Astronomy:25 Aquarii

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Short description: Single, K-type star in the constellation Aquarius

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25 Aquarii
Location of 25 Aquarii (circled)
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
Distance247 ± 2 ly
(75.7 ± 0.5 pc)
Absolute magnitude (MV)+0.768[7]
Details
Mass3.0[2] M
Radius11[6] R
Luminosity54[6] L
Surface gravity (log g)2.67[2] cgs
Temperature4,721[6] K
Metallicity [Fe/H]−0.17[6] dex
Rotational velocity (v sin i)2.5[6] km/s
Age377[2] Myr
Other designations
d  Aquarii, 25 Aqr, 6 Pegasi, BD+01 4517, FK5 3729, HD 206067, HIP 106944, HR 8277, SAO 126965[8]
Database references
SIMBADdata

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

  1. 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. Bibcode1987PASP...99..695R  Constellation record for this object at VizieR.
  2. 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. 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, Bibcode1966MNRAS.133..475A. 
  4. 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, Bibcode2000ApJ...539..732A. 
  5. 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, Bibcode2008MNRAS.389..869E. 
  6. 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, Bibcode2008AJ....135..209M. 
  7. 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, Bibcode2008A&A...480...91S. 
  8. "* d Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+d+Aqr. 
  9. Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy 18 (3): 220, doi:10.1177/002182868701800305, Bibcode1987JHA....18..209W. 
  10. 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, Bibcode2005A&A...430..165F. 
  11. "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.