Astronomy:HD 121056

From HandWiki
Short description: Star in the constellation Centaurus
HD 121056
Observation data
Equinox J2000.0]] (ICRS)
Constellation Centaurus[1]
Right ascension  13h 53m 52.06131s[2]
Declination −35° 18′ 51.6918″[2]
Apparent magnitude (V) 6.17[3]
Characteristics
Evolutionary stage red giant branch[2]
Spectral type K0 III[4]
B−V color index 1.01[5]
Astrometry
Radial velocity (Rv)5.60±0.13[2] km/s
Proper motion (μ) RA: −295.304[2] mas/yr
Dec.: −68.458[2] mas/yr
Parallax (π)15.6261 ± 0.0418[2] mas
Distance208.7 ± 0.6 ly
(64.0 ± 0.2 pc)
Absolute magnitude (MV)+2.08[1]
Details
Mass1.394±0.052[6] M☉
Radius5.948±0.077[6] R☉
Luminosity18.2+2.0
−1.8[6] L☉
Surface gravity (log g)3.034±0.005[6] cgs
Temperature4,867±49[3] K
Metallicity[Mg/H] 0.286±0.05 dex[3]
Metallicity [Fe/H]0.020±0.031[3] dex
Rotational velocity (v sin i)2.38±0.51[3] km/s
Age5.46[7] Gyr
Other designations
CD−34 9223, GJ 532.1, HD 121056, HIP 67851, HR 5224, TYC 7287-1874-1, 2MASS J13535209-3518517[8]
Database references
SIMBADdata
Exoplanet Archivedata

HD 121056, or HIP 67851, is an aging giant star with a pair of orbiting exoplanets located in the southern constellation of Centaurus. This star is dimly visible to the naked eye with an apparent visual magnitude of 6.17.[3] It is located at a distance of 209 light-years from the Sun, based on parallax measurements, and is drifting further away with a radial velocity of 5.6 km/s.[2]

The spectrum of HD 121056 presents as an evolved K-type giant star with a stellar classification of K0 III.[9] It is presently ascending the red-giant branch, having exhausted the supply of hydrogen at its core.[5] The star is about 5.5[7] billion years old and is spinning with a projected rotational velocity of 2.4 km/s. HD 121056’s concentration of heavy elements is similar to the Sun, with a metallicity Fe/H index of 0.020±0.031, although the star is enriched in lighter rock-forming elements like magnesium and aluminum.[3] It has 1.6[10] times the mass of the Sun and has expanded to 5.72 times the Sun's radius.[7] The star is radiating 15.8[7] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,867 K.[3]

Planetary system

In 2014, two planets orbiting HD 121056 were discovered by the radial velocity method,[5] and were confirmed a few months later.[9] The orbits of these planets are stable on astronomical timescales,[11] although the periods are not in orbital resonance.[12] In 2022, the inclination and true mass of HD 121056 c were measured via astrometry, indicating a nearly edge-on orbit.[13] Subsequent studies have provided further updates to the planetary parameters.[6][14]

The planetary system configuration is favorable for direct imaging of exoplanets in the near future, being included in the top ten easiest targets in 2018.[15]

The HD 121056 planetary system[14][lower-alpha 1]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥1.15±0.04 MJ 0.42±0.0002 89.23±0.06 0.13±0.04 — —
c 4.97+0.22
−0.21 MJ 		4.55±0.05 3,128.41+52.09
−47.13 		0.30±0.03 89.86+28.38
−24.73[13]° 		—

Notes

  1. ↑ Most parameters are taken from the most recent study of the system, Fontanet et al. 2025. This does not incorporate astrometry, hence the mass of planet c is technically a minimum mass, but since the inclination measured by Feng et al. 2022 is nearly edge-on, the true mass is about the same as this value.

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Hojjatpanah, S. et al. (2019). "Catalog for the ESPRESSO blind radial velocity exoplanet survey". Astronomy & Astrophysics 629: A80. doi:10.1051/0004-6361/201834729. Bibcode: 2019A&A...629A..80H. 
  4. ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey 5. Bibcode: 1999MSS...C05....0H. 
  5. ↑ 5.0 5.1 5.2 Jones, M. I. et al. (2015). "A planetary system and a highly eccentric brown dwarf around the giant stars HIP 67851 and HIP 97233". Astronomy & Astrophysics 573: A3. doi:10.1051/0004-6361/201424771. Bibcode: 2015A&A...573A...3J. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Lin, Wen-Xu; Qian, Sheng-Bang; Zhu, Li-Ying; Liao, Wen-Ping; Li, Fu-Xing (2024-07-01). "Using Asteroseismology to Calibrate the Physical Parameters of Confirmed Exoplanets and Their Evolved Host Stars". The Astronomical Journal 168 (1): 27. doi:10.3847/1538-3881/ad4ffc. ISSN 0004-6256. Bibcode: 2024AJ....168...27L. 
  7. ↑ 7.0 7.1 7.2 7.3 Soto, M. G. et al. (2021). "SPECIES. II. Stellar parameters of the EXPRESS giant star sample". Astronomy and Astrophysics 647: A157. doi:10.1051/0004-6361/202039357. Bibcode: 2021A&A...647A.157S. 
  8. ↑ "HD 121056". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+121056. 
  9. ↑ 9.0 9.1 Wittenmyer, Robert A. et al. (2015). "The Pan-Pacific Planet Search. II. Confirmation of a Two-planet System around HD 121056". The Astrophysical Journal 800 (1): 74. doi:10.1088/0004-637X/800/1/74. Bibcode: 2015ApJ...800...74W. 
  10. ↑ Sousa, S. G. et al. (2018). "SWEET-Cat updated". Astronomy & Astrophysics 620: A58. doi:10.1051/0004-6361/201833350. Bibcode: 2018A&A...620A..58S. 
  11. ↑ Kane, Stephen R. et al. (2019). "Predicting multiple planet stability and habitable zone companions in the TESS era". Monthly Notices of the Royal Astronomical Society 485 (4): 4703–4725. doi:10.1093/mnras/stz345. Bibcode: 2019MNRAS.485.4703A. 
  12. ↑ Saillenfest, M. et al. (2019). "Secular spin-axis dynamics of exoplanets". Astronomy & Astrophysics 623: A4. doi:10.1051/0004-6361/201834344. Bibcode: 2019A&A...623A...4S. 
  13. ↑ 13.0 13.1 Feng, Fabo et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series 262 (21): 21. doi:10.3847/1538-4365/ac7e57. Bibcode: 2022ApJS..262...21F. 
  14. ↑ 14.0 14.1 Fontanet, E. et al. (May 2025). "CORALIE radial-velocity search for companions around evolved stars (CASCADES) IV: New planetary systems around HD 87816, HD 94890, and HD 102888 and an update on HD 121056". Astronomy & Astrophysics. 
  15. ↑ Martinache, Frantz; Ireland, Michael J. (2018). "Kernel-nulling for a robust direct interferometric detection of extrasolar planets". Astronomy & Astrophysics 619: A87. doi:10.1051/0004-6361/201832847. Bibcode: 2018A&A...619A..87M. 

Coordinates: Sky map 13h 53m 52.0610s, −35° 18′ 51.6809″



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:HD_121056&oldid=3936075"