Driven Arae

Mu Arae (μ Ara/μ Arae) is a Naine yellow comparable with our Sun located at 49,8 light-years in the constellation of the Autel. The star has a Planetary system of four Planet S known. Nearest to Driven Arae is the first " Neptune chaude" with being discovered. Seen since the Earth, the star has an apparent magnitude of +5,12 and is visible with the naked eye.

Stellar characteristics

Mu Arae is considered more 1,1 times more massive than our sun and twice more metal. Its temperature of surface of 5800 Kelvins is similar to our sun. Its ray is 31,5% larger than our sun and its higher luminosity 75%.

Based on its activity, the age of Driven Arae is estimated at 6,4 billion years, 4,4 billion years or 1,4 billion years according to the ideal models used.

Mu Arae has a spectral Type G3IV-V, near to our sun (G2V), uncertainty coming from its age and to know if it begins its transformation into Géante red if it misses Hydrogène (IV being a under-giantess, V the principal sequence).

Planetary system

Discovered

In 2001, a planet extrasolaire is discovered by radial Speed consequently team at the same time as Epsilon Reticuli. Indicated Driven Arae B, one thinks that it has large a orbital Excentricité and orbit a 743 days.

At the beginning of 2004 is discovered a second planet Mu Arae C), and later in the same year a third much smaller Mu Arae D, which is announced with a mass comparable with that of Neptune, the first of the class of the " Neptune chaude". In 2006, two teams announced the discovery of a fourth Mu Arae E based on new model of planetary system with orbits less eccentric than thought précédemment^,. Mu Arae is the second known system having at least four planets, after 55 Cancri.

Structure

a planet of the mass of Uranus Driven Arae D to 0,1 UA of star and a 9 days orbit. It could be a telluric Planet giant or the core of a gas Géante whose external layers were vaporized by stellar radiations.
a gas Giant of 0,5 times mass of Jupiter with 0,9 UA Driven Arae E
a gas Giant , of 1,5 times mass of Jupiter, turning with 1,5 astronomical unit in 640 days Driven Arae B
Another gas giantess of 1,8 times Jupiter mass with 5.2 UA, Driven Arae C

" e" and " b" are in orbital Résonance 2:1 with strong interactions which make the system unstable and would be destroyed after 78 million years (what is much shorter than the estimated age of the system). A more stable solution in which two planets are in fact in resonance (as Gliese 876) gives an life expectancy hardly longer.

No Ceinture of Kuiper was detected.

Habitability

The gas giantess “B” is located in the livable Zone of Mu Arae and of large the possible moons around “B” could have Eau liquid. The such large moons are however problematic in the models of formation. Moreover the moons would not receive enough Ultraviolet to involve the formation of Biomolécule S.

The hypothetical moons of " e" would receive good amounts of ultra-violet but would be well too hot to shelter liquid water.

Conventions of the names

The order of the names (B with E) is not validated yet by the international astronomical Union

See too

Internal bonds

Planet extrasolaire
List of exoplanètes
PSR 1257+12
Habitability of a planet

External bonds

''' the encyclopedia of the planets extrasolaires ''': Notes concerning star Driven Arae
''' SolStation ''': Driven Arae
Representation of the system Driven Arae on the site ''' Extrasolar Visions ''':
Driven Arae on the site of the planetary Project of the University of Illinois
Characteristic of 3 planets turning around Driven Arae on the site of the Observatory of Paris
Article of ''' SPACE.com ''': '' A " super terre" discovered close to a star close ''
Site to L '''' observatory to Geneva ''': '' The discovery of a planet having 14 times mass of the Earth ''
Press release of L '''' ESO ''': '' A extra-solar planet having fourteen times mass of the Earth. ''
Article on the site ''' Science-Citizen ''' of the University Louis Pasteur of Strasbourg: '' HD 160691 D… the lightest planet detected to date ''

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