HD 190228
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 03m 00.773s[1] |
| Declination | +28° 18′ 24.68″[1] |
| Apparent magnitude (V) | 7.307 |
| Characteristics | |
| Spectral type | G5IV |
| Astrometry | |
| Proper motion (μ) | RA: 105.20 ± 0.33[1] mas/yr Dec.: –69.82 ± 0.48[1] mas/yr |
| Parallax (π) | 16.23 ± 0.64[1] mas |
| Distance | 201 ± 8 ly (62 ± 2 pc) |
| Orbit[2] | |
| Period (P) | 1146.0 ± 16.0 d |
| Eccentricity (e) | 0.50 ± 0.04 |
| Inclination (i) | 4.3+1.8 −1.0° |
| Longitude of the node (Ω) | 61.0+22.7 −22.9° |
| Argument of periastron (ω) (primary) | 100.7 ± 3,2° |
| Details | |
| HD 190228 | |
| Mass | 0.83[3] M☉ |
| Surface gravity (log g) | 4.02 ± 10[3] cgs |
| Temperature | 5360 ± 40[3] K |
| Metallicity [Fe/H] | –0.24 ± 0.06[3] dex |
| HD 190228 b | |
| Mass | 0.0472 ± 0.0141[2] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
| Extrasolar Planets Encyclopaedia | data |
HD 190228 is a star located in the constellation Vulpecula. Its apparent magnitude is 7.31 and the absolute magnitude is 3.34. The distance is 201 light years from Earth. The star is definitely old with age over 10 billion years and it is metal-poor.
In 2000, it was announced that a giant planet was orbiting the star with a minimum mass of 5 Jupiter masses, designated HD 190228 b.[4] The planetary nature of the object was questioned because of the low metal content of the star: giant planets are more likely to be found around high-metallicity stars, so it was argued that the object was more likely to be a brown dwarf.[5] Later astrometric measurements confirmed this: HD 190228 b is in fact a brown dwarf of 49.4 Jupiter masses in a nearly face-on orbit. The brown dwarf takes 1146 days to orbit the star, and the orbit is elliptical with an eccentricity of 0.5.[2]
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 Sahlmann, J.; et al. (2011). "The companion of HD 190228: Planet or brown dwarf?". Astronomy and Astrophysics. 525. A95. arXiv:1009.5991. Bibcode:2011A&A...525A..95S. doi:10.1051/0004-6361/201015427.
- 1 2 3 4 Perrier, C.; et al. (2003). "The ELODIE survey for northern extra-solar planets. I. Six new extra-solar planet candidates". Astronomy and Astrophysics. 410 (3): 1039–1049. arXiv:astro-ph/0308281. Bibcode:2003A&A...410.1039P. doi:10.1051/0004-6361:20031340.
- ↑ "European Southern Observatory: Six Extrasolar Planets Discovered". SpaceRef Interactive Inc. 7 August 2000. Retrieved 15 August 2009.
- ↑ Chen, Y. Q.; Zhao, G. (2001). "The companion of HD 190228: Planet or brown dwarf?". Astronomy and Astrophysics. 374 (1): L1–L4. Bibcode:2001A&A...374L...1C. doi:10.1051/0004-6361:20010790.