Halo of sprinkling stars discovered to be giant disc
of Andromeda
Latest
studies based on observations from Keck II Observatory
in Hawaii suggests that Sprinkled of stars which was
earlier thought of as a Halo is actually part of the
main disk in Andromeda galaxy, increasing size of
the Andromeda thrice from initial.
Andromeda Galaxy
is a spiral galaxy like our milky way and is 2 million
light years away from earth. Under dark skies, Andromeda
can be seen by the naked eye. Besides few Dwarf galaxies
Andromeda is the nearest large spiral galaxy to us.
Scott chapman of CALTECH
at 206th meeting of American Astronomical Society
in Minneapolis Presented the results of study conducted
for around 5000 stars in the said halo.
He stated that upon
studying radial velocity of the stars in outer regions
they appeared to part of the galaxy itself. Finding
all these stars in orderly velocity around the center
of galaxy could be a firm explanation for the discovery.
Besides revealing new size of the galaxies it is observed
that all the outer stars are arranged in almost 20
clumps which suggests formation of the arc from smaller
galaxies with the main galaxy. Chapman further added
that merger has to be a recent event around last 200
million years as clumps wouldn't have been visible
otherwise.
Rodrigo Ibata, Astronomer
from Observatory in france suggests that Bumpy structure
of the disc cannot be explained without formation
by smaller galaxies with the larger one. Ibata further
commented that New discovery of these galaxy disk
is very difficult to simulate on a computer software
of forming galaxies. They just can't form giant rotating
disc from smaller galaxies.
Following discovery
is based on the studies done by Ibata and team from
Observatoire Astronomique de Strasbourg in France,
Annette Ferguson, University of Edinburgh; Geraint
Lewis, University of Sydney; Mike Irwin, Cambridge
University; and Nial Tanvir, University of Hertfordshire.
Study involved observation
of 5000 star positions and there velocities, which
was earlier said to be a mere halo.Positions and Velocities
of the stars suggest that there are in the same plane
as of a galaxy and revolving around center of galaxy
forming main disk.
That makes size of
the andromeda galaxy to 220,000 light years across,
tripple to previously estimated 70,000 - 80,000 light
years.
Andromeda is of very
high importance for space researchers and astronomers
as it is a nearest large spiral galaxy similar to
our Milky way galaxy. Discoveries and observations
of the past events in in andromeda will eventually
contribute in study of evolution of our own galaxy.
And of course We cannot study our own galaxy as we
are stuck into it.
Source : Caltech PR
|
