HD 139357
K-type giant star in the constellation Draco
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HD 139357 is a 6th magnitude K-type giant star located approximately 370 light years from Earth, visible in the constellation Draco. Its mass is four thirds that of the Sun 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.
| 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−V color index | 1.184±0.006[1] |
| Astrometry | |
| Radial velocity (Rv) | −8.53±0.13[2] km/s |
| Proper motion (μ) | RA: −18.845±0.051 mas/yr[2] Dec.: 2.097±0.063 mas/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 |
It hosts a substellar companion with a minimum mass of 9.76 MJ, discovered in 2009.[5] A 2022 study estimated the true mass of HD 139357 b at about 16.38 MJ via astrometry, although this estimate is poorly constrained. If this is the true mass, the object would be a brown 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 | — | — |
