السديم الحلزوني
The Helix Nebula (also known as NGC 7293) is a planetary nebula (PN) about 650 light-years away in the constellation Aquarius. It is one of the closest planetary nebulae to Earth[4] and was discovered by Karl Ludwig Harding before 1824. It has a very similar appearance to the Ring Nebula. It is also similar in size, age, and physical characteristics to the Dumbbell Nebula, with the significant difference in appearance being a consequence of the relative proximity and more nearly equatorial viewing angle of the Dumbbell.[2] The Helix has often been referred to as the Eye of God on the Internet, since about 2003[5]. The Helix Nebula was also featured in the 2004 Battlestar Galactica TV series.
| السديم الحلزوني Helix Nebula | |
|---|---|
.jpg) Visible light image of the Helix Nebula, compiled from Hubble telescope and ground-based images in 2004. | |
| Observation data (Epoch J2000) | |
| Right ascension | 22h 29m 38.55s[1] |
| Declination | -20° 50′ 13.6″[1] |
| Distance | 680+150−80 ly (207+46−24 pc)[2] |
| Apparent magnitude (V) | +13.5[1] |
| Apparent dimensions (V) | 25′[3] |
| Constellation | Aquarius |
| Physical characteristics | |
| Radius | 2.87 ly (0.88 pc)[3] |
| Absolute magnitude (V) | 6.58[a] |
| Notable features | One of nearest PNs |
| Other designations | NGC 7293[1] |
| See also: Planetary nebula, Lists of nebulae | |
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
انظر أيضاً
هامش
- ^ 13.5 apparent magnitude - 5 * (log10(242 pc distance) - 1) = 6.58 absolute magnitude
المصادر
- ^ أ ب ت ث "SIMBAD Astronomical Database". Results for Helix Nebula. Retrieved 2006-12-07.
- ^ أ ب O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. (2002). "Knots in Nearby Planetary Nebulae". The Astronomical Journal. 123 (6): 3329–3347. doi:10.1086/340726.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ أ ب O'Dell, C. R.; McCullough, Peter R.; Meixner, Margaret (2004). "Unraveling the Helix Nebula: Its Structure and Knots". The Astronomical Journal. 128 (5): 2339–2356. doi:10.1086/424621.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Hora, Joseph L.; Latter, William B.; Smith, Howard A.; Marengo, Massimo (2006). "Infrared Observations of the Helix Planetary Nebula". The Astrophysical Journal. 652 (1): 426–441. doi:10.1086/507944.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Urban Legends Reference Pages". The Eye of God. Retrieved 2007-07-16.
وصلات خارجية
