7,017 research outputs found
Fenologia da floração e frutificação da bracatinga.
Edição dos Anais do Congresso Florestal Brasileiro, 6., 1990, Campos do Jordão
GHASP: an H kinematic survey of spiral galaxies - X. Surface photometry, decompositions and the Tully-Fisher relation in the Rc-band
We present Rc-band surface photometry for 170 of the 203 galaxies in GHASP,
Gassendi H-Alpha survey of SPirals, a sample of late-type galaxies for which
high-resolution Fabry-Perot H{\alpha} maps have previously been obtained. Our
data set is constructed by new Rc-band observations taken at the Observatoire
de Haute-Provence (OHP), supplemented with Sloan Digital Sky Survey (SDSS)
archival data, obtained with the purpose of deriving homogeneous photometric
profiles and parameters. Our results include Rc-band surface brightness
profiles for 170 galaxies and profiles for 108 of these objects. We
catalogue several parameters of general interest for further reference, such as
total magnitude, effective radius and isophotal parameters -- magnitude,
position angle, ellipticity and inclination. We also perform a structural
decomposition of the surface brightness profiles using a multi-component method
in order to separate disks from bulges and bars, and to observe the main
scaling relations involving luminosities, sizes and maximum velocities.
We determine the Rc-band Tully Fisher relation using maximum velocities
derived solely from H rotation curves for a sample of 80 galaxies,
resulting in a slope of , zero point of and an
estimated intrinsic scatter of . We note that, different from
the TF-relation in the near-infrared derived for the same sample, no change in
the slope of the relation is seen at the low-mass end (for galaxies with
km/s). We suggest that this different behaviour of the Tully
Fisher relation (with the optical relation being described by a single
power-law while the near-infrared by two) may be caused by differences in the
stellar mass to light ratio for galaxies with km/s.Comment: 17 pages, 11 figure
Ages, metallicities and -element enhancement for galaxies in Hickson compact groups
Central velocity dispersions and eight line-strength Lick indices have been
determined from 1.3 resolution long-slit spectra of 16 elliptical
galaxies in Hickson compact groups. These data were used to determine galaxy
properties (ages, metallicities and -element enhancements) and allowed
a comparison with the parameters determined for a sample of galaxies in lower
density environments, studied by Gonz\'alez (1993). The stellar population
parameters were derived by comparison to single stellar population models of
Thomas et al. (2003) and to a new set of SSP models for the indices Mg,
Fe5270 and Fe5335 based on synthetic spetra. These models, based on an update
version of the fitting functions presented in Barbuy et al. (2003), are fully
described here. Our main results are: (1) the two samples have similar mean
values for the metallicities and [/Fe] ratios, (2) the majority of the
galaxies in compact groups seem to be old (median age of 14 Gyr for eight
galaxies for which ages could be derived), in agreement with recent work by
Proctor et al. (2004). These findings support two possible scenarios: compact
groups are either young systems whose members have recently assembled and had
not enough time to experience any merging yet or, instead, they are old systems
that have avoided merging since their time of formation.Comment: Accepted for publication in A
Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding.
The genus Brachiaria comprises more than 100 species and is the single most important genus of forage grass in the tropics. Brachiaria brizantha , widely used in Brazilian pastures for beef and dairy production, is native to tropical Africa. As a subsidy to the breeding program underway in Brazil, cytological studies were employed to determine the chromosome number and to evaluate microsporogenesis in 46 accessions of this species available at Embrapa Beef Cattle (Brazil)
Greenhouse gas reduction strategies for building materials:A reality check with the climate targets
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