Red Spider Nebula
|Red Spider Nebula|
|Right ascension||18h 05m 13.1s|
|Declination||-19° 50′ 34.9″|
|Apparent magnitude (V)||13|
|Apparent dimensions (V)||1.5 arcmin|
|Absolute magnitude (V)||-|
|Notable features||hot white dwarf|
|Other designations||NGC 6537|
The Red Spider Nebula (also catalogued as NGC 6537) is a planetary nebula located near the heart of the Milky Way, in the northwest of  the constellation Sagittarius. The nebula has a prominent two-lobed shape, possibly due to a binary companion or magnetic fields and has an ‘S’-shaped symmetry of the lobes – the lobes opposite each other appear similar. This is believed to be due to the presence of a companion to the central white dwarf. However, the gas walls of the two lobed structures are not at all smooth, but rather are rippled in a complex way. 
The central white dwarf, the remaining compact core of the original star, produces a powerful and hot (≈10,000 K) wind blowing with a speed of 300 kilometers per second, which has generated waves 100 billion kilometres high. The waves are generated by supersonic shocks formed when the local gas is compressed and heated in front of the rapidly expanding lobes. Atoms caught in the shocks radiate a visible light.  These winds are what give this nebula its unique 'spider' shape and also contribute to the expansion of the nebula.
The star at the center of the Red Spider Nebula is surrounded by a dust shell making its exact properties hard to determine. Its surface temperature is probably 150,000-250,000 K although a temperature of 340,000 K or even 500,000 K is not ruled out, making it among the hottest white dwarf stars known.
- "Bizarre Alignment of Planetary Nebulae". ESO Press Release. Retrieved 6 September 2013.
- Matsuura, M. (October 2005). "The symmetric dust shell and the central star of the bipolar planetary nebula NGC 6537". Monthly Notices of the Royal Astronomical Society. Retrieved 9 July 2014.
- "The Red Spider Nebula, a planetary nebula in Sagittarius".
- "Astronomy Picture of the Day". 29 October 2012. Retrieved 9 July 2014.
- "Red Spider Nebula".
- "Red Spider Nebula (NGC 6537)". Encyclopedia of Science, The Worlds of David Darling. Retrieved 16 July 2014.
- "The Red Spider Nebula: Surfing in Sagittarius - not for the faint-hearted!". ESA/Hubble. 24 July 2001. Retrieved 16 July 2014.
- Red Spider Nebula at ESA/Hubble
- White dwarf sends ripples through Red Spider Nebula at Space.com
- NASA Astronomy Picture of the Day
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