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Tag: milky

  • Milky Way’s Galactic Center Secrets: Stellar Nursery Orbiting Sagittarius A*

    Milky Way’s Galactic Center Secrets: Stellar Nursery Orbiting Sagittarius A*

    At the heart of our galaxy, the supermassive black hole Sagittarius A* is the focal point of a captivating celestial dance, drawing in a swarm of newly discovered young stellar objects (YSOs) that orbit it at incredible speeds. Recent observations have revealed that these infant stars, located in the immediate vicinity of Sagittarius A*, follow similar orbits to the previously known young stars, known as “S stars,” forming a distinct pattern around the black hole.

    Sagittarius A*

    This discovery has challenged existing theories about star formation and behavior near supermassive black holes, opening up new avenues for understanding the complex interactions within this dynamic environment.

    Approximately three decades ago, astronomers made the initial discovery of the highly dynamic S stars, which orbit Sagittarius A* at speeds of several thousand kilometers per hour, completing their orbits within a few years. The young age of these stars puzzled scientists, as they had expected to find only old, dim stars in such a hostile environment.

    Building upon these earlier findings, the latest study, led by researchers from the University of Cologne and involving contributions from multiple institutions, has identified about a dozen additional objects near Sagittarius A* that share similar properties to the S stars. Remarkably, these newly discovered YSOs are significantly younger than the previously known high-speed stars.

    “Interestingly, these YSOs exhibit the same behavior as S stars. This means that the YSOs circumnavigate the supermassive black hole with speeds of several thousand kilometers per hour in a few years,” explained study co-author Dr. Florian Peißker. “The S stars were found to be surprisingly young. According to conventional theories, the additional presence of a stellar kindergarten composed of YSOs is completely unexpected.”

    Further analysis of the observations has revealed that these high-velocity YSOs and S stars are not simply a chaotic swarm, but rather follow specific, organized formations. The research shows that both YSOs and S stars are arranged systematically within three-dimensional space, resembling a disk-like structure.

    “This means that there are specific preferred star constellations. The distribution of both star variations resembles a disk, which gives the impression that the supermassive black hole forces the stars to assume an organized orbit,” explained Dr. Peißker.

    These findings challenge our understanding of the dynamic environment around Sagittarius A* and suggest that the black hole may play a crucial role in the formation and behavior of these young stars. The discovery of these high-velocity YSOs orbiting so close to the black hole opens up new avenues for exploring the complex interplay between black holes and their stellar neighbors.

  • Massive Black Hole Found in Milky Way’s Binary System

    Massive Black Hole Found in Milky Way’s Binary System

    Astronomers have found a really big black hole in our Milky Way galaxy. This huge black hole is special because it’s in a pair of stars. The discovery is exciting and surprises scientists. It helps us learn more about black holes.

    Milky Way

    When a very big star in space burns out, it explodes in a big event called a supernova. After the explosion, its center collapses into a tiny, super dense point called a black hole. Black holes have strong gravity, so strong that not even light can escape them. They’re like invisible giants in space.

    Finding black holes is hard because we can’t see them directly. But the European Space Agency’s Gaia spacecraft helps. It maps stars in our galaxy with incredible detail. Scientists use Gaia’s data to study stars and find hidden black holes.

    A team of scientists, including some from Tel Aviv University, looked at Gaia’s data. They focused on pairs of stars called binary systems. In one of these pairs, they noticed something strange. One star moved like it was orbiting something invisible. That something turned out to be a massive black hole.

    This black hole is super heavy, 33 times heavier than our Sun. It’s the biggest black hole found in a binary system in our galaxy. The system is called Gaia BH3. It’s 1,500 light-years away from us.

    The two stars in Gaia BH3 are very different. One is a normal star, while the other is the black hole. The normal star is very old, maybe more than 10 billion years old. This age gap between the star and the black hole is a puzzle for scientists.

    Finding Gaia BH3 was tough. Black holes are hard to spot. But Gaia’s discoveries show there might be many more out there. Scientists are excited about what they might find next. This discovery could change how we think about black holes in our galaxy.

  • Gaia’s Revelation: Uncovering the Earliest Building Blocks of the Milky Way

    Gaia’s Revelation: Uncovering the Earliest Building Blocks of the Milky Way

    Astronomers have identified what might be two of the Milky Way’s earliest building blocks, dubbed “Shakti” and “Shiva,” suggesting they merged with the early Milky Way over 12 to 13 billion years ago, contributing to its initial formation. Combining data from ESA’s Gaia mission with measurements from the SDSS survey, astronomers made this groundbreaking discovery, akin to archeologists uncovering traces of an ancient settlement that evolved into a modern city.

    Milky Way

    The Milky Way’s history involves the merging of smaller galaxies, forming substantial building blocks. Researchers Khyati Malhan and Hans-Walter Rix from the Max Planck Institute for Astronomy identified two potential early building blocks, Shakti and Shiva, remnants of galaxies that merged with the Milky Way billions of years ago. By analyzing Gaia and SDSS data, they found these fragments, akin to discovering the roots of a present-day city.

    When galaxies merge, they bring along their hydrogen gas clouds, leading to the formation of new stars. Stars from merging galaxies mingle, contributing to the stellar population of the newly formed galaxy. Despite the challenge of identifying stars’ origins post-merger, certain physical properties like energy and angular momentum offer clues to trace their ancestry. Stars with similar energy and angular momentum likely originated from the same pre-merger galaxy.

    Lower metallicity indicates older stars. Thus, stars with low metal content, known as “metal-poor” stars, likely formed early in the galaxy’s history. This method, along with Gaia’s extensive data set launched in 2013, enables astronomers to excavate the Milky Way’s ancient past.

    Malhan and Rix used Gaia data combined with stellar spectra from the Sloan Digital Sky Survey to identify Shakti and Shiva. They observed groups of metal-poor stars with specific energy and angular momentum combinations, indicative of stars originating from separate merging galaxies. Named after Hindu deities, Shakti and Shiva show high angular momentum and low metallicity, suggesting they could be among the Milky Way’s earliest ancestors.

    These findings expand our understanding of the Milky Way’s formation. Shakti and Shiva, possibly the first additions to the Milky Way’s core, played a crucial role in its growth into a large galaxy. This discovery underscores the importance of data-driven astronomical research and its role in unraveling the mysteries of the universe.

  • The Milky Way’s Origins: Advances in Galaxy Formation Research

    The Milky Way’s Origins: Advances in Galaxy Formation Research

    Astronomers are using powerful computers to simulate how galaxies formed from the Big Bang until now, 13.8 billion years later. These simulations have some errors. To fix them, a team of researchers from Lund University and other institutions spent eight years and a lot of time.

    Galaxy Formation

    In the past ten years, there have been massive improvements in computer simulations that can show how galaxies form. These simulations are very important for understanding where galaxies, stars, and planets come from. But sometimes, the predictions from these simulations have mistakes because the computers cannot show everything perfectly.

    To make better simulations, 160 researchers from 60 universities worked together. They compared their simulations and looked for mistakes. The leaders of this project are Santi Roca-Fàbrega from Lund University, Ji-hoon Kim from Seoul National University, and Joel R. Primack from the University of California.

    They found out that the gas around galaxies is more important than the number of stars in the galaxy. This is different from what people used to think. This project took eight years and used a lot of computer time. But the researchers are happy with what they found.

    They published three papers in The Astrophysical Journal about their work. They looked at how a galaxy the same size as the Milky Way formed. They used the same ideas about stars, gas, and light as other simulations. Their new results show that galaxies like the Milky Way formed early in the universe’s history. They also solved a problem about small galaxies going around bigger ones.

    They want to keep working to make even better simulations of galaxy formation. With better simulations, they hope to learn more about our galaxy, the Milky Way. This is just the beginning of understanding how galaxies form.