RT Virginis

RT Virginis

A visual band light curve for RT Virginis, plotted from ASAS data
Observation data
Epoch J2000      Equinox ICRS
Constellation Virgo
Right ascension 13h 02m 37.981s
Declination +05° 11′ 08.36″
Apparent magnitude (V) 7.7 to 9.7
Characteristics
Evolutionary stage AGB
Spectral type M8III
B−V color index 1.352±0.031
Variable type SRb
Astrometry
Radial velocity (Rv)17.3±0.2 km/s
Proper motion (μ) RA: +37.037 mas/yr
Dec.: −17.714 mas/yr
Parallax (π)4.417±0.134 mas
Distance740 ± 20 ly
(226 ± 7 pc)
Absolute magnitude (MV)2.94
Details
Mass1.5 M☉
Radius390 R☉
Luminosity (bolometric)5,012+1,154
−938 L☉
Surface gravity (log g)+0.21 cgs
Temperature2,902 K
Metallicity [Fe/H]−0.33 dex
Other designations
RT Vir, BD+05°2708, HD 113285, HIP 63642, SAO 119734, PPM 159423
Database references
SIMBADdata

RT Virginis is a variable star in the equatorial constellation of Virgo, abbreviated RT Vir. It ranges in brightness from an apparent visual magnitude of 7.7 down to 9.7, which is too faint to be visible to the naked eye. Based on parallax measurements made with the VLBI, the distance to this star is approximately 740 light years. It is receding from the Sun with a radial velocity of 17 km/s.

The long period variability of this star was discovered by W. P. Fleming in 1896, based on photographic plates taken between 1886 and 1895. It was listed with its variable star designation, RT Virginis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. A. H. Joy in 1942 categorized it as an irregular variable with a stellar classification of M8III. In 1969 it was classified as a semiregular variable star of the SRb type. The period was determined to be 155 days by P. N. Kholopov and associates in 1985, then re-evaluated as 375 days based on AAVSO light curves in 1997. This is an oxygen-rich red giant star on the asymptotic giant branch of its evolution, and is undergoing mass loss due to thermal pulsation.

Water vapor emission in the vicinity of the star was detected in the microwave band by D. F. Dickinson in 1973. This is originating from strong maser emission in a circumstellar gas-dust shell. The flux density of these water masers is over 100 Jy. The star is losing mass at a rate of 3×10−6 M☉·yr−1; the equivalent of the Sun's mass in 3.3 million years. The velocity of the spherically expanding gas is as high as 11 km/s in the water maser region, at a radius of 5 to 25 AU. In a SiO emitting region located ~400 AU from the star, the gas velocity is 7.8 km/s. This outflow appears clumpy and asymmetrical with a strong temporal variation.

References

  1. ↑ ASAS All Star Catalogue, The All Sky Automated Survey, retrieved 16 September 2022.
  2. 1 2 3 4 Brown, A. G. A.; et al. (Gaia collaboration) (2021), "Gaia Early Data Release 3: Summary of the contents and survey properties", Astronomy & Astrophysics, 649: A1, arXiv:2012.01533, Bibcode:2021A&A...649A...1G, doi:10.1051/0004-6361/202039657, S2CID 227254300 (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. 1 2 3 4 Zhang, Bo; et al. (November 2017), "VLBA Trigonometric Parallax Measurement of the Semi-regular Variable RT Vir", The Astrophysical Journal, 849 (2): 99, Bibcode:2017ApJ...849...99Z, doi:10.3847/1538-4357/aa8ee9, S2CID 125975009, 99.
  4. 1 2 3 4 Brand, J.; et al. (December 2020), "Water vapour masers in long-period variable stars. II. The semi-regular variables R Crt and RT Vir", Astronomy and Astrophysics, 644: A45, arXiv:2011.00294, Bibcode:2020A&A...644A..45B, doi:10.1051/0004-6361/202039157, A45.
  5. 1 2 Joy, Alfred H. (November 1942), "A Survey of the Spectra and Radial Velocities of the Less Regular M-Type Variable Stars", Astrophysical Journal, 96: 344, Bibcode:1942ApJ....96..344J, doi:10.1086/144469.
  6. 1 2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. ↑ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  8. 1 2 Yates, J. A.; et al. (2002), Mineese, Victor; Reid, Mark (eds.), "The H2O maser proper motions of RT Vir and VX Sgr", Cosmic Masers: From Proto-Stars to Black Holes, IAU Symposium, 206, San Francisco: Astronomical Society of the Pacific: 298, Bibcode:2002IAUS..206..298Y.
  9. 1 2 3 Imai, H.; et al. (March 1997), "Measurement of shifts in line-of-sight velocities of stellar water masers using VLBI.", Astronomy and Astrophysics, 319: L1–L4, Bibcode:1997A&A...319L...1I.
  10. 1 2 3 Sharma, Kaushal; et al. (2016), "New atmospheric parameters and spectral interpolator for the MILES cool stars", Astronomy and Astrophysics, 585: A64, arXiv:1512.04882, Bibcode:2016A&A...585A..64S, doi:10.1051/0004-6361/201526111, S2CID 118576178.
  11. ↑ "RT Vir", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-09-07
  12. ↑ Pickering, E. C.; Fleming, W. P. (April 1896), "Harvard College Observatory, circular no. 6. New variable stars", Astrophysical Journal, 3: 296–302, Bibcode:1896ApJ.....3..296P, doi:10.1086/140219.
  13. ↑ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 16 December 2024.
  14. ↑ van der Veen, W. E. C. J.; et al. (March 1995), "The distribution of dust around Asymptotic Giant Branch stars", Astronomy and Astrophysics, 295: 445–458, Bibcode:1995A&A...295..445V.
  15. ↑ Dickinson, D. F. (March 1976), "Water emission from infrared stars", Astrophysical Journal Supplement Series, 30: 259–271, Bibcode:1976ApJS...30..259D, doi:10.1086/190362.
  16. 1 2 Mendoza-Torres, J. E.; et al. (December 1997), "Evolution of H2O maser emission in the direction of the semiregular variable RT Virginis during 1985-1996", Astronomy and Astrophysics Supplement Series, 126 (2): 257–266, Bibcode:1997A&AS..126..257M, doi:10.1051/aas:1997263.
  17. ↑ Sacuto, S.; et al. (March 2013), "The wind of the M-type AGB star RT Virginis probed by VLTI/MIDI", Astronomy and Astrophysics, 551: A72, arXiv:1301.5872, Bibcode:2013A&A...551A..72S, doi:10.1051/0004-6361/201220524, S2CID 18675130, A72.
  18. ↑ Yates, J. A.; et al. (2000), "Is the Outflow from RT Vir Bipolar or Rotating?", in Kastner, J. H.; et al. (eds.), Asymmetrical Planetary Nebulae II: From Origins to Microstructures, ASP Conference Series, vol. 199, p. 79, Bibcode:2000ASPC..199...79Y, ISBN 1-58381-026-9.

Further reading