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: http://www.sao.ru/fetch/HL/leda/param/vdis.html
Дата изменения: Mon Dec 23 18:23:59 2013 Дата индексирования: Fri Feb 28 17:12:19 2014 Кодировка: Поисковые слова: zodiacal light |
The velocity dispersion gives to some
approximation the scale for the
specific kinetic energy contained in in un-ordered motions and combined
with
the velocity of rotation it may give an estimate of the specific
kinetic
energy. For early-type galaxies (E-S0) it is one of the parameters
entering
in the Fundamental-Plane relation, which reflects the self-similarity
of
all early-type galaxies and their equilibrium status.
The velocity dispersions are standardized to an aperture rnorm
of 0.595 h-1kpc, which is equivalent to an angular diameter
of
3.4 arcsec at the distance of Coma. The method of normalization is the
one introduced by Jorgensen et al:
vdisc = vdis . [rmeas/rnorm]0.04
,
where rmeas is the aperture defined by the slit
width
at the distance of the object. All raw vdis values are
rescaled
to the homogeneous system and thus corrected for systematic effects on
the
individual datasets (see
Golev & Prugniel, 1998). At the end of 2003, the total
available
catalog contains 8596 measurements of vdis for 3636 galaxies
This parameter is used to determine the distance modulus
mod0.
HyperLeda | Questions: prugniel@obs.univ-lyon1.fr |