Gaia space telescope rocks asteroid science, astronomy and astrophysics news

The European space mission Gaia has produced an unprecedented amount of new, improved, and detailed data on nearly two billion objects in the Milky Way and the surrounding universe. Monday’s Gaia Data Release 3 revolutionized our knowledge of the Solar System, the Milky Way, and its galaxies.

ESA’s Gaia space mission is building a super-resolution 3D map of our galaxy, the Milky Way, by observing nearly two billion stars, or about one percent of all the stars in our galaxy. Gaia was launched in December 2013 and scientific data was collected from July 2014. On Monday 13th June, ESA published Gaia data in Data Release 3 (DR3). Finnish researchers were heavily involved in the release.

Data from Gaia, for example, allows the orbits and physical properties of asteroids and exoplanets to be derived. The data helps reveal the origin and evolution of the solar system and the Milky Way in the future and helps understand the evolution of the star, the planetary system, and our place in the universe.

Gaia slowly rotates on its axis in about six hours and consists of two optical space telescopes. Three scientific instruments allow precise determination of star positions and velocities, as well as spectral properties. Gaia is located approximately 1.5 million kilometers from Earth in the opposite direction from the Sun, orbiting around the Sun with the Earth near what is called the Lagrangian point L2.

Gaia DR3 on June 13, 2022 was significant throughout astronomy. About 50 scientific papers using DR3 have been published, nine of which are dedicated to highlighting the extremely huge potential of DR3 for future research.

The new DR3 data includes, for example, chemical compositions, temperatures, colours, masses, luminosity, ages, and radial velocities of stars. DR3 includes the largest catalog of binary stars ever created for the Milky Way, more than 150,000 objects in the Solar System, mostly asteroids but also satellites of planets, and millions of galaxies and quasars outside the Milky Way.

“There are so many revolutionary developments that it is difficult to determine which advances are the most significant. Based on Gaia DR3, Finnish researchers will change the design of asteroids in our solar system, exoplanets and stars in our Milky Way, as well as galaxies. Including the Milky Way and its satellite galaxies Returning to our planet, Gaia will produce an ultra-accurate frame of reference for navigation and positioning,” said academic professor Kari Moinonen from the University of Helsinki.

Gaia and the asteroids

A tenfold increase in the number of asteroids reported in Gaia DR3 compared to DR2 means that there has been a significant increase in the number of close encounters between asteroids detected by Gaia. These close encounters can be used to estimate asteroid mass and we expect a significant increase in the number of asteroid masses that will be derived using Gaia DR3 astrometry, especially when combined with astrometry obtained by other telescopes.

In the traditional calculation of the asteroid’s orbit, it is assumed to be a point-like object and its size, shape, rotation and surface light scattering properties are not taken into account. The Gaia DR3 astrometry is very accurate, however, it must take into account the angular displacement between the center of mass of the asteroid and the center of the sunlit region visible to Gaia. Based on Gaia DR3, the offset is adopted for the asteroid (21) Lutetia (Fig. 2). The European Space Agency’s (ESA) Rosetta space mission imaged Lutetia in flight on July 10, 2010. With the help of Rosetta Lutetia images and terrestrial astronomical observations, the rotation period, spindle orientation and detailed shape model were derived. When physical modeling is incorporated into an orbit computation, systematic errors are removed, and unlike traditional computations, all observations can be incorporated into an orbital solution. Therefore, the Gaia astrometry provides information about the physical properties of asteroids. These properties should be taken into account using physical models or empirical error models for astrometry.

Gaia DR3 includes, for the first time, spectroscopic observations. The spectrum measures the color of the target, that is, the brightness at different wavelengths. A particularly interesting feature is that the new version contains about 60,000 spectrums of asteroids in our solar system (Fig. 3). The spectrum of asteroids contains information about their composition and, consequently, their origin and evolution of the entire solar system. Before Gaia DR3, there were only a few thousand asteroid spectra available, so Gaia will double the amount of data by more than an order of magnitude.

Gaia and the outer planets

Gaia is expected to discover up to 20,000 giant exoplanets by measuring the effect of gravity on the motion of their host stars. This will find virtually all Jupiter-like exoplanets in the solar neighborhood over the next few years and determine the frequency of solar system-like structures. The first astronomical discovery of Gaia was a giant exoplanet around Epsilon Indy A, the closest Jupiter-like exoplanet just 12 light-years away. The first of these discoveries is possible because the acceleration visible in radial velocity surveys can be combined with motion data from Gaia to determine the orbits and masses of planets.

Gaia and Galaxies

The microsecond resolution of Gaia DR3 provides accurate measurements of the motions of stars, not only in our galaxy, the Milky Way, but also many of the satellite galaxies that surround it. Through the motion of the stars in the Milky Way itself, we can accurately measure their masses, and with the appropriate motion of the satellites, we can now accurately determine their orbits. This allows us to consider both the past and the future of the Milky Way system. For example, we can find out which of the galaxies surrounding the Milky Way are real satellites and which pass through them. We can also study whether the evolution of the Milky Way conforms to cosmological models, and in particular, whether the orbits of satellites conform to the Standard Model of dark matter.

Gaia and frames of reference

The International Celestial Reference Frame, ICRF3, is based on the location of a few thousand quasars determined by very long fundamental interferometry (VLBI) at radio wavelengths. ICRF3 is used to obtain the coordinates of celestial bodies and to determine the orbits of satellites. ICRF3 quasars are also fixed points in the sky that can be used to determine the exact direction of Earth in space at any time. Without this information, for example, satellite positioning will not work.

The Gaia data contains approximately 1.6 million quasars, which can be used to create a more accurate visible-light celestial reference frame to replace the current one. In the future, this will affect the accuracy of satellite positioning and satellite measurements for exploration of the Earth.

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