Astronomy:25 Aquarii
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Aquarius[1] |
| Right ascension | 21h 39m 33.26719s[2] |
| Declination | +02° 14′ 36.8193″[2] |
| Apparent magnitude (V) | +5.09[3] |
| Characteristics | |
| Evolutionary stage | red clump[4] |
| Spectral type | K0 III[5] |
| U−B color index | +0.90[3] |
| B−V color index | +1.032[6] |
| Astrometry | |
| Radial velocity (Rv) | −34.63±0.11[6] km/s |
| Proper motion (μ) | RA: −30.179[2] mas/yr Dec.: −83.636[2] mas/yr |
| Parallax (π) | 13.2155 ± 0.0892[2] mas |
| Distance | 247 ± 2 ly (75.7 ± 0.5 pc) |
| Absolute magnitude (MV) | +0.768[7] |
| Details | |
| Mass | 3.0[2] M☉ |
| Radius | 11[6] R☉ |
| Luminosity | 54[6] L☉ |
| Surface gravity (log g) | 2.67[2] cgs |
| Temperature | 4,721[6] K |
| Metallicity [Fe/H] | −0.17[6] dex |
| Rotational velocity (v sin i) | 2.5[6] km/s |
| Age | 377[2] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
25 Aquarii (abbreviated 25 Aqr) is a single[5] star in the equatorial constellation of Aquarius. 25 Aquarii is the modern Flamsteed designation; in the past it held the designation 6 Pegasi.[9] It also bears the Bayer designation of d Aquarii. It is located near the border with the modern Pegasus constellation. Although faint at an apparent visual magnitude of +5.09,[3] it is bright enough to be viewed from suburban skies. Based upon an annual parallax shift of 0.0132 arcseconds, it is located at a distance of around 247 light-years (76 parsecs) from Earth. The visual magnitude of the star is diminished by 0.09 from extinction caused by intervening gas and dust.[10]
The spectrum of this star matches a stellar classification of K0 III,[5] with the luminosity class of III indicating that this is a giant star that has evolved away from the main sequence after exhausting the supply of hydrogen at its core. It belongs to a population known as clump giants and hence is generating energy through the nuclear fusion of helium at the core.[4] The outer envelope has expanded to 11 times the radius of the Sun and it is radiating 54 times the Sun's luminosity.[6] This energy is being emitted from the stellar atmosphere at an effective temperature of 4,721 K,[6] causing it to glow with the orange hue of a K-type star.[11]
References
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R Constellation record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 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.
- ↑ 3.0 3.1 3.2 Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society 133 (4): 475–493, doi:10.1093/mnras/133.4.475, Bibcode: 1966MNRAS.133..475A.
- ↑ 4.0 4.1 Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal 539 (2): 732–741, doi:10.1086/309278, Bibcode: 2000ApJ...539..732A.
- ↑ 5.0 5.1 5.2 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.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M.
- ↑ Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S.
- ↑ "* d Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+d+Aqr.
- ↑ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy 18 (3): 220, doi:10.1177/002182868701800305, Bibcode: 1987JHA....18..209W.
- ↑ Famaey, B. et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics 430: 165–186, doi:10.1051/0004-6361:20041272, Bibcode: 2005A&A...430..165F.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16.
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