Astronomy:HD 218108
Observation data Epoch J2000.0 Equinox (celestial coordinates) | |
---|---|
Constellation | Octans |
Right ascension | 23h 08m 23.84044s[1] |
Declination | −79° 28′ 50.4748″[1] |
Apparent magnitude (V) | 6.11±0.01[2] |
Characteristics | |
Spectral type | A6 Vn[3] |
U−B color index | +0.10[4] |
B−V color index | +0.14[4] |
Astrometry | |
Radial velocity (Rv) | −7±4.4[5] km/s |
Proper motion (μ) | RA: +93.016[1] mas/yr Dec.: −35.907[1] mas/yr |
Parallax (π) | 13.1893 ± 0.0236[1] mas |
Distance | 247.3 ± 0.4 ly (75.8 ± 0.1 pc) |
Absolute magnitude (MV) | +1.78[6] |
Details | |
Mass | 1.80[7] M☉ |
Radius | 2±0.1[8] R☉ |
Luminosity | 15.24[9] L☉ |
Surface gravity (log g) | 4.17±0.07[10] cgs |
Temperature | 8,213±244[11] K |
Metallicity [Fe/H] | −0.01[12] dex |
Rotational velocity (v sin i) | 194±2[13] km/s |
Age | 249[7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
HD 218108, also known as HR 8786, is a solitary, white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.11,[2] making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from Gaia DR3, the object is estimated to be 247 light years away.[1] It appears to be approaching the Solar System with a fairly constrained radial velocity of −7 km/s.[5] Paunzen et al. (2001) lists it as a λ Boötis star with a weak magnesium line.[15]
HD 218108 has a stellar classification of A6 Vn,[3] indicating that it is an A-type main-sequence star with broad or nebulous absorption lines due to rapid rotation. In 1966, David Stanley Evans gave it a slightly cooler class of A7 Vn.[16] However, Houk and Cowley (1975) give it a classification of A3/4 V, a main sequence star with the characteristics of an A3 and A4 star.[17] Paunzen et al. (2001) gives it a class of A3 V, indicating that it is instead an ordinary A-type main-sequence star.[15]
Nevertheless, it has 1.8 times the mass of the Sun[7] and twice its radius.[8] It radiates 15.24 times the luminosity of the Sun[9] from its photosphere at an effective temperature of 8,213 K. It is estimated to be 249 million years old[7] and is currently spinning with a high projected rotational velocity of 149 km/s.[13] A solar metallicity was calculated for HD 218108.[12]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H.
- ↑ 3.0 3.1 Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series 99: 135. doi:10.1086/192182. ISSN 0067-0049. Bibcode: 1995ApJS...99..135A.
- ↑ 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J.
- ↑ 5.0 5.1 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.
- ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A.
- ↑ 7.0 7.1 7.2 7.3 David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal 804 (2): 146. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D.
- ↑ 8.0 8.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S.
- ↑ 9.0 9.1 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.
- ↑ Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555–562. ISSN 0004-6361. Bibcode: 1999A&A...352..555A.
- ↑ Paunzen, E.; Schnell, A.; Maitzen, H. M. (October 2006). "An empirical temperature calibration for the Δa photometric system II: The A-type and mid F-type stars". Astronomy & Astrophysics 458 (1): 293–296. doi:10.1051/0004-6361:20064889. ISSN 0004-6361. Bibcode: 2006A&A...458..293P.
- ↑ 12.0 12.1 Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters 38 (12): 771–782. doi:10.1134/S1063773712120031. ISSN 1063-7737. Bibcode: 2012AstL...38..771G.
- ↑ 13.0 13.1 Díaz, C. G.; González, J. F.; Levato, H.; Grosso, M. (July 2011). "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum". Astronomy & Astrophysics 531: A143. doi:10.1051/0004-6361/201016386. ISSN 0004-6361. Bibcode: 2011A&A...531A.143D.
- ↑ "HD 218108". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+218108.
- ↑ 15.0 15.1 Paunzen, E.; Duffee, B.; Heiter, U.; Kuschnig, R.; Weiss, W. W. (July 2001). "A spectroscopic survey for λ Bootis stars". Astronomy & Astrophysics 373 (2): 625–632. doi:10.1051/0004-6361:20010630. ISSN 0004-6361. Bibcode: 2001A&A...373..625P.
- ↑ Evans, D. S. (1966). "Fundamental data for Southern stars (6th list).". Royal Greenwich Observatory Bulletins 110: 185. Bibcode: 1966RGOB..110..185E.
- ↑ Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations −90° to −53°. Bibcode: 1975mcts.book.....H.
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Original source: https://en.wikipedia.org/wiki/HD 218108.
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