HD 181720
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 22m 52.99s[1] |
| Declination | –32° 55′ 08.6″[1] |
| Apparent magnitude (V) | 7.84[2] |
| Characteristics | |
| Spectral type | G1V[2] |
| Apparent magnitude (B) | 8.44 |
| Apparent magnitude (J) | 6.652 |
| Apparent magnitude (H) | 6.346 |
| Apparent magnitude (K) | 6.294 |
| V−R color index | 0.599[2] |
| Astrometry | |
| Radial velocity (Rv) | –57.2 km/s |
| Proper motion (μ) | RA: 88.03 ± 1.44[1] mas/yr Dec.: –414.99 ± 0.90[1] mas/yr |
| Parallax (π) | 17.22 ± 1.16[1] mas |
| Distance | 190 ± 10 ly (58 ± 4 pc) |
| Absolute magnitude (MV) | 4.10[2] |
| Details | |
| Mass | 0.92[2] M☉ |
| Radius | 1.39[2] R☉ |
| Luminosity | 1.94[2] L☉ |
| Surface gravity (log g) | 4.24 ± 0.15[2] cgs |
| Temperature | 5781 ± 18[2] K |
| Metallicity | -0.53 ± 0.02[2] |
| Rotation | 47 days |
| Rotational velocity (v sin i) | 1.5[2] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| Extrasolar Planets Encyclopaedia | data |
HD 181720 is an 8th magnitude G-type main sequence star located approximately 190 light years away in the constellation Sagittarius. This star is larger, hotter, brighter, and less massive than our Sun. Also its metal content is three-tenths as much as the Sun. In 2009, a gas giant planet was found in orbit around the star.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥0.37 MJ | 1.78 | 956 ± 14 | 0.26 ± 0.06 | — | — |
See also
References
- 1 2 3 4 5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752
. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry - 1 2 3 4 5 6 7 8 9 10 11 12 Santos, N. C.; et al. (2010). "The HARPS search for southern extrasolar planets XXI. Three new giant planets orbiting the metal-poor stars HD5388, HD181720, and HD190984". Astronomy and Astrophysics. 512. A47. arXiv:0912.3216. Bibcode:2010A&A...512A..47S. doi:10.1051/0004-6361/200913489.
Coordinates: 
19h 22m 52.9859s, −32° 55′ 08.595″
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