1 research outputs found
UV to radio centimetric spectral energy distributions of optically-selected late-type galaxies in the Virgo cluster
We present a multifrequency dataset for an optically-selected,
volume-limited, complete sample of 118 late-type galaxies (>= S0a) in the Virgo
cluster. The database includes UV, visible, near-IR, mid-IR, far-IR, radio
continuum photometric data as well as spectroscopic data of Halpha, CO and HI
lines, homogeneously reduced, obtained from our own observations or compiled
from the literature. Assuming the energy balance between the absorbed stellar
light and that radiated in the IR by dust, we calibarte an empirical
attenuation law suitable for correcting photometric and spectroscopic data of
normal galaxies. The data, corrected for internal extinction, are used to
construct the spectral energy distribution (SED) of each individual galaxy, and
combined to trace the median SED of galaxies in various classes of
morphological type and luminosity. Low-luminosity, dwarf galaxies have on
average bluer stellar continua and higher far-IR luminosities per unit galaxy
mass than giant, early-type spirals. If compared to nearby starburst galaxies
such as M82 and Arp 220, normal spirals have relatively similar observed
stellar spectra but 10-100 times lower IR luminosities. The temperature of the
cold dust component increases with the far-IR luminosity, from giant spirals to
dwarf irregulars. The SED are used to separate the stellar emission from the
dust emission in the mid-IR regime. We show that the contribution of the
stellar emission at 6.75 micron to the total emission of galaxies is generally
important, from ~ 80% in Sa to ~ 20% in Sc.Comment: 31 pages, 12 figures, 12 tables. Fig 2 avaliable at
(http://goldmine.mib.infn.it/papers/isosed.html). Accepted for publication on
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