2,537 research outputs found
New UBVRI colour distributions in E-type galaxies I.The data
New colour distributions have been derived from wide field UBVRI frames for
36 northern bright elliptical galaxies and a few lenticulars. The classical
linear representations of colours against log r were derived, with some
improvements in the accuracy of the zero point colours and of the gradients.
The radial range of signicant measurements was enlarged both towards the
galaxian center and towards the outskirts of each object. Thus, the "central
colours", integrated within a radius of 3", and the "outermost colours"
averaged near the mu_V = 24 surface brightness, could also be obtained. Some
typical deviations of colour profiles from linearity are described.
Colour-colour relations of interest are presented. Very tight correlations are
found between the U-V colour and the Mg2 line-index, measured either at the
galaxian center or at the effective radius.Comment: 34 pages, 10 figures, to appear in A&A journa
The Eocene unconformity of the Briançonnais domain in the French—Italian Alps, revisited (Marguareis massif, Cuneo); a hint for a Late Cretaceous—Middle Eocene frontal bulge setting
The tectonic significance of the Eocene unconformity in the Brianconnais domain, classically regarded as recording a compressional event, is re-evaluated, based on field studies in the Marguareis m..
The dwarf low surface brightness population in different environments of the Local Universe
The nature of the dwarf galaxy population as a function of location in the
cluster and within different environments is investigated. We have previously
described the results of a search for low surface brightness objects in data
drawn from an East-West strip of the Virgo cluster (Sabatini et al., 2003) and
have compared this to a large area strip outside of the cluster (Roberts et
al., 2004). In this talk I compare the East-West data (sampling sub-cluster A
and outward) to new data along a North-South cluster strip that samples a
different region (part of sub-cluster A, and the N,M clouds) and with data
obtained for the Ursa Major cluster and fields around the spiral galaxy M101.
The sample of dwarf galaxies in different environments is obtained from uniform
datasets that reach central surface brightness values of ~26 B mag/arcsec^2 and
an apparent B magnitude of 21 (M_B=-10 for a Virgo Cluster distance of 16 Mpc).
We discuss and interpret our results on the properties and distribution of
dwarf low surface brightness galaxies in the context of variuos physical
processes that are thought to act on galaxies as they form and evolve.Comment: 10 pages, 3 figures, to appear in "Dark Galaxies and Lost Baryons",
IAU244 conference proceeding
Effect of cavitation on velocity in the near-field of a diesel nozzle
The entire process of atomization of the fuel in an internal combustion
engine plays a very important role in determining the overall efficiency of
these engines. A good atomization process could help the fuel to mix with the
air properly leading to its efficient combustion, thereby reducing the emitted
pollutants as well. The recent trend followed by the engineers focused on
designing fuel injectors for more efficient atomization is to increase the
atomization pressure while decreasing the nozzle orifice diameter. A
consequence of this is the development of cavitation (formation of vapor
cavities or bubbles in the liquid) inside the injector close to the nozzle. The
main reason behind this is the sudden changes in the pressure inside the
injector and these cavities or bubbles are usually formed where the pressure is
relatively low.This work mainly focuses on studying the formation of cavitation
and its effect on the velocity of the spray in the near nozzle region using
asymmetrical transparent nozzle equipped with a needle lift sensor with nozzle
diameter of 0.35 mm at 300 bar of injection pressure. The experiment consists
in recording of several image-pairs, which are separated by about 300 ns,
capturing the dynamics of the spray, a few millimeters from the nozzle in the
direction of the flow. These image-pairs are then used to compute the velocity
from the displacement of the liquid structures and ligaments by correlating the
first image with the second. About 200 of such velocity graphs are then
averaged to obtain a velocity map and is compared with the similar average
velocity maps obtained at different times from the start of the injection. The
angular spread of the spray from each of these images is calculated as well.
The images showing cavitation inside the injector are also recorded at these
same instants of time so as to understand the effects of cavitation on the
velocity and angular spread of the spray close to the nozzle.Comment: 13th International Conference on Liquid Atomization and Spray
Systems, Aug 2015, Tainan, Taiwan. 2015, https://iclass2015.tw
A Correlation between Galaxy Light Concentration and Supermassive Black Hole Mass
We present evidence for a strong correlation between the concentration of
bulges and the mass of their central supermassive black hole (M_bh) -- more
concentrated bulges have more massive black holes. Using C_{r_e}(1/3) from
Trujillo, Graham & Caon (2001b) as a measure of bulge concentration, we find
that log (M_bh/M_sun) = 6.81(+/-0.95)C_{r_e}(1/3) + 5.03(+/-0.41). This
correlation is shown to be marginally stronger (Spearman's r_s=0.91) than the
relationship between the logarithm of the stellar velocity dispersion and log
M_bh (Spearman's r_s=0.86), and has comparable, or less, scatter (0.31 dex in
log M_bh), which decreases to 0.19 dex when we use only those galaxies whose
supermassive black hole's radius of influence is resolved and remove one well
understood outlying data point).Comment: 7 pages, 1 table, 2 figures. ApJ Letters, accepte
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