The cuspy liner nucleus of the S0/A galaxy NGC 2681

The nucleus of the bulge-dominated, multiply barred S0/a galaxy NGC 2681 is studied in detail using the high-resolution Hubble Space Telescope Faint O bject Camera (FOC), Near-Infrared Camera and Multiobject Spectrometer (NICM OS) imaging, and the Faint Object Spectrograph (FOS). The ionized gas centr al velocity dispersion is found to increase by a factor approximate to2 whe n narrowing the aperture from R approximate to 1."5 (ground) to R approxima te to 0."1 (FOS). Dynamical modeling of these velocity dispersions suggests that NGC 2681 does host a supermassive black hole (BH) for which one can e stimate a firm mass upper limit M-BH less than or similar to 6 x 10(7) M. T his upper limit is consistent with the relation between the central BH mass and velocity dispersion M-BH - sigma known for other galaxies. The emissio n-line ratios place the nucleus of NGC 2681 among LINERs. It is likely that the emission-line region comes from a rather mild, but steady, feeding of gas to the central BH in this galaxy. The inner stellar population lacks an y measurable color gradient (to a radius of 0.6 kpc) from the infrared to t he ultraviolet, consistently with FOC, FOS, and IUE data, all indicating th at this system underwent a starburst approximate to1 Gyr ago that encompass ed its whole interior, down to its very center. The most likely source of s uch a widely distributed starburst is the dumping of tidally extruded gas f rom a galaxy neighbor. If so, then NGC 2681 can be considered as the older brother of M82, seen face-on as opposed to the edge-on view we have for M82 .