Context :

Aims : This paper presents detailed analysis and modelisation of the star HD17051 ( alias \iota Hor ) , which appears as a specially interesting case among exoplanet host stars .
As most of these stars , \iota Hor presents a metallicity excess which has been measured by various observers who give different results , ranging from [ Fe/H ] = 0.11 to 0.26 , associated with different atmospheric parameters .
Meanwhile the luminosity of the star may be determined owing to Hipparcos parallax .
Although in the southern hemisphere , this star belongs to the Hyades stream and its external parameters show that it could even be one of the Hyades stars ejected during cluster formation .
The aim of this work was to gather and analyse our present knowledge on this star and to prepare seismic tests for future observations with the HARPS spectrometer ( planned for November 2006 ) .

Methods : We have computed evolutionary tracks with various metallicities , in the two frameworks of primordial overmetallicity and accretion .
We have concentrated on models inside the error boxes given by the various observers in the log g - log T _ { \mbox { eff } } diagram .
We then computed the adiabatic oscillation frequencies of these models to prepare future observations .

Results : The detailed analysis of \iota Hor presented in this paper already allowed to constrain its external parameters , mass and age .
Some values given in the literature could be rejected as inconsistent with the overall analysis .
We found that a model computed with the Hyades parameters ( age , metallicity ) was clearly acceptable , but other ones were possible too .
We are confident that observations with HARPS will allow for a clear conclusion about this star and that it will bring important new light on the physics of exoplanet host stars .

Conclusions :