Baade's Window
Encyclopedia
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...
along the line of sight from the Earth. This area is considered an observational "window" as the normally obscured Galactic Center
Galactic Center
The Galactic Center is the rotational center of the Milky Way galaxy. It is located at a distance of 8.33±0.35 kpc from the Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest...
of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
is visible in this direction. It is named for astronomer Walter Baade
Walter Baade
Wilhelm Heinrich Walter Baade was a German astronomer who worked in the USA from 1931 to 1959.-Biography:He took advantage of wartime blackout conditions during World War II, which reduced light pollution at Mount Wilson Observatory, to resolve stars in the center of the Andromeda galaxy for the...
who first recognized its significance. This area corresponds to one of the brightest visible patches of the Milky Way.
History
Walter Baade surveyed the stars in this area in the mid 1940's using the 100 inches (2.5 m) Hooker telescope on Mt Wilson in CaliforniaMount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...
while searching for the center of the Milky Way galaxy. Up until this time the structure and location of the galactic center was not known with certainty.
Significance
Baade's Window is frequently used to study distant central bulgeBulge (astronomy)
In astronomy, a bulge is a tightly packed group of stars within a larger formation. The term almost exclusively refers to the central group of stars found in most spiral galaxies...
stars in visible and near-visible wavelengths of light. Important information on the internal geometry of the Milky Way is still being refined by measurements made through this "window". It is in the direction of the constellation of Sagittarius
Sagittarius (constellation)
Sagittarius is a constellation of the zodiac, the one containing the galactic center. Its name is Latin for the archer, and its symbol is , a stylized arrow. Sagittarius is commonly represented as a centaur drawing a bow...
. The window is now known to be slightly "south" of the main central galaxy bulge. The window is irregular in outline and subtends about 1 degree of the sky. It is centered around the globular cluster
Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...
NGC 6522
NGC 6522
NGC 6522 is a globular cluster in the constellation Sagittarius. It was discovered by William Herschel on June 24, 1784. It is centered in a region of the sky known as Baade's Window....
.
Baade's Window is the largest of the six areas through which central bulge stars are visible.
OGLE
Optical Gravitational Lensing Experiment
The Optical Gravitational Lensing Experiment or OGLE is a Polish astronomical project based at the University of Warsaw that is chiefly concerned with discovering dark matter using the microlensing technique. Since the project began in 1992, it has discovered several extrasolar planets as a side...
and other observation programs have successfully detected extrasolar planets orbiting around central bulge stars in this area by the gravitational microlensing method.