Gaia Space Telescope Shakes Asteroid Sciences – ScienceDaily
The European space operation Gaia has produced an unprecedented amount of new, improved and detailed information about nearly two billion objects in the Milky Way galaxy and surrounding space. Gaia Data Release 3, released on Monday, will revolutionize our knowledge of the solar system and the Milky Way and its satellite galaxies.
The European Space Agency’s (ESA) Gaia space mission is building an ultra-precise three-dimensional map of our Milky Way galaxy, observing nearly two billion stars, or about one percentage point of all the stars in our galaxy. Gaia was launched in December 2013 and has been collecting scientific data since July 2014. On Monday, June 13, ESA released Gaia data in Data Release 3 (DR3). Finnish researchers were strongly involved in the publication.
The Gaia data allow, for example, the derivation of the orbit and physical properties of asteroids and exoplanets. The information will help reveal the origins and future evolution of the solar system and the Milky Way, and will help us understand the evolution of stars and planets and our place in the cosmos.
Gaia revolves slowly around its axis in about six hours and consists of two optical space telescopes. Three scientific instruments make it possible to accurately determine the position and velocities of stars and the properties of the spectrum. Gaia is located about 1.5 million kilometers from Earth in the direction of the anti-Sun, where it orbits the Sun together with the Earth in the so-called Sun-Earth near Lagrange L2.
Gaia DR3 on June 13, 2022 was significant for astronomy. About 50 scientific articles are published on DR3, nine of which are dedicated to highlighting the exceptionally significant potential of DR3 for future research.
The new DR3 data includes, for example, the chemical compositions, temperatures, colors, masses, brightness, ages, and radial velocities of the stars. DR3 contains the largest-ever binary star list of the Milky Way, more than 150,000 solar system objects, mostly asteroids, but also planetary satellites and millions of galaxies and quasars outside the Milky Way.
“There are so many revolutionary advances that it is difficult to locate the most significant progress. Based on Gaia DR3, Finnish scientists are changing the perception of asteroids in our solar system, exoplanets and stars in the Milky Way galaxy. for an accurate reference framework for navigation and positioning, “says Academy Professor Karri Muinonen from the University of Helsinki.
Gaia and asteroids
A tenfold increase in the number of asteroids reported in Gaia DR3 compared to DR2 means that the number of close encounters between asteroids detected by Gaia has increased significantly. These close encounters can be exploited to estimate the mass of asteroids, and we expect Gaia DR3 astrometry to lead to a significant increase in asteroid masses when combined with astrometry from other telescopes.
In a traditional asteroid orbit calculation, an asteroid is assumed to be a point object and does not take into account its size, shape, rotational ability, or surface light scattering properties. However, the Gaia DR3 astrometry is so accurate that the angular misalignment between the center of mass of the asteroid and the center of the visible area of the Sun and the visible area of Gaia must be taken into account. Based on Gaia DR3, the offset is certified for the asteroid (21) Lutetia (Figure 2). ESA’s Rosetta space mission photographed Lutetia in a bypass flight on 10 July 2010. Rosetta Lutetia images and terrestrial astronomical observations provided an orbital period, the orientation of the rotating poles and a detailed shape model. When physical modeling is included in the orbital calculation, systematic errors are eliminated and, unlike conventional calculation, all observations can be included in the orbital solution. Thus, Gaia astrometry provides information on the physical properties of asteroids. These properties must be taken into account when using physical models or empirical error models of astrometry.
For the first time, Gaia DR3 includes spectral observations. The spectrum measures the color or brightness of an object at different wavelengths. One particularly interesting feature is that the new release contains about 60,000 spectra of asteroids in our solar system (Figure 3). The asteroid spectrum contains information about their composition and thus their origin and the evolution of the entire solar system. Prior to Gaia DR3, only a few thousand asteroid spectra were available, so Gaia multiplies the amount of data by an order of magnitude.
Gaia and exoplanets
Gaia is expected to make observations on up to 20,000 giant exoplanets by measuring the effect of their gravity on the motions of their host stars. This will allow almost all exoplanets like Jupiter to be found in the Sun’s neighborhood over the coming years and determine how common architectures like the solar system are. The first such astrometric Gaia observation was the giant exoplanet around epsilon Indi A, which corresponds to the nearest exoplanet like Jupiter just 12 light-years away. The first such observations are possible because the acceleration observed in radial velocity studies can be combined with Gaia motion data to determine the masses of orbits and planets.
Gaia and the galaxies
Gaia DR3’s microcar second resolution provides accurate measurements of stellar motion, not only in our own Milky Way, but also in many of the surrounding satellite galaxies. From the motion of the stars inside the orbit, we can accurately measure its mass, and together with the correct motion of the satellites, we can now accurately determine their orbits. This allows us to look at the past and future of the Milky Way galaxy system. For example, we can find out which of the galaxies surrounding the Milky Way are real satellites and which are just passing by. We can also examine whether the evolution of the Milky Way is in line with cosmological models and, in particular, whether the orbits of the satellites are suitable for the standard dark matter model.
Gaia and frameworks
The international celestial reference framework, ICRF3, is based on the location of a few thousand quasars determined by the Very Long Baseline Interferometry (VLBI) method at radio wavelengths. ICRF3 is used to determine the coordinates of celestial bodies and to determine the orbit of satellites. The quasars in ICRF3 are also fixed points in the sky that can be used to determine the exact direction of the Earth in space at any time. Without this information, for example, satellite positioning would not work.
The Gaia data contain about 1.6 million quasars, which can be used to create a more accurate celestial frame of reference in the light of the present instead of the present. In the future, this will have an impact on the accuracy of both satellite positioning and Earth-based satellite measurements.