Astronomy:R Aquarii

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R Aquarii
Aquarius constellation map.svg
Red circle.svg
Location of R Aquarii (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  23h 43m 49.46343s[1]
Declination −15° 17′ 04.1763″[1]
Apparent magnitude (V) 5.2 - 12.4[2]
Characteristics
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]
Astrometry
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[1] mas
Distanceapprox. 1,300 ly
(approx. 390 pc)
Orbit[5]
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°
Details
A
Mass1 - 1.5[5] M☉
Radius430[5] R☉
Luminosity4,780[6] L☉
Surface gravity (log g)−0.5[6] cgs
Temperature2,800[6] K
B
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
SIMBADdata
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]

Gallery

  • R Aquarii peculiar stellar relationship captured by SPHERE.[17]

  • R Aquarii as seen in 2012 by ESO's Very Large Telescope.[18]

  • R Aquarii and its surrounding nebulosity

  • Artist's impression of R Aquarii during an outburst

  • The jet and central regions of the nebula around R Aquarii

  • HST image of R Aquarii

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Samus, N. N. 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. ↑ 3.0 3.1 Celis s., L. (1982). "Red variable stars. I - UBVRI photometry and photometric properties". Astronomical Journal 87: 1791. doi:10.1086/113268. Bibcode: 1982AJ.....87.1791C. 
  4. ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode: 1953GCRV..C......0W. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 M. Gromadzki; J. Mikołajewska (March 2009). "The spectroscopic orbit and the geometry of R Aquarii". Astronomy & Astrophysics 495 (3): 931–936. doi:10.1051/0004-6361:200810052. Bibcode: 2009A&A...495..931G. 
  6. ↑ 6.0 6.1 6.2 Mayer, A.; Jorissen, A.; Kerschbaum, F.; Ottensamer, R.; Nowotny, W.; Cox, N. L. J.; Aringer, B.; Blommaert, J. A. D. L. et al. (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. doi:10.1051/0004-6361/201219259. Bibcode: 2013A&A...549A..69M. 
  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. ↑ 8.0 8.1 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. doi:10.3847/1538-4357/ac4792. Bibcode: 2022ApJ...926..177S. 
  9. ↑ "R Aquarii | aavso.org" (in en). https://www.aavso.org/vsots_raqr. 
  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. doi:10.1086/518930. Bibcode: 2007ApJ...665..698S. 
  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. doi:10.1086/310687. Bibcode: 1997ApJ...482L..85H. 
  12. ↑ "Aladin previewer". CDS. http://aladin.u-strasbg.fr/AladinPreview?-c=23+43+49.4616-15+17+04.202&ident=V*+R+Aqr&submit=Aladin+previewer. 
  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. doi:10.1038/298540a0. Bibcode: 1982Natur.298..540K. 
  15. ↑ "The Drama-Ridden Couple of R Aquarii". Sky & Telescope. http://www.skyandtelescope.com/observing/celestial-objects-to-watch/variable-stars/the-drama-ridden-couple-of-r-aquarii/. 
  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" (in en). https://www.eso.org/public/news/eso1840/. 
  18. ↑ "VLT view of binary system R Aquarii from 2012" (in en). https://www.eso.org/public/images/potw1850a/. 

External links



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