Baade's Window is an area of the

sky The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space. In the field of astronomy, ...

with relatively low amounts of

interstellar dust Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...

along the line of sight from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...

. This area is considered an observational "window" as the normally obscured

Galactic Center The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact ...

of the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...

is visible in this direction. It is named for astronomer

Walter Baade Wilhelm Heinrich Walter Baade (March 24, 1893 – June 25, 1960) was a German astronomer who worked in the United States from 1931 to 1959. Biography The son of a teacher, Baade finished school in 1912. He then studied maths, physics and astro ...

, who first recognized its significance. This area corresponds to one of the brightest visible patches of the Milky Way. It is centered at a

galactic longitude The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an a ...

(') of 1.02° and a

galactic latitude The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an a ...

(') of -3.92°, which corresponds to a

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the ( hour circle of the) point in question above the earth. When pai ...

of 18h 03m 32.14s and a

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of t ...

of -30d 02m 06.96s, in the direction of the constellation

Sagittarius Sagittarius ( ) may refer to: *Sagittarius (constellation) *Sagittarius (astrology), a sign of the Zodiac Ships *''SuperStar Sagittarius'', a cruise ship * USS ''Sagittarius'' (AKN-2), a World War II US Navy cargo ship Music *Sagittarius (ban ...

History

Walter Baade observed the stars in this area in the mid-1940s using the

Hooker telescope The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observato ...

Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observ ...

in California 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. In 2006, the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) conducted an

astronomical survey An astronomical survey is a general map or image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of images, spectra, or other observations of ob ...

to monitor 180,000 stars for seven days to detect

extrasolar planets An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

via the

transit method Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty o ...

Significance

Baade's Window is frequently used to study distant central bulge 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". 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 on the

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of memb ...

NGC 6522. Baade's Window is the largest of the six areas through which central bulge stars are visible.

OGLE Ogle may refer to: Places * Ogle County, Illinois, United States * Original name of Ashton, Illinois, a village * Ogle, Kentucky, United States, an unincorporated community * Ogle Township, Somerset County, Pennsylvania, United States * Ogle, N ...

and other observation programs have successfully detected

orbiting around central bulge stars in this area by the

gravitational microlensing Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers ...

method. Stars observed in Baade's Window can be called BW stars, similarly giant stars can be called BW giants.

References

External links

* * * {{Sky, 18, 03, 32.14, -, 30, 02, 06.96 Physical cosmology Milky Way

History

Significance

See also

References

External links