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.
| 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] |
| Distance | 1,050 ± 20 ly (320 ± 6 pc) |
| Absolute magnitude (MV) | −2.05[5] |
| Details | |
| Mass | 7±0.4[6] M☉ |
| Radius | 4.13±0.14[7] R☉ |
| Luminosity | 1,507[8] L☉ |
| Surface gravity (log g) | 3.97[9] cgs |
| Temperature | 18,100[9] K |
| Rotational velocity (v sin i) | 145±6[10] km/s |
| Age | 36.1±9.5[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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.
| 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
edit- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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:
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
