MSGID: 1:317/3 63f98ee9   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    A mysterious object is being dragged into the supermassive black hole at   
   the Milky Way's center    
    Astronomers think the object, X7, might be debris cloud from a stellar   
   collision    
      
     Date:   
         February 24, 2023   
     Source:   
         University of California - Los Angeles   
     Summary:   
         An object near the supermassive black hole at the center of the   
         Milky Way galaxy has drawn the interest of scientists because it   
         has evolved dramatically in a relatively short time. A new study   
         suggests that the object, called X7, could be a cloud of dust and   
         gas that was created when two stars collided. The researchers   
         believe it will eventually be drawn toward the black hole and   
         will disintegrate.   
      
      
         Facebook Twitter Pinterest LinkedIN Email   
   FULL STORY   
   ==========================================================================   
   For two decades, scientists have observed an elongated object named   
   X7 near the supermassive black hole at the center of the Milky Way and   
   wondered what it was. Was it pulled off a larger structure nearby? Was   
   its unusual form the result of stellar winds or was it shaped by jets   
   of particles from the black hole?   
      
   ==========================================================================   
   Now, having examined the evolution of X7 using 20 years of data gathered   
   by the Galactic Center Orbit Inintiative, astronomers from the UCLA   
   Galactic Center Group and the Keck Observatory propose that it could be a   
   cloud of dust and gas that was ejected during the collision of two stars.   
      
   Over time, they report, X7 has stretched, and it is being pulled apart   
   as the black hole drags it closer, exerting its tidal force upon the   
   cloud. They expect that within the next few decades, X7 will disintegrate   
   and the gas and dust of which it is composed will eventually be drawn   
   toward the black hole, which is called Sagittarius A*, or Sgr A*.   
      
   The study is published in The Astrophysical Journal.   
      
   "No other object in this region has shown such an extreme evolution," said   
   Anna Ciurlo, a UCLA assistant researcher and the paper's lead author. "It   
   started off comet-shaped and people thought maybe it got that shape from   
   stellar winds or jets of particles from the black hole. But as we followed   
   it for 20 years we saw it becoming more elongated. Something must have   
   put this cloud on its particular path with its particular orientation."   
   X7 has a mass of about 50 Earths and is on an orbital path around Sgr A*   
   that would take 170 years to complete.   
      
   But that might never happen. Based on its trajectory, the team estimates   
   that X7 will make its closest approach to Sgr A* around the year 2036,   
   and then likely spiral toward Sgr A* and disappear.   
      
   "We anticipate the strong tidal forces exerted by the galactic black   
   hole will ultimately tear X7 apart before it completes even one orbit,"   
   said co-author Mark Morris, UCLA professor of physics and astronomy.   
      
   Tidal forces are the gravitational pull that cause an object approaching   
   a black hole to stretch; the side of the object closest to the black   
   hole is pulled much more strongly than the opposite end.   
      
   X7 shows some of the same properties as the other strange dusty objects   
   orbiting Sgr A*. Those so-called G objects look like gas but behave   
   like stars.   
      
   But X7's shape and velocity have changed more dramatically than G objects'   
   have. As it accelerates toward the black hole, X7 is moving rapidly,   
   clocking in at speeds of up to around 700 miles per second.   
      
   "It's exciting to see significant changes of X7's shape and dynamics in   
   such great detail over a relatively short time scale as the gravitational   
   forces of the supermassive black hole at the center of the Milky Way   
   influences this object," Randy Campbell, a co-author of the paper and   
   the science operations lead at the Keck Observatory, said in a statement.   
      
   Although X7's origin is still the subject of debate, the finding suggests   
   that it arose after two stars collided.   
      
   "One possibility is that X7's gas and dust were ejected at the moment   
   when two stars merged," Ciurlo said. "In this process, the merged star   
   is hidden inside a shell of dust and gas, which might fit the description   
   of the G objects. And the ejected gas perhaps produced X7-like objects."   
   The merger of two stars is very common, especially when they are near   
   black holes, Ciurlo said.   
      
   "This is a very messy process: The stars circle each other, get closer,   
   merge, and the new star is hidden within a cloud of dust and gas," she   
   said. "X7 could be the dust and gas ejected from a merged star that's   
   still out there somewhere."  The findings are the first estimate of   
   X7's mildly elliptical orbit and the most robust analysis to date of the   
   remarkable changes to its appearance, shape and behavior. The research   
   team will continue to use the Keck Observatory to monitor X7's dramatic   
   changes as the power of the black hole's gravity yanks it apart.   
      
   "It's a privilege to be able to study the extreme environment at the   
   center of our galaxy," Campbell said in the statement. "This study can   
   only be done using Keck's superb capabilities, and performed at the very   
   special and revered Maunakea, with honor and respect to the mauna."   
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Black_Holes # Galaxies # Stars # Astronomy #   
                   Astrophysics # Nebulae # Asteroids,_Comets_and_Meteors   
                   # Cosmology   
       * RELATED_TERMS   
             o Spitzer_space_telescope o Galaxy o Black_hole o   
             Magellanic_Clouds o Satellite o Holographic_Universe o   
             Planetary_nebula o Supernova   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_Los_Angeles. Original written by Holly   
   Ober. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Anna Ciurlo, Randall D. Campbell, Mark R. Morris, Tuan Do, Andrea M.   
      
         Ghez, Eric E. Becklin, Rory O. Bentley, Devin S. Chu, Abhimat   
         K. Gautam, Yash A. Gursahani, Aure'lien Hees, Kelly Kosmo O'Neil,   
         Jessica R. Lu, Gregory D. Martinez, Smadar Naoz, Shoko Sakai,   
         Rainer Scho"del. The Swansong of the Galactic Center Source X7:   
         An Extreme Example of Tidal Evolution near the Supermassive   
         Black Hole. The Astrophysical Journal, 2023; 944 (2): 136 DOI:   
         10.3847/1538-4357/acb344   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230224135122.htm   
      
   --- up 51 weeks, 4 days, 10 hours, 50 minutes   
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)   
   SEEN-BY: 15/0 106/201 114/705 123/120 153/7715 226/30 227/114 229/111   
   SEEN-BY: 229/112 113 307 317 400 426 428 470 664 700 292/854 298/25   
   SEEN-BY: 305/3 317/3 320/219 396/45   
   PATH: 317/3 229/426