R Aquarii

Starbox begin
name=R Aquarii Starbox image


caption = R Aquarii Starbox observe
epoch=J2000
ra=23^h 43^m 49.4616^s
dec= -15° 17′ 04.202″
appmag_v=7.69
constell=Aquarius Starbox character
class=M7IIIpev
b-v=1.58
u-b=0.32
variable= Mira Cet Starbox astrometry
radial_v=-22
prop_mo_ra=32.98
prop_mo_dec=-32.61
parallax=5.07
p_error=3.15
absmag_v=8.83 Starbox detail
mass=0,4
radius=0,5
luminosity=0,04 | temperature=2,000–3,500
metal=?
rotation=386.96 days
age=? Starbox catalog
names=GSC 06404-00077, IRC -20642, BD-16 6352, HD 222800, 2MASS J23434939-1517043, TYC 6404-77-1, EM* MWC 400, HIC 117054, PPM 242022, YZ 105 8733, GC 32948, HIP 117054, RAFGL 3136, GCRV 14862, HR 8992, 1RXS J234351.0-151655, AAVSO 2338-15, IRAS 23412-1533, SAO 165849. Starbox reference
Simbad=HD+222800

R Aquarii (R Aqr) is a variable star in the constellation Aquarius.

R Aquarii is a symbiotic star believed to contain a white dwarf and a Mira-type variable in a binary star system. The main Mira-type star is a red giant, and varies in brightness by a factor of several hundred and with a period of slightly more than a year; this variability has been discovered by Karl Ludwig Harding in 1810.

By its gravitational pull, the white dwarf draws in material from the red giant and occasionally ejects some of the surplus in the weird loops to form the nebula seen in the linked image. [cite web | url = http://aladin.u-strasbg.fr/AladinPreview?-c=23+43+49.4616-15+17+04.202&ident=V*+R+Aqr&submit=Aladin+previewer | title = Aladin previewer | publisher = CDS] The whole system appears reddened because it is situated in a very dusty region of space, and its blue light is absorbed before reaching us.

The nebula around R Aquarii is also known as Cederblad 211. According to Tom Polakis [cite journal
author=Polakins, Tom
title=
journal=Astronomy
year= Oct. 1998
volume=Vol. 26, No. 10
pages=p. 83
url=] , at that time, noone had succeeded to observe this challenging object visually. It is possible that the nebula is the remnant of a nova-like outburst, which may have been observed by Japanese astronomers, in the year 930 AD.

References

External links

* [http://aladin.u-strasbg.fr/AladinPreview?-c=23+43+49.4616-15+17+04.202&ident=V*+R+Aqr&submit=Aladin+previewer Weird loop image in R Aquarii]
* [http://www.alcyone.de/cgi-bin/search.pl?object=HR8992 HR 8992]