Red Rectangle Nebula
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{{ Protoplanetary nebula |
| image = [[Image:Redrectangle hst full.jpg|250px]]
|caption =
| name = Red Rectangle Nebula
| epoch = [[J2000]]
| ra = {{RA|06|19|58.2160}}<ref name="simbad">{{Harv|SIMBAD|2007}}</ref>
| dec = {{DEC|-10|38|14.691}}<ref name="simbad" />
| dist_ly = [[1 E19 m|2.3 ± 0.3]] [[light-year|kly]] (710 ± 100 [[parsec|pc]])<ref name="Menshchikovetal2002">{{Harv|Men'shchikov|Schertl|Tuthill|Weigelt|2002}}</ref>
| appmag_v = 9.02<ref name="simbad" />
| size_v =
| constellation = [[Monoceros]]
| radius_ly =
| absmag_v =
| notes =
| names = HD 44179,<ref name="simbad" /><br>
RAFGL 915<ref name="simbad" />
}}
The '''Red Rectangle Nebula''', so called because of its unique shape and color, is a [[protoplanetary nebula]] near the [[Monoceros constellation]]. Also known as HD 44179, the nebula was discovered in 1973 during a rocket flight associated with the AFCRL Infrared Sky Survey called Hi Star. The [[binary system (astronomy)|binary system]] at the center of the nebula was first discovered by [[Robert Grant Aitken]] in 1915.
==Characteristics==
Diffraction-limited speckle images of it in visible and [[near infrared]] light reveal a highly symmetric, compact [[bipolar nebula]] with X shaped spikes which imply toroidal dispersion of the circumstellar material. The central binary system is completely obscured, providing no direct light. {{Harv|Men'shchikov|Schertl|Tuthill|Weigelt|2002}}
Exciting information was reported at the 203<sup>rd</sup> Meeting of the [[American Astronomical Society]] in January 2004 by a team led by A. Witt of the [[University of Toledo|University of Toledo, Ohio]], who discovered the spectral signatures of the [[polycyclic aromatic hydrocarbons]] [[anthracene]] and [[pyrene]] in the ultraviolet light emitted by the nebula - potentially vital organic molecules for the formation of life. Until recently, it was thought that the ultraviolet light would quickly destroy these hydrocarbons; the fact that the hydrocarbons still exist today has been explained by recently discovered [http://space.com/scienceastronomy/070406_red_rectangle.html molecular forces].
So why does it look like an X? A likely explanation is that the central star - actually a close pair of stars - is surrounded by a thick dust [[torus]] which pinches the otherwise spherical outflow into tip-touching cone shapes. Because we view the torus edge-on, the boundary edges of the cone shapes seem to form an X. The distinct rungs suggest the outflow occurs in fits and starts. About 2,300 light-years away toward the fanciful constellation Monoceros, the Red Rectangle nebula should be transformed into a glorious planetary nebula as its cool central star becomes a hot white dwarf over the next few thousand years.
The [[Hubble Space Telescope]] has revealed a wealth of new features in the Red Rectangle that cannot be seen by ground-based telescopes looking through [[Earth]]'s turbulent [[atmosphere]]. The origins of many of the features in this dying [[star]] still remain hidden or even outright mysterious, some are well explained by theorists like the Dutch scientist [[Vincent Icke]] from [[Leiden University]] in the [[Netherlands]].
[[Image:PIA04533.jpg|thumb|200px|left|Proto-Planetary Nebula]]
In 1981 [[Vincent Icke]] and collaborators showed that a spherical [[gas ejection]] from a [[asymptotic giant branch|dying star]] hitting a dust torus would give rise to [[bow shock|shocks]] that can produce cone-like outflows similar to the two cones seen in this nebula.
[[Meteorologists]] produce [[weather]] forecasts by advanced calculations of temperatures, pressures, velocities and densities for the air masses in our atmosphere and, to some degree, theorists like Icke are doing exactly the same for objects in space. Whether modeling the weather in the Earth’s atmosphere or the processes in distant gaseous nebulae, scientists calculate the motion of the gas by using a complicated set of expressions known as [[hydrodynamic equations]], although in astrophysics [[magnetic fields]] are also significant, so the math used is [[magnetohydrodynamics]].
Most of the [[matter]] in the [[Universe]] is in the form of gas. The weather on Earth gives rise to spectacular patterns such as [[thunderclouds]] and [[tornadoes]] in the air masses here. Likewise, the ‘weather’ in gas clouds in space, like the Red Rectangle, can be fascinating. In Astronomy, the shape of an object's clouds is referred to as its [[morphology (astronomy)|morphology]].
Of the many different parameters in Vincent Icke’s calculations, only the density of the gas and the dust are observed in the nebula.
== See also ==
* [[Red Square Nebula]]
* [[Aromatic hydrocarbons]], (AH)
* [[Polycyclic aromatic hydrocarbon]], (PAH)
* [[Nebula]]
== External links ==
* [http://www.esa.int/esaCP/SEMHBNGHZTD_FeatureWeek_0.html The remarkable Red Rectangle: A Stairway to Heaven?]
* [http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/11/ Dying Star Sculpts Rungs of Gas and Dust]
* [http://spacescience.arc.nasa.gov/redglow/ Charged polycyclic aromatic hydrocarbon clusters and the galactic red emission], 2007.
== Notes ==
{{reflist}}
== References ==
<div class="references-small">
* {{Harvard reference
| Surname1 = Cohen
| Given1 = M.
| Surname2 = Anderson
| Given2 = C. M.
| Surname3 = Cowley
| Given3 = A.
| Surname4 = Coyne
| Given4 = G. V.
| Surname5 = Fawley
| Given5 = W.
| Surname6 = Gull
| Given6 = T. R.
| Surname7 = Harlan
| Given7 = E. A.
| Surname8 = Herbig
| Given8 = G. H.
| Surname9 = Holden
| Given9 = F.
| Surname10 = Hudson
| Given10 = H. S.
| Surname11 = Jakoubek
| Given11 = R. O.
| Surname12 = Johnson
| Given12 = H. M.
| Surname13 = Merrill
| Given13 = K. M.
| Surname14 = Schiffer
| Given14 = F. H.
| Surname15 = Soifer
| Given15 = B. T.
| Surname16 = Zuckerman
| Given16 = B.
| Title = The peculiar object HD 44179 'The red rectangle'
| Journal = Astrophysical Journal
| Year = 1975
| Date = [[February 15]] [[1975]]
| Volume = 196
| Issue = 1
| Pages = 179-189
| URL = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJ...196..179C
}}
* {{Harvard reference
| Surname1 = American Astronomical Society
| Title = Meeting program contents (Retrieved January 2, 2006)
| Year = 2004
| URL = http://www.aas.org/meetings/aas203/
}}
* {{Harvard reference
| Surname1 = Battersby
| Given1 = Stephen
| Title = Space molecules point to organic origins (Retrieved January 2, 2006)
| Journal = New Scientist
| Year = 2004
| URL = http://www.newscientist.com/news/news.jsp?id=ns99994552
}}
* {{Harvard reference
| Surname1 = SIMBAD
| Title = Results for Red Rectangle
| Authorlink = SIMBAD
| Journal =
| Year = 2007
| Date = [[January 7]] [[2007]]
| Publisher = SIMBAD, Centre de Données Astronomiques de Strasbourg
| URL = http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=Red+Rectangle
}}
* {{Harvard reference
| Surname1 = Men'shchikov
| Given1 = A. B.
| Surname2 = Schertl
| Given2 = D.
| Surname3 = Tuthill
| Given3 = P. G.
| Surname4 = Weigelt
| Given4 = G.
| Surname5 = Yungelson
| Given5 = L. R.
| Title = Properties of the close binary and circumbinary torus of the Red Rectangle
| Journal = Astronomy and Astrophysics
| Year = 2002
| Volume = 393
| Pages = 867-885
| URL = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002A%26A...393..867M
}}
</div>
[[Category:Protoplanetary nebulae]]
[[Category:Monoceros constellation]]
[[de:Roter Rechteck-Nebel]]