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  • Mark Andrew Holmes
    Mark Andrew Holmes (mahtezcatpoc@yahoo.com) has sent you a news article. (Email address has not been verified.) ... Personal message: Smallest Black Hole Found
    Message 1 of 3 , Apr 5, 2008
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      Mark Andrew Holmes (mahtezcatpoc@...) has sent you a news article.
      (Email address has not been verified.)
      ------------------------------------------------------------
      Personal message:



      Smallest Black Hole Found - Yahoo! News

      http://news.yahoo.com/s/space/20080401/sc_space/smallestblackholefound

      ============================================================
      Yahoo! News
      http://news.yahoo.com/
    • mahtezcatpoc
      ... BLGD... Mark A. Holmes Begin story.-- Smallest Black Hole Found Andrea Thompson Staff Writer SPACE.com Tue Apr 1, 2:46 PM ET NASA scientists have
      Message 2 of 3 , Apr 5, 2008
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        --- In thefixedstars@yahoogroups.com, Mark Andrew Holmes
        <mahtezcatpoc@...> wrote:
        >
        >
        > Mark Andrew Holmes (mahtezcatpoc@...) has sent you a news article.
        > (Email address has not been verified.)
        > ------------------------------------------------------------
        > Personal message:
        >
        >
        >
        > Smallest Black Hole Found - Yahoo! News
        >
        > http://news.yahoo.com/s/space/20080401/sc_space/smallestblackholefound



        BLGD...


        Mark A. Holmes



        Begin story.--


        Smallest Black Hole Found

        Andrea Thompson
        Staff Writer
        SPACE.com Tue Apr 1, 2:46 PM ET



        NASA scientists have identified the smallest, lightest black hole yet
        found.

        The new lightweight record-holder weighs in at about 3.8 times the
        mass of our sun and is only 15 miles (24 kilometers) in diameter.

        "This black hole is really pushing the limits," said study team leader
        Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in
        Greenbelt, Md. "For many years astronomers have wanted to know the
        smallest possible size of a black hole, and this little guy is a big
        step toward answering that question."

        The low-mass black hole sits in a binary system in our galaxy known as
        XTE J1650-500 in the southern hemisphere constellation Ara. NASA's
        Rossi X-ray Timing Explorer (RXTE) satellite discovered the system in
        2001, and astronomers soon realized that the system harbored a
        relatively lightweight black hole. But the black hole's mass had never
        been precisely measured.

        Black holes can't be seen, but they're identified by the activity
        around them, which also helps astronomers estimate a size of the
        region inside the activity, and how much mass must be in that confined
        region to generate all the surrounding activity. More specifically,
        astronomers can weigh black holes by using a relationship between the
        apparent size of the black hole and the X-rays emitted by the torrent
        of gas that swirls into the black hole's disk from its companion star.

        As the gas piles up near the black hole, it "becomes very dense and
        congested," like a traffic jam, Shaposhnikov said at a press
        conference announcing the find. "So matter has to literally squeeze
        into the black hole."

        As it is squeezed, the gas heats up and radiates X-rays. The intensity
        of the X-rays varies in a pattern repeated over a nearly regular
        interval. Astronomers have long suspected that the frequency of this
        signal, called the quasi-periodic oscillation, or QPO, depends on the
        mass of the black hole.

        As the black hole gets bigger, the zone of swirling gas is pushed
        farther out, so the QPO ticks away slowly. But for smaller black
        holes, the gas sits closer in and the QPO ticks rapidly.

        Shaposhnikov and his colleague Lev Titarchuk of George Mason
        University used this method to "weigh" XTE J1650-500 and found a mass
        of 3.8 suns. This value is well below the previous record holder GRO
        1655-40, which tips the scales at about 6.3 suns.

        This new �mass measurement could help shed light on what the smallest
        star that will produce a black hole is. Astronomers know that some
        unknown critical threshold, possibly between 1.7 and 2.7 solar masses,
        marks the boundary between a star that generates a black hole upon its
        death and one that produces a neutron star.

        "This new result brings us much closer to the theoretically predicted
        limit," Shaposhnikov said.

        Knowing this boundary would help scientists understand the behavior of
        matter when it is scrunched to extraordinarily high densities.

        "The question of black hole masses has concerned us for more than a
        decade now," said astrophysicist Vicky Kalogera of Northwestern
        University, who was not involved with the study, during the press
        conference. Scientists had predicted that their should be more black
        holes at the lower end of the mass range than astronomers had
        identified, so this study helps clear up some confusion as to where
        these lightweight black holes were, she added.

        Kalogera did caution that the method used by Shaposhnikov and
        Titarchuk is not the main way that black hole masses are measured, but
        noted that their measurements of the masses of other black holes
        agreed well with the results from the standard method.

        Shaposhnikov and Titarchuk presented their findings on March 31 at the
        American Astronomical Society's High-Energy Astrophysics Division
        meeting in Los Angeles.


        --End story.
      • mahtezcatpoc
        http://chandra.harvard.edu/photo/2003/bhspin/ RA 17h 02m 49.50s | Dec -48º 47 23.00 (2000) 19 Sagittarius 42. Mark A. Holmes ... smallest
        Message 3 of 3 , Apr 6, 2008
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          http://chandra.harvard.edu/photo/2003/bhspin/

          RA 17h 02m 49.50s | Dec -48º 47' 23.00" (2000)

          19 Sagittarius 42.

          Mark A. Holmes




          --- In thefixedstars@yahoogroups.com, "mahtezcatpoc"
          <mahtezcatpoc@...> wrote:
          >
          > --- In thefixedstars@yahoogroups.com, Mark Andrew Holmes
          > <mahtezcatpoc@> wrote:
          > >
          > >
          > > Mark Andrew Holmes (mahtezcatpoc@) has sent you a news article.
          > > (Email address has not been verified.)
          > > ------------------------------------------------------------
          > > Personal message:
          > >
          > >
          > >
          > > Smallest Black Hole Found - Yahoo! News
          > >
          > > http://news.yahoo.com/s/space/20080401/sc_space/smallestblackholefound
          >
          >
          >
          > BLGD...
          >
          >
          > Mark A. Holmes
          >
          >
          >
          > Begin story.--
          >
          >
          > Smallest Black Hole Found
          >
          > Andrea Thompson
          > Staff Writer
          > SPACE.com Tue Apr 1, 2:46 PM ET
          >
          >
          >
          > NASA scientists have identified the smallest, lightest black hole yet
          > found.
          >
          > The new lightweight record-holder weighs in at about 3.8 times the
          > mass of our sun and is only 15 miles (24 kilometers) in diameter.
          >
          > "This black hole is really pushing the limits," said study team leader
          > Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in
          > Greenbelt, Md. "For many years astronomers have wanted to know the
          > smallest possible size of a black hole, and this little guy is a big
          > step toward answering that question."
          >
          > The low-mass black hole sits in a binary system in our galaxy known as
          > XTE J1650-500 in the southern hemisphere constellation Ara. NASA's
          > Rossi X-ray Timing Explorer (RXTE) satellite discovered the system in
          > 2001, and astronomers soon realized that the system harbored a
          > relatively lightweight black hole. But the black hole's mass had never
          > been precisely measured.
          >
          > Black holes can't be seen, but they're identified by the activity
          > around them, which also helps astronomers estimate a size of the
          > region inside the activity, and how much mass must be in that confined
          > region to generate all the surrounding activity. More specifically,
          > astronomers can weigh black holes by using a relationship between the
          > apparent size of the black hole and the X-rays emitted by the torrent
          > of gas that swirls into the black hole's disk from its companion star.
          >
          > As the gas piles up near the black hole, it "becomes very dense and
          > congested," like a traffic jam, Shaposhnikov said at a press
          > conference announcing the find. "So matter has to literally squeeze
          > into the black hole."
          >
          > As it is squeezed, the gas heats up and radiates X-rays. The intensity
          > of the X-rays varies in a pattern repeated over a nearly regular
          > interval. Astronomers have long suspected that the frequency of this
          > signal, called the quasi-periodic oscillation, or QPO, depends on the
          > mass of the black hole.
          >
          > As the black hole gets bigger, the zone of swirling gas is pushed
          > farther out, so the QPO ticks away slowly. But for smaller black
          > holes, the gas sits closer in and the QPO ticks rapidly.
          >
          > Shaposhnikov and his colleague Lev Titarchuk of George Mason
          > University used this method to "weigh" XTE J1650-500 and found a mass
          > of 3.8 suns. This value is well below the previous record holder GRO
          > 1655-40, which tips the scales at about 6.3 suns.
          >
          > This new �mass measurement could help shed light on what the
          smallest
          > star that will produce a black hole is. Astronomers know that some
          > unknown critical threshold, possibly between 1.7 and 2.7 solar masses,
          > marks the boundary between a star that generates a black hole upon its
          > death and one that produces a neutron star.
          >
          > "This new result brings us much closer to the theoretically predicted
          > limit," Shaposhnikov said.
          >
          > Knowing this boundary would help scientists understand the behavior of
          > matter when it is scrunched to extraordinarily high densities.
          >
          > "The question of black hole masses has concerned us for more than a
          > decade now," said astrophysicist Vicky Kalogera of Northwestern
          > University, who was not involved with the study, during the press
          > conference. Scientists had predicted that their should be more black
          > holes at the lower end of the mass range than astronomers had
          > identified, so this study helps clear up some confusion as to where
          > these lightweight black holes were, she added.
          >
          > Kalogera did caution that the method used by Shaposhnikov and
          > Titarchuk is not the main way that black hole masses are measured, but
          > noted that their measurements of the masses of other black holes
          > agreed well with the results from the standard method.
          >
          > Shaposhnikov and Titarchuk presented their findings on March 31 at the
          > American Astronomical Society's High-Energy Astrophysics Division
          > meeting in Los Angeles.
          >
          >
          > --End story.
          >
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