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Zeta Reticuli

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This is an old revision of this page, as edited by 81.157.226.225 (talk) at 02:41, 6 December 2012 (Calculated luminosities (see notes) and added an individual metallicity for zeta2 from 2012 paper. Quoted paper takes -0.21 dex from "del Peloso, E. F et al, 2000" as the metallicity for zeta1 but paper recalculates -0.16 dex for zeta2.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Zeta Reticuli
Diagram showing star positions and boundaries of the Reticulum constellation and its surroundings
Location of ζ Reticuli (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Reticulum
Zeta1 Reticuli
Right ascension 03h 17m 46.16324s[1]
Declination −62° 34′ 31.1563″[1]
Apparent magnitude (V) 5.52[2]
Zeta2 Reticuli
Right ascension 03h 18m 12.81853s[1]
Declination −62° 30′ 22.9048″[1]
Apparent magnitude (V) 5.22[2]
Characteristics
Spectral type G3−5V / G2V[3]
U−B color index +0.08 / +0.01[2]
B−V color index +0.63 / +0.58[2]
R−I color index +0.34 / +0.34[3]
Astrometry
Radial velocity (Rv)+12.2[4] km/s
Proper motion (μ) RA: 1,337.57[1] mas/yr
Dec.: 649.12[1] mas/yr
Parallax (π)83.28 ± 0.20 mas[1]
Distance39.16 ± 0.09 ly
(12.01 ± 0.03 pc)
Radial velocity (Rv)+11.5[4] km/s
Proper motion (μ) RA: 1,330.74[1] mas/yr
Dec.: 647.11[1] mas/yr
Parallax (π)83.11 ± 0.19 mas[1]
Distance39.24 ± 0.09 ly
(12.03 ± 0.03 pc)
Details
Zeta1 Reticuli
Mass0.958[5] M☉
Radius0.84[6] R☉
Luminosity0.69[note 1] L☉
Surface gravity (log g)4.54 ± 0.02[3] cgs
Temperature5,746 ± 27[3] K
Metallicity [Fe/H]−0.22[3] dex
Rotational velocity (v sin i)1.98[7] km/s
Age1.5–3.0[8] Gyr
Zeta2 Reticuli
Mass0.985[5] M☉
Radius0.88[6] R☉
Luminosity0.82[note 1] L☉
Surface gravity (log g)4.46 ± 0.01[3] cgs
Temperature5,859 ± 27[3] K
Metallicity [Fe/H]−0.16[9] dex
Rotational velocity (v sin i)1.74[7] km/s
Other designations
Zeta1 Reticuli
ζ1 Reticuli, ζ1 Ret, Zeta1 Ret, CPD −63°217, GCTP 701.00, GJ 136, HD 20766, HIP 15330, HR 1006, LFT 275, LHS 171, LTT 1573, SAO 248770
Zeta2 Reticuli
ζ2 Reticuli, ζ2 Ret, Zeta2 Ret, CPD −62°265, GCTP 705.00, GJ 138, HD 20807, HIP 15371, HR 1010, LFT 276, LHS 172, LTT 1576, SAO 248774
Database references
SIMBADdata
Database references
SIMBADdata

Zeta Reticuli (Zeta Ret, ζ Reticuli, ζ Ret) is the Bayer designation for a wide binary star system in the southern constellation of Reticulum. From the southern hemisphere the pair can be seen as a naked eye double star in very dark skies. Based upon parallax measurements, this system is located at a distance of about 39 light-years (12 parsecs) from the Earth. Zeta2 Reticuli is orbited by a circumstellar debris disk. Both stars are solar analogs that share similar characteristics with the Sun. They belong to the Zeta Herculis Moving Group of stars that share a common origin.

Characteristics

At a declination of −62°, the system is not visible from Britain's latitude of +53°, so it never received a Flamsteed designation in John Flamsteed's 1712 Historia Coelestis Britannica. The Bayer designation for this star system, Zeta (ζ) Reticuli, originated in a 1756 star map by the French astronomer Abbé Nicolas Louis de Lacaille.[10] Subsequently, the two stars received separate designations in the Cape Photographic Durchmusterung, which was processed between 1859 and 1903, then in the Henry Draper Catalogue, published between 1918 and 1924.[11]

The two stars are located at similar distances from the Sun and share the same motion through space,[12] confirming that they are gravitationally bound and form a wide binary star system. They have an angular separation of 309.2 arc seconds (5.2 arc minutes);[13] far enough apart to appear as a close pair of separate stars to the naked eye under suitable viewing conditions. The distance between the two stars is at least 3,750 AU, so their orbital period is 170,000 years or more.[14]

Both stars share similar physical characteristics to the Sun,[12] so they are considered solar analogs. Their stellar classification is nearly identical to that of the Sun. ζ1 has 96% of the Sun's mass and 84% of the Sun's radius. ζ2 is slightly larger and more luminous than ζ1, with 99% of the Sun's mass and 88% of the Sun's radius.[5][6] The two stars are somewhat deficient in metals, having only 60% of the proportion of elements other than hydrogen and helium as compared to the Sun.[3][15] For reasons that remain uncertain, they have an anomalously low abundance of beryllium.[7] Both stars are considered unusual because they have a lower luminosity than is normal for main sequence stars of their age and surface temperature. That is, they lie below the main sequence curve on the Hertzsprung-Russell diagram for newly formed stars. Most stars will evolve above this curve as they age.[13]

ζ1 has an intermediate level of magnetic activity in its chromosphere.[16] Although the kinematics of this system suggest that they belong to a population of older stars, the properties of their stellar chromospheres suggests that they are only about 2 billion years old.[17]

On September 20, 1996, a tentative discovery of a hot Jupiter around ζ2 was reported, but the discovery was quickly retracted as the signal was shown to be caused by pulsations of the star.[18] In 2002, ζ1 was examined at an infrared wavelength of 25 μm, but no indication of an excess of infrared radiation was found.[19] In 2007, the Spitzer Space Telescope was used to find an infrared excess at a wavelength of 70 μm around ζ2. This radiation is likely being emitted by a debris disk with a mean temperature of 150 K (−123 °C) that is orbiting the host star at a distance of 4.3 AU.[20] In 2010, the Herschel Space Observatory, looking for debris disks analogous to the Kuiper belt around Sun-like stars, detected signs of a possible exo-Kuiper belt, with a semi-major axis of 100 AU around ζ2.[21]

This star system belongs to the Zeta Herculis Moving Group of stars that share a common motion through space, suggesting that they have a common origin. In the galactic coordinate system, the [U, V, W] components of the space velocity for this system are equal to [−70.2, −47.4, +16.4] km/s for ζ1 and [−69.7, −46.4, +16.8] km/s for ζ2.[3] They are currently following an orbit through the Milky Way galaxy that has an eccentricity of 0.24. This orbit will carry the system as close as 17.4 kly (5.33 kpc) and as far as 28.6 kly (8.77 kpc) from the Galactic Center. The inclination of this orbit will carry the stars as much as 1.3 kly (0.4 kpc) from the plane of the galactic disk.[22] This likely puts them outside the thick disk population of stars.[23]

See also

Notes

  1. ^ a b From L=4πR2σTeff4, where L is the luminosity, R is the radius, Teff is the effective surface temperature and σ is the Stefan–Boltzmann constant.

References

  1. ^ a b c d e f g h i j 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 {{citation}}: Unknown parameter |month= ignored (help)
  2. ^ a b c d Feinstein, A. (1966), "Photoelectric observations of Southern late-type stars", Informational Bulletin of the Southern Hemisphere, 8: 30, Bibcode:1966IBSH....8...30F
  3. ^ a b c d e f g h i del Peloso, E. F.; da Silva, L.; Porto de Mello, G. F. (2000). "zeta1 and zeta2 Reticuli and the existence of the zeta Herculis group". Astronomy and Astrophysics. 358: 233–241. Bibcode:2000A&A...358..233D. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ a b Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E {{citation}}: Unknown parameter |booktitle= ignored (help)
  5. ^ a b c Takeda, G.; et al. (2007). "Stellar parameters of nearby cool stars. II. Physical properties of ~1000 cool stars from the SPOCS catalog". Astrophysical Journal Supplement Series. 168: 297–318. Bibcode:2008yCat..21680297T. Note: see VizieR catalogue J/ApJS/168/297.
  6. ^ a b c Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. {{cite journal}}: Unknown parameter |month= ignored (help) Note: using the method of Perrin and Karoji (1987).
  7. ^ a b c Santos, N. C.; et al. (2004). "Beryllium anomalies in solar-type field stars". Astronomy and Astrophysics. 425 (3): 1013–1027. arXiv:astro-ph/0408109. Bibcode:2004A&A...425.1013S. doi:10.1051/0004-6361:20040510. {{cite journal}}: Unknown parameter |month= ignored (help)
  8. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. {{cite journal}}: Unknown parameter |month= ignored (help)
  9. ^ Maldonado, J.; et al. (2012). "Metallicity of solar-type stars with debris discs and planets". Astronomy and Astrophysics. 541 month=May. arXiv:1202.5884. Bibcode:2012A&A...541A..40M. doi:10.1051/0004-6361/201218800.
  10. ^ Ridpath, Ian (1989), Star tales, James Clarke & Co., p. 11, ISBN 0-7188-2695-7
  11. ^ Naming astronomical objects, International Astronomical Union, retrieved 2011-12-16
  12. ^ a b da Silva, L.; Foy, R. (1987). "Zeta-1 and Zeta-2 RETICULI - A puzzling solar-type twin system". Astronomy and Astrophysics. 177 (1–2): 204–216. Bibcode:1987A&A...177..204D. {{cite journal}}: Unknown parameter |month= ignored (help)
  13. ^ a b Makarov, V. V.; Zacharias, N.; Hennessy, G. S. (2008). "Common Proper Motion Companions to Nearby Stars: Ages and Evolution". The Astrophysical Journal. 687 (1): 566–578. arXiv:0808.3414. Bibcode:2008ApJ...687..566M. doi:10.1086/591638. {{cite journal}}: Unknown parameter |month= ignored (help)
  14. ^ Kaler, James B., "ZETA RET (Zeta Reticuli)", Stars, University of Illinois, retrieved 2011-11-16
  15. ^ A metallicity of −0.22 indicates that they have the following proportion of metals compared to the Sun: 10−0.22 = 0.603, or 60%.
  16. ^ Vieytes, M.; Mauas, P.; Cincunegui, C. (2005). "Chromospheric models of solar analogues with different activity levels". Astronomy and Astrophysics. 441 (2): 701–709. Bibcode:2005A&A...441..701V. doi:10.1051/0004-6361:20052651. {{cite journal}}: Unknown parameter |month= ignored (help)
  17. ^ Rocha-Pinto, Helio J.; Maciel, Walter J.; Castilho, Bruno V. (2002). "Chromospherically young, kinematically old stars". Astronomy and Astrophysics. 384 (3): 912–924. arXiv:astro-ph/0112452. Bibcode:2002A&A...384..912R. doi:10.1051/0004-6361:20011815. {{cite journal}}: Unknown parameter |month= ignored (help)
  18. ^ "Life on Zeta Reticuli?". ZetaTalk. Retrieved 2010-02-10.
  19. ^ Laureijs, R. J.; et al. (2002). "A 25 micron search for Vega-like disks around main-sequence stars with ISO". Astronomy and Astrophysics. 387 (1): 285–293. Bibcode:2002A&A...387..285L. doi:10.1051/0004-6361:20020366. {{cite journal}}: Unknown parameter |month= ignored (help)
  20. ^ Trilling, D. E.; et al. (2008). "Debris Disks around Sun-like Stars". The Astrophysical Journal. 674 (2): 1086–1105. arXiv:0710.5498. Bibcode:2008ApJ...674.1086T. doi:10.1086/525514. {{cite journal}}: Unknown parameter |month= ignored (help) See table 6.
  21. ^ Eiroa, C.; et al. (2010). "Cold DUst around NEarby Stars (DUNES). First results. A resolved exo-Kuiper belt around the solar-like star ζ2 Ret". Astronomy and Astrophysics. 518. arXiv:1005.3151. Bibcode:2010A&A...518L.131E. doi:10.1051/0004-6361/201014594. {{cite journal}}: Unknown parameter |month= ignored (help)
  22. ^ Holmberg, J.; Nordström, B.; Andersen, J. (2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941–947. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. {{cite journal}}: Unknown parameter |month= ignored (help)
  23. ^ Makarov, V. V.; Zacharias, N.; Hennessy, G. S. (2008). "Common Proper Motion Companions to Nearby Stars: Ages and Evolution". The Astrophysical Journal. 687 (1): 566–578. arXiv:0808.3414. Bibcode:2008ApJ...687..566M. doi:10.1086/591638. {{cite journal}}: Unknown parameter |month= ignored (help)
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