The European Space Agency (ESA) Gaia mission has just released new data. The Gaia satellite was launched in 2013, aiming to measure the exact locations of one billion stars. In addition to measuring the positions, velocities and brightness of stars, the satellite has collected data on a huge range of other objects. There is much to excite astronomers. Here are five of our favorite information that data can provide.

  1. Secrets of the past and future of our galaxy Everything in space moves and the stars are no exception. The latest version of the data contains the largest 3D map of the galaxy ever created – showing how stars travel in our galaxy. Previous data included star movements in two dimensions: up-down and left-right (collectively known as appropriate star movements). But the latest data also show how fast stars move away from or towards us, something we call star radial velocities. By combining radial velocity with proper motion, we can discover how fast the stars move in three dimensions as they orbit our galaxy. This means that we now not only have the best map of where the stars of the galaxy are now, but we can track their movements forward to see how things will change and backwards to see how things used to be. . This can tell us things about the history of our galaxy, such as which stars may have originated in other galaxies and merged with ours in the past. Radial velocity measurements can also help us find hidden objects, such as planets and brown dwarfs (extremely faint, low-mass stars), from the tiny oscillations they cause as they orbit a host star.
  2. Details on how the stars die Gaia not only counts the stars in our galaxy, but also counts them in the neighboring Andromeda galaxy. The data includes something called Gaps: Gaia Andromeda photometric research. A photometric survey measures the brightness of stars and how they change over time. With Gaps, Gaia has measured the luminosity over time for each star in the direction of the Andromeda Galaxy. That includes 1.2 million stars. Some of these will be stars in the galaxy that happened to be an obstacle, but should include about the brightest 1% of the stars in the Andromeda Galaxy. This will allow us to study how the largest, brightest stars in Andromeda change in brightness, telling us about their evolution and where they are in their life cycle. This could tell us more about old stars coming to the end of their lives – some of which could eventually produce supernovae (huge explosions) eventually.
  3. The truth about the strange expansion of the universe Quasars, extremely energetic galaxy nuclei on the edge of the observable universe, are the brightest objects in the universe and the farthest objects we can see. And the new data includes measurements of 1.1 million of them. Quasars contain oversized black holes that are trapped in a violent feeding frenzy. In addition to these confirmed quasars, Gaia found another 6.6 million quasar candidates. This potentially greatly increases the number of known quasars, and this could be very important because they allow us to measure the distance to the farthest point in the universe. This in turn allows us to measure how fast the universe is expanding. Being able to measure it more accurately is important because we have two conflicting measurements of expansion and we do not know which one is correct – the problem is called “Hubble intensity”.
  4. How many asteroids have moons? Not everything Gaia studies is so far from home. The data contains 158,000 objects in our solar system. This includes new measurements of 156,000 known asteroids, which tell us exactly which paths they follow as they orbit the Sun. Not only that, but Gaia’s team has been shown to be able to find moons orbiting asteroids, based on how the moons make asteroids oscillate. Hundreds of asteroids with moons are already known, but Gaia can find asteroids even when the moon is too small to see it directly. It can also measure the positions of asteroids so accurately that it sees the slight oscillation in the position caused by the gravity of a moon. Esa says the latest data contains at least one such new moon, but it could be much more. Gathering better data on asteroids can tell us about the chaos of the early Solar System, when larger planets dropped smaller planets and asteroids into new orbits around the Sun and led to the current solar system.
  5. How stars are formed and function Our Sun is a solitary star, but many stars have companions – orbiting each other around a common center. The new data contains the first taste of Gaia’s list of such multi-star systems. This is an initial list, with the full list to be released in a later data version, but it already contains 813,000 binary systems (two stars). Binary stars can tell us a lot about how stars work and how they form. This is especially true of what are called binary eclipse systems. These are binary systems that happen to be lined up so that the stars pass in front of each other from our point of view. Binary eclipse files are special because we can take measurements to calculate all the physical properties of the system, such as the masses and sizes of the stars and how far away they are. This allows us to learn much more than we could from studying single stars. This new data will excite astrophysicists around the world and we look forward to sticking to it to see what we can find. We may have some of these answers in the coming months, while others may need more. The authors are with Open University, UK