V4381 Sagittarii is a variable star in the constellation Sagittarius. A white supergiant of spectral type A2/A3Iab, it is an Alpha Cygni variable that varies between apparent photographic magnitudes 6.57 and 6.62. Its visual apparent magnitude is about 6.54.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 08m 38.58558s[2] |
| Declination | −21° 26′ 58.4136″[2] |
| Apparent magnitude (V) | 6.538[3] (6.57p - 6.62p[4]) |
| Characteristics | |
| Evolutionary stage | Supergiant[3] |
| Spectral type | A2 Iab[3] |
| U−B color index | +0.279[3] |
| B−V color index | +0.856[3] |
| Variable type | α Cyg[4] |
| Astrometry | |
| Radial velocity (Rv) | −16[5] km/s |
| Proper motion (μ) | RA: −1.65[2] mas/yr Dec.: −1.05[2] mas/yr |
| Parallax (π) | 2.25 ± 0.55 mas[2] |
| Distance | approx. 1,400 ly (approx. 400 pc) |
| Absolute magnitude (MV) | −6.6[6] |
| Details | |
| Mass | 7.00[7] M☉ |
| Luminosity | 39,000[3] L☉ |
| Surface gravity (log g) | 1.50[3] cgs |
| Temperature | 9,000[3] K |
| Rotational velocity (v sin i) | 18[3] km/s |
| Age | 43.3[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
V4381 Sagittarii is associated with a small reflection and emission nebula, although it is not actually seen within the nebulosity. The nebula is catalogued as GN 18.05.6.[8] It was first listed as VdB 113 and described as possibly associated with a loose open cluster.[9] That name has since been used for the cluster itself, which is much more distant than the distance of V4381 Sagittarii derived from its Hipparcos parallax.[10] The whole cluster is less than a quarter of a degree across, with dozens of members from 8th magnitude downwards. V4381 Sagittarii is listed as a probable member, while the nearby bright stars HD 165516 and WR 111 are considered unlikely to be members.[11]
Distance estimations
editThe distance to V4381 remains poorly determined as of 2021. The 2018 research based on radio interferometry has measured 2.2±0.6 milliarcseconds parallax,[12] while Gaia Early Data Release 3, based on optical astrometry, have resulted in measured parallax 0.6273±0.0372.[13]
References
edit- ^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
- ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
- ^ a b c d e f g h i Firnstein, M.; Przybilla, N. (2012). "Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters". Astronomy & Astrophysics. 543: A80. arXiv:1207.0308. Bibcode:2012A&A...543A..80F. doi:10.1051/0004-6361/201219034. S2CID 54725386.
- ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal. 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559.
- ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
- ^ Magakian, T. Yu. (2003). "Merged catalogue of reflection nebulae". Astronomy and Astrophysics. 399: 141–145. Bibcode:2003A&A...399..141M. doi:10.1051/0004-6361:20021743.
- ^ Van Den Bergh, S. (1966). "A study of reflection nebulae". Astronomical Journal. 71: 990. Bibcode:1966AJ.....71..990V. doi:10.1086/109995.
- ^ Piskunov, A. E.; Schilbach, E.; Kharchenko, N. V.; Röser, S.; Scholz, R.-D. (2008). "Tidal radii and masses of open clusters". Astronomy and Astrophysics. 477 (1): 165–172. Bibcode:2008A&A...477..165P. doi:10.1051/0004-6361:20078525.
- ^ Kharchenko, N. V.; Piskunov, A. E.; Schilbach, E.; Röser, S.; Scholz, R.-D. (2013). "Global survey of star clusters in the Milky Way. II. The catalogue of basic parameters". Astronomy & Astrophysics. 558: A53. arXiv:1308.5822. Bibcode:2013A&A...558A..53K. doi:10.1051/0004-6361/201322302. S2CID 118548517.
- ^ Xu, Shuangjing; Zhang, Bo; Reid, Mark J.; Menten, Karl M.; Zheng, Xingwu; Wang, Guangli (2018), "The Parallax of the Red Hypergiant VX SGR with Accurate Tropospheric Delay Calibration", The Astrophysical Journal, 859 (1): 14, arXiv:1804.00894, Bibcode:2018ApJ...859...14X, doi:10.3847/1538-4357/aabba6, S2CID 55572194
- ^ 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.
External links
edit- Image of VdB 113 V4381 Sgr is the upper of the two bright white stars.
- WEBDA page for vdBergh 113 V4381 Sgr is the brightest star
- Drawing of VdB 113 Archived 2016-11-11 at the Wayback Machine