Astronomy:Psi2 Draconis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Draco |
| Right ascension | 17h 55m 11.15296s[1] |
| Declination | +72° 00′ 18.4470″[1] |
| Apparent magnitude (V) | 5.45[2] |
| Characteristics | |
| Spectral type | F2 III+[3] or F3 II-III[4] |
| U−B color index | +0.15[2] |
| B−V color index | +0.30[2] |
| Astrometry | |
| Radial velocity (Rv) | −2.0[5] km/s |
| Proper motion (μ) | RA: +8.545[1] mas/yr Dec.: −2.133[1] mas/yr |
| Parallax (π) | 3.4888 ± 0.0832[1] mas |
| Distance | 930 ± 20 ly (287 ± 7 pc) |
| Absolute magnitude (MV) | −2.12±0.14[6] |
| Details[5] | |
| Mass | 2.02 M☉ |
| Radius | 14.70+0.64 −0.34[1] R☉ |
| Luminosity | 448±13[1] L☉ |
| Surface gravity (log g) | 2.32 cgs |
| Temperature | 6925+83 −152[1] K |
| Metallicity [Fe/H] | −1.29 dex |
| Rotational velocity (v sin i) | 50[7] km/s |
| Age | 800 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Psi2 Draconis is a solitary[9] giant star in the northern circumpolar constellation of Draco, also designated 34 Draconis. It lies just over a degree east of the brighter Psi1 Draconis.[10] Psi2 Draconis has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.45.[2] It is located at a distance of 940 light-years (287 parsecs) from the Sun based on parallax, but is drifting closer with a radial velocity of −2 km/s.[5]
According to R. O. Gray and associates (2001), the stellar classification of Psi2 Draconis is F2III+;[3] a star that has used up its core hydrogen, cooled, and expanded away from the main sequence. A. P. Cowley and W. P. Bidelman (1979) found a similar class of F3 II-III, with the comment that the spectrum showed "many weak lines".[4] Based on the abundance of iron, the metallicity of this star is much lower than in the Sun. It is about 800[5] million years old and is spinning with a projected rotational velocity of 50 km/s.[7] The star has double[5] the mass of the Sun but has expanded to 15[1] times the Sun's radius. It is radiating 448[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 6,925 K.[1]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Oja, T. (April 1983), "UBV photometry of FK4 and FK4 supplement stars", Astronomy and Astrophysics Supplement Series 52: 1311–34, Bibcode: 1983A&AS...52..131O.
- ↑ 3.0 3.1 Gray, R. O. et al. (April 2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal 121 (4): 2148–2158, doi:10.1086/319956, Bibcode: 2001AJ....121.2148G.
- ↑ 4.0 4.1 "MK spectral types for some F and G stars", Publications of the Astronomical Society of the Pacific 91: 83–86, February 1979, doi:10.1086/130446, Bibcode: 1979PASP...91...83C.
- ↑ 5.0 5.1 5.2 5.3 5.4 Casagrande, L. et al. (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): 21, doi:10.1051/0004-6361/201016276, Bibcode: 2011A&A...530A.138C.
- ↑ Holmberg, J. et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics 501 (3): 941–947, doi:10.1051/0004-6361/200811191, Bibcode: 2009A&A...501..941H.
- ↑ 7.0 7.1 Danziger, I. J.; Faber, S. M. (May 1972), "Rotation of evolving A and F stars", Astronomy and Astrophysics 18: 428, Bibcode: 1972A&A....18..428D.
- ↑ "psi02 Dra -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=psi02+Dra, retrieved 2017-05-29.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas, 3, Sky Publishing Corporation and the European Space Agency, p. 1054, ISBN 0-933346-84-0.
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