| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Draco[1] |
| Right ascension | 15h 35m 16.19859s[2] |
| Declination | +53° 55′ 19.7094″[2] |
| Apparent magnitude (V) | 5.97[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K4III[3] |
| B−Vcolor index | 1.184±0.006[1] |
| Astrometry | |
| Radial velocity (Rv) | −8.53±0.13[2] km/s |
| Proper motion (μ) | RA: −18.845±0.051mas/yr[2] Dec.: 2.097±0.063mas/yr[2] |
| Parallax (π) | 8.8114±0.0460 mas[2] |
| Distance | 370 ± 2 ly (113.5 ± 0.6 pc) |
| Absolute magnitude (MV) | 0.61[1] |
| Details | |
| Mass | 1.1±0.1 M☉[4] 1.35±0.24 M☉[5] 2.16±0.18[3] M☉ |
| Radius | 11.47±0.75 R☉[5] 14.4±0.4[3] R☉ |
| Luminosity | 74±1[4] L☉ |
| Surface gravity (log g) | 2.2±0.1 cgs[4] 2.63±0.10 cgs[6] 2.9±0.15[5] cgs |
| Temperature | 4,601±28[6] K |
| Metallicity[Fe/H] | −0.13±0.05 dex[5] 0.34±0.05[3] dex |
| Age | 1.19±0.33 Gyr[6] 3.07±1.47 Gyr[3] 7.20±1.80[4] Gyr |
| Other designations | |
| BD+54°1756,GC 20977,HD 139357,HIP 76311,HR 5811,SAO 29583,PPM 35043,GCRV 9003[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 139357 is a 6thmagnitudeK-typegiantstar located approximately 370light years from Earth, visible in theconstellationDraco. Its mass is four thirds that of theSun but its radius is 11.47 times larger. However, despite being a giant star, it is only 3.07 billion years old, which is younger than the Sun.
It hosts a substellar companion with aminimum mass of9.76 MJ, discovered in 2009.[5] A 2022 study estimated the true mass of HD 139357 b at about16.38 MJ viaastrometry, although this estimate is poorly constrained. If this is the true mass, the object would be abrown dwarf.[8]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥9.76 ± 2.15 MJ | 2.36 ± 0.02 | 1125.7 ± 9 | 0.10 ± 0.02 | — | — |
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