HOW FAR IS THE MILKY WAYS FARTHEST STAR?

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Image Credit & Copyright: Uniview by SCISS Data: SOHO (ESA & NASA), John Bochanski (Haverford College) and Jackie Faherty (American Museum of Natural History and Carnegie Institute’s Department of Terrestrial Magnetism).

Here’s an amazing discovery that was just brought to bear this year; first week of July actually.  It’s believed that the Milky Way is roughly (very roughly) 100,000 light years in diameter with 100-400 billion stars (which means we don’t know) and a halo extending out to a mind blowing 500,000 light years from the nucleus.  Well astronomers have apparently just been forced to push back the boundaries of what’s allowed for residency in our star city.  If we, at 25,000 light years from the galactic center are in the suburbs, then these two newly discovered stars are officially in the sticks!

The two stars are cataloged as ULAS J0744+25 (in the constellation Gemini) and ULAS J0015+01 (in the constellation Pisces) and are a ridiculous 775,000 and 900,000 light years from Earth.

John Bochansky; the discoverer and his team set out to find the most distant stars by taking the furthest 6 million plus stars in the galaxy and slowly sifting through them until they had 404 M-type stars remaining.  From those, two turned out to possess the signature of cool red giants.  This fact is very rare as the abundance of heavy elements is slim that far away but none the less, the finding is true.  How they got there or even, where they came from is still not known.

Beth Willman of Haverford College explains; “Theory predicts the presence of such an extended stellar halo, formed by the destroyed remains of small dwarf galaxies that merged over the cosmic ages to form the Milky Way itself. The properties of cool red giants in the halo thus preserve the formation history of our Milky Way. These stars are truly ghosts of galaxies past.”

FUN STUFF:

*They’re so far away in fact, that if you lived there the Milky Way wouldn’t look much different than Andromeda in your sky.  The illustration used for this post is what the Milky Way might look like from the most distant stars viewpoint.

*They’re about one third of the distance to Andromeda galaxy.

*That’s over 50 percent farther than any other star ever discovered in the galaxy.

*Prior to this discovery, only seven stars had ever been discovered beyond 400,000 light years away.

*If they orbit at a speed relatively close to the sun’s orbital seed they haven’t even made 2 full orbits as it takes them about 8 billion Earth years to complete one galactic year.  The universe itself is only 13.8 billion years old!

*When those detected photons left those stars, here on Earth Homo Erectus was honing the new skill of controlled fire, the last magnetic field reversal (Brunhes-Matuyama reversal) was roughly 100,000 years from taking place and the last eruption of the Yellowstone caldera (Lava Creek eruption) was 200,000+ years from occurring.

*The further of the two stars is 33 times further from the galactic core than we are.

*With one star in Gemini and the other in Pisces they are more than a million light years away from each other.

Here’s the Sky & Telescope article from John Bochanski himself: http://www.skyandtelescope.com/astronomy-news/the-most-distant-milky-way-stars-070920142/

Haverford press release on this discovery: http://www.haverford.edu/physics-astro/bochanski/mgiants_press.html

The Astrophysical Journal Letters release on this discovery: http://iopscience.iop.org/2041-8205/790/1/L5/

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