HD 145457

HD 145457 is a star located in the northern constellation of Corona Borealis (The Northern Crown) at a distance of around 443 light-years from the Sun,[1] as determined through parallax measurements. It has been formally named Kamuy by the IAU,[7] after a spiritual or divine being in Ainu mythology. With an apparent magnitude of 6.57,[8] 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.[1]

HD 145457
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Corona Borealis
Right ascension 16h 10m 03.91437s[1]
Declination +26° 44′ 33.8937″[1]
Apparent magnitude (V) 6.57[2]
Characteristics
Evolutionary stage Giant[3]
Spectral type K0 III[4]
B−V color index +1.037±0.005[2]
Astrometry
Radial velocity (Rv)−3.15±0.13[1] km/s
Proper motion (μ) RA: −18.336[1] mas/yr
Dec.: +36.824[1] mas/yr
Parallax (π)7.3625 ± 0.0219[1] mas
Distance443 ± 1 ly
(135.8 ± 0.4 pc)
Absolute magnitude (MV)1.09[2]
Details
Mass1.57±0.46[3] M☉
Radius10.49+0.13
−0.41[1] R☉
Luminosity49.97±0.27[1] L☉
Surface gravity (log g)2.72±0.11[3] cgs
Temperature4,738+95
−28[1] K
Metallicity [Fe/H]−0.177[5] dex
Age5.2[5] Gyr
Other designations
BD+27°2595, HD 145457, HIP 79219, SAO 84223[6]
Database references
SIMBADdata

HD 145457 is an aging giant star with a stellar classification of K0 III[4] that has cooled and expanded off the main sequence after exhausting its core hydrogen supply. 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.[9] With the assumption that it is a helium-burning object, the properties of HD 145457 can be derived by comparison with evolutionary tracks.[10] With an age of 5.2 billion years old,[5] it is around 1.57 times as massive as the Sun[3] 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.[1]

Companion

HD 145457 has a 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.[8]

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.[7]

References
  1. 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.
  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. University of Toronto, Toronto, Canada: University of Toronto Press. 2 (4): 107–143. Bibcode:1956PDDO....2..107H.
  5. Ting, Yuan-Sen; Rix, Hans-Walter (2019). "The Vertical Motion History of Disk Stars throughout the Galaxy". The Astrophysical Journal. 878: 21. arXiv:1808.03278. Bibcode:2019ApJ...878...21T. doi:10.3847/1538-4357/ab1ea5. S2CID 119211560.
  6. "HD 145457". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-04.
  7. "Japan". NameExoworlds. IAU. Retrieved 2019-12-30.
  8. 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.
  9. 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.
  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.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.