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We present the results of contemporaneous spectroscopic and photometricmonitoring of the young solar-type star HD171488 (Prot~1.337 d) aimed atstudying surface inhomogeneities at photospheric/chromospheric levels. EchelleFOCES spectra (R~40000) and Johnson photometry have been performed in 2006.Spectral type, rotational velocity, metallicity, and gravity were determinedusing a code developed by us. The metallicity was measured from the analysis ofiron lines. The spectral subtraction technique was applied to the most relevantchromospheric diagnostics included in the FOCES spectral range (CaII IRT,Halpha, HeI-D3, Hbeta, CaII H&K). A model with two large high-latitude spots issufficient to reproduce the B/V light curves and the radial velocitymodulation, if a temperature difference between photosphere and spots of 1500 Kis used. A Doppler imaging analysis of photospheric lines confirms a similarspot distribution. With the help of an analogous geometric two-spot model, weare able to reproduce the modulations in the residual chromospheric emissionsadopting different values of ratios between the flux of plages and quietchromosphere (5 for Halpha and 3 for CaII). Facular regions of solar typeappear to be the main responsible for the modulations of chromosphericdiagnostics. Both the spot/plage model and the cross-correlation between thelight curve and the chromospheric line fluxes display a lead effect of plageswith respect to spots (20-40 deg in longitude). The active regions of therapidly rotating star HD171488 are similar to the solar ones in some respect,because the spot temperature is close to that of sunspot umbrae and the plageflux-contrast is consistent with the average solar values. The main differenceswith respect to the Sun are larger sizes and higher latitudes.

Photospheric and chromospheric activity on the young solar-type star HD 171488