View source for Sh 2-101

{{Short description|Nebula}}
{{Refimprove|date=January 2008}}
{{Infobox nebula
| image =[[File:Tulip-Nebula.jpg|SH2-101 - The Tulip Nebula - 2011-06-06 (5806773518)|300px]]
|caption=Sh 2-101
| credit = Chuck Ayoub
| name = Sh 2-101
| type = H II region 
| epoch = J2000.0
| ra = {{RA|20|00|29.37}}
| dec = {{DEC|35|19|13.9}}
| dist_ly = 6,000
| dist_pc = 1,800
| appmag_v = 9.0
| size_v = 16[[degree (angle)|']] x 9[[degree (angle)|']]
| constellation  = [[Cygnus (constellation)|Cygnus]]
| radius_ly = 
| absmag_v = 
| notes = 
| names = [[Sharpless catalog|Sharpless]] 101, Sh 2-101, Cygnus Star Cloud
}}

[[File:Noao-cyg x1.jpg|thumb|left|350px|The companion star of the black hole Cygnus X-1 is the brighter of the two stars in the middle of the photo. Credit: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOIRLab/NSF/AURA)]]

'''Sharpless 101''' ('''Sh 2-101''') is a [[H II region]]<ref>{{cite simbad|title=Sh2-101}}</ref> [[emission nebula]] located in the constellation [[Cygnus (constellation)|Cygnus]]. It is sometimes also called the ''Tulip Nebula'' because it appears to resemble the outline of a [[tulip]] when imaged photographically. It was catalogued by astronomer [[Stewart Sharpless]] in his 1959 catalog of nebulae. It lies at a distance of about {{convert|6000|ly|km mi|lk=in}} from [[Earth]].

Sh 2-101, at least in the field seen from Earth, is in close proximity to [[microquasar]] [[Cygnus X-1]], site of one of the first suspected [[black holes]]. Cygnus X-1 is located about {{val|15|ul='}} west of Sh 2-101. The companion star of Cygnus X-1 is a spectral class O9.7 Iab supergiant with a mass of 21 solar masses and 20 times the radius of the Sun. The period of the binary system is 5.8 days and the pair is separated by 0.2 astronomical units. The black hole has a mass of 15 solar masses and a Schwarzschild radius of 45 km. A bowshock is created by a jet of energetic particles from the black hole as they interact with the interstellar medium. It can be seen as an arc at the top of the photo below.
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==See also==
*[[Sharpless catalogue]]

==References==
{{Reflist}}

==External links==
{{commons category}}
*[http://galaxymap.org/cgi-bin/sharpless.py?s=101 Sharpless Catalog] {{Webarchive|url=https://web.archive.org/web/20110930102539/http://galaxymap.org/cgi-bin/sharpless.py?s=101 |date=2011-09-30 }}


{{Sh2 objects}}
{{Cygnus (constellation)}}

[[Category:H II regions]]
[[Category:Cygnus (constellation)]]
[[Category:Sharpless objects]]