Astronomy:HD 121056

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Short description: Star in the constellation Centaurus
HD 121056
Observation data
Equinox J2000.0]] (ICRS)
Constellation Centaurus
Right ascension  13h 53m 52.06131s[1]
Declination −35° 18′ 51.6918″[1]
Apparent magnitude (V) 6.17[2]
Characteristics
Evolutionary stage giant star
Spectral type K0 III[3]
B−V color index 1.01[4]
Astrometry
Radial velocity (Rv)5.60±0.13[1] km/s
Proper motion (μ) RA: −295.304±0.040[1] mas/yr
Dec.: −68.458±0.058[1] mas/yr
Parallax (π)15.6261 ± 0.0418[1] mas
Distance208.7 ± 0.6 ly
(64.0 ± 0.2 pc)
Absolute magnitude (MV)+2.08[5]
Details
Mass1.60±0.18[6] M☉
Radius5.72[7] R☉
Luminosity15.8[7] L☉
Surface gravity (log g)3.261±0.105[2] cgs
Temperature4,867±49[2] K
Metallicity[Mg/H] 0.286±0.05 dex[2]
Metallicity [Fe/H]0.020±0.031[2] dex
Rotational velocity (v sin i)2.38±0.51[2] km/s
Age5.46[7] Gyr
Other designations
CD−34 9223, Gaia DR2 6169943210465504384, GJ 532.1, HD 121056, HIP 67851, HR 5224, TYC 7287-1874-1, 2MASS J13535209-3518517[8]
Database references
SIMBADdata

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.[2] 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.[1]

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.[4] 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.[2] It has 1.6[6] 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.[2]

Planetary system

In 2014, two planets orbiting HD 121056 were discovered by the radial velocity method,[4] and were confirmed a few months later.[9] The orbits of these planets are stable on astronomical timescales,[10] although the periods are not in orbital resonance.[11] In 2022, the inclination and true mass of HD 121056 c were measured via astrometry.[12]

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.[13]

The HD 121056 planetary system[12]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥ 1.568+0.071
−0.072 MJ 		0.482+0.009−0.010 88.9±0.1 0.063+0.031−0.032 — —
c 6.937+2.045−0.518 MJ 6.032+0.651−0.362 3,923.7+617.5−330.2 0.356+0.112−0.085 89.863+28.378−24.730° —

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 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. 
  3. ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey 5. Bibcode: 1999MSS...C05....0H. 
  4. ↑ 4.0 4.1 4.2 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. 
  5. ↑ Anderson, E.; Francis, Ch. (2012-05-01). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  6. ↑ 6.0 6.1 Sousa, S. G. et al. (2018). "SWEET-Cat updated". Astronomy & Astrophysics 620: A58. doi:10.1051/0004-6361/201833350. Bibcode: 2018A&A...620A..58S. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 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. ↑ 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. 
  11. ↑ 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. 
  12. ↑ 12.0 12.1 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. 
  13. ↑ 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″



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