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Explanation: A major discovery was lurking in the data. By accident, while preparing a talk on the Galaxy's spiral arms for a meeting of the American Astronomical Society, Tom Dame (Harvard-Smithsonian CfA) found it - a new spiral arm in the Milky Way. The arm is labeled in this illustration as the Far 3kpc Arm, located at a distance of 3 kpc (kiloparsecs) or about 10,000 light-years from the galactic center, on the opposite side from the Sun. Along with the Near 3kpc Arm whose presence was known since the mid 1950s, the counterpart inner arms now establish that the galaxy has a simple symmetry. The arms are defined by shocked interstellar gas flowing along both sides of the Milky Way's central bar. Dame and his collaborator Patrick Thaddeus recorded the presence of both inner spiral arms in their radio data tracking emission from carbon monoxide molecules along the galactic plane. How much star formation goes on in the counterpart arms? Despite this depiction of stars and star forming regions along the arms, the last attempt to search for star formation in the Near 3kpc Arm was in 1980 and didn't turn up any. The discovery of the Far 3kpc Arm has renewed interest in this and other questions about the center of the Milky Way.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: spiral arms - Milky Way
Publications with words: spiral arms - Milky Way
See also:
- APOD: 2023 December 12 Á Aurora and Milky Way over Norway
- Milky Way Rising
- APOD: 2023 July 18 Á Milky Way above La Palma Observatory
- APOD: 2023 July 16 Á Meteor and Milky Way over the Alps
- APOD: 2023 July 2 Á Milky Way and Aurora over Antarctica
- APOD: 2023 June 20 Á The Nandu in the Milky Way
- APOD: 2023 May 29 Á Milky Way over a Turquoise Wonderland