HD 219828
| Observation data Epoch 2000 Equinox 2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 18m 46.7353s |
| Declination | +18° 38′ 44.590″ |
| Apparent magnitude (V) | +8.04 |
| Distance | 264.5 ly (81.1 pc) |
| Spectral type | G0IV |
| Other designations | |
BD+17° 4896, GSC 01716-01182, HIP 115100, SAO 108536 | |
| Database references | |
| SIMBAD | data |
HD 219828 is an 8th magnitude star approximately 265 light years away in the constellation of Pegasus. It is a yellow subgiant, meaning that hydrogen fusion has ceased in its core.
Planetary system
In 2007, a Neptune-mass planet was found orbiting the star by Melo. According to the author, assuming an Earth-like rocky composition,[1] the planet could yield a radius 2.2 times that of Earth. This could be furtherly proved if transit were observed, though, as authors state, it is a difficult task.[2] Moreover a best fit orbital solution hints the presence of an additional planetary companion (so far unconfirmed) with 70% of Jupiter's mass, likely orbital separation of 0.68 Astronomical units and eccentric orbit (e=0.3).
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >0.066 MJ | 0.052 | 3.8335 ± 0.0013 | 0 | — | — |
| c (unconfirmed) | ≥0.7 MJ | ≈0.68 | ≥181 | ≥0.3 | — | — |
See also
- HD 159868
- List of extrasolar planets
References
- ↑ Valencia et al.; Oconnell, R; Sasselov, D (2006). "Internal structure of massive terrestrial planets". Icarus 181 (2): 545–554. arXiv:astro-ph/0511150. Bibcode:2006Icar..181..545V. doi:10.1016/j.icarus.2005.11.021.
- ↑ Melo, C. et al. (2007). "A new Neptune-mass planet orbiting HD 219828". Astronomy and Astrophysics 467 (2): 721–727. arXiv:astro-ph/0702459. Bibcode:2007A&A...467..721M. doi:10.1051/0004-6361:20066845.
External links
- "HD 219828". The Extrasolar Planets Encyclopaedia.
Coordinates: 
23h 18m 46.7353s, +18° 38′ 44.590″
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