NGC 6791

From Wikipedia, the free encyclopedia

NGC 6791 is an open star cluster in the Lyra constellation. It was discovered by Friedrich August Theodor Winnecke in 1853. At roughly 8 billion years old, and with an Iron to Hydrogen abundance ratio that is more than twice that of the Sun, it is one of the oldest and most metal-rich clusters in the Milky Way. This is contrary to the typical rule-of-thumb where older means more metal-poor. Compounded with the fact that it has an unusually high population of stars, NGC 6791 is among the most studied clusters in the sky.

[edit] External links

• NGC 6791, SEDS NGC pages
• NGC 6791, Astronomy Picture of the Day
• NGC 6791, SIMBAD Query

[edit] References

• Chaboyer, B., Green, E. M., & Liebert, J. 1999, Astronomical Journal, 117, 1360
• Kaluzny, J., & Udalski, A. 1992, Acta Astron., 42, 29