HR 6806
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules[1] |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 6.40[3] |
| Characteristics | |
| Spectral type | K2 V[4] |
| U−B Template:Engvar | +0.585[3] |
| B−V Template:Engvar | +0.875[3] |
| Astrometry | |
| Radial velocity (Rv) | Script error: No such module "val".[2] km/s |
| Proper motion (μ) | RA: −316.520[2] mas/yr Dec.: −468.214[2] mas/yr |
| Parallax (π) | 90.1264±0.0200 mas[2] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 6.17[5] |
| Details | |
| Mass | Script error: No such module "val".[6] Template:Solar mass |
| Radius | Script error: No such module "val".[6] Template:Solar radius |
| Luminosity | 0.35[6] Template:Solar luminosity |
| Surface gravity (log g) | 4.53[4] cgs |
| Temperature | 4,900[4] K |
| Metallicity [Fe/H] | −0.61[4] dex |
| Rotation | 42 d[7] |
| Rotational velocity (v sin i) | 4.82[8] km/s |
| Age | 5.8–7.1[9] Gyr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[10] | |
| Database references | |
| SIMBAD | data |
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HR 6806 or HD 166620 is a solitary, orange, main sequence, and Sun-like (K2 V) star located thirty-six light-years away,[11] in the constellation Hercules. The star is smaller than the Sun, with around 79% of the solar mass and radius, and 35% of the solar luminosity.[6] It appears to be rotating slowly with an estimated period of 42 days. In 1988, it was noticed that the star had an inactive chromosphere, with a surface magnetic field strength of only 1,500 G.[7] From 1990 activity in the chromosphere increased, inline with a 16 year stellar cycle previously observed. But, sometime after 1994 (exact date unknown because of a data collection gap between 1995 and 2004) chromospheric activity greatly reduced, and has stayed flat for more than 16 years. As of 2022,[update]Template:Dated maintenance category (articles)Script error: No such module "Check for unknown parameters". the star appears to have entered the equivalent of a Maunder minimum.[11] The star is around six billion years of age.[9]
There was suspected to be a nearby very cool, and very dim, T9 to Y brown dwarf companion, WISE J180901.07+383805.4, at an angular separation of 769″, which would have corresponded to a projected separation of 8460 AU at the distance of HR 6806. However, with further observation it was found to be bluer than at first thought and more typical of a slightly brighter T7 dwarf, which would place it at a much greater distance of Script error: No such module "convert".—ruling out a physical association. This is confirmed by the differing proper motion of the star and this object.[12]
References
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- ↑ Template:Cite simbad
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External links
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- NStars: 1809+3827Script error: No such module "Unsubst".