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HD 134606 is a yellow-hued star with a planetary system, positioned in the southern constellation of Apus. It is below the nominal limit for visibility with the naked eye, having an apparent visual magnitude of 6.86. Based upon an annual parallax shift of 37.3 mas, it is located 87.44 light-years away. The star appears to be moving further from the Earth with a heliocentric radial velocity of +1.9 km/s.

This is an evolving G-type subgiant star with a stellar classification of G6 IV and is not considered active, having a chromospheric activity index of −5.04. It has about the same mass as the Sun but is 25% more luminous. The photosphere is radiating energy at an effective temperature of 5,614 K. It has a higher than solar metallicity – a term astronomers use to describe the abundance of elements other than hydrogen and helium.

There is a companion star of spectral type M3V at a separation of ~1500 AU, designated L 72-1. This companion presents a bimodal distribution of the Gaia DR3 G-band light-curve, indicating that it is a close binary.

Planetary system

The discovery of a planetary system orbiting HD 134606 was announced in 2011 following an eight-year survey carried out at the La Silla Observatory in Chile. The detection was made via the radial velocity method using the HARPS instrument. Applying a Keplerian fit to the data suggests the presence of three planets in moderately eccentric orbits. None of the planetary orbits displays a mean motion resonance with the others.

The system was updated by a 2024 study, which confirmed the three previously reported planets, though with a longer period for planet d, and detected two new ones. While all five planets are very likely to be real, the study advises caution regarding planet f due to the similarity of its period to the lunar cycle. The five planets range from super-Earth to super-Neptune mass, and the outermost, HD 134606 d, is a small gas giant orbiting within the habitable zone that may be a candidate for future space-based direct imaging missions. A long-period radial velocity trend was also detected, suggesting the presence of a distant sixth substellar companion of some kind.

References

1. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. ^ 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.
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/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
4. ^ Li, Zhexing; Kane, Stephen R.; Brandt, Timothy D.; Fetherolf, Tara; Robertson, Paul; Zhao, Jinglin; Dalba, Paul A.; Wittenmyer, Robert A.; Butler, R. Paul (April 2024). "Revised Architecture and Two New Super-Earths in the HD 134606 Planetary System". The Astronomical Journal. 167 (4): 155. arXiv:2401.17415. Bibcode:2024AJ....167..155L. doi:10.3847/1538-3881/ad2461.
5. "HD 134606". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 20, 2018.
6. Jenkins, J. S.; et al. (October 2006), "An activity catalogue of southern stars", Monthly Notices of the Royal Astronomical Society, 372 (1): 163–173, arXiv:astro-ph/0607336, Bibcode:2006MNRAS.372..163J, doi:10.1111/j.1365-2966.2006.10811.x, S2CID 17524675.
7. ^ Tsantaki, M.; et al. (July 2013). "Deriving precise parameters for cool solar-type stars. Optimizing the iron line list". Astronomy & Astrophysics. 555: A150. arXiv:1304.6639. Bibcode:2013A&A...555A.150T. doi:10.1051/0004-6361/201321103. S2CID 118388752.
8. "L 72-1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 February 2024.
9. González-Payo, J.; Caballero, J. A.; Gorgas, J.; Cortés-Contreras, M.; Gálvez-Ortiz, M.-C.; Cifuentes, C. (2024-07-29). "Multiplicity of stars with planets in the solar neighbourhood". arXiv:2407.20138 .
10. Mayor, M.; Marmier, M.; Lovis, C.; Udry, S.; Ségransan, D.; Pepe, F.; Benz, W.; Bertaux, J.-L.; Bouchy, F.; Dumusque, X.; Lo Curto, G.; Mordasini, C.; Queloz, D.; Santos, N. C. (September 13, 2011), The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets, arXiv:1109.2497
11. Giuppone, C. A.; et al. (December 2013), "A semi-empirical stability criterion for real planetary systems with eccentric orbits", Monthly Notices of the Royal Astronomical Society, 436 (4): 3547–3556, arXiv:1309.6861, Bibcode:2013MNRAS.436.3547G, doi:10.1093/mnras/stt1831

v t e Constellation of Apus
Apus in Chinese astronomy List of stars in Apus
Stars	Bayer α β γ δ ε ζ η θ ι κ κ Variable R (not variable) S Z MY NN NO HR 5240 5279 5306 5327 5389 5520 5547 5555 5628 5757 5786 5955 6135 6357 6373 6635 6646 6731 6751 HD 128294 129899 131664 134606 137366 137388 (Karaka) 141846 152010 Other Godzilla star
Star clusters	NGC 6101 Other IC 4499
Nebulae Hen 2-131
Galaxies Sunburst galaxy
Category

• G-type subgiants
• Planetary systems with five confirmed planets
• Apus
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• 2MASS objects