Science & Technology

1.3 million pairs of stars surround the sun

Data from the Galactic Mapping satellite revealed that the vicinity of the Sun is full of stars moving in pairs. Using data from the Gaia project, researchers have identified 1.3 million binary pairs (2.6 million stars) within approximately 3,200 light-years from the Sun, based on the position and orbit of the stars. From this discovery, researchers find that about half of all Sun-like stars are gravitationally bound to their companion stars, and that the paired stars are separated by the distance between the Sun and Pluto. I learned to like it.

Previous catalogs identified about 200 binary pairs through independent measurements and about 100,000 unconfirmed candidates. This 3D atlas not only makes a big leap in the identification of binaries, but also allows astronomers to better understand star formation and dynamic evolution, identify the ages of some stars and their planets, and of stellar stars. It helps to study how peers affect star formation. Planetary system.

“Like a single star, many binaries have planets around them,” he said. Kareem El Badry, A PhD student in astronomy at the University of California, Berkeley, catalog.. “By studying the binary demographics in this catalog (such as the distribution of cycles, eccentricities, separations, masses, etc.), you will learn more about how the star-forming process occurs. This is closely related. It is related. How the planet is formed.. “

One Star, Two Star, Close Star, Far Star

When it comes to objects in space, the distance to them is one of the most difficult and most important measurements. For example, a star that is very close to Earth but very dim can look very bright and look like a star very far away. But knowing which one it is is very important to understand the star and the planets it can host, form, and evolve.

Parallax is the most accurate way to measure the distance from Earth to a star (see video to the right) and can only be done for stars that are close enough to Earth and visible in motion. About 30 years ago, the European Space Agency (ESA) Hipparchus Space Astrometry Mission Using this method, we measured the distance to approximately 2.5 million stars in the Milky Way. Astronomers used these data as a starting point to calculate distances to distant objects.But in the last few years, ESA Gaia mission I’m picking up a torch. Gaia systematically measures the position, distance, and movement of nearly a billion stars inside and outside the galaxy to create an unprecedented 3D map of the Earth’s cosmologists.

Using these data, El-Badry’s team searched for nearby binaries, two stars that are simultaneously formed from the same gas and dust cloud and interact by gravity. According to Gaia’s data, the binaries are at the same distance from Earth, move through the galaxy in the same direction and velocity, and appear to be separated from each other within about three light-years. (Beyond that separation, gravity is not strong enough to keep the pair together.) Researchers also have the possibility that the pair has one star with a random background, the pair is three. We have ruled out one of those likely pairs that may have a second star, and that pair was part of a cluster that evaluated the possibility that it might be.

The team identified a pair of 1.3 million stars that are likely to be bound by gravity from about 65 million stars within about 3,200 light-years from the Sun and about 2 trillion possible combinations. (See video below). Of these pairs, about 900,000 are sun-like pairs of hydrogen-burning stars, about 16,000 have one hydrogen-burning star and one white dwarf, and about 1,400 have two white dwarfs. Result is, Release To Monthly Notification of the Royal Astronomical Society In February, most sun-like stars have binaries, which are usually 30 to 50 times the distance between the Earth and the Sun (astronomical units, or AU), approximately from Sun to Pluto.

This study showed that “in the case of stars about the mass of the Sun, something like 25% of them have a companion of over about 30 AU.” “And from other studies, I think another 25% have a companion closer to 30 AU. So, in total, about half of the sun-like stars have stellar companions.”

Twins, white dwarfs, planets

“Another thing we can see is the distribution of mass ratios in the system. Do you like stars to have about the same mass, or do you like them to be very different?” El-Badry Explained. “One of the most amazing and exciting results that came out of [this work] It means that there is an unexpected overpopulation of binaries where the two stars are almost exactly the same mass. We call them identical twins. This result is amazing. Because at such wide intervals, the stars should be formed independently of each other, and therefore their mass ratios should be more randomized. The team suspects that the twin stars were actually born much closer and drifted apart for years. Researchers say these dynamics can affect the stability of virtual planetary systems.

About half of all sun-like stars are one in a pair. Above, some collages of these binary pairs seen by the Gaia spacecraft. credit: ESA / Gaia / DPAC

In addition, this catalog can help astronomers determine the age of hydrogen-burning stars, which is also very difficult. “It’s relatively easy to measure the age of a white dwarf, at least compared to how difficult it is to measure the age of a normal star,” Elbadry said. For a pair with a hydrogen-burning star and a white dwarf, you can estimate the age of the white dwarf for all components in the system, including exoplanets.

That’s exactly how the team led by astronomers David Martin, Study using this catalog Planet candidate TOI-1259Ab, first discovered by the Transiting Exoplanet Exploration Satellite (TESS). “TESS satellite discovered Thousands of candidates pass through exoplanets, “Martin said. “What we did was to crossmatch the two catalogs and limit the Gaia binary to a special one containing at least one white dwarf. Then we came up with this candidate, TOI-1259. It has planets and white dwarf companions that pass through the main sequence stars. The fact that there are white dwarf companions [El-Badry’s] catalog. Such systems are rare and tell us a lot about how stars and planetary systems evolve. The age of the white dwarf is calculated to be 4.1 billion years, and TOI-1259Ab is one of the oldest known ages of exoplanets. Martin of Ohio State University in Columbus was not involved in the creation of the binary star catalog.

Martin will continue to work on the new catalog. “Currently, we are working to extend this work from this first candidate to other similar systems, including both planets and white dwarfs,” Martin said. There are at least 300 of these types of systems in the El-Badry catalog. “Of course, it’s just a targeted use …. In fact, if you find a planet that passes through a star, you need to crossmatch it. [the] Catalog to see if there are any stellar companions! “

El-Badry uses these data to study population-level demographics of these systems by other astronomers, as well as their relationship to easily measurable characteristics such as star age and rotation. Hope it helps to calibrate. According to El-Badry, future releases of Gaia data will improve the accuracy of calculating star positions and movements, allowing scientists to detect very close binary stars. Black Hole..

— Kimberly MS Cartier (@AstroKimCartier), Staff writer

1.3 million pairs of stars surround the sun 1.3 million pairs of stars surround the sun

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