Westerhout 5

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
Absolute magnitude (V)	6.5
Designations	Sh2-199, LBN 667 - Cluster is IC 1848

Westerhout 5 (Sharpless 2-199, LBN 667, Soul Nebula) is an emission nebula located in Cassiopeia. Several small open clusters are embedded in the nebula: CR 34, 632, and 634 (in the head) and IC 1848 (in the body). The object is more commonly called by the cluster designation IC 1848.

Small emission nebula IC 1871 is present just left of the top of the head, and small emission nebulae 670 and 669 are just below the lower back area.

The galaxies Maffei 1 and Maffei 2 are both nearby 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.

This complex is the eastern neighbor of IC1805 (Heart Nebula) and the two are often mentioned together as the "Heart and Soul".

Generations of stars can be seen in this infrared portrait from NASA's Spitzer Space Telescope.
The Heart Nebula and Westerhout 5 are seen in this infrared mosaic from NASA's WISE telescope.
IC 1848 area imaged using amateur telescope (Credit: Jeff Johnson).

Star formation

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.[1]

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References

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.

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[1] 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.