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HD 145457 is a star located in the northern constellation of Corona Borealis (The Northern Crown) at a distance of around 442 light-years from the Sun, as determined through parallax measurements. It has been formally named Kamuy by the IAU, after a spiritual or divine being in Ainu mythology. With an apparent magnitude of 6.57, it is barely visible to the unaided eye on dark nights clear of light pollution. It is drifting closer to the Sun with a radial velocity of −3.2 km/s.

HD 145457 is an aging giant star with a stellar classification of K0 III that has cooled and expanded off the main sequence after exhausting its core hydrogen supply. With the assumption that it is a helium-burning object, the properties of HD 145457 can be derived by comparison with evolutionary tracks. With an age of 5.2 billion years old, it is around 1.57 times as massive as the Sun and has swollen to around 10 times its diameter. It is radiating 50 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,738 K.

It is a lithium-rich giant, unusual since lithium is rapidly destroyed once a star becomes a red giant. One explanation for the excess lithium in these stars has been a recent engulfment of a planet, but it is now thought more likely to be due to nucleosynthesis in the star. It is generally assumed that these lithium-rich giants are members of the red clump, core helium burning stars at the cool end of the horizontal branch.

Planetary system

HD 145457 has an exoplanetary companion called HD 145457 b discovered in 2010. 2.9 times as massive as Jupiter, it orbits about every 176 days with an orbital eccentricity of 0.112±3.1. Its semimajor axis is 0.76 AU. HD 145457 b was discovered by precise Doppler measurements with the Subaru Telescope.

As part of the IAU NameExoWorlds project in 2019, HD 145457 b has been formally named Chura. The name was selected by Japan. Chura is a word in the Ryukyuan/Okinawan language meaning natural beauty.

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. ^ Feuillet, Diane K.; et al. (2016). "Determining Ages of APOGEE Giants with Known Distances". The Astrophysical Journal. 817 (1): 40. arXiv:1511.04088. Bibcode:2016ApJ...817...40F. doi:10.3847/0004-637X/817/1/40. S2CID 118675933.
4. ^ Heard, John Frederick (1956). "The radial velocities, spectral classes and photographic magnitudes of 1041 late-type stars". Publications of the David Dunlap Observatory. 2 (4). University of Toronto, Toronto, Canada: University of Toronto Press: 107–143. Bibcode:1956PDDO....2..107H.
5. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
6. ^ Ting, Yuan-Sen; Rix, Hans-Walter (2019). "The Vertical Motion History of Disk Stars throughout the Galaxy". The Astrophysical Journal. 878 (1): 21. arXiv:1808.03278. Bibcode:2019ApJ...878...21T. doi:10.3847/1538-4357/ab1ea5. S2CID 119211560.
7. "HD 145457". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-04.
8. ^ "Japan". NameExoworlds. IAU. Retrieved 2019-12-30.
9. ^ Sato, Bun'ei; et al. (2010). "Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314". Publications of the Astronomical Society of Japan. 62 (4): 1063–69. arXiv:1005.2860. Bibcode:2010PASJ...62.1063S. doi:10.1093/pasj/62.4.1063. S2CID 119113950.
10. Kumar, Yerra Bharat; Reddy, Bacham E.; Lambert, David L. (2011). "Origin of Lithium Enrichment in K Giants". The Astrophysical Journal. 730 (1): L12. arXiv:1102.2299. Bibcode:2011ApJ...730L..12K. doi:10.1088/2041-8205/730/1/L12. S2CID 118383042.
11. Holanda, N.; Drake, N. A.; Pereira, C. B. (2020). "HD 150382: A Lithium-rich Star at the Early-AGB Stage?". The Astronomical Journal. 159 (1): 9. Bibcode:2020AJ....159....9H. doi:10.3847/1538-3881/ab5528.
12. Teng, Huan-Yu; Sato, Bun'ei; et al. (December 2023). "Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars". Publications of the Astronomical Society of Japan. 75 (6): 1030–1071. arXiv:2308.05343. Bibcode:2023PASJ...75.1030T. doi:10.1093/pasj/psad056.

• K-type giants
• Planetary systems with one confirmed planet
• Corona Borealis
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Stars with proper names