Astronomy:HD 202908
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Short description: Triple star system; Equuleus
| Observation data {{#ifeq:J2000.0 (ICRS)|J2000.0 (ICRS)|Epoch J2000.0 Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000.0 (ICRS)]] [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0 (ICRS)}} | |
|---|---|
| Constellation | Equuleus |
| A | |
| Right ascension | 21h 18m 34.85s[1] |
| Declination | +11° 34′ 08.2″[1] |
| Apparent magnitude (V) | 7.25±0.03[2] |
| B | |
| Right ascension | 21h 18m 34.80s[1] |
| Declination | +11° 34′ 08.0″[1] |
| Apparent magnitude (V) | 8.87±0.14[2] |
| Characteristics | |
| Spectral type | G0 V (combined)[3] |
| U−B color index | +0.07[4] |
| B−V color index | +0.56[4] |
| Aa | |
| Spectral type | F9 V[5] or G1 V[6] |
| Ab | |
| Spectral type | G0 V[5] or G2 V[6] |
| B | |
| Spectral type | G1.5 V[5] or G6 V[7] |
| Astrometry | |
| Radial velocity (Rv) | 6.24±0.04[8] km/s |
| Proper motion (μ) | RA: +29.213[9] mas/yr Dec.: −49.564[9] mas/yr |
| Parallax (π) | 19.3447 ± 0.0543[9] mas |
| Distance | 168.6 ± 0.5 ly (51.7 ± 0.1 pc) |
| A | |
| Absolute magnitude (MV) | +3.73±0.13[2] |
| B | |
| Absolute magnitude (MV) | +5.35±0.19[2] |
| Orbit[10] | |
| Primary | A |
| Companion | B |
| Period (P) | 28,685±173 d |
| Semi-major axis (a) | 0.5177±0.0046″ |
| Eccentricity (e) | 0.8651±0.0008 |
| Inclination (i) | 100.36±0.16° |
| Longitude of the node (Ω) | 255.03±0.17° |
| Periastron epoch (T) | 24,468,123±3 JD |
| Argument of periastron (ω) (secondary) | 171.9±0.3° |
| Semi-amplitude (K1) (primary) | 6.13±0.07 km/s |
| Semi-amplitude (K2) (secondary) | 13.95±0.09 km/s |
| Orbit[10] | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 3.9660465±0.0000015 d |
| Eccentricity (e) | 0.0033±0.0008 |
| Argument of periastron (ω) (secondary) | 271±13° |
| Semi-amplitude (K1) (primary) | 66.03±0.06 km/s |
| Semi-amplitude (K2) (secondary) | 69.69±0.06 km/s |
| Details | |
| The System | |
| Metallicity [Fe/H] | −0.04[11] dex |
| Age | 6.4±0.7[12] Gyr |
| The A Subystem | |
| Temperature | 6,100±150[13] K |
| Rotational velocity (v sin i) | 10[14] km/s |
| Aa | |
| Mass | 1.14[15] M☉ |
| Radius | 1.06±0.08[13] R☉ |
| Luminosity | 1.41+0.15−0.14[13] L☉ |
| Ab | |
| Mass | 1.08[15] M☉ |
| Radius | 0.97±0.08[13] R☉ |
| Luminosity | 1.16+0.13−0.11[13] L☉ |
| B | |
| Mass | 0.97[15] M☉ |
| Radius | 0.91±0.08[13] R☉ |
| Luminosity | 0.84+0.09−0.08[13] L☉ |
| Temperature | 5,703±1,090[2] K |
| Rotational velocity (v sin i) | 9[14] km/s |
| Other designations | |
| Database references | |
| SIMBAD | The system |
| A | |
| B | |
HD 202908, also known as HIP 105200, is a triple star located in the equatorial constellation Equuleus. It has an apparent magnitude of 7.01,[17] making it readily visible in binoculars but not to the naked eye. When resolved, the components have apparent magnitudes of 7.25 and 8.87 respectively.[2] The system is located relatively close at a distance of 169 light years based on Gaia DR3 parallax measurements[9] but it is receding with a heliocentric radial velocity of 6.24 km/s.[8]
Stellar system
| Aa | |||||||||||||||
| Period = 3.966 d | |||||||||||||||
| Ab | |||||||||||||||
| Separation = 0.5″ Period = 78 y | |||||||||||||||
| B | |||||||||||||||
Hierarchy of orbits in the HD 202908 system[5]
The system was first observed by astronomer S.W. Burnham.[18]
The "A" component is a double-lined spectroscopic binary that contains two solar-type stars with spectral classifications of F9 V and G0 V respectively.[5] The pair take roughly 4 days to orbit each other.[10]
The tertiary companion designated "B" has a class of G1.5 V, indicating that it is an ordinary G-type main-sequence star like our Sun. HD 202908 A and B both complete an eccentric orbit every 78 years.[10]
Physical characteristics
HD 202908 Aa and Ab have masses 1.08 and 1.14 times that of the Sun[15] and radii 97% and 106% of the Sun respectively.[13] The former radiates 1.41 times the luminosity of the Sun from its photosphere and the latter radiates 1.16 times the Sun's luminosity.[13] The A subsystem has an effective temperature of 6,100 K,[13] giving it a whitish-yellow hue.
The B component has 97% the mass of the Sun[15] and 91% of its radius. It radiates 84% of the Sun's luminosity[13] from its photosphere at an effective temperature of 5,703 K.[2] The system is estimated to be 6.4 billion years old.[12]
References
- ↑ 1.0 1.1 1.2 1.3 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.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 ten Brummelaar, Theo; Mason, Brian D.; McAlister, Harold A.; Roberts, Jr., Lewis C.; Turner, Nils H.; Hartkopf, William I.; Bagnuolo, Jr., William G. (May 2000). "Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory". The Astronomical Journal 119 (5): 2403–2414. doi:10.1086/301338. ISSN 0004-6256. Bibcode: 2000AJ....119.2403T.
- ↑ Abt, H. A. (March 1981). "Visual multiples. VII - MK classifications". The Astrophysical Journal Supplement Series 45: 437. doi:10.1086/190719. ISSN 0067-0049. Bibcode: 1981ApJS...45..437A.
- ↑ 4.0 4.1 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD, Bibcode: 1986EgUBV........0M
- ↑ 5.0 5.1 5.2 5.3 5.4 Fekel, F. C. Jr. (September 1981). "HD 202908 - A young, solar-type triple system". The Astrophysical Journal 248: 670. doi:10.1086/159191. ISSN 0004-637X. Bibcode: 1981ApJ...248..670F.
- ↑ 6.0 6.1 Docobo, Jose A.; Andrade, Manuel (20 November 2006). "A Methodology for the Description of Multiple Stellar Systems with Spectroscopic Subcomponents". The Astrophysical Journal 652 (1): 681–695. doi:10.1086/508053. ISSN 0004-637X. Bibcode: 2006ApJ...652..681D.
- ↑ Christy, James W.; Walker, R. L. Jr. (October 1969). "MK Classification of 142 Visual Binaries". Publications of the Astronomical Society of the Pacific 81: 643. doi:10.1086/128831. ISSN 0004-6280. Bibcode: 1969PASP...81..643C.
- ↑ 8.0 8.1 Karataş, Y.; Bilir, S.; Eker, Z.; Demircan, O. (April 2004). "Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution". Monthly Notices of the Royal Astronomical Society 349 (3): 1069–1092. doi:10.1111/j.1365-2966.2004.07588.x. ISSN 0035-8711. Bibcode: 2004MNRAS.349.1069K.
- ↑ 9.0 9.1 9.2 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.
- ↑ 10.0 10.1 10.2 10.3 Fekel, Francis C.; Scarfe, C. D.; Barlow, D. J.; Duquennoy, Antoine; McAlister, Harold A. (March 1997). "New and Improved Parameters of HD 202908=ADS 14839: A Spectroscopic-Visual Triple System". The Astronomical Journal 113: 1095. doi:10.1086/118327. ISSN 0004-6256. Bibcode: 1997AJ....113.1095F.
- ↑ Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (26 May 2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s): Improved astrophysical parameters for the Geneva-Copenhagen Survey⋆". Astronomy & Astrophysics 530: A138. doi:10.1051/0004-6361/201016276. ISSN 0004-6361. Bibcode: 2011A&A...530A.138C.
- ↑ 12.0 12.1 Holmberg, J.; Nordström, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood: III. Improved distances, ages, and kinematics". Astronomy & Astrophysics 501 (3): 941–947. doi:10.1051/0004-6361/200811191. ISSN 0004-6361. Bibcode: 2009A&A...501..941H.
- ↑ 13.00 13.01 13.02 13.03 13.04 13.05 13.06 13.07 13.08 13.09 13.10 Torres, G.; Andersen, J.; Giménez, A. (7 October 2009). "Accurate masses and radii of normal stars: modern results and applications". The Astronomy and Astrophysics Review 18 (1–2): 67–126. doi:10.1007/s00159-009-0025-1. ISSN 0935-4956. Bibcode: 2010A&ARv..18...67T.
- ↑ 14.0 14.1 Cutispoto, G.; Pastori, L.; Pasquini, L.; de Medeiros, J. R.; Tagliaferri, G.; Andersen, J. (March 2002). "Fast-rotating nearby solar-type stars". Astronomy & Astrophysics 384 (2): 491–503. doi:10.1051/0004-6361:20020040. ISSN 0004-6361. Bibcode: 2002A&A...384..491C.
- ↑ 15.0 15.1 15.2 15.3 15.4 Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun". The Astronomical Journal 147 (4): 86. doi:10.1088/0004-6256/147/4/86. ISSN 0004-6256. Bibcode: 2014AJ....147...86T.
- ↑ "HD 202908". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+202908.
- ↑ 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.
- ↑ Burnham, S. W. (12 December 1873). "A Third Catalogue of 76 New Double Stars, discovered with a 6-inch Alvan Clark Refractor". Monthly Notices of the Royal Astronomical Society 34 (2): 59–71. doi:10.1093/mnras/34.2.59. ISSN 0035-8711. Bibcode: 1873MNRAS..34...59B.
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