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]
Distance740 ± 20 ly
(226 ± 7 pc)
Absolute magnitude (MV)2.94[6]
Details
Mass1.5[8] M☉
Radius390[9] R☉
Luminosity (bolometric)5,012+1,154
−938[4] L☉
Surface gravity (log g)+0.21[10] cgs
Temperature2,902[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
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,[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] 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.[13] 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.[14] This is originating from strong maser emission in a circumstellar gas-dust shell.[15] 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.[16] This outflow appears clumpy and asymmetrical[17] with a strong temporal variation.[15]

  1. ^ Cite error: The named reference ASASServer was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Zhang_et_al_2017 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Brand_et_al_2020 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Joy_1942 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Yates_et_al_2002 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Imai_et_al_1997 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference miles2016 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Pickering_Fleming_1896 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference van_der_Veen_et_al_1995 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Dickinson_1976 was invoked but never defined (see the help page).
  15. ^ a b Cite error: The named reference Mendoza-Torres_et_al_1997 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Sacuto_et_al_2013 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Yates_et_al_2000 was invoked but never defined (see the help page).