RT Virginis

RT Virginis

A visual band light curve for RT Virginis, plotted from ASAS data [1]
Observation data Epoch J2000       Equinox J2000
Constellation	Virgo
Right ascension	13h 02m 37.981s [2]
Declination	+05° 11′ 08.36″ [2]
Apparent magnitude  (V)	7.7 to 9.7 [3]
Characteristics
Evolutionary stage	AGB [4]
Spectral type	M8III [5]
B−V color index	1.352±0.031 [6]
Variable type	SRb [7]
Astrometry
Radial velocity (Rv)	17.3±0.2 [4] km/s
Proper motion (μ)	RA: +37.037 mas/yr [2] Dec.: −17.714 mas/yr [2]
Parallax (π)	4.417±0.134  mas [3]
Distance	740 ± 20  ly (226 ± 7  pc)
Absolute magnitude  (MV)	2.94 [6]
Details
Mass	1.5 [8]   M☉
Radius	390 [9]   R☉
Luminosity (bolometric)	5,012+1,154 −938 [4]   L☉
Surface gravity (log g)	+0.21 [10]   cgs
Temperature	2,902 [10]   K
Metallicity [Fe/H]	−0.33 [10]   dex
Other designations
RT Vir, BD+05°2708, HD 113285, HIP 63642, SAO 119734, PPM 159423 [11]
Database references
SIMBAD	data

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, ^[3] 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. ^[3] It is receding from the Sun with a radial velocity of 17 km/s. ^[4]

The long period variability of this star was discovered by W. P. Fleming in 1896, based on photographic plates taken between 1886 and 1895. ^[12] It was listed with its variable star designation, RT Virginis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. ^[13] A. H. Joy in 1942 categorized it as an irregular variable with a stellar classification of M8III. ^[5] In 1969 it was classified as a semiregular variable star of the SRb type. ^[14] 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. ^[9]

Water vapor emission in the vicinity of the star was detected in the microwave band by D. F. Dickinson in 1973. ^[15] This is originating from strong maser emission in a circumstellar gas-dust shell. ^[16] The flux density of these water masers is over 100  Jy . ^[9] The star is losing mass at a rate of 3×10⁻⁶ M_☉·yr⁻¹; ^[8] 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. ^[17] This outflow appears clumpy and asymmetrical ^[18] with a strong temporal variation. ^[16]

References

1. ASAS All Star Catalogue, The All Sky Automated Survey, retrieved 16 September 2022.
2. 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. 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. 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. 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. 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. 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. 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. 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. 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), Kastner, J. H.; et al. (eds.), "Is the Outflow from RT Vir Bipolar or Rotating?", Asymmetrical Planetary Nebulae II: From Origins to Microstructures, ASP Conference Series, 199: 79, Bibcode:2000ASPC..199...79Y, ISBN   1-58381-026-9.

Further reading

• Imai, Hiroshi; et al. (June 2003), "The Three-dimensional Kinematics of Water Masers around the Semiregular Variable RT Virginis", The Astrophysical Journal, 590 (1): 460–472, arXiv: astro-ph/0302389 , Bibcode:2003ApJ...590..460I, doi:10.1086/374887, S2CID   18661079.
• Etoka, S.; et al. (November 2001), "Monitoring of long term behaviour of OH masers in semiregular variables: R Crt, W Hya and RT Vir", Astronomy and Astrophysics, 378 (2): 522–538, Bibcode:2001A&A...378..522E, doi: 10.1051/0004-6361:20011184 .
• Lekht, E. E.; et al. (March 1999), "Dynamics of the circumstellar envelope of RT Virginis on the basis of the H₂O maser monitoring", Astronomy and Astrophysics, 343: 241–250, Bibcode:1999A&A...343..241L.
• Richards, A. M. S.; et al. (1999), Le Bertre, T.; et al. (eds.), "A MERLIN movie of mass-loss from RT Vir", Asymptotic Giant Branch Stars, IAU Symposium, 191: 315, Bibcode:1999IAUS..191..315R, ISBN   1-886733-90-2.