View source for NGC 6302

{{short description|Bipolar planetary nebula in the constellation Scorpius}}
{{Other uses of|Butterfly Nebula|Butterfly Nebula (disambiguation)}}
{{Sky|17|13|44.211|-|37|06|15.94|1000000000}}
{{Planetary nebula |
| image = [[Image:NGC 6302 Hubble 2009.full.jpg|240px]]
| caption = NGC 6302, as taken by [[Hubble Space Telescope]]
| name = [[New General Catalogue|NGC]] 6302
| type = Planetary
| epoch = [[J2000]]
| ra = {{RA|17|13|44.211}}<ref name="simbad">{{Harv|SIMBAD|2007}}</ref>
| dec = {{DEC|-37|06|15.94}}<ref name="simbad"/>
| dist_ly = 3400 ± 500<ref name="Meaburnetal2005">{{Harv|Meaburn|López|Steffen|Graham|2005}}</ref>
| appmag_v = 7.1B<ref name="simbad"/>
| size_v = >3′.0<ref name="Meaburnetal2005"/>
| constellation  = [[Scorpius]]
| radius_ly = >1.5 ± 0.2 [[light-year|ly]]<ref>Radius = distance × sin(angular size / 2) = 3.4 ± 0.5 kly * sin(>3′.0 / 2) = >1.5 ± 0.2 ly</ref>
| absmag_v = -3.0B {{±|0.4|0.3}}<ref>7.1B apparent magnitude - 5 * (log<sub>10</sub>(1040 ± 160 pc distance) - 1) = -3.0B {{±|0.4|0.3}} absolute magnitude</ref>
| notes = Dual chemistry, hot central star
| names = Bipolar Nebula,<ref name="simbad"/> Bug Nebula,<ref name="simbad"/><br>
PK 349+01 1,<ref name="simbad"/> Butterfly Nebula,<ref name="APoD1998">{{Harv|Nemiroff|Bonnell|1998}}</ref><ref name="APoD2004">{{Harv|Nemiroff|Bonnell|2004}}</ref> [[Sharpless catalog|Sharpless]] 6, [[RCW Catalogue|RCW]] 124, Gum 60, [[Caldwell catalogue|Caldwell]] 69
|dist_pc=1040 ± 160<ref name="Meaburnetal2005">{{Harv|Meaburn|López|Steffen|Graham|2005}}</ref>}}

'''NGC 6302''' (also known as the '''Bug Nebula''', '''Butterfly Nebula''', or '''Caldwell 69''') is a [[bipolar nebula|bipolar]] [[planetary nebula]] in the constellation [[Scorpius]]. The structure in the nebula is among the most complex ever seen in planetary nebulae. The spectrum of Butterfly Nebula shows that its central [[star]] is one of the hottest stars known, with a surface temperature in excess of 250,000 degrees Celsius, implying that the star from which it formed must have been very large.

The central star, a [[white dwarf]], was identified in 2009, using the upgraded [[Wide Field Camera 3]] on board the [[Hubble Space Telescope]].<ref>{{Harv|Szyszka|Walsh|Zijlstra|Tsamis|2009}}</ref> The star has a current mass of around 0.64 [[solar mass]]es. It is surrounded by a dense equatorial disc composed of gas and dust. This dense disc is postulated to have caused the star's outflows to form a bipolar structure<ref>{{Harv|Gurzadyan|1997}}</ref> similar to an [[hourglass]]. This bipolar structure shows features such as ionization walls, knots and sharp edges to the lobes.

==Observation history==
[[File:NGC6302map.png|thumb|left|Position of NGC 6302]]

As it is included in the ''[[New General Catalogue]]'', this object has been known since at least 1888.<ref>Many sources credit its discovery to [[James Dunlop]] in 1826. E.g. (1) Wolfgang Steinicke, ''Nebel und Sternhaufen: Geschichte ihrer Entdeckung, Beobachtung und Katalogisierung- von Herschel bis Dreyers'', 2009, p. 429. (2) [http://www.universetoday.com/2008/06/23/ngc-6302-by-don-goldman/ Universe Today]; (3) [https://books.google.com/books?id=3Hg6YHgx9nAC&pg=PA274 Stephen James O'Meara, ''The Caldwell objects''. Cambridge University Press, 2002, p.274.].<br>(O'Meara argues that Barnard credited it to Dunlop—but may have been mistaken.)</ref> The earliest-known study of NGC 6302 is by [[Edward Emerson Barnard]], who drew and described it in 1907.<ref name="Meaburnetal2005"/>

The nebula featured in some of the first images released after the final servicing mission of the Hubble Space Telescope in September 2009.<ref>News Release Number: STScI-2009-25: Hubble Opens New Eyes on the Universe [http://www.hubblesite.org/newscenter/archive/releases/2009/25/image/f] {{Webarchive|url=https://web.archive.org/web/20161113083135/http://hubblesite.org/newscenter/archive/releases/2009/25/image/f/ |date=2016-11-13 }}</ref>

==Characteristics==
NGC 6302 has a complex structure, which may be approximated as bipolar with two primary lobes, though there is evidence for a second pair of lobes that may have belonged to a previous phase of mass loss. A dark lane runs through the waist of the nebula obscuring the central star at all wavelengths.<ref>{{Harv|Matsuura|Zijlstra|Molster|Waters|2005}}</ref>

The nebula contains a prominent northwest lobe which extends up to 3.0′ away from the central star and is estimated to have formed from an eruptive event around 1,900 years ago. It has a circular part whose walls are expanding such that each part has a speed proportional to its distance from the central star. At an angular distance of 1.71′ from the central star, the flow velocity of this lobe is measured to be 263&nbsp;km/s. At the extreme periphery of the lobe, the outward velocity exceeds 600&nbsp;km/s. The western edge of the lobe displays characteristics suggestive of a collision with pre-existing globules of gas which modified the outflow in that region.<ref name="Meaburnetal2005"/>

==Central star==
The central star, among the hottest stars known, had escaped detection because of a combination of its high temperature (meaning that it radiates mainly in the ultraviolet), the dusty torus (which absorbs a large fraction of the light from the central regions, especially in the ultraviolet) and the bright background from the star. It was not seen in the first [[Hubble Space Telescope]] images;<ref name="APoD2004"/> the improved resolution and sensitivity of the new [[Wide Field Camera 3]] of the same telescope later revealed the faint star at the centre.<ref>{{Harv|Szyszka|Walsh|Zijlstra|Tsamis|2009}}</ref> A temperature of 200,000 Kelvin is indicated, and a mass of 0.64 solar masses. The original mass of the star was much higher, but most was ejected in the event which created the planetary nebula. The luminosity and temperature of the star indicate it has ceased nuclear burning and is on its way to becoming a [[white dwarf]], fading at a predicted rate of 1% per year.

==Dust chemistry==
The prominent dark lane that runs through the centre of the nebula has been shown to have an unusual composition, showing evidence for multiple crystalline silicates, crystalline water ice and [[quartz]], with other features which have been interpreted as the first extra-solar detection of carbonates.<ref name="Kemper 2002">{{Harv|Kemper|Molster|Jaeger|Waters|2002}}</ref> This detection has been disputed, due to the difficulties in forming carbonates in a non-aqueous environment.<ref>{{Harv|Ferrarotti|Gail|2005}}</ref> The dispute remains unresolved.

One of the characteristics of the dust detected in NGC 6302 is the existence of both oxygen-bearing silicate molecules and carbon-bearing [[polycyclic aromatic hydrocarbon]]s (PAHs).<ref name="Kemper 2002"/> Stars are usually either oxygen-rich or carbon-rich, the change from the former to the latter occurring late in the evolution of the star due to nuclear and chemical changes in the star's atmosphere. NGC 6302 belongs to a group of objects where hydrocarbon molecules formed in an oxygen-rich environment.<ref>
{{Harv|Matsuura|Zijlstra|Molster|Waters|2005}}.</ref>

== See also ==
* [[List of largest nebulae]]
* [[Lists of nebulae]]

== Notes ==
{{Reflist}}

==References==
{{refbegin}}
* {{Cite APOD
 | title = NGC 6302: The Butterfly Nebula | date = June 2, 1998
 | access-date = }}
* {{Cite APOD
 | title = NGC 6302: Big, Bright, Bug Nebula | date = May 5, 2004
 | access-date = }}
* {{Citation
 | last1 = Szyszka | first1 = C.
 | last2 = Walsh | first2 = J. R
 | last3 = Zijlstra | first3 = A. A.
 | last4 = Tsamis | first4 = Y.G.
 | title = Detection of the Central Star of the Planetary Nebula NGC 6302
 | journal = Astrophysical Journal Letters
 | date = 2009 | volume = 707 | issue = 1
 | pages = L32–L36
 | doi=10.1088/0004-637x/707/1/l32
|arxiv = 0909.5143 |bibcode = 2009ApJ...707L..32S | s2cid = 16952715
 }}
* {{Citation
 | last = Gurzadyan | first = Grigor A.
 | title = The Physics and Dynamics of Planetary Nebulae
 | publisher = Springer | place = Germany
 | isbn = 978-3-540-60965-0 | date = 1997 | pages = 3
}}
* {{Citation
 | last1 = Meaburn | first1 = J.
 | display-authors = 4
 | last2 = López | first2 = J. A.
 | last3 = Steffen | first3 = W.
 | last4 = Graham | first4 = M. F.
 | last5 = Holloway | first5 = A. J.
 | title = The Hubble-Type Outflows from the High-Excitation, Polypolar Planetary Nebula NGC 6302
 | journal = The Astronomical Journal
 | date = 2005 | volume = 130 | issue = 5 | pages = 2303–2311
 | url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005AJ....130.2303M
|arxiv = astro-ph/0507675 |bibcode = 2005AJ....130.2303M |doi = 10.1086/496978 | s2cid = 17361839
 }}
* {{Citation
 | last = SIMBAD | author-link = SIMBAD
 | title = Results for NGC 6302
 | date = January 11, 2007
 | publisher = SIMBAD, Centre de Données Astronomiques de Strasbourg
 | url = http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=NGC+6302
}}
* {{Citation
 | last1 = Kemper | first1 = F. | last2 = Molster | first2 = F. J.
 | last3 = Jaeger | first3 = C. | last4 = Waters | first4 = L.B.F.M.
 | journal = Astronomy and Astrophysics | volume=394 | issue = 2 | pages=679–690
 | title = The mineral composition and spatial distribution of the dust ejecta of NGC 6302
 | date = 2002
 | arxiv = astro-ph/0208110 |bibcode = 2002A&A...394..679K
 | doi = 10.1051/0004-6361:20021119 | s2cid = 15598841 }}
* {{Citation
 | last1 = Ferrarotti | first1 = A. S. | last2 = Gail | first2 = H.-P.
 | title = Mineral formation in stellar winds. V. Formation of calcium carbonate
 | journal = Astronomy and Astrophysics | date=2005 | volume=430 | issue = 3 | pages=959–965
 |bibcode = 2005A&A...430..959F |doi = 10.1051/0004-6361:20041856 | doi-access = free }}
* {{Citation
 | last1= Matsuura | first1 = M. | display-authors = 4 | last2 = Zijlstra | first2 = A. A.
 | last3= Molster | first3 = F.J. | last4 = Waters | first4 = L. B. F. M.
 | last5 = Nomura | first5 = H. | last6 = Sahai | first6 = R.
 | last7 = Hoare | first7 = M. G
 | title = The dark lane of the planetary nebula NGC 6302
 | journal = [[Monthly Notices of the Royal Astronomical Society]]
 | date=2005 | volume=359 | issue = 1 | pages=383–400
 |bibcode = 2005MNRAS.359..383M |doi = 10.1111/j.1365-2966.2005.08903.x | doi-access = free }}
{{refend}}

==External links==
{{Commons category|NGC 6302}}
*[http://www.spacetelescope.org/news/html/heic0407.html NASA News Release]
*[https://web.archive.org/web/20110720152214/http://www.jodrellbank.manchester.ac.uk/news/2009/BugNebula/ Discovery of the star]
*[http://www.spacetelescope.org/news/html/heic0407.html ESA/Hubble News Release]
*[http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=ngc+6302&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2004&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0 SIMBAD Query Result]
*{{WikiSky}}
*[http://www.constellation-guide.com/butterfly-nebula/ Butterfly Nebula at Constellation Guide]
*{{APOD |date=1 October 2014 |title=The Butterfly Nebula from Hubble}}

{{Sh2 objects}}
{{RCW}}
{{Gum catalogue}}
{{Catalogs|C=69|NGC=6302}}
{{Caldwell catalogue}}
{{Ngc65}}
{{Portal bar|Stars|Outer space}}
{{DEFAULTSORT:Ngc 6302}}
[[Category:Caldwell objects|069b]]
[[Category:NGC objects|6302]]
[[Category:Planetary nebulae]]
[[Category:Scorpius]]
[[Category:Sharpless objects]]