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NGC 6729 (also known as Caldwell 68) is a 
reflection Reflection or reflexion may refer to:
Science and technology
* Reflection (physics), a common wave phenomenon
** Specular reflection, reflection from a smooth surface
*** Mirror image, a reflection in a mirror or in water
** Signal reflection, in s ...
/emission
Emission may refer to:
Chemical products
* Emission of air pollutants, notably:
**Flue gas, gas exiting to the atmosphere via a flue
** Exhaust gas, flue gas generated by fuel combustion
** Emission of greenhouse gases, which absorb and emit radi ...
nebula of the Corona Australis Molecular Cloud
Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-centu ...
in the constellation Corona Australis
Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-centu ...
. It was discovered by Johann Friedrich Julius Schmidt
Johann Friedrich Julius Schmidt (25 October 1825 in Eutin, Germany – 7 February 1884 in Athens, Greece) was a German astronomer and geophysicist. He was the director of the National Observatory of Athens in Greece from 1858 to 1884. Julius Schmi ...
in 1861.
This fan-shaped nebula opens from the star R Coronae Australis
R Coronae Australis (R CrA) is a variable binary system in the constellation Corona Australis. It has varied between magnitudes 10 and 14.36. A small reflection/ emission nebula NGC 6729 extends from the star towards SE. It is also ...
toward the star T CrA to the south-east. R CrA is a pre-main-sequence star in the Corona Australis molecular complex, one of the closer star-forming regions of the galaxy at a distance of 130 pc. NGC 6729 is a variable nebula which shows irregular variations in brightness and in shape.Robert Burnham, Jr.: ''Burnham's Celestial Handbook, Volume 2: Chamaeleon through Orion'', pages 695-696: NGC 6726-6727-6729 and R Coronae Australis
See also
*McNeil's Nebula
McNeil's Nebula is a variable nebula discovered January 23, 2004 by Jay McNeil of Paducah, Kentucky. It is illuminated by the star V1647 Ori.
Discovery
McNeil's Nebula is a cometary-type reflection nebula, illuminated by the reddish star V1647 ...
*NGC 1555
NGC 1555, sometimes known as Hind's Variable Nebula, is a variable nebula, illuminated by the star T Tauri, located in the constellation Taurus. It is also in the second Sharpless catalog as 238. It is a Herbig–Haro object. The nebula was d ...
(Hind's Variable Nebula)
*NGC 2261
NGC 2261 (also known as Hubble's Variable Nebula or Caldwell 46) is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis (R Mon), which is not directly visible itself.
Observing history
NG ...
(Hubble's Variable Nebula)
References
External links
* * Diffuse nebulae Reflection nebulae Emission nebulae 068b Corona Australis Astronomical objects discovered in 1861 6729 {{nebula-stub