HD 190228

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
Distance201 ± 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
Mass0.83[3] M
Surface gravity (log g)4.02 ± 10[3] cgs
Temperature5360 ± 40[3] K
Metallicity [Fe/H]–0.24 ± 0.06[3] dex
HD 190228 b
Mass0.0472 ± 0.0141[2] M
Other designations
BD+27° 3593, GCRV 70273, HIP 98714, SAO 88118
Database references
SIMBADdata
ARICNSdata
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


This article is issued from Wikipedia - version of the Monday, December 29, 2014. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.