R Aquarii

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R Aquarii
Location of R Aquarii (circled in red)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 23h 43m 49.46343s[1]
Declination −15° 17′ 04.1763″[1]
Apparent magnitude (V) 5.2 - 12.4[2]
Spectral type M5e-M8.5e + pec[2]
U−B color index −0.62[3]
B−V color index +1.98[3]
Variable type Mira + Z And[2]
Radial velocity (Rv)−22.0[4] km/s
Proper motion (μ) RA: +40.587[1] mas/yr
Dec.: −30.411[1] mas/yr
Parallax (π)2.5931 ± 0.3333 mas[1]
Distanceapprox. 1,300 ly
(approx. 390 pc)
Period (P)15,943±471
Semi-major axis (a)0.071 - 0.084"
(14.2 - 16.8 AU)
Eccentricity (e)0.25±0.07
Inclination (i)70°
Mass1 - 1.5[5] M
Radius430[5] R
Luminosity4,780[6] L
Surface gravity (log g)−0.5[6] cgs
Temperature2,800[6] K
Mass0.6 - 1[5] M
Radius>0.1[7] R
Luminosity5-20[8] L
Temperature60,000[8] K
Other designations
R Aqr, BD−16°6352, HD 222800, HIP 117054, HR 8992, SAO 165849
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

R Aquarii (R Aqr) is a variable star in the constellation Aquarius.[9]

R Aquarii is a symbiotic star believed to contain a white dwarf and a Mira-type variable in a binary system. The orbital period is approximately 44 years.[5] 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 was discovered by Karl Ludwig Harding in 1810. It has a distance of about 390 parsecs,[1] and is one of the nearest symbiotic stars and a well-known jet source.[10] The two components have been resolved at a separation of 55 mas.[11]

By its gravitational pull, the white dwarf draws in material from the red giant and occasionally ejects some of the surplus in loops to form the nebula seen in the linked image.[12] The whole system appears reddened because it is situated in a very dusty region of space, and its blue light is absorbed before reaching Earth.

The light curve of R Aquarii, from AAVSO V band data

The nebula around R Aquarii is also known as Cederblad 211.[13] 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.[14] It is reasonably bright but small and dominated by its central star. Visual observations are difficult and rare.[15] The central region of the jet shows an ejection that took place around 190 years ago, as well as much younger structures.[16]

The giant primary star is a Mira variable, a star that pulsates and changes temperature, leading to very large visual brightness changes. The total range of 5.2 - 12.4 is a variation of 750 times in brightness, from a naked eye star to one beyond the range of binoculars. The pulsations occur every 390 days but are not entirely regular.[2]



  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ a b Celis s., L. (1982). "Red variable stars. I - UBVRI photometry and photometric properties". Astronomical Journal. 87: 1791. Bibcode:1982AJ.....87.1791C. doi:10.1086/113268.
  4. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  5. ^ a b c d e M. Gromadzki & J. Mikołajewska (March 2009). "The spectroscopic orbit and the geometry of R Aquarii". Astronomy & Astrophysics. 495 (3): 931–936. arXiv:0804.4139. Bibcode:2009A&A...495..931G. doi:10.1051/0004-6361:200810052. S2CID 2034734.
  6. ^ a b c Mayer, A.; Jorissen, A.; Kerschbaum, F.; Ottensamer, R.; Nowotny, W.; Cox, N. L. J.; Aringer, B.; Blommaert, J. A. D. L.; Decin, L.; Van Eck, S.; Gail, H.-P.; Groenewegen, M. A. T.; Kornfeld, K.; Mecina, M.; Posch, Thomas; Vandenbussche, B.; Waelkens, C. (2013). "Large-scale environments of binary AGB stars probed by Herschel. I. Morphology statistics and case studies of R Aquarii and W Aquilae". Astronomy & Astrophysics. 549: A69. arXiv:1211.3595. Bibcode:2013A&A...549A..69M. doi:10.1051/0004-6361/201219259. S2CID 55538633.
  7. ^ Burgarella, D.; Vogel, M.; Paresce, F. (1992). "R Aquarii : An attempt at a unified model". Astronomy and Astrophysics. 262: 83. Bibcode:1992A&A...262...83B.
  8. ^ a b Sankrit, Ravi; Omelian, Eric; Gorti, Uma; Wagner, R. Mark; Goldman, Steven; Whitelock, Patricia A. (2022). "SOFIA/FORCAST Monitoring of the Dust Emission from R Aqr: Start of the Eclipse". The Astrophysical Journal. 926 (2): 177. arXiv:2112.13118. Bibcode:2022ApJ...926..177S. doi:10.3847/1538-4357/ac4792. S2CID 245502364.
  9. ^ "R Aquarii | aavso.org". www.aavso.org. Retrieved 2018-07-11.
  10. ^ Stute, Matthias; Sahai, Raghvendra (2007). "Hydrodynamical Simulations of the Jet in the Symbiotic Star MWC 560. III. Application to X-Ray Jets in Symbiotic Stars". The Astrophysical Journal. 665 (1): 698–706. arXiv:0704.2240. Bibcode:2007ApJ...665..698S. doi:10.1086/518930. S2CID 11053317.
  11. ^ Hollis, J. M.; Pedelty, J. A.; Lyon, R. G. (1997). "Spatial Resolution of the R Aquarii Binary System". The Astrophysical Journal. 482 (1): L85–L88. Bibcode:1997ApJ...482L..85H. doi:10.1086/310687.
  12. ^ "Aladin previewer". CDS.
  13. ^ Cederblad, S (1946). "Studies of bright diffuse galactic nebulae with special regard to their spatial distribution". Lund Medd. Astron. Obs. Series II. 119: 1. Bibcode:1946MeLuS.119....1C.
  14. ^ Kafatos, Minas; Michalitsianos, Andrew G (1982). "The peculiar variable star R Aquarii and its jet". Nature. 298 (5874): 540. Bibcode:1982Natur.298..540K. doi:10.1038/298540a0. S2CID 4238750.
  15. ^ "The Drama-Ridden Couple of R Aquarii". Sky & Telescope. Retrieved 2018-01-18.
  16. ^ Paresce, Francesco; Hack, Warren (1994). "New HST observations of the core of R Aquarii. 1: Imaging". Astronomy and Astrophysics. 287: 154. Bibcode:1994A&A...287..154P.
  17. ^ "Dancing with the Enemy - ESO's R Aquarii Week continues with the sharpest R Aquarii image ever". www.eso.org. Retrieved 12 December 2018.
  18. ^ "VLT view of binary system R Aquarii from 2012". www.eso.org. Retrieved 10 December 2018.

External links[edit]