Delta Pyxidis
Delta Pyxidis (δ Pyxidis) is binary star system in southern constellation of Pyxis. Having an apparent visual magnitude of +4.877, 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, 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.) This is an astrometric binary system, as determined by changes in the proper motion of the primary. The visible component has a stellar classification of A3 IV, 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, it is 92.5% of the way through its main sequence lifetime and is spinning with a projected rotational velocity of 68 km/s. The star has an estimated 1.8 times the mass of the Sun and about 1.6 times the Sun's radius. It is radiating 59 times the Sun's luminosity from its photosphere at an effective temperature of roughly 8,609 K.
  | |
| 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] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A3 IV[3] |
| U−B color index | +0.224[2] |
| B−V color index | +0.130[2] |
| Astrometry | |
| 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 mas[1] |
| Distance | 250 ± 10 ly (76 ± 4 pc) |
| Absolute magnitude (MV) | +0.67[5] |
| Details | |
| Mass | 1.84[6] M☉ |
| Radius | 1.6[7] R☉ |
| Luminosity | 59[3] L☉ |
| Surface gravity (log g) | 3.77±0.14[6] cgs |
| Temperature | 8,609±293[6] K |
| Rotational velocity (v sin i) | 68[6] km/s |
| Age | 296[6] Myr |
| Other designations | |
| δ Pyx, CPD−27°3497, HD 76483, HIP 43825, HR 3556, SAO 176697, WDS J08555-2741A[8] | |
| Database references | |
| SIMBAD | data |
Delta Pyxidis (δ Pyxidis) is binary star[9] 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.)[10]
This is an astrometric binary system, as determined by changes in the proper motion of the primary.[11] 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,[6] 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.[6] The star has an estimated 1.8[6] times the mass of the Sun and about 1.6[7] 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.[6]
References
[edit]- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, 1, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, Bibcode:1966PDAUC...1....1G.
- ^ a b c d e f Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
- ^ 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, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ 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, 367 (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ "del Pyx". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-19.
{{cite web}}: CS1 maint: postscript (link) - ^ 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.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日 Archived 2012-02-04 at the Wayback Machine
- ^ 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, arXiv:astro-ph/0612449, Bibcode:2007A&A...464..377F, doi:10.1051/0004-6361:20065526, S2CID 14010423.
