Delta Pavonis

Delta Pavonis
Diagram showing star positions and boundaries of the Pavo constellation and its surroundings

Location of δ Pavonis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pavo
Right ascension 20h 08m 43.60953s[1]
Declination −66° 10′ 55.4436″[1]
Apparent magnitude (V) 3.56[2]
Characteristics
Spectral type G8 IV[3]
U−B color index 0.45[2]
B−V color index 0.76[2]
Variable type Suspected[4]
Astrometry
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
Distance19.92 ± 0.02 ly
(6.108 ± 0.006 pc)
Absolute magnitude (MV)4.62[6]
Details
Mass0.991[7] M☉
Radius1.22[7] R☉
Luminosity1.22 ± 0.04[8] L☉
Surface gravity (log g)4.26[9] cgs
Temperature5,604[9] K
Metallicity [Fe/H]+0.33[9] dex
Rotational velocity (v sin i)1.0[8] km/s
Age6.6–6.9[10] Gyr
9.3[6] Gyr
Other designations
CD-66 2367, GCTP 4754, GJ 780, HD 190248, HIP 99240, HR 7665, LHS 485, LTT 7946, LFT 1520, NSV 12790, SAO 254733.[11]
Database references
SIMBADdata

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, meaning it is about to stop fusing hydrogen in its core and is starting the process of becoming a red giant. Because of that, Delta Pavonis is 22%[8] brighter than the Sun even though the effective temperature of its outer atmosphere is lower, at 5,604 K.[9] It has 99.1% of the Sun's mass and 122% of the Sun's radius. The 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 this star shows that it has a higher abundance of elements heavier than helium (or metallicity, as astronomers call it) than does the Sun. This value is typically given in terms of the relative ratio of iron (chemical symbol Fe) to hydrogen (H) as compared to the Sun's atmosphere (iron being a relatively easy element to detect in a stellar atmosphere). For Delta Pavonis, the metallicity is about:

(This notation gives the logarithm of the iron-to-hydrogen ratio relative to the Sun.) This corresponds to a 214% abundance of iron in this star's atmosphere compared to the solar abundance. Past studies have shown a correlation between the heavy element abundance in stars and the presence of a planetary system,[12] suggesting Delta Pavonis has a greater than average probability of harboring planets. However, no planetary companions have yet been discovered in orbit around this star.[13]

The age of this star is in the range of 6.6–6.9 billion years old,[10] and the star's luminosity has increased 60% since it was a zero-age main-sequence star. It appears to be rotating slowly with a projected rotational velocity of 1.0 km s−1.[8]

SETI

It has been identified by Maggie Turnbull and Jill Tarter of the SETI Institute as the "Best SETI target" among the list of the 100 nearest 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. The lack of detected radial velocity variation suggests that there are no gas giants orbiting near the star's habitable zone, which may otherwise destabilize a hypothetical Earth-like planet in that orbital zone. As of 1999, no radio source of technological origin has been detected coming from this star.[14] Delta Pavonis is the nearest solar analog that is not a member of a binary or multiple star system. This is a type of star that is a close photometric match to the Sun.[13]

In fiction

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. 1 2 3 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:astro-ph/0603770Freely accessible, 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. 1 2 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:0811.3982Freely accessible, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  7. 1 2 3 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. 1 2 3 4 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:1002.4268Freely accessible, Bibcode:2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x
  9. 1 2 3 4 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:0805.4826Freely accessible. Bibcode:2008A&A...487..373S. doi:10.1051/0004-6361:200809698. See VizieR catalogue J/A+A/487/373.
  10. 1 2 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:0807.1686Freely accessible. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
  11. 1 2 "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. 1 2 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:astro-ph/0511180Freely accessible. 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.

External links

Coordinates: 20h 08m 43.6084s, −66° 10′ 55.446″

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