Press Release
Sister Star World 2.5 Million Light-Years Away
September 7, 2001
The Andromeda
Galaxy in color using Suprime-Cam [(5 x 2-minute)
exposures through B, V and H-alpha filters; 18' x
25' FOV] Mid Res (353KB) High Res (3.5MB) |
Presented here is a new color image of
the southwest region of the Andromeda
Galaxy taken with Subaru's prime focus camera "Suprime-Cam".
We see the stars of the Andromeda Galaxy as a great many
small white dots. Many of the stars, star clusters, and
nebulae in the image are seen clearly
resolved for the first time. It is expected that new
knowledge about the formation and evolution of stars within
a galaxy will result from detailed studies of these observations.
This spectacular image was constructed from a total of 15
exposures lasting 2 minutes each, made through filters passing
blue ("B"), green ("V") and red ("H-alpha")
light. The red filter is specially designed to accentuate
the light emitted by glowing hydrogen gas. The area shown
covers a field spanning 18 arc-minutes by 25 arc-minutes
on the sky. Analysis of the data is being carried out by
Drs. Satoshi Miyazaki (NAOJ), Keiichi Kodaira (Graduate
University for Advanced Studies, Japan) and Vladas Vansevicius
(Vilnius Observatory).
The Andromeda Galaxy lies 2.3 million light-years away (see
notes below), making it the nearest large galaxy to our
own. In many respects, the Andromeda Galaxy (also known
as M31 or NGC224) is quite similar to our Milky Way Galaxy.
Our "bird's-eye" view of the Andromeda Galaxy
makes it relatively easy to obtain an answer to the question
of how star-formation varies as a function of distance from
the center of a galaxy. A remarkable color gradient is seen
running diagonally across the image (yellow towards the
upper left, blue towards the lower right). This gradient
is caused by the history of star-formation and evolution
within the galaxy. It is believed that, as we look in the
direction of the galaxy's center (towards the upper left
in this image), we are seeing light produced predominantly
by stars created many billions of years ago when the galaxy
was just forming; the combined yellowish glow of these stars
gives way to a bluish light produced by much younger stars
found further out from the galaxy's center (towards the
lower right).
Subaru Telescope can produce significantly sharper wide-field
images and has a four-time increase in light-gathering power
over the previous generation of large telescopes used to
produce the currently best available catalogs and maps for
the Andromeda Galaxy. Using Subaru in combination with Suprime-Cam,
new maps with much finer detail and catalogs containing
far more objects is now possible. The Andromeda Galaxy has
long been recognized as an important stepping stone to test
our understanding of how galaxies came to be and how they
evolve. Subaru Telescope is taking a leading role in bringing
this approach to greater fruition.
Additional Notes:
A "light-year" is the distance light travels in one year. In more familiar units, a light-year equals about 6 trillion miles (9.46 trillion km), or over 12 million round-trips to the Moon.