31 Aquilae
 Location of 31 Aquarii (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 24m 58.20027s[1] |
| Declination | +11° 56′ 39.8862″[1] |
| Apparent magnitude (V) | 5.16[2] |
| Characteristics | |
| Spectral type | G8 IV[2] |
| U−B color index | +0.42[3] |
| B−V color index | +0.77[2] |
| Astrometry | |
| Radial velocity (Rv) | –100.5[4] km/s |
| Proper motion (μ) | RA: +721.02[1] mas/yr Dec.: +642.49[1] mas/yr |
| Parallax (π) | 65.89 ± 0.26[1] mas |
| Distance | 49.5 ± 0.2 ly (15.18 ± 0.06 pc) |
| Absolute bolometric magnitude (Mbol) |
4.01[5] |
| Details | |
| Mass | 1.16 ± 0.07[5] M☉ |
| Radius | 1.379 ± 0.042[6] R☉ |
| Luminosity | 1.904 ± 0.045[6] L☉ |
| Surface gravity (log g) | 4.18 ± 0.03[5] cgs |
| Temperature | 5,510 ± 90[2] K |
| Metallicity [Fe/H] | +0.37[7] dex |
| Age | 4.5 ± 0.2[5] Gyr |
| Other designations | |
31 Aquilae (abbreviated 31 Aql) is a star in the equatorial constellation of Aquila. 31 Aquilae is its Flamsteed designation though it also bears the Bayer designation b Aquilae. This star has an apparent visual magnitude of 5.16 and is 49.5 light years from Earth. It has no known companions.
Properties[edit]
31 Aquilae has an apparent visual magnitude of 5.16,[2] making it bright enough to be seen with the naked eye in dark skies. The annual parallax shift of 65.89 mas[1] yields a distance estimate of 49.5 light-years (15.2 parsecs) from Earth. It is a variable star with a magnitude change of less than 0.02.[5]
With a stellar classification of G8 IV,[2] the luminosity class of IV indicates this is a subgiant star. Compared to the Sun, it has 116%[5] of the mass and 138%[6] of the radius. It is radiating nearly double[6] the luminosity of the Sun from its outer atmosphere at an effective temperature of 5,510 K,[2] giving it the yellow hue of an G-type star.[9] Its age is probably similar to NGC 188, the oldest open cluster known, which was calculated to be over 5 billion years. For its age, it is surprisingly rich in elements other than hydrogen or helium, contrary to common assumptions that the oldest stars should be metal-poor.
No certain substellar companion has been detected so far around 31 Aquilae. McDonald Observatory team has set limits to the presence of one or more planets [10] around 31 Aquilae with masses between 0.22 and 1.9 Jupiter masses and average separations spanning between 0.05 and 5.2 Astronomical Units.
Optical companions[edit]
The following stars are optical companions that are coincidentally aligned near the line of sight to 31 Aquilae.
| Companion | HD 231345 | BD+11 3833C |
|---|---|---|
| Right ascension | 19h 24m 51.8595s | 19h 24m 50.8s |
| Declination | +11° 57′ 14.692″ | +11° 57′ 36″ |
| Magnitude | 8.56 | 10.6 |
| Spectral type | G0 | |
| Reference | Simbad | Simbad |
References[edit]
- ^ a b c d e f 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. - ^ a b c d e f g Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M.
- ^ Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
- ^ Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W.
- ^ a b c d e f Trevisan, M.; et al. (November 2011), "Analysis of old very metal rich stars in the solar neighbourhood", Astronomy & Astrophysics, 535: A42, arXiv:1109.6304, Bibcode:2011A&A...535A..42T, doi:10.1051/0004-6361/201016056. See Table 13.
- ^ a b c d Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101. See Table 10.
- ^ Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788.
- ^ "b Aql -- Variable Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-22.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16
- ^ Detection Limits from the McDonald Observatory Planet Search Program
External links[edit]
- The Old Disk Metal-Rich Subgiant 31 Aquilae doi:10.1086/151065
- Image 31 Aquilae
- HR 7373
- CCDM 19249+1157
- R.A. Wittenmeyer et al., "Detection Limits from the McDonald Observatory Planet Search Program", The Astronomical Journal, Volume 132, Issue 1, pp. 177–188, May 2006.
