16 Delphini

16 Delphini is a star in the equatorial constellation Delphinus. It has an apparent magnitude of 5.54,^[2] making it faintly visible to the naked eye. The star is relatively close at a distance of 198 light years^[1] but is receding with a poorly constrained radial velocity of 2 km/s.^[5]

16 Delphini

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Delphinus
Right ascension	20h 55m 38.5698s[1]
Declination	+12° 34′ 06.8774″[1]
Apparent magnitude (V)	5.54±0.01[2]
Characteristics
Evolutionary stage	main sequence[3]
Spectral type	A5 V[4]
U−B color index	+0.09[2]
B−V color index	+0.11[2]
Astrometry
Radial velocity (Rv)	2.0±4.3[5] km/s
Proper motion (μ)	RA: +39.558 mas/yr[1] Dec.: +27.772 mas/yr[1]
Parallax (π)	16.4866 ± 0.06 mas[1]
Distance	197.8 ± 0.7 ly (60.7 ± 0.2 pc)
Absolute magnitude (MV)	+1.63[6]
Details
Mass	2.0±0.1[7] M☉
Radius	1.9±0.1[8] R☉
Luminosity	18.7[6] L☉
Surface gravity (log g)	4.10±0.14[7] cgs
Temperature	9,093±309[7] K
Metallicity [Fe/H]	−0.01[9] dex
Rotational velocity (v sin i)	159[10] km/s
Age	400+150 −215[7] Myr
Other designations
16 Del, AG+12°2414, BD+12°4501, GC 29202, HD 199254, HIP 103298, HR 8012, SAO 106666, WDS J20556+1234A
Database references
SIMBAD	data

16 Delphini is a chemically peculiar A-type main-sequence star with a stellar classification of A5 V. It has twice the Sun's mass,^[7] 1.9 times it's radius,^[8] and shines at 18.7 L_☉.^[6] This yields an effective temperature of 9,039 K,^[7] giving it a white glow. 16 Del is 400 million years old^[7] – 56.5% through its main sequence lifetime^[3] – and spins rapidly with a projected rotational velocity of 159 km/s.^[10]

16 Del has a companion that was first discovered by John Herschel and was even noted to be a spectroscopic binary.^[11] It is now considered to be a single star. ^[12]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
2. Oja, T. (August 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89: 415. Bibcode:1991A&AS...89..415O. ISSN 0365-0138.
3. Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. S2CID 55586789.
4. Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182. ISSN 0067-0049.
5. Gontcharov, G. A. (November 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. ISSN 1063-7737. S2CID 119231169.
6. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 255204555.
7. David, Trevor J.; Hillenbrand, Lynne A. (12 May 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. ISSN 0004-637X.
8. Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. ISSN 0004-6361.
9. Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. ISSN 0320-0108. S2CID 255201789.
10. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007). "Rotational velocities of A-type stars: III. Velocity distributions". Astronomy & Astrophysics. 463 (2): 671–682. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224. ISSN 0004-6361.
11. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.
12. 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.