Gempa bumi! Pesawat ruang angkasa Gaia melihat bintang-bintang aneh dalam survei Bima Sakti paling detail hingga saat ini

Salah satu penemuan mengejutkan yang keluar dari rilis data Gaia 3 adalah bahwa Gaia mampu mendeteksi gempa bintang — gerakan kecil di permukaan bintang — yang mengubah bentuk bintang, sesuatu yang awalnya tidak dibuat observatorium. Kredit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO

Gaia adalah misi Badan Antariksa Eropa (ESA) untuk membuat peta 3D yang akurat dari lebih dari satu miliar bintang di seluruh[{” attribute=””>Milky Way galaxy and beyond. Although it launched all the way back in 2013, it is still working to accurately map the the motions, luminosity, temperature and composition of the stars in our galaxy.

Along the way it has made numerous discoveries, such as detecting a shake in the Milky Way, the observation of almost 500 explosions in galaxy cores, crystallization in white dwarfs, and discovering a billion-year-old river of stars. It also revealed the total weight of the Milky Way, a direct measurement of the galactic bar in the Milky Way, mysterious fossil spiral arms in the Milky Way, and a new member of the Milky Way family.

Today marks the data of the third data release from Gaia. The first data release was on September 14, 2016, followed by the second data release on April 25, 2018. On December 3, 2020, they did an early third data release with detailed data on more than 1.8 billion stars. All this data is helping to reveal the origin, structure, and evolutionary history of our galaxy.

This image shows four sky maps made with the new ESA Gaia data released on June 13, 2022. Credit: © ESA/Gaia/DPAC; CC BY-SA 3.0 IGO

Today (June 13, 2022), ESA’s Gaia mission releases its new treasure trove of data about our home galaxy. Astronomers describe strange ‘starquakes’, stellar DNA, asymmetric motions, and other fascinating insights in this most detailed Milky Way survey to date.

Gaia is ESA’s mission to create the most accurate and complete multi-dimensional map of the Milky Way. This allows astronomers to reconstruct our home galaxy’s structure and past evolution over billions of years, and to better understand the lifecycle of stars and our place in the Universe.

Apa yang baru di data versi 3?

Rilis data Gaia 3 berisi detail baru dan lebih baik dari hampir dua miliar bintang di galaksi kita. Katalog mencakup informasi baru termasuk komposisi kimiasuhu bintang, warna, massa, usia, dan kecepatan bintang bergerak menuju atau menjauh dari kita (kecepatan radial). Banyak dari informasi ini diungkapkan oleh yang baru dirilis Spektroskopi Data, teknologi di mana cahaya bintang dibagi menjadi warna komponennya (seperti pelangi). Data tersebut juga mencakup himpunan bagian khusus dari bintang, seperti bintang yang berubah kecerahannya dari waktu ke waktu.

Yang juga baru dalam kumpulan data ini adalah katalog bintang biner terbesar hingga saat ini, ribuan objek Tata Surya seperti asteroid dan bulan planet, serta jutaan galaksi dan quasar di luar Bima Sakti.

gempa bumi

Salah satu penemuan paling mengejutkan yang muncul dari data baru adalah bahwa Gaia mampu mendeteksi gempa bintang — gerakan kecil di permukaan bintang — yang mengubah bentuk bintang, sesuatu yang awalnya tidak dibuat observatorium.

Sebelumnya, Gaia telah menemukan osilasi radial yang menyebabkan bintang membengkak dan berkontraksi secara berkala, sambil mempertahankan bentuk bolanya. Namun Gaya kini juga mendeteksi getaran lain yang sangat mirip dengan tsunami skala besar. Osilasi non-radial ini mengubah bentuk global bintang dan karenanya sulit dideteksi.

Gaia telah menemukan gempa bumi non-radial yang kuat di ribuan bintang. Gaia juga mendeteksi getaran seperti itu pada bintang yang jarang terlihat sebelumnya. Bintang-bintang ini seharusnya tidak mengalami gempa bumi menurut teori saat ini, sementara Gaia mendeteksinya di permukaannya.

“Gempa bintang mengajari kita banyak tentang bintang, terutama cara kerjanya. Gaia membuka tambang emas untuk ilmu bintang besar-besaran,” kata Connie Aerts dari KU Leuven di Belgia, anggota Gaya Collaboration.

DNA bintang

Bahan penyusun bintang dapat memberi tahu kita tentang di mana mereka dilahirkan dan perjalanan mereka selanjutnya, dan dengan demikian tentang sejarah Bima Sakti. Dengan rilis data hari ini, Gaia mengungkapkan peta kimia galaksi terbesar yang digabungkan dengan gerakan 3D, dari lingkungan matahari kita ke galaksi yang lebih kecil di sekitar kita.

Beberapa bintang mengandung lebih banyak “logam berat” daripada yang lain. selama[{” attribute=””>Big Bang, only light elements were formed (hydrogen and helium). All other heavier elements – called metals by astronomers – are built inside stars. When stars die, they release these metals into the gas and dust between the stars called the interstellar medium, out of which new stars form. Active star formation and death will lead to an environment that is richer in metals. Therefore, a star’s chemical composition is a bit like its DNA, giving us crucial information about its origin.

This image shows an artistic impression of the Milky Way, and on top of that an overlay showing the location and densities of a young star sample from Gaia’s data release 3 (in yellow-green). The “you are here” sign points towards the Sun. Credit: © ESA/Gaia/DPAC; CC BY-SA 3.0 IGO

With Gaia, we see that some stars in our galaxy are made of primordial material, while others like our Sun are made of matter enriched by previous generations of stars. Stars that are closer to the center and plane of our galaxy are richer in metals than stars at larger distances. Gaia also identified stars that originally came from different galaxies than our own, based on their chemical composition.

“Our galaxy is a beautiful melting pot of stars,” says Alejandra Recio-Blanco of the Observatoire de la Côte d’Azur in France, who is a member of the Gaia collaboration.

“This diversity is extremely important, because it tells us the story of our galaxy’s formation. It reveals the processes of migration within our galaxy and accretion from external galaxies. It also clearly shows that our Sun, and we, all belong to an ever-changing system, formed thanks to the assembly of stars and gas of different origins.”

This image shows the orbits of the more than 150,000 asteroids in Gaia’s data release 3, from the inner parts of the Solar System to the Trojan asteroids at the distance of Jupiter, with different color codes. The yellow circle at the center represents the Sun. Blue represents the inner part of the Solar System, where the Near Earth Asteroids, Mars crossers, and terrestrial planets are. The Main Belt, between Mars and Jupiter, is green. Jupiter trojans are red. Credit: © ESA/Gaia/DPAC; CC BY-SA 3.0 IGO, Acknowledgements: P. Tanga (Observatoire de la Côte d’Azur)

Binary stars, asteroids, quasars, and more

Other papers that are published today reflect the breadth and depth of Gaia’s discovery potential. A new binary star catalog presents the mass and evolution of more than 800 thousand binary systems, while a new asteroid survey comprising 156 thousand rocky bodies is digging deeper into the origin of our Solar System. Gaia is also revealing information about 10 million variable stars, mysterious macro-molecules between stars, as well as quasars and galaxies beyond our own cosmic neighborhood.

The position of each asteroid at 12:00 CEST on June 13, 2022, is plotted. Each asteroid is a segment representing its motion over 10 days. Inner bodies move faster around the Sun (yellow circle at the center). Blue represents the inner part of the Solar System, where the Near Earth Asteroids, Mars crossers, and terrestrial planets are. The Main Belt, between Mars and Jupiter, is green. The two orange ‘clouds’ correspond to the Trojan asteroids of Jupiter. Credit: © ESA/Gaia/DPAC; CC BY-SA 3.0 IGO, Acknowledgements: P. Tanga (Observatoire de la Côte d’Azur)

“Unlike other missions that target specific objects, Gaia is a survey mission. This means that while surveying the entire sky with billions of stars multiple times, Gaia is bound to make discoveries that other more dedicated missions would miss. This is one of its strengths, and we can’t wait for the astronomy community to dive into our new data to find out even more about our galaxy and its surroundings than we could’ve imagined,” says Timo Prusti, Project Scientist for Gaia at ESA.