Space

New map of Milky Way contains over a billion stars

Representation of the first large scale release from ESA's Gaia satellite
Representation of the first large scale release from ESA's Gaia satellite
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Representation of the first large scale release from ESA's Gaia satellite
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Representation of the first large scale release from ESA's Gaia satellite
Artist's impression of the Gaia probe in space
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Artist's impression of the Gaia probe in space
Visual representation of Gaia data overlaid with the positions of various galaxies open clusters and globular clusters
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Visual representation of Gaia data overlaid with the positions of various galaxies open clusters and globular clusters

ESA (the European Space Agency) has released a colossal star catalog detailing the precise positions and brightness of over a billion stellar bodies spread across the Milky Way. Created from dataharvested by the agency's Gaia satellite, the new catalog, which isby far the largest of its kind, is a significant step on the road tothe probe's ultimate mission of creating the most precise andcomprehensive 3D map of our galaxy ever.

The new release accounts for datacollected by the satellite over the first 14 months of observation,ending in September this year. The task of converting the probe's rawdata into a useful tool for the scientific community fell to the GaiaData Processing and Analysis Consortium (DPAC) – a group of around450 scientists and software engineers hailing from over 20 countries.

This highly skilled workforce has striven and succeeded in creating a resource that details the brightness,location and motion of 1,142 million stars, with a precision twicethat of any previous large-scale catalog. The general public canappreciate the magnitude of the release in a more accessible formatvia a visualization of the data that is freely available on the Gaia webpage.

Artist's impression of the Gaia probe in space
Artist's impression of the Gaia probe in space

DPAC was able to provide a moredetailed analysis of some 2 million stars by combining Gaia data withthat of the 1997 Hipparcos and Tycho-2 catalogs. Thenew observations, when combined with the old, allowed scientists toaccount for parallax and apparent motion effects, facilitating accurate estimates regarding the stellarbodies' motion and distance from Earth.

To further demonstrate the capabilitiesof the new catalog, DPAC carried out a study of open star clusters.Under the Hipparcos and Tycho-2 star catalogs, scientists couldonly accurately map the disposition, motion, and distance of stellarbodies composing the closest open cluster to Earth, which, known asthe Hyades cluster, sits 151 light-years from our planet.

Using the Gaia catalog, DPAC was ableto map the distance, distribution and motion of around 400 openclusters up to a maximum range of roughly 4,800 light-years – amassive leap forward.

Gaia has the capacity to improve theaccuracy of techniques used to map vast cosmic distances by providingdetailed observations of celestial objects such as Cepheid variable stars. These stellar bodies are so named owing to thefact that they periodically expand and contract, brightening anddimming in the process.

Visual representation of Gaia data overlaid with the positions of various galaxies open clusters and globular clusters
Visual representation of Gaia data overlaid with the positions of various galaxies open clusters and globular clusters

In 1912, American astronomer HenriettaSwan Leavitt discovered that the periodical expanding and contractingof Cepheid stars relates directly to the star's luminosity. Withthis relationship established, astronomers are now able to work outthe actual brightness of a Cepheid star by observing pulsationperiods, and then compare this luminosity with the observedbrightness of the stellar body as perceived from Earth in order towork out the distance.

During the first 14 months of Gaia'soperational life, the satellite has discovered 386 previously unknownCepheids. It is hoped that further observations will allowastronomers to gain a greater understanding of this unusual breed ofstar, and thus improve their ability to accurately chart vast cosmicdistances.

Gaia may also have a significant roleto play in the study of the atmospheres of planets within our ownsolar system, by providing a greater understanding of the movement ofstars across the sky. In July 2016, the early release of data fromthe satellite was instrumental in allowing astronomers to observe thetenuous atmosphere clinging to the dwarf planet Pluto as it passed betweenEarth and a distant star.

Scroll down to see a visualization of how Gaia mapped the entire sky.

Source: ESA

Gaia scanning the sky

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