Baade's Window

Baade's Window on the Milky Way

Baade's Window is an area of the sky with relatively low amounts of interstellar dust along the line of sight from Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. This makes the apparent Large Sagittarius Star Cloud visible.

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 a galactic longitude (l) of 1.02° and a galactic latitude (b) of -3.92°,^[1] which corresponds to a right ascension of 18h 03m 32.14s and a declination of -30d 02m 06.96s, in the direction of the constellation Sagittarius.^[2][3]

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.^[4]

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.^[5]

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". 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.^{[citation needed]}

See also

• Zone of Avoidance
• Large Sagittarius Star Cloud

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. "NAME Baade Window". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-03-13.
3. "Your NED Search Results-Input: Galactic/Output: Equatorial J2000.0". ned.ipac.caltech.edu. Retrieved 2020-06-02.
4. 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.
5. "SIMBAD Details on Acronym: SWEEPS". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-21.
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. S2CID 11590782.
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. S2CID 15619180.

External links

• NASA Astronomy Picture of the Day: Stars and Dust Through Baade's Window (19 December 2007)
• NASA Astronomy Picture of the Day: Stars and Dust Through Baade's Window (23 December 2002)
• NASA Astronomy Picture of the Day: Lensing Through Baade's Window (1 February 1996)