The Double Nucleus of M31
Credit & Copyright: T. R. Lauer (KPNO/NOAO)
et al., HST
Explanation:
The center of M31 is twice as unusual as previously
thought. In 1991 the Planetary Camera then onboard the
Hubble
Space Telescope
pointed toward the center of our
Milky Way's
closest major galactic neighbor:
Andromeda (M31).
To everyone's surprise, M31's
nucleus showed a double structure.
The nuclear hot-spots are quite close together when considering
Galactic distances: M31 is about 150,000 light years across while
the above shows only the central 30 light-years. Subsequent ground-based
observations have led to speculation that indeed two nuclei exist,
are
moving with respect to each other,
that
one nucleus is slowly tidally disrupting the other,
and
that one nucleus may
be the remains of smaller galaxy "eaten" by M31.
The nuclei of many galaxies, including M31, are known to be
quite
violent places,
and the existence of massive
black holes
are frequently postulated to explain them.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
