| 
                                                                       An
                                                                      Unwelcome
                                                                      Place for
                                                                      New Stars 
                                                                      This
                                                                      artist's
                                                                      concept
                                                                      depicts a
                                                                      supermassive
                                                                      black hole
                                                                      at the
                                                                      center of
                                                                      a galaxy.
                                                                      NASA's
                                                                      Galaxy
                                                                      Evolution
                                                                      Explorer
                                                                      found
                                                                      evidence
                                                                      that black
                                                                      holes --
                                                                      once they
                                                                      grow to a
                                                                      critical
                                                                      size --
                                                                      stifle the
                                                                      formation
                                                                      of new
                                                                      stars in
                                                                      elliptical
                                                                      galaxies.
                                                                      Black
                                                                      holes are
                                                                      thought to
                                                                      do this by
                                                                      heating up
                                                                      and
                                                                      blasting
                                                                      away the
                                                                      gas that
                                                                      fuels star
                                                                      formation. 
                                                                       
                                                                      The blue
                                                                      color here
                                                                      represents
                                                                      radiation
                                                                      pouring
                                                                      out from
                                                                      material
                                                                      very close
                                                                      to the
                                                                      black
                                                                      hole. The
                                                                      grayish
                                                                      structure
                                                                      surrounding
                                                                      the black
                                                                      hole,
                                                                      called a
                                                                      torus, is
                                                                      made up of
                                                                      gas and
                                                                      dust.
                                                                      Beyond the
                                                                      torus,
                                                                      only the
                                                                      old
                                                                      red-colored
                                                                      stars that
                                                                      make up
                                                                      the galaxy
                                                                      can be
                                                                      seen.
                                                                      There are
                                                                      no new
                                                                      stars in
                                                                      the
                                                                      galaxy.  |