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HD 196775
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Delphinus
Right ascension 20h 39m 04.9681s [1]
Declination +15° 50′ 17.5112″ [1]
Apparent magnitude (V) 5.98 [2]
Characteristics
Spectral type B3 V [3]
U−B color index −0.71 [2]
B−V color index −0.16 [2]
Astrometry
Radial velocity (Rv)−4.6±1 [4] km/s
Proper motion (μ) RA: −0.868  mas/ yr [1]
Dec.: −15.290  mas/ yr [1]
Parallax (π)3.1211 ± 0.0617  mas [1]
Distance1,050 ± 20  ly
(320 ± 6  pc)
Absolute magnitude (MV)−2.05 [5]
Details
Mass7±0.4 [6]  M☉
Radius4.13±0.14 [7]  R☉
Luminosity1,507 [8]  L☉
Surface gravity (log g)3.97 [9]  cgs
Temperature18,100 [9]  K
Rotational velocity (v sin i)145±6 [10] km/s
Age36.1±9.5 [6]  Myr
Other designations
AG+15°2265, BD+15°4220, GC 28785, HD 196775, HIP 101909, HR 7899, SAO 106347, WDS J20391+1550A
Database references
SIMBAD data

HD 196775 (HR 7899) is a solitary star in the equatorial constellation Delphinus. It has an apparent magnitude of 5.98, allowing it to be faintly seen with the naked eye. The object is relatively far at a distance of 1,050 light years but is approaching the Solar System with a heliocentric radial velocity of −4.6  km/s. HD 196775 has a high peculiar velocity of 21.8+1.9
−4.1  km/s [6] compared to neighboring stars, indicating that it may be a runaway star.

HD 196775 has a general stellar classification of B3 V, [3] indicating that it is an ordinary B-type main-sequence star. However, once source gives it a class of B4 Vn, [11] making it slightly cooler and having broad absorption lines due to rapid rotation. It has an angular diameter of 0.12  mas, [12] yielding a radius 4.13 times that of the Sun. [7] At present it has 7 times the mass of the Sun [6] and shines at 1507  L☉ [8] from its photosphere at an effective temperature of 18,100  K, [9] giving it a whitish blue hue. HD 196775 is 36 million years old [6] and is spinning rapidly with a projected rotational velocity of 145  km/s. [10]

HD 196775 has four faint optical companions whose parameters are listed below.

HD 196775's Companions [13]
Companion mv PA (°) Year Sep. ( ″)
B 12.40 154 2006 5.2
C 11.31 122 2012 39.9
D 14.40 146 2012 28.8
E 14.40 33 2012 23.3

References

  1. ^ a b c d 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.
  2. ^ a b c Oja, T. (September 1984). "UBV photometry of stars whose positions are accurately known". Astronomy and Astrophysics Supplement Series. 57: 357–359. Bibcode: 1984A&AS...57..357O. ISSN  0365-0138.
  3. ^ a b Cucchiaro, A.; Jaschek, M.; Jaschek, C.; Macau-Hercot, D. (May 1980). "Spectral classification from the ultraviolet line features of S2/68 spectra". Astronomy and Astrophysics Supplement Series. 40: 207–213. Bibcode: 1980A&AS...40..207C. ISSN  0365-0138.
  4. ^ Gontcharov, G. A. (November 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. ISSN  1063-7737. S2CID  119231169.
  5. ^ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. ISSN  1063-7737. S2CID  255204555.
  6. ^ a b c d e Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (October 12, 2010). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1). Oxford University Press (OUP): 190–200. arXiv: 1007.4883. Bibcode: 2011MNRAS.410..190T. doi: 10.1111/j.1365-2966.2010.17434.x. ISSN  0035-8711.
  7. ^ a b Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. Vol. 1 (3 ed.). Birkhäuser. ISBN  3-540-29692-1.. The radius (R*) is given by:
  8. ^ a b McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv: 1208.2037. Bibcode: 2012MNRAS.427..343M. doi: 10.1111/j.1365-2966.2012.21873.x. ISSN  0035-8711.
  9. ^ a b c Lyubimkov, L. S.; Rostopchin, S. I.; Lambert, D. L. (21 June 2004). "Surface abundances of light elements for a large sample of early B-type stars – III. An analysis of helium lines in spectra of 102 stars". Monthly Notices of the Royal Astronomical Society. 351 (2): 745–767. Bibcode: 2004MNRAS.351..745L. doi: 10.1111/j.1365-2966.2004.07825.x. eISSN  1365-2966. ISSN  0035-8711.
  10. ^ a b Bragança, G. A.; Daflon, S.; Cunha, K.; Bensby, T.; Oey, M. S.; Walth, G. (October 1, 2012). "Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk". The Astronomical Journal. 144 (5). American Astronomical Society: 130. arXiv: 1208.1674. Bibcode: 2012AJ....144..130B. doi: 10.1088/0004-6256/144/5/130. ISSN  0004-6256.
  11. ^ de Vaucouleurs, A. (August 1, 1957). "Spectral Types and Luminosities of B, A and F Southern Stars". Monthly Notices of the Royal Astronomical Society. 117 (4). Oxford University Press (OUP): 449–462. Bibcode: 1957MNRAS.117..449D. doi: 10.1093/mnras/117.4.449. ISSN  0035-8711.
  12. ^ Bourgés, L.; Lafrasse, S.; Mella, G.; Chesneau, O.; Bouquin, J. L.; Duvert, G.; Chelli, A.; Delfosse, X. (May 2014). "The JMMC Stellar Diameters Catalog v2 (JSDC): A New Release Based on SearchCal Improvements". Astronomical Data Analysis Software and Systems Xxiii. 485: 223. Bibcode: 2014ASPC..485..223B.
  13. ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode: 2001AJ....122.3466M. doi: 10.1086/323920. ISSN  0004-6256.
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