New insight in the solar T(sub MIN) region from the CO lines at 4.67 micron

Harvard-Smithsonian Center for Astrophysics.60 Garden Street. Cambridge MA 02136. USAAbstract. We discuss recent observations of the fundamental vibration-rotation transitions ofcarbon monoxide (CO) in the solar infrared spectrum. Employing a new array detector at theMcMath-Pierce facility on Kitt Peak we find that the CO lines sketch a rich picture of the dynamicsof the solar temperature minimum region, the lower boundary of the chromosphere. In a spectra-spectroheliogram and a time-sequence of slit-spectra obtained during exceptional seeing conditionswe observe small-scale bright, ring shaped, blueshifted features. We speculate that they are thesignature of granular overshoot into the convectiveiy stable temperature minimum. The centers ofthe rings are among the coolest elements seen in strong CO-line heliograms on the disk, and maybe instrumental to the low temperatures observed in CO close to the solar limb.Key words: CO molecule, temperature minimum, infrared, granulation