Delta Pyxidis

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Delta Pyxidis
Pyxis IAU.svg
Red circle.svg

Location of δ Pyxidis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pyxis
Right ascension 08h 55m 31.56948s[1]
Declination −27° 40′ 54.7315″[1]
Apparent magnitude (V) +4.877[2]
Spectral type A3 IV[3]
U−B color index +0.224[2]
B−V color index +0.130[2]
Radial velocity (Rv) 5.4±0.8[4] km/s
Proper motion (μ) RA: +81.90[1] mas/yr
Dec.: −100.43[1] mas/yr
Parallax (π) 13.19 ± 0.77[1] mas
Distance 250 ± 10 ly
(76 ± 4 pc)
Mass 1.84[5] M
Radius 1.6[6] R
Luminosity 59[3] L
Surface gravity (log g) 3.77±0.14[5] cgs
Temperature 8,609±293[5] K
Rotational velocity (v sin i) 68[5] km/s
Age 296[5] Myr
Other designations
δ Pyx, CPD−27° 3497, HD 76483, HIP 43825, HR 3556, SAO 176697, WDS J08555-2741A[7]
Database references

Delta Pyxidis (δ Pyxidis) is binary star[8] system in southern constellation of Pyxis. Having an apparent visual magnitude of +4.877,[2] it is bright enough to be visible to the naked eye. Based upon an annual parallax shift of 13.19 mas as seen from Earth,[1] it is located around 250 light years from the Sun.

In Chinese, 天狗 (Tiān Gǒu), meaning Celestial Dog, refers to an asterism consisting of δ Pyxidis, e Velorum, f Velorum, β Pyxidis, α Pyxidis and γ Pyxidis. Consequently, δ Pyxidis itself is known as 天狗七 (Tiān Gǒu qī, English: the Seventh Star of Celestial Dog.)[9]

This is an astrometric binary system, as determined by changes in the proper motion of the primary.[10] The visible component has a stellar classification of A3 IV,[3] indicating it has the spectrum of an A-type subgiant star that is consuming the last of the hydrogen at its core. At the age of around 296 million years,[5] it is 92.5%[3] of the way through its main sequence lifetime and is spinning with a projected rotational velocity of 68 km/s.[5] The star has an estimated 1.8[5] times the mass of the Sun and about 1.6[6] times the Sun's radius. It is radiating 59[3] times the Sun's luminosity from its photosphere at an effective temperature of roughly 8,609 K.[5]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G. 
  3. ^ a b c d e Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, Bibcode:2012A&A...537A.120Z, arXiv:1201.2052Freely accessible, doi:10.1051/0004-6361/201117691. 
  4. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, Bibcode:2012A&A...546A..61D, arXiv:1208.3048Freely accessible, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ a b c d e f g h i David, Trevor J.; Hillenbrand, Lynne A. (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, Bibcode:2015ApJ...804..146D, arXiv:1501.03154Freely accessible, doi:10.1088/0004-637X/804/2/146. 
  6. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289Freely accessible, doi:10.1051/0004-6361:20000451. 
  7. ^ "del Pyx". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-19. 
  8. ^ 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  9. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日
  10. ^ Frankowski, A.; et al. (March 2007), "Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data", Astronomy and Astrophysics, 464 (1): 377–392, Bibcode:2007A&A...464..377F, arXiv:astro-ph/0612449Freely accessible, doi:10.1051/0004-6361:20065526.