Astronomy:HD 74156

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Short description: Star in the constellation Hydra
HD 74156
Observation data
Equinox J2000.0]] (ICRS)
Constellation Hydra
Right ascension  08h 42m 25.12195s[1]
Declination +04° 34′ 41.1457″[1]
Apparent magnitude (V) +7.614[2]
Characteristics
Spectral type G0V
U−B color index ?
B−V color index 0.581[2]
V−R color index 0.4
R−I color index 0.2
Variable type “None”
Astrometry
Radial velocity (Rv)3.90±0.13[1] km/s
Proper motion (μ) RA: 24.666±0.025[1] mas/yr
Dec.: −200.238±0.019[1] mas/yr
Parallax (π)17.4242 ± 0.0247[1] mas
Distance187.2 ± 0.3 ly
(57.39 ± 0.08 pc)
Absolute magnitude (MV)+3.57 ± 0.15
Details
Mass1.24[2] M☉
Radius1.64 ± 0.19[2] R☉
Luminosity (bolometric)3.037 ± 0.485[2] L☉
Surface gravity (log g)4.4 ± 0.15[2] cgs
Temperature5960 ± 100[2] K
Metallicity [Fe/H]+0.13[2] dex
Rotational velocity (v sin i)4.3[2] km/s
Age3.7 ± 0.4[2] Gyr
Other designations
HIP 42723, SAO 117040, BD+05 2035, 2MASS J08422511+0434411
Database references
SIMBADdata

HD 74156 is a yellow dwarf star (spectral type G0V) in the constellation of Hydra, 187 light years from the Solar System.[1] It is known to be orbited by two giant planets.

Star

This star is 24% more massive and 64% larger than the Sun. The total luminosity is 2.96 times that of the Sun and its temperature 5960 K.[2] The age of the star is estimated at 3.7 billion years,[2] with metallicity 1.35 times that of the Sun based on its abundance of iron.

Planetary system

In April 2001, two giant planets were announced orbiting the star.[3][4] The first planet HD 74156 b orbits the star at a distance closer than Mercury is to the Sun, in an extremely eccentric orbit. The second planet HD 74156 c is a long-period, massive planet (at least 8 times the mass of Jupiter), which orbits the star in an elliptical orbit with a semimajor axis of 3.90 astronomical units.[2] In 2022, the inclination and true mass of HD 74156 c were measured via astrometry.[5]

The HD 74156 planetary system[6][5]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥1.778±0.020 MJ 0.2916±0.0033 51.6385±0.0015 0.6380±0.0061 — —
c 8.665+1.385
−0.470 MJ 		3.678+0.145
−0.159 		2448.5±4.2 0.377±0.006 120.162+7.601
−66.225° 		—

Claims of a third planet

Given the two-planet configuration of the system under the assumption that the orbits are coplanar and have masses equal to their minimum masses, an additional Saturn-mass planet would be stable in a region between 0.9 and 1.4 AU between the orbits of the two known planets.[7] Under the "packed planetary systems" hypothesis, which predicts that planetary systems form in such a way that the system could not support additional planets between the orbits of the existing ones, the gap would be expected to host a planet.

In September 2007, a third planet with a mass at least 0.396 Jupiter masses was announced to be orbiting between planets b and c with an eccentric orbit.[8] The planet, orbiting in a region of the planetary system previously known to be stable for additional planets, was seen as a confirmation of the "packed planetary systems" hypothesis.[9] However, Roman V. Baluev has cast doubt on this discovery, suggesting that the observed variations may be due to annual errors in the data.[10] A subsequent search using the Hobby-Eberly Telescope also failed to confirm the planet,[11] and further data obtained using HIRES instrument strongly contradicts its existence.[2]

See also

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. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 Meschiari, Stefano et al. (2011). "The Lick-Carnegie Survey: Four New Exoplanet Candidates". The Astrophysical Journal 727 (2): 117. doi:10.1088/0004-637X/727/2/117. Bibcode: 2011ApJ...727..117M. http://iopscience.iop.org/0004-637X/727/2/117/article. 
  3. ↑ "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 27, 2012.
  4. ↑ Naef, Dominique; Mayor, Michel; Beuzit, Jean-Luc; Perrier, Christian; Queloz, Didier; Sivan, Jean-Pierre; Udry, Stéphane (2004). "The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE". Astronomy and Astrophysics 414 (1): 351–359. doi:10.1051/0004-6361:20034091. Bibcode: 2004A&A...414..351N. http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/pdf/2004/04/aa0091.pdf. 
  5. ↑ 5.0 5.1 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. 
  6. ↑ Feng, Y. Katherina et al. (2015). "The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-period Planets". The Astrophysical Journal 800 (1): 22. doi:10.1088/0004-637X/800/1/22. Bibcode: 2015ApJ...800...22F. 
  7. ↑ Sean N. Raymond; Rory Barnes (2005). "Predicting Planets in Known Extrasolar Planetary Systems. II. Testing for Saturn Mass Planets". The Astrophysical Journal 619 (1): 549–557. doi:10.1086/426311. Bibcode: 2005ApJ...619..549R. http://www.iop.org/EJ/article/0004-637X/619/1/549/60354.html. 
  8. ↑ Jacob L. Bean (2008). "Detection of a Third Planet in the HD 74156 System Using the Hobby-Eberly Telescope". The Astrophysical Journal 672 (2): 1202–1208. doi:10.1086/523701. Bibcode: 2008ApJ...672.1202B. http://www.iop.org/EJ/article/0004-637X/672/2/1202/72746.html. 
  9. ↑ Barnes, Rory et al. (2008). "The Successful Prediction of the Extrasolar Planet HD 74156 d". The Astrophysical Journal Letters 680 (1): L57–L60. doi:10.1086/589712. Bibcode: 2008ApJ...680L..57B. http://iopscience.iop.org/1538-4357/680/1/L57/fulltext/. 
  10. ↑ Baluev, Roman V. (2008). "Accounting for velocity jitters in planet search surveys". Monthly Notices of the Royal Astronomical Society 393 (3): 969–978. doi:10.1111/j.1365-2966.2008.14217.x. Bibcode: 2009MNRAS.393..969B. 
  11. ↑ Wittenmyer, Robert A.; Endl, Michael; Cochran, William D.; Levison, Harold F.; Henry, Gregory W. (2009). "A Search for Multi-Planet Systems Using the Hobby-Eberly Telescope". The Astrophysical Journal Supplement 182 (1): 97–119. doi:10.1088/0067-0049/182/1/97. Bibcode: 2009ApJS..182...97W. 

External links

Coordinates: Sky map 08h 42m 25.1222s, +04° 34′ 41.151″



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