Astronomy:RX Boötis

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Short description: Star in the constellation Boötes
RX Boötis
250px
A visual band light curve for RX Boötis, plotted from data published by Cadmus (2024)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Boötes[2]
Right ascension  14h 24m 11.62532s[3]
Declination 25° 42′ 13.3942″[3]
Apparent magnitude (V) 6.43 - 9.1[4]
Characteristics
Evolutionary stage AGB[5]
Spectral type M7.5e[5]
Variable type Semiregular (SRB)[4]
Astrometry
Radial velocity (Rv)3.8±1[6] km/s
Proper motion (μ) RA: +24.55[7] mas/yr
Dec.: −49.67[7] mas/yr
Parallax (π)7.31 ± 0.50[7] mas
Distance440+33
−29 ly
(136+10
−9 pc)
Details
Mass2.2[8] M☉
Radius270[7] R☉
Luminosity3630[7] L☉
Surface gravity (log g)1.94[8] cgs
Temperature2750[7] K
Metallicity [Fe/H]−0.32[8] dex
Other designations
RX Boo, BD+26°2563, HD 126327, HIP 70401, SAO 83331[9]
Database references
SIMBADdata

RX Boötis is a variable star in the northern constellation of Boötes. Varying in brightness from magnitude 6.43 to 9.1, it is too faint to be seen with the naked eye, but can be seen with binoculars. Based on parallax measurements, it is 440 light-years away.

During the period from 1880 through 1892, Ernst Hartwig observed the star (then known as BD +26°2563) and discovered that its brightness varies. This discovery was announced in 1893,[10] and in 1911 it was given its variable star designation, RX Boötis.[11] Many periods have been reported for this star's brightness changes, including 78,[12] 158,[13] 160,[14] 179,[15] 278[14] and 340[5] days. Some studies have found pairs of periods, indicating that the star is a double-mode oscillator.[14][15][12]

RX Boötis is an oxygen-rich AGB star,[5] and it is losing mass via a stellar wind, producing a circumstellar envelope (CSE). Near-infrared radiation from dust in this CSE was detected during the Two-Micron Sky Survey, published in 1969.[16] The 60 micron data from the IRAS satellite showed a dust shell 6.6 arc minutes (~0.8 lightyear) in radius.[17] In the late 1970s, CO was detected in the CSE, expanding from the star at 7.8±1.5 km/sec.[6] A later study of the CO emission lines produced an estimate for the star's mass loss rate of 3.6×10−7 M☉ per year.[5] RX Boötis may not yet have begun losing mass at a high rate.[7] Strong, variable, water maser emission at 22 GHz is seen, arising from an incomplete ring of bright spots, each of which lasts for about a year, arranged in an incomplete ring whose inner radius is 15 AU with a thickness of 22 AU.[18] A far-ultraviolet image of the star obtained from GALEX shows a bow shock 325 arc seconds (~0.7 lightyears) from the star, where the wind from RX Boötis collides with the interstellar medium.[19]

VLBI observations of RX Boötis have yielded a distance estimate to RX Boötis of 136±10 parsecs, smaller than Gaia's value of 156±6 parsecs.[7] Optically measured parallaxes for AGB stars, like Gaia's, may have larger than normal errors due to the pulsations and dusty environments of these stars.[20]

References

  1. ↑ Cadmus, Robert R. (May 2024). "The Long-term Photometric Behavior of 39 Semiregular Variable Stars". The Astronomical Journal 167 (5): 200. doi:10.3847/1538-3881/ad303a. Bibcode: 2024AJ....167..200C. 
  2. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  3. ↑ 3.0 3.1 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  4. ↑ 4.0 4.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 De Beck, E.; Decin, L.; de Koter, A.; Justtanont, K.; Verhoelst, T.; Kemper, F.; Menten, K. M. (November 2010). "Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles. II. CO line survey of evolved stars: derivation of mass-loss rate formulae". Astronomy and Astrophysics 523: A18. doi:10.1051/0004-6361/200913771. Bibcode: 2010A&A...523A..18D. 
  6. ↑ 6.0 6.1 Knapp, G. R.; Phillips, T. G.; Leighton, R. B.; Lo, K. Y.; Wannier, P. G.; Wootten, H. A.; Huggins, P. J. (January 1982). "Mass loss from evolved stars. I. Observations of 17 stars in the CO(2-1) line". Astrophysical Journal 252: 616–634. doi:10.1086/159589. Bibcode: 1982ApJ...252..616K. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Kamezaki, Tatsuya; Nakagawa, Akiharu; Omodaka, Toshihiro; Kurayama, Tomoharu; Imai, Hiroshi; Tafoya, Daniel; Matsui, Makoto; Nishida, Yoshiro et al. (February 2012). "VLBI Astrometry of the Semiregular Variable RX Bootis". Publications of the Astronomical Society of Japan 64 (1): 7. doi:10.1093/pasj/64.1.7. Bibcode: 2012PASJ...64....7K. 
  8. ↑ 8.0 8.1 8.2 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K. 
  9. ↑ "R Boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=R+Boo. 
  10. ↑ Hartwig, Ernst (1893). "Jahresberichte der Sternwarten fur 1892 (in German)". Vierteljahrsschrift der Astronomischen Gesellschaft 28: 152–153. https://archive.org/details/vierteljahrssch61unkngoog/page/152/mode/2up. Retrieved 1 April 2025. 
  11. ↑ Dunér, N.; Hartwig, E.; Müller, K. (December 1911). "Benennung von neu entdeckten veränderlichen Sternen (in German)". Astronomische Nachrichten 190 (4): 57–72. doi:10.1002/asna.19111900402. Bibcode: 1911AN....190...57.. 
  12. ↑ 12.0 12.1 Taylor, M. D. (August 1987). "The Semiregular Variable RX Bootis". Journal of the British Astronomical Association 97 (5): 277–279. Bibcode: 1987JBAA...97..277T. 
  13. ↑ "RX Boo". AAVSO. https://www.aavso.org/vsx/index.php?view=detail.top&oid=4319. 
  14. ↑ 14.0 14.1 14.2 Speil, J. (June 2006). "Period Analysis of the Light Curves of Three Semiregular Variables: AA Cygni, U Delphini, and RX Bootis". The Journal of the American Association of Variable Star Observers 35 (1): 88–90. Bibcode: 2006JAVSO..35...88S. 
  15. ↑ 15.0 15.1 Andronov, I. L.; Kudashkina, L. S. (1988). "Semiregular variable RX Bootis : double-period optical variation of acosmical maser ?". Astronomische Nachrichten 309 (5): 323–325. doi:10.1002/asna.2113090505. Bibcode: 1988AN....309..323A. https://articles.adsabs.harvard.edu/pdf/1988AN....309..323A. Retrieved 2 April 2025. 
  16. ↑ Leighton, R. B.; Neugebauer, G. (August 1969). "Two-micron sky survey - A preliminary catalog". NASA. https://ntrs.nasa.gov/citations/19690028611. 
  17. ↑ Young, K.; Phillips, T. G.; Knapp, G. R. (June 1993). "Circumstellar Shells Resolved in the IRAS Survey Data. I. Data Processing Procedure, Results, and Confidence Tests". Astrophysical Journal Supplement Series 86: 517–540. doi:10.1086/191789. Bibcode: 1993ApJS...86..517Y. 
  18. ↑ Winnberg, A.; Engels, D.; Brand, J.; Baldacci, L.; Walmsley, C. M. (May 2008). "Water vapour masers in long-period variable stars. I. RX Bootis and SV Pegasi". Astronomy and Astrophysics 482 (3): 831–848. doi:10.1051/0004-6361:20078295. Bibcode: 2008A&A...482..831W. https://www.aanda.org/articles/aa/pdf/2008/18/aa8295-07.pdf. Retrieved 2 April 2025. 
  19. ↑ Sahai, Raghvendra; Stenger, Benjamin (June 2023). "Faint but Not Forgotten. I. First Results from a Search for Astrospheres around AGB Stars in the Far-ultraviolet". The Astronomical Journal 165 (6): 229–254. doi:10.3847/1538-3881/acccf2. Bibcode: 2023AJ....165..229S. 
  20. ↑ Andriantsaralaza, M.; Ramstedt, S.; Vlemmings, W. H. T.; De Beck, E. (November 2022). "Distance estimates for AGB stars from parallax measurements". Astronomy & Astrophysics 667: A74. doi:10.1051/0004-6361/202243670. Bibcode: 2022A&A...667A..74A. 

Coordinates: Sky map 14h 24m 11.6253s, +25° 42′ 13.394″



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