Hard Science and Gaia: Bob Zimmerman BehindtheBlack.com

Apr 26, 04:29 PM
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AUTHOR.

(Photo: A map of the sky by star density.

Gaia is a space observatory of the European Space Agency (ESA) designed for astrometry: measuring the positions and distances of stars with unprecedented precision.[7][8] The mission aims to construct the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars but also planets, comets, asteroids and quasars among others.

The spacecraft will monitor each of its target objects about 70 times[9] over a period of five years to study the precise position and motion of each target.[10][11] The spacecraft has enough consumables to operate for approximately nine years, and its detectors are not degrading as fast as initially expected. The mission could therefore be extended.[2] The Gaia targets represent approximately 1% of the Milky Way population[9] with all stars brighter than magnitude 20 in a broad photometric band that covers most of the visual range.[12] Additionally, Gaia is expected to detect thousands to tens of thousands of Jupiter-sized exoplanets beyond the Solar System,[13] 500,000 quasars and tens of thousands of new asteroids and comets within the Solar System.[14][15][16])

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Hard Science and Gaia: Bob Zimmerman BehindtheBlack.com

http://behindtheblack.com/?s=gaia

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.