Delta Pavonis

Delta Pavonis

Observation data Epoch J2000      Equinox J2000
Constellation	Pavo
Right ascension	20h 08m 43.6084s[1]
Declination	−66° 10′ 55.446″[1]
Apparent magnitude (V)	3.56[1]
Characteristics
Spectral type	G8IV[1]
U−B color index	0.45[2]
B−V color index	0.76[2]
Variable type	Suspected
Astrometry
Radial velocity (Rv)	–21.7±0.9[1] km/s
Proper motion (μ)	RA: 1210.50±0.58[1] mas/yr Dec.: −1130.27±0.44[1] mas/yr
Parallax (π)	163.74 ± 0.65[1] mas
Distance	19.92 ± 0.08 ly (6.11 ± 0.02 pc)
Absolute magnitude (MV)	4.62
Details
Mass	0.991[3] M☉
Radius	1.22[3] R☉
Surface gravity (log g)	4.26[4]
Luminosity	1.18 L☉
Temperature	5,604[4] K
Metallicity	$\begin{smallmatrix}\left[\frac{Fe}{H}\right]\ =\ 0.33\end{smallmatrix}$[4]
Rotation	1 km/s (~54 days)
Age	6.6–6.9 × 109[5] years
Other designations
HD 190248, HR 7665, CD-66°2367, GCTP 4754, GJ 780, LHS 485, SAO 254733, LTT 7946, LFT 1520, NSV 12790, and HIP 99240.[1]

Delta Pavonis (δ Pav, δ Pavonis) is a star about 19.9 light years away from Earth. It is in the constellation Pavo.

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 slightly brighter than the Sun even though it is cooler. It has 99.1% of the Sun's mass and is 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.^[3]

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:

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

(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,^[6] suggesting Delta Pavonis has a greater probability of harbouring a planetary system.

The age of this star is in the range of 6.6–6.9 Gyr, and the luminosity has increased 60% since it became a zero-age main sequence star. (The later increase is similar to the Sun.) No planetary companions have yet been discovered in orbit around this star.^[7]

SETI

It has been identified by Maggie Turnbull and Jill Tarter of the SETI Institute as the "Best SETI target" in a survey of nearby stars.^[8] Delta Pavonis is the nearest sun-like star not a member of a binary or multiple star system.^[7]

In fiction

• Delta Pavonis in fiction

References

1. ^ ^{a b c d e f g h i} "NSV 12790 -- Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+190248. Retrieved 2009-08-21. 
2. ^ ^{a b} Cousins, A. W. J.; Stoy, R. H. (1962). "Photoelectric magnitudes and colours of Southern stars". Royal Observatory Bulletins 64: 103–248. 
3. ^ ^{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: J/ApJS/168/297. Originally published in: 2007ApJS..168..297T 216: 80297. Bibcode 2008yCat..21680297T. 
4. ^ ^{a b c} 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. Bibcode 2008A&A...487..373S. doi:10.1051/0004-6361:200809698.  See VizieR catalogue J/A+A/487/373.
5. ^ 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. Bibcode 2008ApJ...687.1264M. doi:10.1086/591785. 
6. ^ 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. 
7. ^ ^{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:astro-ph/0511180. Bibcode 2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. 
8. ^ 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

• "Delta Pavonis". SolStation. http://www.solstation.com/stars/dpavonis.htm. Retrieved November 3, 2005. 

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