{{Short description|Planetary nebula in the constellation Centaurus}} {{Infobox nebula |name = Southern Crab Nebula |image = [[File:The Crab of the Southern Sky Hen 2-104.tif|260px]] |caption = The Southern Crab Nebula image taken by [[Hubble Space Telescope|Hubble]]<ref>{{cite web |title=Hubble Celebrates its 29th Birthday with Unrivaled View of the Southern Crab Nebula |url=https://www.spacetelescope.org/news/heic1907/ |website=www.spacetelescope.org |access-date=18 April 2019 }}</ref> |credit = [[ESA]], [[NASA]], and STScI |type = planetary |epoch = [[J2000]] |subtype = |class = |ra = {{RA|14|11|52.06}}<ref name=SIMBAD>{{cite simbad|title=Hen 2-104}}</ref> |dec = {{DEC|-51|26|24.1}}<ref name=SIMBAD/> |dist_ly = {{convert|7000|ly|pc|abbr=on|lk=on}}<ref name=AAN>{{cite web|title=The Southern Crab Nebula, a planetary nebula in Centaurus|url=http://annesastronomynews.com/photo-gallery-ii/nebulae-clouds/the-southern-crab-nebula-he2-104/|work=Anne's Astronomy News|date=18 November 2012 |access-date=22 January 2017}}</ref> |appmag_v = 14.20<ref name=SIMBAD/> |appdia = |size_v = |constellation = [[Centaurus]] |radius_ly = |radius_pc = |dimensions = |absmag_v = |notes = Has a [[Symbiotic nova|symbiotic]] star system at its center |names = [[Variable star designation|V852]] Cen, Hen 2-104, [[IRAS]] 14085-5112, PN G315.4+09.4, Wray 16-147, [[2MASS]] J14115206-5126241 }} The '''Southern Crab Nebula''' (or '''WRAY 16-147''' or '''Hen 2-104''') is a [[nebula]] in the constellation [[Centaurus]]. The nebula is several thousand [[light year]]s from Earth, and its central star is a [[symbiotic variable star|symbiotic]] [[Mira variable]] − [[white dwarf]] pair. It is named for its resemblance to the [[Crab Nebula]], which is in the northern sky.
The Southern Crab was noted in a 1967 catalog, and was also observed using a [[CCD imager]] with the 2.2 meter telescope at the La Sila observatory in 1989.<ref name=":2"/> The 1989 observation marked a major expansion of knowledge about the nebula, and it was observed using various filters.<ref name=":2">{{Cite journal|last=Chiu|first=Liang-Tai George|date=August 1980|title=Space Telescope Astrometry from CCD images|journal=Celestial Mechanics|volume=22|issue=2|pages=191–196|doi=10.1007/bf01228806|s2cid=121065447 |issn=0008-8714}}</ref>
The nebula had already been observed using Earth-based telescopes,<ref name=":2" /> but images taken with the [[Hubble Space Telescope]] in 1999 have provided much more detail, revealing that at the center of the nebula are a pair of stars, a [[red giant]] and a [[white dwarf]]. It was imaged again by HST in 2019 with a newer instrument.
In 1999, it was imaged by the Hubble Space Telescope's [[Wide Field and Planetary Camera 2]],<ref name=":0">{{Cite web|url=https://www.spacetelescope.org/images/opo9932a/|title=Southern Crab Nebula|last=|website=www.spacetelescope.org|access-date=2019-09-17}}</ref> noted for its unique "stair-step" crop and for such astrophotos as the [[Pillars of Creation]].
The WFPC2 images were taken at an optical light wavelength of 658 nm.<ref name=":0" />
The nebula was imaged again by the Hubble Space Telescope in 2019, and a set of images to celebrate the anniversary of the space telescope's launch in 1990 (29 years) by the [[Space Shuttle]].<ref>{{Cite web|url=http://www.nasa.gov/image-feature/goddard/2019/hubble-celebrates-29th-anniversary-with-a-colorful-look-at-the-southern-crab-nebula|title=Hubble Celebrates 29th Anniversary with the Southern Crab Nebula|last=Hille|first=Karl|date=2019-04-18|website=NASA|access-date=2019-09-17}}</ref> This time a newer camera the [[Wide Field Camera 3|WFC3]] was used to image the nebula, at wavelengths filters of about 502, 656, 658, and 673 nanometers.<ref>{{Cite web|url=https://www.spacetelescope.org/images/heic1907a/|title=The Crab of the Southern Sky|last=|website=www.spacetelescope.org|access-date=2019-09-17}}</ref>
The designation {{Proper name|He2-104}} (or Hen 2-104) comes from the [[Henize catalog]] of 1967, ''Observations of Southern Planetary Nebulae''.<ref>{{Cite web|url=http://www.messier.seds.org/xtra/supp/cats.html|title=List of Common Deep Sky Catalogs|website=www.messier.seds.org|access-date=2019-09-17}}</ref> The catalog includes 459 items identified as [[planetary nebula]] (or likely as such).<ref>{{Cite journal|last=Henize|first=Karl G.|date=April 1967|title=Observations of Southern Planetary Nebulae|url=https://ui.adsabs.harvard.edu/1967ApJS...14..125H/abstract|journal=The Astrophysical Journal Supplement Series|volume=14|pages=125|doi=10.1086/190151|bibcode=1967ApJS...14..125H }}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> (note that in this meaning it does not imply exoplanets)
Another designation that it has been recorded for this object is WRAY-16-47.<ref>15677 - Spectroscopy and Imaging of the Southern Crab Nebul</ref>
In 2008, an investigation of the Southern Crab with its symbiotic (astronomical term) star was published.<ref name=":1">{{Cite web|url=https://www.researchgate.net/publication/1913657|title=Hen 2-104: A close-up look at the Southern Crab|website=ResearchGate|access-date=2019-09-18}}</ref> The study used imaging and spectroscopic data from space and Earth-surface telescopes including Hubble and [[Very Large Telescope|VLT]] observatories.<ref name=":1" /> The ESO defines a symbiotic star system as "binaries in which a small hot star (white dwarf or main sequence star) orbits around a red giant star. These systems are often surrounded by an envelope of gas or dust; those with gas are known as S-types and those with dust as D-types."<ref>{{Cite web|url=https://www.eso.org/public/news/eso8901/|title=The "Southern Crab" Nebula|last=|website=www.eso.org|access-date=2019-09-18}}</ref>
== Gallery == <gallery> Southern Crab Nebula_center.jpg|Close up of the center of the Nebula Southern Crab Nebula_overview.jpg|The Southern Crab Nebula in its entirety STSCI-H-p1915b-f-SouthernCrabNebula-20190418.png|Southern Crab Nebula – (18 April 2019;annotated) STSCI-H-p1915d-f-SouthernCrabNebula-Shape-20190418.png|Southern Crab Nebula – (18 April 2019;Shape) </gallery>
==See also== *[[List of Hubble anniversary images ]]
== References == {{Reflist}}
==External links== {{commonscat}} *[https://www.eso.org/public/usa/images/eso8901a/ The "Southern Crab" Nebula (He2-104) in 1989] {{Webarchive|url=https://web.archive.org/web/20211108224131/https://www.eso.org/public/usa/images/eso8901a/ |date=2021-11-08 }} (captures the crab like presentation)
{{Centaurus|state=collapsed}}
{{DEFAULTSORT:Southern Crab Nebula}} [[Category:Centaurus]] [[Category:Planetary nebulae]] [[Category:Emission nebulae]]