Astronomy:4 Sagittarii
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Sagittarius[1] |
| Right ascension | 17h 59m 47.55646s[2] |
| Declination | −23° 48′ 58.0130″[2] |
| Apparent magnitude (V) | 4.74[1] |
| Characteristics | |
| Spectral type | B9V[3] |
| U−B color index | −0.03[4] |
| B−V color index | -0.05[4] |
| Astrometry | |
| Radial velocity (Rv) | 64.33±1.32[2] km/s |
| Proper motion (μ) | RA: −0.900[2] mas/yr Dec.: −51.149[2] mas/yr |
| Parallax (π) | 7.9879 ± 0.3689[2] mas |
| Distance | 410 ± 20 ly (125 ± 6 pc) |
| Absolute magnitude (MV) | −0.77[1] |
| Details | |
| Mass | 3.23[5] M☉ |
| Radius | 5.53[5][lower-alpha 1] R☉ |
| Luminosity | 240[5] L☉ |
| Temperature | 9,661[5] K |
| Rotational velocity (v sin i) | 149[5] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
4 Sagittarii is a suspected astrometric binary[7] star system in the zodiac constellation of Sagittarius, located approximately 410 light-years away based on parallax.[2] It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.74.[1] The system is moving away from the Earth with a heliocentric radial velocity of +64 km/s.[2]
The visible component is a B-type main-sequence star with a stellar classification of B9 V.[3] It has a high rate of spin, displaying a projected rotational velocity of 149 km/s.[5] This is giving it an oblate shape with an equatorial bulge that is an estimated 14% larger than the polar radius.[8] 4 Sagittarii has 3.23 times the mass of the Sun and is radiating 240 times the Sun's luminosity from its photosphere at an effective temperature of 9,661 K.[5]
Notes
- ↑ Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:
References
- ↑ 1.0 1.1 1.2 1.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. Vizier catalog entry
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H 5050. Bibcode: 1995yCat.5050....0H.
- ↑ 4.0 4.1 Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers 42 (2): 443. Bibcode: 2014JAVSO..42..443M.Vizier catalog entry
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. Vizier catalog entry
- ↑ "4 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=4+Sgr.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E.
- ↑ van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review 20 (1). doi:10.1007/s00159-012-0051-2. Bibcode: 2012A&ARv..20...51V.
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