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We select a sample of young passive galaxies from the Sloan Digital SkySurvey Data Release 7 in order to study the processes that quench starformation in the local universe. Quenched galaxies are identified based on thecontribution of A-type stars to their observed (central) spectra and relativelack of ongoing star formation; we find that such systems account for roughly2.5 per cent of all galaxies with log M_sun >= 9.5, and have a space density of~2.2x10^-4 Mpc^-3. We show that quenched galaxies span a range of morphologies,but that visual classifications suggest they are predominantly early-typesystems. Their visual early-type classification is supported by quantitativestructural measurements Sersic indices that show a notable lack ofdisk-dominated galaxies, suggesting that any morphological transformationassociated with galaxies' transition from star-forming to passive--e.g. theformation of a stellar bulge--occurs contemporaneously with the decline oftheir star-formation activity. We show that there is no clear excess of opticalAGN in quenched galaxies, suggesting that: i) AGN feedback is not associatedwith the majority of quenched systems or ii) that the observability of quenchedgalaxies is such that the quenching phase in general outlives any associatednuclear activity. Comparison with classical post-starburst galaxies shows thatboth populations show similar signatures of bulge growth, and we suggest thatthe defining characteristic of post-starburst galaxies is the efficiency oftheir bulge growth rather than a particular formation mechanism.

Towards a physical picture of star-formation quenching: the photometric properties of recently-quenched galaxies in the Sloan Digital Sky Survey