98 Aquarii
98 Aquarii (abbreviated 98 Aqr) is a star in the equatorial constellation of Aquarius. 98 Aquarii is the Flamsteed designation, although it also bears the Bayer designation b1 Aquarii. It is visible to the naked eye with an apparent visual magnitude of +3.97.[2] The distance to this star, 163 light-years (50 parsecs), is known from parallax measurements made with the Hipparcos spacecraft.[1]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 23h 22m 58.22606s[1] |
| Declination | –20° 06′ 02.0963″[1] |
| Apparent magnitude (V) | +3.97[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| U−B color index | +0.948[2] |
| B−V color index | +1.089[2] |
| Astrometry | |
| Radial velocity (Rv) | –6.5[4] km/s |
| Proper motion (μ) | RA: –121.28[1] mas/yr Dec.: –97.59[1] mas/yr |
| Parallax (π) | 19.96 ± 0.23 mas[1] |
| Distance | 163 ± 2 ly (50.1 ± 0.6 pc) |
| Details | |
| Mass | 2.1[5] M☉ |
| Radius | 14[6] R☉ |
| Surface gravity (log g) | 2.4[5] cgs |
| Temperature | 4,630[5] K |
| Metallicity [Fe/H] | –0.30[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
With over double the mass of the Sun,[5] this is an evolved giant star that has a stellar classification of K0 III.[3] The measured angular diameter of this star is 2.54 ± 0.13 mas.[8] At the estimated distance of 98 Aquarii,[1] this yields a physical size of about 14 times the radius of the Sun.[6] The expanded outer envelope has an effective temperature of 4,630 K,[5] giving it the orange glow of a K-type star.[9]
References edit
- ^ a b c d e f g van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.", Monthly Notices of the Royal Astronomical Society, 172 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
- ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H
- ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
- ^ a b c d e f Melo, C. H. F.; et al. (August 2005), "On the nature of lithium-rich giant stars. Constraints from beryllium abundances", Astronomy and Astrophysics, 439 (1): 227–235, arXiv:astro-ph/0504133, Bibcode:2005A&A...439..227M, doi:10.1051/0004-6361:20041805, S2CID 10580797.
- ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
- ^ "* 98 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-05.
- ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
- ^ , Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16.