Westerhout 5
| Emission nebula | |
|---|---|
| H II region | |
 Detail of Westerhout 5 | |
| Observation data: J2000.0 epoch | |
| Right ascension | 02h 55m 24s |
| Declination | +60° 24′ 36″ |
| Distance | 7,500 ly |
| Apparent dimensions (V) | 150' × 75' |
| Constellation | Cassiopeia |
| Physical characteristics | |
| Radius | 165 [1] ly |
| Absolute magnitude (V) | 6.5 |
| Designations | Sh2-199, LBN 667 - Cluster is IC 1848 |
Westerhout 5 (also known as W5, Sharpless 2-199, LBN 667, or Soul Nebula) is an emission nebula located in Cassiopeia. Several small open clusters are embedded in the nebula: Collinder 33 and 34 in the head and IC 1848 (Collinder 32) in the body. [2] The small emission nebula IC 1871 is present just left of the top of the head, and Sh2 199 is just below the lower back area.[2]
The object is often called by the cluster designation IC 1848. W5 with W3 and W4 forms part of the larger W3/W4/W5 Complex.
The galaxies Maffei 1 and Maffei 2 are both located in apparent proximity to the nebula, although light extinction from the Milky Way makes them very hard to see. Once thought to be part of the Local Group, they are now known to belong to their own group – the IC 342/Maffei Group.
Westerhout 5 is the eastern neighbor of IC 1805 (Heart Nebula) and the two are often mentioned together as the "Heart and Soul".
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W3/W4/W5 complex (yellowish) in emission lines seen by the Northern Sky Narrowband Survey. W5 is the bright nebula at the bottom left of the center.
Star formation
[edit]
W5, a radio source within the nebula, spans an area of sky equivalent to four full moons and is about 6,500 light-years away in the constellation Cassiopeia. Like other massive star-forming regions, such as Orion and Carina, W5 contains large cavities that were carved out by radiation and winds from the region's most massive stars. According to the theory of triggered star formation, the carving out of these cavities pushes gas together, causing it to ignite into successive generations of new stars. The image in the gallery above contains some of the best evidence yet for the triggered star formation theory. Scientists analyzing the photo have been able to show that the ages of the stars become progressively and systematically younger with distance from the center of the cavities.[3]
References
[edit]- ^ distance × sin( diameter_angle / 2 ) = 165 ly. radius
- ^ a b JavaScript presentation of the mentioned emission nebulae
- ^ Koenig, Xavier P. & Lori E. Allen (Harvard-Smithsonian CfA) (August 22, 2008). "Spitzer Reveals Stellar 'Family Tree'". NASA/JPL-Caltech. Archived from the original on April 23, 2009.
