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The Gaia mission: five insights astronomers can glean from its latest data

By Adam McMaster PhD Student in Astronomy, UK Open University,  Andrew Norton Professor of Astrophysics Education, British Open University

The spaceship Gaia. Figure: European Space Agency
The spaceship Gaia. Figure: European Space Agency

Gaia mission of the European Space Agency (Esa) has just published new data. The Gaia satellite was launched in 2013, with the aim of measuring the exact position of a billion stars. In addition to measuring the positions, velocities and brightness of the stars, the satellite collected data on a huge variety of other objects.

There are many things that make astronomers excited. Here are five of our favorite insights the data might provide.

1. The secrets of our galaxy's past and future

Everything in space moves, and the stars are no exception. The latest release of the data contains the largest XNUMXD map of the Milky Way ever produced – showing how the stars in our galaxy move. Previous data included the movements of the stars in two dimensions: up-down and left-right (collectively known as the right movements of stars). But the latest data also shows how fast stars are moving away from us or toward us, something we call the stars' radial velocities.

By combining the radial velocity with the proper motions, we can find out how fast stars move in three dimensions as they orbit the Milky Way. 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 backward to see how things were in the past.

This can tell us about the history of our galaxy, for example which stars may have come from other galaxies and merged with those in our galaxy in the past. Radial velocity measurements can also help us find hidden objects, such as planets Brown pineapples (extremely faint low-mass stars), from the tiny wobbles they cause as they orbit a host star.

2. Details of how stars die

Gaia not only measures the stars in our galaxy, she also measures those in the neighboring Andromeda galaxy. The data includes something called Gaps: The photometric survey of Gaia Andromeda. A photometric survey measures the brightness of stars and how they change over time. With Gaps, Gaia measured the brightness over time for each star in the direction of the Andromeda Galaxy.

This region includes 1.2 million stars. Some are foreground stars in the Milky Way that happened to be in the way, but they should also comprise about 1% of the brightest stars in the Andromeda Galaxy. This will allow us to study how the largest and brightest stars in Andromeda change in brightness, telling us about their evolution and where they are in their life cycles.

This instrument can tell us more about ancient stars that reach the end of their lives - some of which can go on to produce supernovae (huge explosions) in the end.

3. The truth about the strange expansion of the universe

Quasars, highly energetic cores of galaxies at the edge of the observable universe, are the most luminous objects in the universe and the most distant objects we can see. And the new data includes measurements of 1.1 million of them. Quasars contain supermassive black holes that are caught in a violent feeding frenzy. In addition to these certain quasars, Gaia found 6.6 million other quasar candidates.

expansion of the universe. NASA/WMAP

This could greatly increase the number of known quasars, which could be very important because they allow us to measure the distance to the farthest edges of 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 Contradictory measurements of the spread, and we don't know which one is correct - the problem is called the "mourning gap".

4. Some asteroids have moons

Not everything Gaia investigates is so far from home. The data contains 158,000 details about objects in our solar system. Among other things, these are new measurements of 156,000 known asteroids, which tell us exactly which paths they follow as they orbit the sun.

Not only that, but the Gaia team has shown that they are able to find moons orbiting asteroids, based on how the moons cause the asteroids to wobble. Several hundred asteroids with moons are already known, but Gaia can find asteroid moons even when the moon is too small to see directly. It can also measure the position of asteroids so precisely that it sees the slight wobble in position caused by the moon's gravity. Asa says the latest data contains at least one such new moon, but there could be many more.

Asteroids around the Sun as seen by Gaia. Each asteroid is a segment representing its motion over 10 days (with the blue band representing the inner solar system). ESA/Gaia/DPAC, CC BY-ND
Asteroids around the Sun as seen by Gaia. Each asteroid is a segment representing its motion over 10 days (with the blue band representing the inner solar system). ESA/Gaia/DPAC, CC BY-ND

Collecting better data on asteroids can tell us about the chaos of the early solar system when the larger planets threw smaller planets and asteroids into new orbits around the sun and led to today's solar system.

5. How stars form and work

Our sun is a single star, but many stars have companions - surrounding each other around a common center. The new data contains the first taste of Gaia's catalog of such multi-star systems. This is a preliminary list pending publication of the full catalog in a later data release, 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 for so-called eclipsing binary systems. These are binary systems that happen to be arranged so that the stars pass opposite each other from our perspective. Binary eclipses are special because we can make measurements of them to understand 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 individual stars.

This new data will excite astrophysicists around the world, and we can't wait to dig into it to see what we can find. We may receive some of these answers in the coming months, while others may take longer to generate.

לArticle in The Conversation

More of the topic in Hayadan:

One response

  1. At the time, when Gaia was just sent into space, I asked/suggested to Professor Shai Zucker who was on the team that researched Gaia, (and maybe still there) to check with the help of Gaia the movement of the double-double in the constellation known as Epsilon Lyra (ADS11635).
    What is known about this group is that a double star orbits another double star at a distance of about 10,000 astronomical units in the analysis of the movement of the two pairs can prove or "God forbid" disprove Newton's gravitation formula and/or Kepler's laws to a distance of about ten thousand astronomical units (about six light years) . which is much more than anything measured in the solar system. I wonder if it was done?
    I noticed a deviation from Newton's laws. For those interested - article 73 in my blog Simple Universe.
    All good and good week.
    Please respond gently
    Sabdarmish Yehuda

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