Press Release

Sister Star World 2.5 Million Light-Years Away

By SpaceRef Editor
September 11, 2001
Filed under , ,

Presented here is a new color image of the southwest region of the Andromeda
Galaxy [http://www.naoj.org/Latestnews/200109/M31/M31_oj.jpg] 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
[http://www.naoj.org/Latestnews/200109/M31/M31_oj.jpg]. 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.

IMAGE CAPTION:
[Low-res., http://www.naoj.org/Latestnews/200109/M31/M31_m.jpg (353KB)
Hi-res., http://www.naoj.org/Latestnews/200109/M31/M31_b.jpg (3.5MB)]

The Andromeda Galaxy in color using Suprime-Cam [(5 x 2-minute) exposures
through B, V and H-alpha filters; 18′ x 25′ FOV]

SpaceRef staff editor.