19 Aquarii

19 Aquarii is a star in the zodiac constellation of Aquarius. With an apparent magnitude of about 5.7,[2] the star is barely visible to the naked eye as a white-hued star (see Bortle scale). Parallax estimates put it at a distance of about 260 light years away from the Sun.[1] The star is moving closer to the Earth with a heliocentric radial velocity of −21 km/s.[5]

19 Aquarii
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension  21h 25m 13.01629s[1]
Declination −09° 44′ 54.7923″[1]
Apparent magnitude (V) +5.713[2]
Characteristics
Spectral type A8V[3]
B−V color index +0.20[4]
Astrometry
Radial velocity (Rv)−20.6±1.8[5] km/s
Proper motion (μ) RA: +25.943[1] mas/yr
Dec.: −167.548[1] mas/yr
Parallax (π)12.5593 ± 0.1676[1] mas
Distance260 ± 3 ly
(80 ± 1 pc)
Absolute magnitude (MV)0.90[6]
Details
Mass1.86[7] M☉
Radius2.76+0.18
−0.16[1] R☉
Luminosity26.1+0.4
−0.4[1] L☉
Surface gravity (log g)4.13[7] cgs
Temperature8,078±275[7] K
Rotational velocity (v sin i)102[8] km/s
Age788[7] Myr
Other designations
19 Aqr, BD−10°5668, HD 203875, HIP 105761, HR 8195, SAO 145382[9]
Database references
SIMBADdata

This object is an A-type main-sequence star with a stellar classification of A8V.[3] It is around 788[7] million years old with a fairly fast rotation rate, as its projected rotational velocity is about 155 km/s,[8] so it must be rotating at least that fast. It has 1.86[7] times the mass of the Sun and 2.76[1] times the Sun's radius. 19 Aquarii is radiating 26[1] times the luminosity of the Sun from its photosphere at an effective temperature of 8,078 K.[7] Eggen has this star flagged as a blue straggler and a member of the HR1614 supercluster.[10]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  3. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5: 0. Bibcode:1999MSS...C05....0H.
  4. Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.
  7. David, Trevor J.; Hillenbrand, Lynne A. (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. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
  8. Royer, F.; Zorec, J.; Gómez, A. E. (2007). "Rotational velocities of A-type stars". Astronomy and Astrophysics. 463 (2): 671. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224.
  9. "* 19 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 22 March 2017.
  10. Eggen, Olin J. (October 1996). "Star Streams and Galactic Structure". Astronomical Journal. 112: 1595. Bibcode:1996AJ....112.1595E. doi:10.1086/118126.
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