Astronomy:HD 196775

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Short description: Star in the constellation Delphinus
HD 196775
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
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[1] mas/yr
Dec.: −15.290[1] mas/yr
Parallax (π)3.1211 ± 0.0617[1] mas
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
Database references
SIMBADdata

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 solar luminosity[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. ↑ 1.0 1.1 1.2 1.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Oja, T. (September 1984). "UBV photometry of stars whose positions are accurately known.". Astronomy and Astrophysics Supplement Series 57: 357–359. ISSN 0365-0138. Bibcode: 1984A&AS...57..357O. 
  3. ↑ 3.0 3.1 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. ISSN 0365-0138. Bibcode: 1980A&AS...40..207C. 
  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. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  5. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation" (in en). Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 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 (Oxford University Press (OUP)) 410 (1): 190–200. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. Bibcode: 2011MNRAS.410..190T. 
  7. ↑ 7.0 7.1 Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1. https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. . The radius (R*) is given by:
    [math]\displaystyle{ \begin{align} 2\cdot R_* & = \frac{(320\cdot 0.12\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 8.26\cdot R_{\bigodot} \end{align} }[/math]
  8. ↑ 8.0 8.1 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. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711. Bibcode: 2012MNRAS.427..343M. 
  9. ↑ 9.0 9.1 9.2 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. doi:10.1111/j.1365-2966.2004.07825.x. ISSN 0035-8711. Bibcode: 2004MNRAS.351..745L. 
  10. ↑ 10.0 10.1 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 (American Astronomical Society) 144 (5): 130. doi:10.1088/0004-6256/144/5/130. ISSN 0004-6256. Bibcode: 2012AJ....144..130B. 
  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 (Oxford University Press (OUP)) 117 (4): 449–462. doi:10.1093/mnras/117.4.449. ISSN 0035-8711. Bibcode: 1957MNRAS.117..449D. 
  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. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 



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