25 percent more luminous than the Milky Way and lies 2.5 million light-years away.

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Measuring The Universe More Accurately Than Ever Before


After nearly a decade of careful observations an international team of astronomers has measured the distance to our neighbouring galaxy, the Large Magellanic Cloud, more accurately than ever before. This new measurement also improves our knowledge of the rate of expansion of the Universe — the Hubble Constant — and is a crucial step towards understanding the nature of the mysterious dark energy that is causing the expansion to accelerate. The team used telescopes at ESO’s La Silla Observatory in Chile as well as others around the globe. These results appear in the 7 March 2013 issue of the journal Nature.

Astronomers survey the scale of the Universe by first measuring the distances to close-by objects and then using them as standard candles to pin down distances further and further out into the cosmos. But this chain is only as accurate as its weakest link. Up to now finding an accurate distance to the Large Magellanic Cloud (LMC), one of the nearest galaxies to the Milky Way, has proved elusive. As stars in this galaxy are used to fix the distance scale for more remote galaxies, it is crucially important.

But careful observations of a rare class of double star have now allowed a team of astronomers to deduce a much more precise value for the LMC distance: 163 000 light-years.

Full Story: http://www.eso.org/public/news/eso1311/

Crowdsourcing The Cosmos: Astronomers Welcome All To Identify Star Clusters In Andromeda Galaxy

December 8, 2012 Leave a comment

Credit: Robert Gendler

Credit: Robert Gendler

Astronomers are inviting the public to search Hubble Space Telescope images of the Andromeda galaxy to help identify star clusters and increase understanding of how galaxies evolve.

The new Andromeda Project, set to study thousands of high-resolution Hubble images, is a collaboration among scientists at the University of Washington, the University of Utah and several other partners.

“It’s an amazing opportunity to discover something new,” said Julianne Dalcanton, UW astronomy professor. “Anyone can look at these beautiful Hubble images and participate in the scientific process. And it’s a huge help to us.”

Full Story: http://www.washington.edu/news/2012/12/04/crowdsourcing-the-cosmos-astronomers-welcome-all-to-identify-star-clusters-in-andromeda-galaxy/
Also: http://unews.utah.edu/news_releases/andromeda-wants-you/

Bright Object in Andromeda Caused by ‘Normal’ Black Hole

February 23, 2012 Leave a comment

Image Credit: MPE

Image Credit: MPE

A spectacularly bright object recently spotted in one of the Milky Way’s neighbouring galaxies is the result of a “normal” stellar black hole, astronomers have found.

An international team of scientists, led by Dr Matt Middleton, of Durham University, analysed the Ultraluminous X-ray Source (ULX), which was originally discovered in the Andromeda galaxy by NASA’s Chandra x-ray observatory. They publish their results in the journals Monthly Notices of the Royal Astronomical Society and Astronomy and Astrophysics.

Many ULXs are too far away for astronomers to study, but the relatively close proximity of Andromeda to the Milky Way – around 2.5 million light years – gave the team opportunity to study the phenomenon.

The researchers say their study could begin to answer the question about what causes ULXs. Some scientists believe they are caused by relatively small black holes, a few times the mass of our Sun. These black holes rapidly pull in gas and dust which forms an “accretion disc” and heats up causing the material to emit X-rays.

Full Story: http://www.ras.org.uk/news-and-press/219-news-2012/2075-spectacularly-bright-object-in-andromeda-caused-by-normal-black-hole

Rare Ultra-Blue Stars Found in Andromeda’s Hub

January 11, 2012 Leave a comment

Credit: NASA; ESA; B. Williams and J. Dalcanton, University of Washington, Seattle

Credit: NASA; ESA; B. Williams and J. Dalcanton, University of Washington, Seattle

Peering deep inside the hub of the neighboring Andromeda galaxy, NASA’s Hubble Space Telescope has uncovered a large, rare population of hot, bright stars.

Blue is typically an indicator of hot, young stars. In this case, however, the stellar oddities are aging, sun-like stars that have prematurely cast off their outer layers of material, exposing their extremely blue-hot cores.

Astronomers were surprised when they spotted these stars because physical models show that only an unusual type of old star can be as hot and as bright in ultraviolet light. 

While Hubble has spied these ultra-blue stars before in Andromeda, the new observation covers a much broader area, revealing that these stellar misfits are scattered throughout the galaxy’s bustling center. Astronomers used Hubble’s Wide Field Camera 3 to find roughly 8,000 of the ultra-blue stars in a stellar census made in ultraviolet light, which traces the glow of the hottest stars. The study is part of the multi-year Panchromatic Hubble Andromeda Treasury survey to map stellar populations across the galaxy.

Full Story: http://www.nasa.gov/mission_pages/hubble/science/ultra-blue.html

Hubble Zooms In on Andromeda’s Double Nucleus

January 11, 2012 Leave a comment

Credit: NASA, ESA, and T. Lauer (National Optical Astronomy Observatory)

Credit: NASA, ESA, and T. Lauer (National Optical Astronomy Observatory)

A new Hubble Space Telescope image centers on the 100-million-solar-mass black hole at the hub of the neighboring spiral galaxy M31, or the Andromeda galaxy, the only galaxy outside the Milky Way visible to the naked eye and the only other giant galaxy in the local group.

This is the sharpest visible-light image ever made of the nucleus of an external galaxy.

The event horizon, the closest region around the black hole where light can still escape, is too small to be seen, but it lies near the middle of a compact cluster of blue stars at the center of the image. The compact cluster of blue stars is surrounded by the larger “double nucleus” of M31, discovered with the Hubble Space Telescope in 1992. The double nucleus is actually an elliptical ring of old reddish stars in orbit around the black hole but more distant than the blue stars. When the stars are at the farthest point in their orbit they move slower, like cars on a crowded freeway. This gives the illusion of a second nucleus.

Full Story: http://www.nasa.gov/mission_pages/hubble/science/double-nucleus.html