* Astronomy

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RE: Milky Way

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Milky Way in mid-life crisis

The Milky Way is suffering from a mid-life crisis with most of it star formation behind it, new research from Swinburne University of Technology has shown.
Galaxies typically fall into one of two categories energetic blue galaxies that form new stars at an impressive rate, or lethargic red galaxies which are slowly dying.
In a paper accepted for publication in the Astrophysical Journal, Mr Simon Mutch, Dr Darren Croton and Dr Gregory Poole, have shown that our own Milky Way galaxy is neither of these. Rather it is a rare green valley galaxy that is half way between a youthful blue galaxy and a geriatric red one.
This is the first time that astronomers have compared both the colour and the star formation rate of the Milky Way to that of other galaxies in the Universe.
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Astronomers Spot a Newfound Piece of the Milky Way Galaxy

A new study identifies a previously unseen spiral arm of the Milky Way.
The newfound structure, some 70,000 light-years away, may be the continuation of a major, previously known spiral arm, part of which is visible much closer to Earth. Thomas Dame and Patrick Thaddeus of the HarvardSmithsonian Centre for Astrophysics announce the finding in a study that is set to appear in The Astrophysical Journal Letters.
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It may be our home but just how special is the Milk Way?

That's the question a team including Oxford University scientists have been looking to answer using simulations of our galaxy and our neighbours, the Magellanic Clouds.
Their findings, reported in a paper in The Astrophysical Journal could help in the hunt for dark matter. I asked one of the paper's authors, Phil Marshall of Oxford University's Department of Physics, about Universal assumptions, starless galaxies, and telltale gamma rays...
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Title: The mid-life crisis of the Milky Way and M31
Authors: Simon J. Mutch, Darren J. Croton, Gregory B. Poole (Swinburne University of Technology)

Upcoming next generation galactic surveys, such as GAIA and HERMES, will deliver unprecedented detail about the structure and make-up of our Galaxy, the Milky Way, and promise to radically improve our understanding of it. However, to benefit our broader knowledge of galaxy formation and evolution we first need to quantify how typical the Galaxy is with respect to other galaxies of its type. Through modelling and comparison with a large sample of galaxies drawn from the Sloan Digital Sky Survey and Galaxy Zoo, we provide tentative yet tantalizing evidence to show that both the Milky Way and nearby M31 are undergoing a critical transformation of their global properties. Both appear to possess attributes that are consistent with galaxies midway between the distinct blue and red bimodal colour populations. In extragalactic surveys, such 'green valley' galaxies are transition objects whose star formation typically will have all but extinguished in less than ~5 Gyrs. This finding reveals the possible future of our own galactic home, and opens a new window of opportunity to study such galactic transformations up close.

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Just Four Percent of Galaxies Have Neighbours Like the Milky Way

How unique is the Milky Way?
To find out, a group of researchers led by Stanford University astrophysicist Risa Wechsler compared the Milky Way to similar galaxies and found that just four percent are like the galaxy Earth calls home.
The research team compared the Milky Way to similar galaxies in terms of luminosity--a measure of how much light is emitted--and distance to other bright galaxies. They found galaxies that have two satellites that are as bright and close by as the Milky Way's two closest satellites, the Large and Small Magellanic Clouds, are rare.
Published in the May 20 issue of the Astrophysical Journal, the findings are based on analyses of data collected from the Sloan Digital Sky Survey (SDSS). The work is the first of three papers that study the properties of the Milky Way's two most massive satellites.