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Hubble Finds Intergalactic Stars


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The Hubble telescope has found a long-sought population of "stellar outcasts" ? stars tossed out of their home galaxies into the dark emptiness of intergalactic space. This is the first time stars have been found more than 300,000 light-years (three Milky Way diameters) from the nearest big galaxy.

The isolated stars dwell in the Virgo cluster of galaxies, about 60 million light-years from Earth. The results suggest this population of "lone stars" accounts for 10 percent of the Virgo cluster's mass, or 1 trillion Sun-like stars adrift among the 2,500 galaxies in Virgo. This is an illustration of the view of the nighttime sky from the surface of a hypothetical planet orbiting an "outcast" star in the Virgo cluster.

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      Download this image

      The enhanced infall rate and proximity of the accretion disk to the star make FU Ori objects much brighter than a typical T Tauri star. In fact, during an outburst, the star itself is outshined by the disk. Furthermore, the disk material is orbiting rapidly as it approaches the star, much faster than the rotation rate of the stellar surface. This means that there should be a region where the disk impacts the star and the material slows down and heats up significantly. 
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      Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contacts:
      Claire Andreoli (claire.andreoli@nasa.gov)
      NASA’s Goddard Space Flight Center, Greenbelt, MD
      Abigail Major, Ray Villard
      Space Telescope Science Institute, Baltimore, MD
      Share








      Details
      Last Updated Nov 21, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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      To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video
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      Download this image

      This NASA/ESA Hubble Space Telescope image depicts the cosmic tangle that is MCG+05-31-045, a pair of interacting galaxies located 390 million light-years away and a part of the Coma galaxy cluster.
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      NASA’s Goddard Space Flight Center, Greenbelt, MD
      claire.andreoli@nasa.gov
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      Details
      Last Updated Nov 14, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
      Astrophysics Astrophysics Division Hubble Space Telescope Spiral Galaxies Keep Exploring Discover More Topics From Hubble
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      Download this image

      Though quite a bit worse for wear, the LMC still retains a compact, stubby halo of gas – something that it wouldn’t have been able to hold onto gravitationally had it been less massive. The LMC is 10 percent the mass of the Milky Way, making it heftier than most dwarf galaxies.
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      “I like to think of the Milky Way as this giant hairdryer, and it’s blowing gas off the LMC as it comes into us,” said Fox. “The Milky Way is pushing back so forcefully that the ram pressure has stripped off most of the original mass of the LMC’s halo. There’s only a little bit left, and it’s this small, compact leftover that we’re seeing now.”
      As the ram pressure pushes away much of the LMC’s halo, the gas slows down and eventually will rain into the Milky Way. But because the LMC has just gotten past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the whole halo will be lost.
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      To conduct this study, the research team analyzed ultraviolet observations from the Mikulski Archive for Space Telescopes at STScI. Most ultraviolet light is blocked by the Earth’s atmosphere, so it cannot be observed with ground-based telescopes. Hubble is the only current space telescope tuned to detect these wavelengths of light, so this study was only possible with Hubble.
      The team surveyed the halo by using the background light of 28 bright quasars. The brightest type of active galactic nucleus, quasars are believed to be powered by supermassive black holes. Shining like lighthouse beacons, they allow scientists to “see” the intervening halo gas indirectly through the absorption of the background light. Quasars reside throughout the universe at extreme distances from our galaxy.
      This artist’s concept illustrates the Large Magellanic Cloud’s (LMC’s) encounter with the Milky Way galaxy’s gaseous halo. In the top panel, at the middle of the right side, the LMC begins crashing through our galaxy’s much more massive halo. The bright purple bow shock represents the leading edge of the LMC’s halo, which is being compressed as the Milky Way’s halo pushes back against the incoming LMC. In the middle panel, part of the halo is being stripped and blown back into a streaming tail of gas that eventually will rain into the Milky Way. The bottom panel shows the progression of this interaction, as the LMC’s comet-like tail becomes more defined. A compact LMC halo remains. Because the LMC is just past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the residual halo will be lost. NASA, ESA, Ralf Crawford (STScI)
      Download this image

      The scientists used data from Hubble’s Cosmic Origins Spectrograph (COS) to detect the presence of the halo’s gas by the way it absorbs certain colors of light from background quasars. A spectrograph breaks light into its component wavelengths to reveal clues to the object’s state, temperature, speed, quantity, distance, and composition. With COS, they measured the velocity of the gas around the LMC, which allowed them to determine the size of the halo.
      Because of its mass and proximity to the Milky Way, the LMC is a unique astrophysics laboratory. Seeing the LMC’s interplay with our galaxy helps scientists understand what happened in the early universe, when galaxies were closer together. It also shows just how messy and complicated the process of galaxy interaction is.
      Looking to the Future
      The team will next study the front side of the LMC’s halo, an area that has not yet been explored.
      “In this new program, we are going to probe five sightlines in the region where the LMC’s halo and the Milky Way’s halo are colliding,” said co-author Scott Lucchini of the Center for Astrophysics | Harvard & Smithsonian. “This is the location where the halos are compressed, like two balloons pushing against each other.”
      The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, Colorado, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, Maryland, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
      Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contacts:
      Claire Andreoli (claire.andreoli@nasa.gov)
      NASA’s Goddard Space Flight Center, Greenbelt, MD
      Ann Jenkins, Ray Villard
      Space Telescope Science Institute, Baltimore, MD
      Share








      Details
      Last Updated Nov 14, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
      Astrophysics Astrophysics Division Galaxies Hubble Space Telescope Irregular Galaxies Spiral Galaxies The Milky Way Keep Exploring Discover More Topics From NASA
      Hubble Space Telescope


      Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.


      Galaxy Details and Mergers



      Hubble’s Galaxies



      Explore the Night Sky


      View the full article
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