| Online: | |
| Visits: | |
| Stories: |
Think Earth is off the beaten path? Two stars in Milky Way’s outer halo are most faraway ever discovered
thespacereporter.com
The outermost stars of our Milky Way galaxy are a diffuse bunch, with only seven identified more than 400,000 light-years away. However, a new study led by John Bochanski of Haverford College has now found two stars in the Milky Way’s outer halo of scattered stars. According to a Haverford statement, the cool red giants ULAS J0744+25 and ULAS J0015+01 are an immense 775,000 and 900,000 light-years away, respectively.
The two stars are staggeringly far from the Sun. They are five times farther away than the Large Magellanic Cloud, a small satellite galaxy of the Milky Way 163,000 light-years away. They are a full third of the distance to the Andromeda Galaxy, the nearest large spiral galaxy at 2.5 million light-years away.
“The distances to these two stars are almost too large to comprehend,” Bochanski said. “To put it in perspective, when the light from ULAS J0015+01 left the star, our early human ancestors were just starting to make fires here on Earth.”
Both stars were revealed in data collected by the UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey. Bochanski and team employed a combination of filters that emphasized different parts of the optical and near-infrared spectra to locate the two stars. Such red giants are comparatively rare in relation to red dwarf stars. However, the red giants are around 10,000 times more luminous and more easily detected at great distances. The existence of the two stars was verified with spectroscopic data from the 6.5-meter telescope at the MMT Observatory in Arizona.
The newly discovered distant stars could reveal more about the evolution of the Milky Way. The halo of distant stars of which they are a part probably represents the remnants of the collisions and mergers of numerous smaller galaxies with the Milky Way. A larger sample of halo stars could allow Bochanski and colleagues to test existing models of the Milky Way’s formation; many current models do not predict such distant stars as ULAS J0744+25 and ULAS J0015+01.
The new discoveries were published on July 3 in the journal Astrophysical Journal Letters.
Source: http://www.ascensionearth2012.org/2014/07/think-earth-is-off-beaten-path-two.html
