# Delta Pavonis

Observation data Epoch J2000      Equinox J2000 Constellation Location of δ Pavonis (circled) Pavo 20h 08m 43.60953s[1] −66° 10′ 55.4436″[1] 3.56[2] G8 IV[3] 0.45[2] 0.76[2] Suspected[4] Radial velocity (Rv) −21.7±0.9[5] km/s Proper motion (μ) RA: +1,211.03[1] mas/yr Dec.: –1,130.05[1] mas/yr Parallax (π) 163.71 ± 0.17[1] mas Distance 19.92 ± 0.02 ly (6.108 ± 0.006 pc) Absolute magnitude (MV) 4.62[6] Mass 0.991[7] M☉ Radius 1.22[7] R☉ Luminosity 1.22 ± 0.04[8] L☉ Surface gravity (log g) 4.26[9] cgs Temperature 5,604[9] K Metallicity [Fe/H] +0.33[9] dex Rotational velocity (v sin i) 1.0[8] km/s Age 6.6–6.9[10] Gyr9.3[6] Gyr CD-66 2367, GCTP 4754, GJ 780, HD 190248, HIP 99240, HR 7665, LHS 485, LTT 7946, LFT 1520, NSV 12790, SAO 254733.[11] SIMBAD data

Delta Pavonis (δ Pav, δ Pavonis) is a star in the southern circumpolar constellation of Pavo. It has an apparent visual magnitude of 3.56,[11] making it a fourth-magnitude star that is visible to the naked eye from the southern hemisphere. Parallax measurements from the Hipparcos satellite yield an estimated distance of 19.92 light-years (6.11 parsecs) from Earth.[1] This makes it one of the nearest bright stars to the Solar System.

## Observations

It is a subgiant of spectral type G8 IV; it will stop fusing hydrogen relatively soon, starting the process of becoming a red giant. Hence, Delta Pavonis is 22% brighter than the Sun[8], but the effective temperature of its outer atmosphere is less: 5,604 K.[9] Its mass is 99.1% of Sol's mass, with a mean radius 122% of Sol's radius. Delta Pavonis's surface convection zone extends downward to about 43.1% of the star's radius, but only contains 4.8% of the star's mass.[7]

Spectroscopic examination of Delta Pavonis shows that it has a higher abundance of elements heavier than helium (metallicity) than does the Sun. This value is typically given in terms of the ratio of iron (chemical symbol Fe) to hydrogen (H) in a star's atmosphere, relative to that in Sol's atmosphere (iron being a good proxy for the presence of other heavy elements). The metallicity of Delta Pavonis is approximately

${\displaystyle {\begin{smallmatrix}\left[{\frac {Fe}{H}}\right]\ =\ 0.33\end{smallmatrix}}}$

This notation gives the logarithm of the iron-to-hydrogen ratio, relative to that of the Sun, meaning that Delta Pavonis's iron abundance is 214% of that of Sol. Studies have shown a correlation between abundant heavy elements in stars, and the presence of a planetary system,[12] so Delta Pavonis has a greater than average probability of harboring planets. However, no planets of Delta Pavonis have been discovered to date.[13]

The age of Delta Pavonis is approximately 6.6 to 6.9 billion years.[10] It appears to be rotating slowly, with a projected rotational velocity of 1.0 kilometers per second.[8]

## SETI

Delta Pavonis has been identified by Maggie Turnbull and Jill Tarter of the SETI Institute as the "Best SETI target" among the 100 closest G-type stars. Properties in its favor include a high metallicity, minimal level of magnetic activity, low rotation rate, and kinematic membership in the thin disk population of the Milky Way. Gas giants orbiting in, near, or through a star's habitable zone may destabilize the orbits of terrestrial planets in that zone; the lack of detected radial velocity variation suggests that there are no such gas giants orbiting Delta Pavonis. However, observation has detected no artificial radio sources.[14] Delta Pavonis, a close photometric match to the Sun, is the nearest solar analog that is not a member of a binary or multiple star system. [13]

## References

1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
2. ^ a b c Cousins, A. W. J.; Stoy, R. H. (1962). "Photoelectric magnitudes and colours of Southern stars". Royal Observatory Bulletin. 64: 103–248. Bibcode:1962RGOB...64..103C.
3. ^ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
4. ^ Ruban, E. V.; et al. (September 2006), "Spectrophotometric observations of variable stars", Astronomy Letters, 32 (9): 604–607, Bibcode:2006AstL...32..604R, doi:10.1134/S1063773706090052
5. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E.
6. ^ a b Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
7. ^ a b c Takeda, G.; Ford, E. B.; Sills, A.; Rasio, F. A.; Fischer, D. A.; Valenti, J. A.; Ford; Sills; Rasio; Fischer; Valenti (November 2008). "Stellar parameters of nearby cool stars (Takeda+, 2007)". VizieR On-line Data Catalog. 216: 80297. Bibcode:2008yCat..21680297T. J/ApJS/168/297. Originally published in: 2007ApJS..168..297T.
8. ^ a b c d Bruntt, H.; et al. (July 2010), "Accurate fundamental parameters for 23 bright solar-type stars", Monthly Notices of the Royal Astronomical Society, 405 (3): 1907–1923, arXiv:, Bibcode:2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x
9. ^ a b c d Sousa, S. G.; et al. (August 2008). "Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes". Astronomy and Astrophysics. 487 (1): 373–381. arXiv:. Bibcode:2008A&A...487..373S. doi:10.1051/0004-6361:200809698. See VizieR catalogue J/A+A/487/373.
10. ^ a b Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
11. ^ a b "NSV 12790 -- Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-08-21.
12. ^ Sousa, S.G.; et al. (2006). "Spectroscopic parameters for a sample of metal-rich solar-type stars". Astronomy and Astrophysics. 458 (3): 873–880. Bibcode:2006A&A...458..873S. doi:10.1051/0004-6361:20065658.
13. ^ a b G. F. Porto de Mello, E. F. del Peloso, L. Ghezzi (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649.
14. ^ M.C. Turnbull; J.C. Tarter (2003). "Target Selection for SETI. II. Tycho-2 Dwarfs, Old Open Clusters, and the Nearest 100 Stars". The Astrophysical Journal Supplement Series. 149 (2): 423–436. Bibcode:2003ApJS..149..423T. doi:10.1086/379320.