Utente:Paperoastro/Sandbox3
La Galassia del Triangolo, detta anche M33 (oggetto numero 33 del catalogo di Charles Messier), è una galassia a spirale di tipo Sc situata nella costellazione del Triangolo.
The Triangulum Galaxy (also known as Messier 33 or NGC 598) is a spiral galaxy approximately 3 million light-years away in the constellation Triangulum. The galaxy is also sometimes informally referred to as the Pinwheel Galaxy by some amateur astronomy references[1]
and in some public outreach websites.[2]
However, the SIMBAD Astronomical Database, a professional astronomy database that contains formal designations for astronomical objects, indicates that the name "Pinwheel Galaxy" is used to refer to Messier 101,[3]
and several other amateur astronomy resources and other public outreach websites also identify Messier 101 by that name.[4][5]
With a diameter of about 50,000 light-years, it is the third largest galaxy in the Local Group, a group of galaxies which also contains the Milky Way Galaxy and the Andromeda Galaxy, and it may be a gravitationally bound companion of the Andromeda Galaxy. Estimates indicate that Triangulum may be home to between 30 and 40 billion stars,[6] compared to the 1000 billion stars for Andromeda and c. 200-400 billion for the Milky Way. The Pisces Dwarf (LGS 3), one of the small Local Group member galaxies, is possibly a satellite of Triangulum.
- ^ S. J. O'Meara, The Messier Objects, Cambridge, Cambridge University, 1998, ISBN 0-521-55332-6.
- ^ NASA Spitzer Telescope Reveals Pinwheel Galaxy's Hidden Wonders, su spaceref.com. URL consultato il 7 aprile 2007.
- ^ SIMBAD Astronomical Database, in Results for Messier 101.. URL consultato il 7 aprile 2007.
- ^ Messier Object 101, su seds.org. URL consultato il 7 aprile 2007.
- ^ Best of AOP: M101: Pinwheel Galaxy, su simbad.u-strasbg.fr. URL consultato il 7 aprile 2007.
- ^ http://home.att.net/~numericana/answer/sagan.htm