Astronomy:HD 16955

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Short description: Multiple star in the constellation Aries
HD 16955
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aries[1]
Right ascension  02h 43m 51.24421s[2]
Declination +25° 38′ 18.0493″[2]
Apparent magnitude (V) 6.376[3]
Characteristics
Evolutionary stage main sequence[4]
Spectral type A3 V[5]
B−V color index 0.089±0.002[1]
Astrometry
Radial velocity (Rv)−10.3±3.1[6] km/s
Proper motion (μ) RA: −4.98±0.70[2] mas/yr
Dec.: +6.04±0.52[2] mas/yr
Parallax (π)9.59 ± 0.76[2] mas
Distance340 ± 30 ly
(104 ± 8 pc)
Absolute magnitude (MV)+1.18±0.13[3]
Details
HD 16955 A
Mass2.25±0.08[7] M☉
Radius2.4[8] R☉
Luminosity26.9+3.3
−2.9[3] L☉
Surface gravity (log g)3.97[9] cgs
Temperature8,450±164[3] K
Rotational velocity (v sin i)175[10] km/s
Age1.6[9] Gyr
Other designations
BD+25°441, HD 16955, HIP 12744, HR 803, SAO 75539[11]
Database references
SIMBADdata

HD 16955, also known as HR 803, is a double or multiple star. With an apparent visual magnitude of 6.376,[3] 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.[6]

This is an A-type main-sequence star with a stellar classification of A3 V.[5] Hauck et al. (1995) identified this as a Lambda Boötis star with a circumstellar shell,[12] but this now appears to be unlikely.[3] It has 2.25[7] times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 175 km/s.[10] The star is radiating about 27[3] times the Sun's luminosity from its photosphere at an effective temperature of roughly 8,450 K.[3]

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°.[13] 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.[14] 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.[13]

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 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. doi:10.1093/mnras/stw3141. Bibcode: 2017MNRAS.466..546M. 
  4. ↑ Lambert, David L.; Reddy, Bacham E. (2004). "Lithium abundances of the local thin disc stars". Monthly Notices of the Royal Astronomical Society 349 (2): 757–767. doi:10.1111/j.1365-2966.2004.07557.x. Bibcode: 2004MNRAS.349..757L. 
  5. ↑ 5.0 5.1 Cowley, A. et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal 74: 375–406. doi:10.1086/110819. Bibcode: 1969AJ.....74..375C. 
  6. ↑ 6.0 6.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  8. ↑ Schofield, Mathew et al. (2019). "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite". The Astrophysical Journal Supplement Series 241 (1): 12. doi:10.3847/1538-4365/ab04f5. Bibcode: 2019ApJS..241...12S. 
  9. ↑ 9.0 9.1 Aguilera-Gómez, Claudia et al. (2018). "Lithium abundance patterns of late-F stars: An in-depth analysis of the lithium desert". Astronomy and Astrophysics 614: A55. doi:10.1051/0004-6361/201732209. Bibcode: 2018A&A...614A..55A. 
  10. ↑ 10.0 10.1 Royer, F. et al. (February 2007). "Rotational velocities of A-type stars. III. Velocity distributions". Astronomy and Astrophysics 463 (2): 671–682. doi:10.1051/0004-6361:20065224. Bibcode: 2007A&A...463..671R. 
  11. ↑ "HD 16955". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+16955. 
  12. ↑ 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. 
  13. ↑ 13.0 13.1 Mason, B. D. et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M. 
  14. ↑ Schröder, C.; Schmitt, J. H. M. M. (November 2007). "X-ray emission from A-type stars". Astronomy and Astrophysics 475 (2): 677−684. doi:10.1051/0004-6361:20077429. Bibcode: 2007A&A...475..677S. 



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