Baade's Window

Baade's Window is an area of the sky with relatively low amounts of interstellar "dust" along the line of sight from the Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. It is named for astronomer Walter Baade who first recognized its significance. This area corresponds to one of the brightest visible patches of the Milky Way. It is centered at Galactic longitude l=1.02 degree and Galactic latitude b=-3.92 degrees,[1] which corresponds to a right ascension of 18h 03m 32.14s and a declination of -30d 02m 06.96s.[2]

Baade's Window on the Milky Way

History

Walter Baade observed the stars in this area in the mid-1940s using the 100-inch (2.5 m) Hooker telescope at Mount Wilson Observatory 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.[3]

In 2006, the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) conducted an astronomical survey to monitor 180,000 stars for seven days to detect extrasolar planets via the transit method.[4]

Significance
NGC 6522 (upper right) and NGC 6528 (lower left) are visible within Baade's Window.

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". It is in the direction of the constellation of Sagittarius.[5] 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 NGC 6522.[6]

Baade's Window is the largest of the six areas through which central bulge stars are visible.[7]

OGLE and other observation programs have successfully detected extrasolar planets orbiting around central bulge stars in this area by the gravitational microlensing method.

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

See also

References
  1. Church, Ross P.; Johnson, Jennifer A.; Feltzing, Sofia (May 2011). "Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window". Astronomy & Astrophysics. 529: A104. arXiv:1103.5462. Bibcode:2011A&A...529A.104C. doi:10.1051/0004-6361/201116829. ISSN 0004-6361.
  2. "Your NED Search Results-Input: Galactic/Output: Equatorial J2000.0". ned.ipac.caltech.edu. Retrieved 2020-06-02.
  3. Baade, W. (August 1946). "A Search For the Nucleus of Our Galaxy". Publications of the Astronomical Society of the Pacific. 58 (343): 249–252. Bibcode:1946PASP...58..249B. doi:10.1086/125835.
  4. "SIMBAD Details on Acronym: SWEEPS". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-21.
  5. "NAME Baade Window". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-03-13.
  6. Stanek, K.Z. (1996). "Extinction Map of Baade's Window". Astrophysical Journal Letters. 381 (1): 219–226. arXiv:astro-ph/9512137. Bibcode:1996ApJ...460L..37S. doi:10.1086/309976.
  7. Dutra C.M.; Santiago B.X.; Bica E. (2002). "Low-extinction windows in the inner Galactic Bulge". Astronomy & Astrophysics. 460 (1): L37. arXiv:astro-ph/0110658. Bibcode:2002A&A...381..219D. doi:10.1051/0004-6361:20011541.

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