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2018년 4월 30일 월요일

우주 이야기 776 - 17억개의 별 지도를 공개한 가이아




(Gaia’s all-sky view of our Milky Way Galaxy and neighbouring galaxies, based on measurements of nearly 1.7 billion stars. The map shows the total brightness and colour of stars observed by the ESA satellite in each portion of the sky between July 2014 and May 2016. Brighter regions indicate denser concentrations of especially bright stars, while darker regions correspond to patches of the sky where fewer bright stars are observed. The colour representation is obtained by combining the total amount of light with the amount of blue and red light recorded by Gaia in each patch of the sky.  The bright horizontal structure that dominates the image is the Galactic plane, the flattened disc that hosts most of the stars in our home Galaxy. In the middle of the image, the Galactic centre appears vivid and teeming with stars. Darker regions across the Galactic plane correspond to foreground clouds of interstellar gas and dust, which absorb the light of stars located further away, behind the clouds. Many of these conceal stellar nurseries where new generations of stars are being born. Sprinkled across the image are also many globular and open clusters – groupings of stars held together by their mutual gravity, as well as entire galaxies beyond our own.  The two bright objects in the lower right of the image are the Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way.  In small areas of the image where no colour information was available – to the lower left of the Galactic centre, to the upper left of the Small Magellanic Cloud, and in the top portion of the map – an equivalent greyscale value was assigned. The second Gaia data release was made public on 25 April 2018 and includes the position and brightness of almost 1.7 billion stars, and the parallax, proper motion and colour of more than 1.3 billion stars. It also includes the radial velocity of more than seven million stars, the surface temperature of more than 100 million stars, and the amount of dust intervening between us and of 87 million stars. There are also more than 500 000 variable sources, and the position of 14 099 known Solar System objects – most of them asteroids – included in the release.  Credit: Gaia Data Processing and Analysis Consortium (DPAC); A. Moitinho / A. F. Silva / M. Barros / C. Barata, University of Lisbon, Portugal; H. Savietto, Fork Research, Portugal.)


(Gaia’s all-sky view of our Milky Way Galaxy and neighbouring galaxies. The maps show the total brightness and colour of stars (top), the total density of stars (middle) and the interstellar dust that fills the Galaxy (bottom).  These images are based on observations performed by the ESA satellite in each portion of the sky between July 2014 and May 2016, which were published as part of Gaia second data release on 25 April 2018. Credit: Gaia Data Processing and Analysis Consortium (DPAC); Top and middle: A. Moitinho / A. F. Silva / M. Barros / C. Barata, University of Lisbon, Portugal; H. Savietto, Fork Research, Portugal;Bottom: Gaia Coordination Unit 8; M. Fouesneau / C. Bailer-Jones, Max Planck Institute for Astronomy, Heidelberg, Germany.)


 사상 최대의 항성 관측 데이터를 품고 있는 유럽 우주국(ESA)의 가이아(Gaia) 관측 자료가 공개됐습니다. 2013년부터 우주에서 우리 은하와 주변 위성은하의 데이터를 수집하고 있는 가이아는 이미 1차 데이터를 공개한 바 있습니다. 




 이번에 공개된 2차 데이터는 무려 17억개의 별에 대한 관측치로 이전에 공개된 것보다 더 거대한 데이터입니다. 여기에는 13억 개의 별의 고유 속도 및 연주 시차가 포함되어 있으며 10%정도는 직접 거리 측정이 가능한 수준으로 역대 가장 상세한 별의 3차원 지도를 구할 수 있을 것으로 기대됩니다. 



(동영상)


 동시에 이번 데이터 공개에는 50만 개에 달하는 변광성의 밝기 및 색상 변화 데이터, 백만개의 별 표면 온도 데이터 등 우리 은하에 있는 별에 대한 매우 유용한 빅데이터가 들어 있어 앞으로 천문학 연구에 획기적인 전기를 마련할 것으로 기대됩니다. 


 물론 가이아 데이터에는 별에 관련된 데이터만 담겨 있는 것은 아닙니다. 태양계의 소행성 14000개에 대한 관측 데이터는 물론 주변 위성 은하와 구상 성단 등 다양한 데이터가 같이 포함되어 앞으로 우주를 연구하는 과학자들에게 귀중한 데이터를 제공할 것으로 기대되고 있습니다. 


 참고

More information: A series of scientific papers describing the data contained in the release and their validation process will appear in a special issue of Astronomy & Astrophysics.

A series of 360-degree videos and other Virtual Reality visualisation resources are available at sci.esa.int/gaia-vr

Gerard Gilmore. Gaia: 3-dimensional census of the Milky Way Galaxy, Contemporary Physics (2018). DOI: 10.1080/00107514.2018.1439700



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