Gaia satellite data reveals information on nearly 2 billion stars

On June 13, the Gaia space mission released its third data release, releasing massive data from the Gaia satellite, providing highly accurate indications of the position and brightness of 1.8 billion stars, as well as data from 2.9 million stars. Additional information obtained from observations. galaxy. The data, which consists of 400 engineers, researchers and technicians, can more realistically describe the solar system and the Milky Way, detect planets orbiting other stars (exoplanets), and describe more distant galaxies. The mission is led by the European Space Agency (ESA) and Gaia – the Data Processing and Analysis Consortium (DPAC), with professors from USP’s Institute for Astronomy, Geophysics and Atmospheric Sciences (IAG) as collaborators.

The Gaia space mission began to be considered in the early 1990s and was accepted by the ESA in 2006. “The launch of the mission satellite took place in December 2013 when it was placed in a very special and crowded spot in space called the Lagrange 2 (L2) point 1.5 million kilometers (km) from Earth. Science Watch Started in July 2014,” reports Ramachrisna Teixeira, IAG Professor, Gaia DPAC Member. “The data published now corresponds to 34 months of observations. In about two years, we will publish the fourth data, which is after 66 months of observations, so it is richer and more accurate. The fifth version, covering 120 months , expected to be released around 2030.”

Professor IAG pointed out that on the Gaia satellite, there are two special telescopes with a common focal plane, in which there are three instruments for astrometry (position, distance and motion), photometry (brightness in white light), Spectroscopic measurements of light (brightness, color and low-resolution spectroscopy) and spectroscopy (radial velocity and chemical composition).

“Over time, these observations allowed us to achieve previously unimaginable precision,” he explained. “For example, the most important quantity in astronomy, stellar parallax, the tiny displacement of stars in the sky due to the orbital motion of the Earth, which gives distance and calibrates the distance scale of the universe, is being measured to microsecond-level accuracy. “

The satellite revolves around itself in six hours, and its axis of rotation is about two months. “In this way, the satellite continuously scans the sky, measuring all the brightest stars. This scan of the sky has been extended by two years and is expected to be extended for another three years, with observations ending in March 2025,” the professor said. “It is the richness of the data, the precision of the measurements, and the diversity of objects observed, almost all celestial bodies that exist, that ensure this revolutionary feature of Gaia observations.”

Brightness and position

The stellar content in the third data release includes the location and brightness of 1.8 billion stars. “For 1.5 billion of these objects, we have complete astrometric technology, including position, distance, appropriate motion and color. In addition, there is data from more than 800,000 binary star systems, 40 times more than before, and nearly 50 astrophysical parameters such as luminosity, radius, temperature, chemical composition, mass, age and metallicity) of over 200 million stars and types,” Teixeira described. “The radial component of stellar motion has been measured for 33 million stars, almost 150 times larger than before the mission, and 3.5 million of them have similar rotation rates.”

“As far as the solar system is concerned, we have orbital solutions for nearly 160,000 objects, including various asteroids, non-Neptunian objects (trans-Neptune) and 31 planetary moons,” the professor emphasized. “Finally, the other big novelty of this launch is the extragalactic content, there are 1.9 million quasars with position, redshift (distance) and brightness, 60,000 of which we were able to detect their host galaxies, And 15,000 morphological features were detected. Determined… In addition, we observed 2.9 million galaxies, of which 800,000 we obtained their brightness distribution and morphological parameters.

Teixeira believes that of all the quantities extracted from the Gaia space mission’s observations, the most important is distance (stellar parallax). “Actually, this is the most important quantity in astronomy, because we can convert the observed apparent quantities into absolute quantities,” he stressed. “Without the knowledge of distances, astrophysics and cosmology would be very limited, probably to this day we still don’t know how stars shine and the universe is expanding.”

According to the professor, the task data is so rich that it is free to choose the best of them and still continue to use a robust sample. “Everything we say about the solar system, the Milky Way and the universe will become more real and reliable from this data, which may underpin astronomy for the next 20, 30 years,” he observed. “Scientific information extracted from digital codes sent to Earth by satellites is guaranteed by the Gaia DPAC, divided into groups dedicated to observations and aspects of celestial bodies.”

The IAG is part of an extended astronomical group led by Christine Ducourant of the Bordeaux Astrophysics Laboratory, France, which relies on the work of Professors Ramachrisna Teixeira, Sandra dos Anjos and Ronaldo Eustáquio de Souza, and former PhD student, Alberto Krone Martins, University of California professor. The collaboration began with a doctoral dissertation expanding the horizons of the Gaia space mission through galaxy observations, which Martins defended for IAG in 2011. “Gaia data is available to the world at the same time. Anyone can access them without problems and without paying any fees”, Teixeira concluded.



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