Gaia releases 3D map of galaxy


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The science team for the space telescope Gaia, designed to map the positions of billions of stars, have released the probe’s second catalog, producing a 3D map of 1.7 billion stars in the Milky Way

The new data release, which covers the period between 25 July 2014 and 23 May 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision. For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the Moon.

With these accurate measurements it is possible to separate the parallax of stars – an apparent shift on the sky caused by Earth’s yearly orbit around the Sun – from their true movements through the Galaxy. The new catalogue lists the parallax and velocity across the sky, or proper motion, for more than 1.3 billion stars. From the most accurate parallax measurements, about ten per cent of the total, astronomers can directly estimate distances to individual stars.

The catalog provides much more information than this. For example:

As well as positions, the data include brightness information of all surveyed stars and colour measurements of nearly all, plus information on how the brightness and colour of half a million variable stars change over time. It also contains the velocities along the line of sight of a subset of seven million stars, the surface temperatures of about a hundred million and the effect of interstellar dust on 87 million.

Gaia also observes objects in our Solar System: the second data release comprises the positions of more than 14 000 known asteroids, which allows precise determination of their orbits. A much larger asteroid sample will be compiled in Gaia’s future releases.

Further afield, Gaia closed in on the positions of half a million distant quasars, bright galaxies powered by the activity of the supermassive black holes at their cores. These sources are used to define a reference frame for the celestial coordinates of all objects in the Gaia catalogue, something that is routinely done in radio waves but now for the first time is also available at optical wavelengths.

I guarantee that many theories about specific strange stars, such as the plethora of different types of variable stars, are going to change drastically with this new and precise information. At the article they describe just one example relating to white dwarf stars.

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3 comments

  • Robert Pratt

    I wish for better writing than this: “The new data release, which covers the period between 25 July 2014 and 23 May 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision.” Greater precision than what? The sentence leaves us to assume the answer.
    Nitpick of the day.

  • Localfluff

    This is such an important milestone in astronomy. How great that it works so well, in spite of some minor issues with reflections from some contaminations early on. Knowing where stuff is and when, is the defining job of the astronomer. Still, they are greedy. One complained that while everything else has improved fantastically, during all of his career stellar temperatures have not been determined to better than to within 50 degrees Kelvin. Should be able to do better than that, despite sunspots and other stuff going on.

    The real 3D motion of 7 million stars has been determined. Finally we know where we are and where we come from the last several million years. Basic orientation of our immediate neighborhood.

  • Robert Pratt: They left out the simple phrase “than any previous such catalog.”

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