HD 219828

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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[edit]

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).

The HD 219828 planetary system
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[edit]

References[edit]

  1. ^ 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. 
  2. ^ 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[edit]

Coordinates: Sky map 23h 18m 46.7353s, +18° 38′ 44.590″