View source for Calabash Nebula

{{Short description|Protoplanetary nebula in the constellation of Puppis}}
{{Infobox nebula
| name = Calabash Nebula
| image = The Calabash clash.jpg
| caption = The Calabash Nebula, as taken by [[Hubble Space Telescope]]
| type = protoplanetary
| epoch = [[J2000]]
| ra = {{RA|07|42|16.83}}<ref name="simbad">{{Harv|SIMBAD|2007}}</ref>
| dec = {{DEC|-14|42|52.1}}<ref name="simbad" />
| dist_ly = [[1 E19 m|4,200]]<ref name="Kastneretal1998">{{Harv|Kastner|Weintraub|Merrill|Gatley|1998}}</ref>
| dist_pc = 1,300
| appmag_v = 9.47<ref name="simbad" />
| size_v = 10 × 60 [[Minute and second of arc|arcsec]]<ref name="<MRASL2912">{{cite journal |last1=Forde |first1=K. P. |last2=Gledhill |first2=T. M. |title=Discovery of shocked H2 around OH 231.8+4.2 |journal=Monthly Notices of the Royal Astronomical Society: Letters |date=March 2012 |volume=421 |issue=1 |pages=L49–L53 |bibcode=2012MNRAS.421L..49F |doi=10.1111/j.1745-3933.2011.01204.x |doi-access=free |arxiv=1112.1025 }}</ref>
| constellation = [[Puppis]]
| radius_ly = 0.7{{Ref_label|A|a|none}}
| absmag_v = -1.4{{Ref_label|B|b|none}}
| notes = 
| names = OH 231.84 +4.22,<ref name="simbad" /> <br />Rotten Egg Nebula<ref name="simbad" />
}}
{{starbox begin
|name=QX Puppis
}}
{{starbox image
| image = [[File:QXPupLightCurve.png|220px]]
| caption = A [[near-infrared]] ([[Photometric_system#Photometric_letters|I band]]) light curve for QX Puppis, plotted from [[AAVSO]] data<ref name="aavso">{{cite web |title=Download Data |url=https://www.aavso.org/data-download |website=aavso.org |publisher=AAVSO |access-date=1 October 2021}}</ref>
}}
{{starbox character
|type=[[OH/IR star]]<ref name="simbad" />
|class=M10III + A<ref name="simbad" />
|variable=[[Mira variable|Mira]]<ref name="simbad" />
}}
{{Starbox reference
|Simbad=QX+Pup
}}
{{starbox end}}
The '''Calabash Nebula''', also known as the '''Rotten Egg Nebula''' or by its technical name '''OH 231.84 +4.22''', is a [[protoplanetary nebula]] (PPN) 1.4 [[light year]]s (13 Pm) long and located some 5,000 light years (47 Em) from [[Earth]] in the constellation [[Puppis]]. The name "Calabash Nebula" was first proposed in 1989 in an early paper on its expected nebular dynamics, based on the nebula's appearance.<ref name="IckePreston1989">{{Harv|Icke|Preston|1989}}</ref>
The Calabash is almost certainly a member of the open cluster [[Messier 46]], as it has the same distance, radial velocity, and proper motion.<ref name=vickers2015>
{{cite journal
 |author=Vickers S.B. |author2=Frew D.J. |author3=Parker Q.A. |author4=Bojicic I.S.
 |date=2015
 |title=New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=447 |issue=2 |pages=1673–1691
 |arxiv=1403.7230
 |bibcode=2015MNRAS.447.1673V
 |doi=10.1093/mnras/stu2383
|doi-access=free }}</ref> The central star is '''QX Puppis''', a [[binary star|binary]] composed of a very cool [[Mira variable]] and an [[A-type main-sequence star]].

==Description==
Violent gas collisions that produced supersonic shock fronts in a dying star are seen in a detailed image from [[NASA]]'s [[Hubble Space Telescope]].

The object is sometimes called the Rotten Egg Nebula as it contains a relatively large amount of [[sulphur]].  The densest parts of the nebula are composed of material ejected recently by the central star and accelerated in opposite directions. This material, shown as yellow in the image, is zooming away at speeds up to one and a half million kilometers per hour (one million miles per hour). Most of the star's original mass is now contained in these [[bipolar nebula|bipolar]] gas structures.

A team of Spanish and US astronomers used NASA's Hubble Space Telescope to study how the gas stream rams into the surrounding material, shown in blue. They believe that such interactions dominate the formation process in planetary nebulae. Due to the high speed of the gas, shock-fronts are formed on impact and heat the surrounding gases. Although computer calculations had predicted the existence and structure of such shocks for some time, previous observations had not been able to prove the theory.

This new Hubble image used filters that only let through light from ionized hydrogen and nitrogen atoms. Astronomers were able to distinguish the warmest parts of the gas heated by the violent shocks and found that they form a complex double-bubble shape. The bright yellow-orange colors in the picture show how dense, high-speed gas is flowing from the star, like supersonic speeding bullets ripping through a medium in opposite directions. The central star itself is hidden in the dusty band at the center.

Much of the gas flow observed today seems to stem from a sudden acceleration that took place about 800 years ago. Astronomers believe that 1,000 years from now, the Calabash Nebula will become a fully developed planetary nebula.

==Ground-based imagery==
[[File:n2438s.jpg|thumb|right|[[NGC 2438]] (upper left) and the Calabash Nebula (lower right) taken from the Mount Lemmon SkyCenter using the 0.8&nbsp;m Schulman Telescope.]]

In wide field images, the Calabash nebula is visible near the bright planetary nebula [[NGC 2438]] in deep photographs. Although the Calabash Nebula is at the same distance as [[Messier 46|M46]], NGC 2438 is a larger object in the foreground.

== Notes ==
{{refbegin}}
<ol type="a">
<li>{{Note_label|A|a|none}}Radius = distance × sin(angular size / 2) = 5 kly * sin(1{{prime}} / 2) = 0.7 ly</li>
<li>{{Note_label|B|b|none}}9.47 apparent magnitude - 5 * (log<sub>10</sub>(1,500 pc distance) - 1) = -1.4 absolute magnitude</li>
</ol>
{{refend}}

==References==
{{reflist}}

==Sources==
* {{Citation
 |last1=Icke | first1 = Vincent |author-link=:nl:Vincent Icke| last2 = Preston | first2 = Heather L.
 | title = The Dynamics of the Calabash Nebula
 | journal = Astronomy and Astrophysics 
 | year = 1989 | volume = 211 | issue = 2 | pages = 409–412
 | publisher = NASA Astrophysics Data System (ADS)
 | url = http://articles.adsabs.harvard.edu//full/1989A%26A...211..409I/0000410.000.html
 | bibcode = 1989A&A...211..409I 
}}
* {{Citation
 | last1 = Kastner | first1 = Joel H. | last2 = Weintraub | first2 = David A.
 | last3 = Merrill | first3 = K. M. | last4 = Gatley | first4 = Ian
 | title = Direct Detection of the Mira at the Heart of OH 231.8+4.2
 | journal = The Astronomical Journal 
 | year = 1998 | volume = 116 | issue = 3 | pages = 1412–1418
 | publisher = SIMBAD, Centre de Données Astronomiques de Strasbourg
 |bibcode = 1998AJ....116.1412K |doi = 10.1086/300520 | s2cid = 119845097 | doi-access = free }}
* {{Citation
 | title = Results for Red Rectangle
 | date = January 4, 2007
 |website=SIMBAD Astronomical Database
 | url = http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=Calabash+Nebula |ref={{harvid|SIMBAD|2007}}
}}

==External links==
{{commons category|Calabash Nebula}}
*[http://photojournal.jpl.nasa.gov/catalog/PIA04228 PIA04228: Rotten Egg Nebula], NASA Planetary Photojournal
*[https://apod.nasa.gov/apod/ap991101.html  The Rotten Egg Planetary Nebula], APOD 1999 November 1
*[https://apod.nasa.gov/apod/ap010903.html The Making of the Rotten Egg Nebula], APOD 2001 September 3
* [http://www.constellation-guide.com/calabash-nebula-rotten-egg-nebula/ Calabash Nebula at Constellation Guide]
*[http://www.eso.org/public/archives/images/screen/eso8703a.jpg Calabash Nebula imaged and interpreted by Bo Reipurth at the European Southern Observatory in 1987]

{{Puppis}}

[[Category:Protoplanetary nebulae]]
[[Category:Puppis]]
[[Category:Mira variables]]
[[Category:M-type giants]]
[[Category:A-type main-sequence stars]]
[[Category:Objects with variable star designations|Puppis, QX]]
[[Category:Binary stars]]