Part of the Milky Way Is Much Older Than Previously Believed

Basic structure of our home galaxy, edge-on view. The new results from ESA's Gaia mission provide for a reconstruction of the history of the Milky Way, in particular of the evolution of the so-called thick disc. Image Credit: Stefan Payne-Wardenaar / MPIA

The Milky Way is older than astronomers thought, or part of it is. A newly-published study shows that part of the disk is two billion years older than we thought. The region, called the thick disk, started forming only 0.8 billion years after the Big Bang.

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A New Way to Measure the Age of the Milky Way

Artist’s impression of the warped and twisted Milky Way disk. Credit: Chen Xiaodian/Kavli Institute of Astronomy and Astrophysics

Like many other spiral galaxies in the Universe, the Milky Way Galaxy consists of two disk-like structures – the thin disk and the thick disk. The thick disk, which envelopes the thin disk, contains about 20% of the Milky Way’s stars and is thought to be the older of the pair based on the composition of its stars (which have greater metallicity) and its puffier nature.

However, in a recent study, a team of 38 scientists led by researchers from Australia’s ARC Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO-3D) used data from the now-retired Kepler mission to measure starquakes in the Milky Way’s disk. From this, they have revised the official estimates on the age of the Milky Way’s thick disk, which they conclude is around 10 billion years old.

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The Milky Way is Actually Warped

Artist’s impression of the warped and twisted Milky Way disk. Credit: Chen Xiaodian/Kavli Institute of Astronomy and Astrophysics

For centuries, astronomers have been studying the Milky Way in order to get a better understanding of its size and structure. And while modern instruments have yielded invaluable observations of our galaxy and others (which have allowed astronomers to gain a general picture of what it looks like), a truly accurate model of our galaxy has been elusive.

For example, a recent study by a team of astronomers from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) has shown that the large-scale structure of the Milky Way is quite warped. Based on their findings, it appears that this effect becomes increasingly evident the farther away one ventures from the core.

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