| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 18h 32m 15.4933s[1] |
| Declination | 06° 56′ 44.6858″[1] |
| Apparent magnitude (V) | 8.301[2] |
| Characteristics | |
| Spectral type | G0[3] |
| B−V color index | 0.61[3] |
| Astrometry | |
| Radial velocity (Rv) | +13.48±0.28[1] km/s |
| Proper motion (μ) | RA: −42.869±0.084[1] mas/yr Dec.: −14.705±0.077[1] mas/yr |
| Parallax (π) | 8.9274 ± 0.0497 mas[1] |
| Distance | 365 ± 2 ly (112.0 ± 0.6 pc) |
| Details | |
| Mass | 1.01±0.06[2] M☉ |
| Radius | 2.42+0.01 −0.03[1] R☉ |
| Luminosity | 5.406+0.042 −0.041[1] L☉ |
| Surface gravity (log g) | 3.84±0.03[2] cgs |
| Temperature | 5,671±16[2] K |
| Metallicity [Fe/H] | −0.48±0.01[2] dex |
| Rotational velocity (v sin i) | 2.3[3] km/s |
| Age | 4.890±0.229[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 171028 is a star with an exoplanet companion in the equatorial constellation of Ophiuchus. With an apparent visual magnitude of 8.3,[2] it is too faint to be readily visible with the naked eye. Unlike most planet-harboring stars, it does not have a Hipparcos number. The star is located at a distance of approximately 365 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13.5 km/s.[1]
This is a yellow-hued G-type star of unknown luminosity class with a stellar classification of G0.[3] It is a metal-poor star belonging to the thin disk population.[6] HD 171028 is estimated to be nearly five billion years old and is spinning with a projected rotational velocity of 2.3 km/s.[3] It has the same mass as the Sun, but the radius is 2.4 times larger. The star is radiating 5.4[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,671 K.[2]
In the summer of 2007, a Jovian planetary companion was discovered by the HARPS planet search program using the radial velocity method.[3] This object is orbiting at a distance of 1.32 AU from the host star with a period of 1.5 years and an eccentricity (ovalness) of 0.59. Since the inclination of the orbit is unknown, only a minimum mass can be determined. This planet has at least double the mass of Jupiter.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥1.98 MJ | 1.32 | 550±3 | 0.59±0.01 | — | — |
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