Spiral Galaxy Ancestors Discovered
Our galaxy is a Spiral Galaxy, twisting ever so gently into the familiar curve we recognise as the Milky Way. Galaxies come in many shapes and sizes, and astronomers have long scanned the heavens for the origins of these star clusters. Before now they had discovered the ancestors of Elliptical Galaxies, but recently our Spiral Galaxy Ancestors have been discovered.
2 Billion Years Old
The most recent estimation of the age of the universe is about 13.7 billion years, which means the discovery of the 2 billion year old spiral galaxy progenitors has been about 12 billion years in the making.The discovery was not happenstance, by any stretch of the imagination; discovering a galaxy this old and this far away is not the equivalent of spotting a shooting star, or even stumbling across a visible planet using the Hubble Space Telescope. It took the combined efforts of researchers using both land based and space based telescopes, some creative thinking, and about five years to make this discovery.
Baby Galaxies
Due to the time it takes light to travel the distance, viewing these galaxies is akin to taking a photograph back in time. We see them as they looked 2 billion years ago, and as might be expected they are quite a bit smaller than our home galaxy. Only one-fortieth the stars are found in these newly discovered galaxies, which are about one-twentieth the mass of ours. Over all they are one-tenth the size, which is important in defining what they will grow up to be.Previously astronomers had discovered ancient galaxies with less mass and fewer stars, but they were too big. What they knew of cosmological theory told the scientists that these galaxies would grow up not to be Spiral Galaxies like our Milky Way, but Elliptical.
The size was one key that these new galaxies were the ancestors to Spirals, but there was another important factor, one that lead to their discovery in the first place.
Lyman Alpha Emitters
While these new galaxies might be spotted by a ground based telescope, they would have passed off as a single star. It took examination by the Hubble Telescope, unhindered by our Earth's atmosphere, and the detection of a type of ultraviolet light known as Lyman alpha to clue in the researchers.Like many important discoveries in astronomy, this was the result of many people working hard at their passions. The Multi-Wavelength Survey by Yale and Chile, or MUSYC, kicked off five years ago and is essentially an effort to catalogue the early universe. Part of the survey was the specific search for Lyman alpha emitting galaxies, which the scientists knew would be indicative of low-mass star clusters, an important clue to finding a spiral galaxy predecessor.
Final Thoughts
Small galaxies are typically pulled together, as many as a dozen in one location, to join one larger galaxy. Our Milky Way was formed in such a fashion. Astronomers will use this discovery to continue to unlock the secrets about the beginnings - and perhaps the endings - of our solar system, galaxy, and universe.Related Articles in the 'Galaxies' Category...
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