HD 11343

HD 11343 (HIP 8541) is a wide binary system between HD 11343 A, a K-type borderline giant star, and HD 11343 B, a red dwarf companion, located in the southern constellation of Eridanus about 500 light-years (150 pc) distant. Two gas giant exoplanets are known to orbit the primary star.

HD 11343

Location of HD 11343 (circled)
Observation data Epoch J2000.0[1]      Equinox J2000.0[1]
Constellation	Eridanus
Right ascension	01h 50m 06.33044s
Declination	−54° 27′ 53.8624″
Apparent magnitude (V)	7.88[2]
Characteristics
Evolutionary stage	Red-giant branch star
Spectral type	K2III/IV[2]
B−V color index	1.10[2]
J−H color index	0.556[2]
J−K color index	0.722[2]
Astrometry
Radial velocity (Rv)	6.61[3] km/s
Proper motion (μ)	RA: 110.617[1] mas/yr Dec.: −46.798[1] mas/yr
Parallax (π)	6.4964 ± 0.0156 mas[1]
Distance	502 ± 1 ly (153.9 ± 0.4 pc)
Absolute magnitude (MV)	1.240+0.275 −0.225[a]
Orbit
Primary	HD 11343 A
Companion	HD 11343 B
Semi-major axis (a)	~2600 AU[4]
Details[4]
HD 11343 A
Mass	1.17±0.28[4] / 2.009±0.115[5] M☉
Radius	7.83±1.02[6] R☉
Luminosity	25.1+5.8 −5.6[6] L☉
Surface gravity (log g)	2.70±0.20 cgs
Temperature	4670±100 K
Metallicity [Fe/H]	−0.15±0.08 dex
Rotational velocity (v sin i)	1.3±0.9[6] km/s
HD 11343 B
Mass	0.680+0.078 −0.083[7] M☉
Radius	0.698+0.062 −0.060[7] R☉
Surface gravity (log g)	4.58+0.11 −0.09[7] cgs
Temperature	4351+142 −113[7] K
Other designations
CD−55 412, CPD−55 351, Gaia DR3 4912062772547406976, GC 2232, HD 11343, HIP 8541, SAO 232538, PPM 331373, TIC 231019255, TYC 8482-1124-1, GSC 08482-01124, 2MASS J01500631-5427539[2]
Database references
SIMBAD	data

Stellar characteristics

The HD 11343 system has an apparent magnitude of 7.88,^[2] making it too faint to be visible by the naked eye from Earth under most circumstances, but can be observed using binoculars^[8] as an orangish dot near Achernar.

The primary component, HD 11343 A, is a red-giant branch star slightly more massive than the Sun (albeit one estimate places its mass at a significantly higher 2.0 M_☉^[5]), but approximately eight times as large in radius and 25 times as luminous. It has an effective temperature of 4,670 K (4,400 °C; 7,950 °F), corresponding to its spectral type of K2, and is slightly metal-poor, with an iron content 71% that of the Sun.^[6]

During a 2021 survey^[9] searching for binaries within data from Gaia EDR3, the star was found to be orbited by a 13th-magnitude^[10] M-dwarf, designated HD 11343 B. It is about 70% as large as the Sun both in mass and radius, is slightly cooler than the primary red giant at 4,351 K (4,078 °C; 7,372 °F), and is situated at a separation of roughly 2,600 astronomical units (0.041 ly) from its brighter companion.^[4][7]

Planetary system

In 2016, a super-Jupiter planet orbiting HD 11343 A was discovered from radial-velocity observations, alongside three other substellar companions to giant stars, namely HIP 74890 b, HIP 84056 b, and HIP 95124 b.^[6] This planet, HD 11343 b, is estimated to be slightly larger than Jupiter and has a mass of 5.7 M_J,^[4] close to the initially estimated minimum of 5.5 M_J.^[6] It revolves around its host star at a semi-major axis of 2.8 AU (420,000,000 km), around where the asteroid belt would lie in the Solar System, every 1,585 days (4.34 years) in a mildly eccentric orbit.^[6]

Another planet, HD 11343 c, was discovered in 2022 closer to HD 11343 A, also using the radial-velocity method. The planet is reportedly a Jupiter analog, larger than the previous planet but likely considerably less massive, with a minimum mass of 0.804 M_J. It orbits its star at a distance of 0.923 AU (138,100,000 km) every 228.5 days (0.626 years). Due to the faintness of the astrometric signals it produces, its orbital inclination cannot be well-constrained. The discovery paper for HD 11343 c notably presents a higher mass (7.71+0.73
−1.19 M_J), semi-major axis (3.729 AU), orbital period (5.07 years), and eccentricity (0.360) for HD 11343 b.^[5]

The HD 11343 A planetary system^[5][4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
c	≥0.804 MJ	0.923 +0.019 −0.022	228.5 +3.3 −3.8	0.169 +0.142 −0.102	—	~1.24[11] RJ
b	5.7 +1.2 −1.1 MJ	2.80 +0.21 −0.25	1585 +27 −40	0.122 +0.060 −0.067	73.0 +12.0 −16.0°	~1.13[12] RJ

Footnotes

1. Calculated from star's luminosity.

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
2. "HD 11343". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 September 2024.
3. 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.
4. Xiao, Guang-Yao; et al. (1 May 2023). "The Masses of a Sample of Radial-velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. 23 (5): 055022. arXiv:2303.12409. doi:10.1088/1674-4527/accb7e. ISSN 1674-4527.
5. Feng, Fabo; Butler, R. Paul; Vogt, Steven S.; Clement, Matthew S.; Tinney, C. G.; Cui, Kaiming; Aizawa, Masataka; Jones, Hugh R. A.; Bailey, J.; Burt, Jennifer; Carter, B. D.; Crane, Jeffrey D.; Dotti, Francesco Flammini; Holden, Bradford; Ma, Bo; Ogihara, Masahiro; Oppenheimer, Rebecca; O’Toole, S. J.; Shectman, Stephen A.; Wittenmyer, Robert A.; Wang, Sharon X.; Wright, D. J.; Xuan, Yifan (1 September 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (1): 21. arXiv:2208.12720. doi:10.3847/1538-4365/ac7e57. ISSN 0067-0049. This article incorporates text from this source, which is available under the CC BY 4.0 license.
6. Jones, M. I.; et al. (2016). "Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars". Astronomy & Astrophysics. 590: A38. arXiv:1603.03738. doi:10.1051/0004-6361/201628067. ISSN 0004-6361.
7. Stassun, Keivan G.; et al. (1 October 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256.
8. Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
9. El-Badry, Kareem; Rix, Hans-Walter; Heintz, Tyler M (20 July 2021). "A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties". Monthly Notices of the Royal Astronomical Society. 506 (2): 2269–2295. arXiv:2101.05282. doi:10.1093/mnras/stab323. ISSN 0035-8711.
10. "HIP 8541 Overview". NASA Exoplanet Archive. Retrieved 21 September 2024.
11. "HD 11343 c - NASA Science". Retrieved 21 September 2024.
12. "HIP 8541 b - NASA Science". Retrieved 21 September 2024.

External links

• HD 11343 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• Extrasolar Planets Encyclopaedia links: HD 11343 b, c