Summary
HD 16955, also known as HR 803, is a double or multiple star. With an apparent visual magnitude of 6.376,[2] is lies at or below the nominal limit for visibility with a typical naked eye. The measured annual parallax shift is 9.59 milliarcseconds, which yields an estimated distance of around 340 light years. The star is moving closer to the Sun with a heliocentric radial velocity of around -10 km/s.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 02h 43m 51.24421s[1] |
| Declination | +25° 38′ 18.0493″[1] |
| Apparent magnitude (V) | 6.376[2] |
| Characteristics | |
| Spectral type | A3 V[3] |
| B−V color index | 0.089±0.002[4] |
| Astrometry | |
| Radial velocity (Rv) | −10.3±3.1[5] km/s |
| Proper motion (μ) | RA: −4.98±0.70[1] mas/yr Dec.: +6.04±0.52[1] mas/yr |
| Parallax (π) | 9.59 ± 0.76 mas[1] |
| Distance | 340 ± 30 ly (104 ± 8 pc) |
| Absolute magnitude (MV) | +1.18±0.13[2] |
| Details | |
| HD 16955 A | |
| Mass | 2.25±0.08[6] M☉ |
| Luminosity | 26.9+3.3 −2.9[2] L☉ |
| Temperature | 8,450±164[2] K |
| Rotational velocity (v sin i) | 175[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an A-type main-sequence star with a stellar classification of A3 V.[3] Hauck et al. (1995) identified this as a Lambda Boötis star with a circumstellar shell,[9] but this now appears to be unlikely.[2] It has 2.25[6] times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 175 km/s.[7] The star is radiating about 27[2] times the Sun's luminosity from its photosphere at an effective temperature of roughly 8,450 K.[2]
HD 16955 has a magnitude 10.36 companion, component B, which is located, as of 2015, at an angular separation of 3.0 arcseconds along a position angle of 19°.[10] This is the likely source for the detected X-ray emission with a luminosity of 262.5×1020 W coming from these coordinates, since A-type stars are not expected to emit X-rays.[11] Component C is a more distant magnitude 12.94 companion located at a separation of 51.10 arcseconds along a position angle of 92°, as of 2015.[10]
References edit
- ^ 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 Murphy, Simon J.; Paunzen, Ernst (April 2017), "Gaia's view of the λ Boo star puzzle", Monthly Notices of the Royal Astronomical Society, 466 (1): 546−555, arXiv:1612.01528, Bibcode:2017MNRAS.466..546M, doi:10.1093/mnras/stw3141, S2CID 119328659
- ^ a b Cowley, A.; et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
- ^ 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.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 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.
- ^ a b Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
- ^ a b Royer, F.; et al. (February 2007). "Rotational velocities of A-type stars. III. Velocity distributions". Astronomy and Astrophysics. 463 (2): 671–682. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224. S2CID 18475298.
- ^ "HD 16955". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-26.
- ^ Hauck, B.; et al. (March 1995), "Three other λ Bootis stars with a shell", Astronomy and Astrophysics Supplement, 109: 505−510, Bibcode:1995A&AS..109..505H
- ^ a b Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
- ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677−684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.