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SW Virginis
View on Wikipedia| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Virgo[2] |
| Right ascension | 13h 14m 04.383s[3] |
| Declination | −02° 48′ 25.13″[3] |
| Apparent magnitude (V) | 6.65 to 7.95[4] |
| Characteristics | |
| Evolutionary stage | AGB[5] |
| Spectral type | M7III:[6] |
| U−B color index | 0.72[7] |
| B−V color index | 1.67[7] |
| Variable type | SRb[8] |
| Astrometry | |
| Radial velocity (Rv) | −15.78±3.51[9] km/s |
| Proper motion (μ) | RA: −35.131 mas/yr[3] Dec.: −2.769 mas/yr[3] |
| Parallax (π) | 5.5526±0.4437 mas[3] |
| Distance | 590 ± 50 ly (180 ± 10 pc) |
| Details | |
| Mass | 1–1.25[10] M☉ |
| Radius | 244±42[11] R☉ |
| Luminosity | 4,500±1,100[10] L☉ |
| Surface gravity (log g) | −0.3±0.1[10] cgs |
| Temperature | 3,060±130[11] K |
| Metallicity [Fe/H] | ~0.0[10] dex |
| Other designations | |
| SW Vir, BD−02°3653, HD 114961, HIP 64569, SAO 139236, PPM 179000[12] | |
| Database references | |
| SIMBAD | data |
SW Virginis is a variable star in the equatorial constellation of Virgo, abbreviated SW Vir. It ranges in brightness from an apparent visual magnitude of 6.65 down to 7.95,[4] with a pulsation period of 153.8 days.[13] The star is located at a distance of approximately 590 light years from the Sun based on parallax measurements,[3] but is drifting closer with a radial velocity of −16 km/s.[9] SW Vir is located near the ecliptic and is subject to lunar occultation, which has allowed its angular diameter to be directly measured.[14][15][11]
The variability of this star was discovered by W. P. Fleming and announced in 1901, when it was known as BD−02°3653.[16] It was given its variable star designation, SW Virginis, in 1912.[17] The star was initially catalogued as an irregular variable but later was classed as a semi-regular variable of type SRb.[4] The stellar classification of M7III: indicates this is an evolved red giant, with the trailing colon indicating some uncertainty about the classification.[6] In 2003, the isotope 99Tc was detected in the atmosphere of SW Vir. The short lifespan of this element is an indicator that the star is undergoing the third dredge-up during the thermally pulsating phase of the asymptotic giant branch (AGB).[5]
This is an oxygen-rich non-Mira AGB star[18][19] that is shedding mass at a rate of 4×10−7 M☉·yr−1.[20] An infrared excess indicates the star has a circumstellar dust envelope consisting of grains of matter that have condensed out of expelled gas.[21] This dust shell displays an asymmetric appearance.[18][19] Polarization of light from these dust grains indicate a typical size of less than a μm.[19] The shell's thermal (non-maser) mm-wave spectral line emission from carbon monoxide was detected in 1986, and showed that the circumstellar envelope is expanding at 8.6 km/sec.[22] The spectrum of molecular water has been detected in the star's extended outer atmosphere – out to twice the stellar radius – with a column density of 1019–1020 cm–2.[23]
References
[edit]- ^ Percy, John R.; Wilson, Joseph B.; Henry, Gregory W. (August 2001). "Long-Term VRI Photometry of Small-Amplitude Red Variables. I. Light Curves and Periods". Publications of the Astronomical Society of the Pacific. 113 (786): 983–996. Bibcode:2001PASP..113..983P. doi:10.1086/322153.
- ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- ^ a b c d e 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.
- ^ a b c Armour, J. E.; et al. (October 1990), "A Period Analysis of the Semi-Regular Variable SW Vir", Information Bulletin on Variable Stars, 3521: 1, Bibcode:1990IBVS.3521....1A.
- ^ a b Lebzelter, T.; Hron, J. (December 2003), "Technetium and the third dredge up in AGB stars. I. Field stars", Astronomy and Astrophysics, 411 (3): 533–542, arXiv:astro-ph/0310018, Bibcode:2003A&A...411..533L, doi:10.1051/0004-6361:20031458.
- ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- ^ a b Ducati, J. R. (2002), "Catalogue of Stellar Photometry in Johnson's 11-color system.", VizieR Online Data Catalog, CDS/ADC Collection of Electronic Catalogues, 2237, Bibcode:2002yCat.2237....0D.
- ^ 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.
- ^ a b Famaey, B.; et al. (May 2009), "Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations", Astronomy and Astrophysics, 498 (2): 627–640, arXiv:0901.0934, Bibcode:2009A&A...498..627F, doi:10.1051/0004-6361/200810698, S2CID 18739721.
- ^ a b c d Hadjara, M.; Cruzalèbes, P.; Nitschelm, C.; Chen, X.; Michael, E. A.; Moreno, E. (2019-10-01). "A CO-multilayer outer atmosphere for eight evolved stars revealed with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 489 (2): 2595–2614. arXiv:1909.03997. Bibcode:2019MNRAS.489.2595H. doi:10.1093/mnras/stz2240. ISSN 0035-8711.
- ^ a b c Mondal, Soumen; Chandrasekhar, T. (2005-08-01). "Angular Diameter Measurements of Evolved Variables by Lunar Occultations at 2.2 and 3.8 Microns". The Astronomical Journal. 130 (2): 842–852. arXiv:astro-ph/0504326. Bibcode:2005AJ....130..842M. doi:10.1086/430457. ISSN 0004-6256.
- ^ "SW Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-10-03.
- ^ Percy, John R.; et al. (May 2008), "Further Studies of the Photometric Variability of Bright Pulsating Red Giants", Publications of the Astronomical Society of the Pacific, 120 (867): 523, Bibcode:2008PASP..120..523P, doi:10.1086/588612.
- ^ Schmidtke, P. C.; et al. (April 1986), "Angular diameters by the lunar occultation technique. VII", Astronomical Journal, 91: 961–970, Bibcode:1986AJ.....91..961S, doi:10.1086/114072.
- ^ Bogdanov, M. B.; Cherepashchuk, A. M. (August 1990), "Estimation of Brightness Distributions Over Stellar Disks from an Analysis of Infrared Observations of Lunar Occultations - the Red Giants SW-Virginis and FY-Librae", Soviet Astronomy, 34 (4): 393, Bibcode:1990SvA....34..393B.
- ^ Pickering, E. C.; et al. (April 1901), "Sixty-four new variable stars", Astrophysical Journal, 13: 226–230, Bibcode:1901ApJ....13..226P, doi:10.1086/140808.
- ^ Dunér, Nils Christofer; Hartwig, Ernst; Müller, G. (June 1912). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten. 191 (19): 341–358. Bibcode:1912AN....191..341.. doi:10.1002/asna.19121911902.
- ^ a b Guha Niyogi, Suklima; et al. (October 2011), "Investigating spatial distribution of dust around SW Vir", Astronomical Review, 6 (8): 27–38, Bibcode:2011AstRv...6h..27G, doi:10.1080/21672857.2011.11519689.
- ^ a b c Khouri, T.; et al. (March 2020), "Inner dusty envelope of the AGB stars W Hydrae, SW Virginis, and R Crateris using SPHERE/ZIMPOL", Astronomy & Astrophysics, 635, id. A200, arXiv:2003.06195, Bibcode:2020A&A...635A.200K, doi:10.1051/0004-6361/201834618.
- ^ Olofsson, H.; et al. (September 2002), "Mass loss rates of a sample of irregular and semiregular M-type AGB-variables", Astronomy and Astrophysics, 391 (3): 1053–1067, arXiv:astro-ph/0206172, Bibcode:2002A&A...391.1053O, doi:10.1051/0004-6361:20020841.
- ^ 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.
- ^ Zuckerman, B.; Dyck, H. M. (May 1986). "Carbon Monoxide Emission from Stars in the IRAS and Revised AFGL Catalogs. I. Mass Loss Driven by Radiation Pressure on Dust Grains". Astrophysical Journal. 304: 394–400. Bibcode:1986ApJ...304..394Z. doi:10.1086/164173.
- ^ Ohnaka, K.; et al. (January 2019), "Spatially resolving the atmosphere of the non-Mira-type AGB star SW Vir in near-infrared molecular and atomic lines with VLTI/AMBER", Astronomy & Astrophysics, 621, id. A6, arXiv:1811.05989, Bibcode:2019A&A...621A...6O, doi:10.1051/0004-6361/201834171.
