The broadening of the photospheric lines in ζ Ophiuchu by very rapid rotation allows not ony mapping of its surface velocities and temperature distribution, but makes the star an excellent probe for a profusion of sharp interstellar lines. Being bright, it is a good object for smaller telescopes. Apart from discovering nonradial oscillations in its atmosphere over twenty years ago and a significant temperature differential between pole and equator (the von Zeipel effect), I have recently assisted in the discovery of some 30 lines of interstellar C3 near 405 nm - the first carbon chain to have been found in a diffuse interstellar cloud and at a much higher concentration than expected.
\vspace{-1.6cm} The paper studies the relations between ϕ-divergences and fundamental concepts of decision theory such as sufficiency, Bayes sufficiency, and LeCam's deficiency. A new and considerably simplified approach is given to the spectral representation of ϕ-divergences already established in Österreicher and Feldman \cite{OestFeld} under restrictive conditions and in Liese and Vajda \cite{LiV06}, \cite{LiV08} in the general form. The simplification is achieved by a new integral representation of convex functions in terms of elementary convex functions which are strictly convex at one point only. Bayes sufficiency is characterized with the help of a binary model that consists of the joint distribution and the product of the marginal distributions of the observation and the parameter, respectively. LeCam's deficiency is expressed in terms of ϕ-divergences where ϕ belongs to a class of convex functions whose curvature measures are finite and satisfy a normalization condition.