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Reproduced by permission of the AAS. © 2009. The American Astronomical Society. All rights reserved. We thank J. Cenarro for his help on investigating the spectra for potential problems and for providing the GC data. We are also grateful to Russell Smith for providing the data from the Hectospec Coma cluster survey and double checking our measurements. R. G. gratefully acknowledges University of Yale for the awarded nights at WIYN telescope. P. Sánchez Blázquez acknowledges the support by a Marie Curie Intra-European Fellowship within the 6th European Community Framework Programme. We also thank the anonymous referee whose suggestions have improved this work., We present line-strength measurements for 74 early-type galaxies in the core of the Coma cluster reaching down to velocity dispersions, sigma, of 30 km s(-1). The index-sigma relations for our sample, including galaxies with sigma < 100 km s(-1) (low-sigma), differ in shape depending on which index is used. We note two types of relations for the metallic indices: one showing a break in the slope around similar to 100 km s(-1) and another group with strong linear relations between an index and log s. We find no connection between the behavior of index-sigma relations with either alpha- or Fe-peak elements. However, we find indications that the relations are tighter for indices which do not depend on the microturbulent velocities of stellar atmospheres. We confirm previous results that low-sigma galaxies including dE/dS0s are on average younger, less metal rich, and have lower [alpha/Fe] in comparison with E/S0s. Our data show that these trends derived for high-sigma galaxies extend down to dE/dS0s. This is a factor of similar to 2 lower in sigma than previously published work. We confirm that the observed anticorrelation between age and metallicity for high-sigma galaxies is consistent with the effects of correlated errors. Low-sigma galaxies also show a similar relation between age and metallicity as a result of correlated errors. However, they are offset from this relationship so that, on average, they are less metal rich and younger than their high-sigma counterparts., Marie Curie Intra-European Fellowship, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO, 2012. We thank the anonymous referee for his/her comments that have helped us to significantly improve this manuscript. E. T. thanks Juan Carlos Muñoz Mateos, Armando Gil de Paz, Mina Koleva, Sven de Rijcke, Puragra GuhaThakurta and Joshua Simon for very useful discussions. We thank the MAGPOP EU Marie Curie Training Network for financial support for the collaborating research visits and observations that allowed to make this paper. The observing time used in this work was part of the International Time Program (ITP 2005-2007, ITP4) at El Roque de los Muchachos Observatory (La Palma, Spain). E. T. thanks the financial support of the Fulbright Program jointly with the Spanish Ministry of Education. E. T. and J.G. have received financial support through the Spanish research projects AYA2007-67752-C03-03 and AYA2010-21322-C03-03. J.F.B. acknowledges support from the Ramón y Cajal Program as well as grant AYA2010-21322-C03-02 by the Spanish Ministry of Science and Innovation. This paper made use of the following public databases: SDSS (York et al. 2000), NASA/IPAC Extagalactic Database (NED, operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration), 2MASS (Two Micron All Sky Survey, Skrutskie et al. 2006, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation), HyperLEDA (Paturel et al. 2003), GOLDMine (Gavazzi et al. 2003)., We place our sample of 18 Virgo dwarf early-type galaxies (dEs) on the (V - K)_e-velocity dispersion, Faber-Jackson, and fundamental plane (FP) scaling relations for massive early-type galaxies (Es). We use a generalized velocity dispersion, which includes rotation, to be able to compare the location of both rotationally and pressure supported dEs with those of early and late-type galaxies. We find that dEs seem to bend the Faber-Jackson relation of Es to lower velocity dispersions, being the link between Es and dwarf spheroidal galaxies (dSphs). Regarding the FP relation, we find that dEs are significantly offset with respect to massive hot stellar systems, and re-casting the FP into the so-called.-space suggests that this offset is related to dEs having a total mass-to-light ratio higher than Es but still significantly lower than dSph galaxies. Given a stellar mass-to-light ratio based on the measured line indices of dEs, the FP offset allows us to infer that the dark matter fraction within the half light radii of dEs is on average ≳42% (uncertainties of 17% in the K band and 20% in the V band), fully consistent with an independent estimate in an earlier paper in this series. We also find that dEs in the size-luminosity relation in the near-infrared, like in the optical, are offset from early-type galaxies, but seem to be consistent with late-type galaxies. We thus conclude that the scaling relations show that dEs are different from Es, and that they further strengthen our previous findings that dEs are closer to and likely formed from late-type galaxies., Ministerio de Ciencia e Innovación (MCINN), Unión Europea. FP6, Fulbright Program, Ministerio de Educación, Cultura y Deporte (MECD), España, Programa Ramón y Cajal, Marie Curie Research Training Networks (UE), Marie Skłodowska-Curie Actions (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub