R Aquarii and Cederblad 211 (Gary Imm)

R Aquarii and Cederblad 211

This object is located 1000 light years away in the constellation of Aquarius at a declination of -15 degrees. It spans 1.7 arc-minutes in our apparent view, which corresponds to a diameter of about 0.5 light years. But what is it?

My image appears to show a bright white star that is emitting 2 bi-polar jets. The jets start out straight but then curl. Surrounding the star and bi-polar jets is a horizontal oval red hydrogen nebula. The entire system seems to be distorted by interaction with the interstellar medium (ISM).

This system has been extensively studied for almost 100 years. The central star, R Aquarii, is classified as a Mira variable star. Mira variables are pulsating red giant stars named after the prototype star Mira. R Aquarii currently varies in visual magnitude from 8 to 12 over a period of 387 days. At the time of this image, R Aquarii was fairly dim, at a magnitude of 11.

If this object was simply a Mira variable star, it would just appear as a star. What is causing the jets and nebula?

R Aquarii is one of the nearest symbiotic stars, consisting of a binary star system. In addition to the Mira-type red giant, there is also a nearby white dwarf. The two stars are separated by only 0.06 arc-seconds. The white dwarf cannot be seen in my image. It orbits the red giant every 44 years.

The bipolar jets are moving outward at tremendous speeds. Scientists believe that the jets are outflow from an accretion disk that has formed around the white dwarf, from material that it has stolen from the red giant. Occasionally, the accreted material is ejected in the form of a nova-like outburst, forming a hydrogen nebula. The red oval nebula seen here is believed to be the result of an ejection that occurred about 200 years ago. This nebula has been designated Cederblad 211.

Final
Original
B

B

Description: Comparison to Hubble Space Telescope Image

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Status	Advanced success
Started	...
Astrometry.net job	5178979
PixInsight job	FSJ7TKIGGRM0ROU2W39VA6326Z1XV44H
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	23h43m49s.331
RA (top/left)	23h44m18s.438
RA (top/right)	23h43m19s.917
RA (bottom/right)	23h43m20s.221
RA (bottom/left)	23h44m18s.760

Dec (center)	-15°17′02″.80
Dec (top/left)	-15°12′05″.51
Dec (top/right)	-15°12′11″.91
Dec (bottom/right)	-15°22′00″.54
Dec (bottom/left)	-15°21′54″.30

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