500 research outputs found
The Circumnuclear Ring of Ionized Gas in NGC3593
We present the results of narrow-band Halpha+NII imaging of the early-type
spiral NGC3593 in combination with a study of the flux radial profiles of the
NII (lambda: 654.80, 658.34 nm), Halpha, and SII (lambda: 671.65, 673.08 nm)
emission lines along its major axis. The galaxy is known to contain two
counterrotating stellar discs of different size and luminosity. We find that
the Halpha emission mainly derives from a small central region of 57 arcsec x
25 arcsec. It consists of a filamentary pattern with a central ring. This has a
diameter of about 17 arcsec (~ 0.6/h kpc) and it contributes about half of the
total Halpha flux. The ring is interpreted as the result of the interaction
between the acquired retrograde gas which later formed the smaller
counterrotating stellar disc and the pre-existing prograde gas of the galaxy.Comment: Accepted for pubblication in Astronomy and Astrophysics; one latex
file (corsini.tex), and 2 encapsulated postscript figures
(corsini_fig1.ps,corsini_fig2.ps). To be compiled with aa.cls latex2e macro
style (pslatex option): 6 pages after latex compilatio
The bulge-disk orthogonal decoupling in galaxies: NGC 4698 and NGC 4672
We report the case of the geometrical and kinematical decoupling between the
bulge and the disk of the Sa galaxy NGC 4698. The R-band isophotal map of this
spiral shows that the bulge structure is elongated perpendicularly to the major
axis of the disk. At the same time a central stellar velocity gradient is found
along the major axis of the bulge. We also present the Sa NGC 4672 as good
candidate of a spiral hosting a bulge and a disk orthogonally decoupled with
respect to one other. This decoupling of the two fundamental components of a
visible galaxy suggests that the disk could represent a second event in the
history of early-type spirals.Comment: 4 pages, 3 figures (LaTeX, cupconf.sty). To appear in "The Formation
of Bulges" C. M. Carollo, H. C. Ferguson, R. F. G. Wyse (eds.), Cambridge
University Pres
Portable diagnostic platform for detection of microorganisms Coliforms and E. coli.
Portable diagnostic devices are a viable and low-cost alternative for the detection of pathogens, since they reduce the time of analysis of results availability. Ease of sample collection and quick diagnosis allow this new input to be applied in the diagnosis of the main contaminating microorganisms present in the water. Laboratory tests evaluated the technical viability of the diagnostic device, using commercial strains which were inoculated and optimized in the devices and their growth compared to the conventional method in Petri dishes. Samples of 100 μL bacterial suspension were tested and compared with the traditional sample inoculation method. The device viability was determined by detecting characteristic bacterial colonies in a specific culture medium through the colorimetric development of the obtained colonies. The feasibility assessments allow us to affirm that the device enables both qualitative and quantitative detection of the target bacteria present in liquid samples, and is promising to be applied to assess the quality of water, food and environmental surfaces
The Bulge-Disk Orthogonal Decoupling in Galaxies: NGC 4698
The R-band isophotal map of the Sa galaxy NGC 4698 shows that the inner
region of the bulge structure is elongated perpendicularly to the major axis of
the disk, this is also true for the outer parts of the bulge if a parametric
photometric decomposition is adopted. At the same time the stellar component is
characterized by an inner velocity gradient and a central zero-velocity plateau
along the minor and major axis of the disk respectively. This remarkable
geometric and kinematic decoupling suggests that a second event occurred in the
formation history of this galaxy.Comment: 12 pages, LaTex, with 4 PostScript figures. Accepted for publication
in The Astrophysical Journal Letter
ANĂLISE DO PERFIL PROTĂICO DOS PRODUTOS DE EXCREĂĂO/SECREĂĂO DE LARVAS DE Cochliomyia hominivorax.
Modeling gas and stellar kinematics in disc galaxies
We present V-band surface photometry and major-axis kinematics of stars and
ionized gas of three early-type spiral galaxies, namely NGC 772, NGC 3898 and
NGC 7782. For each galaxy we built a self-consistent Jeans model for the
stellar kinematics, adopting the light distribution of bulge and disc derived
by means of a two-dimensional parametric photometric decomposition. This
allowed us to investigate the presence of non-circular gas motions, and derive
the mass distribution of luminous and dark matter in these objects. We found
that the observed gas rotation corresponds to the circular velocity except for
the innermost region (|r|<8") of NGC 3898. This behaviour is quite common,
although not ubiquitous, in the few bulge-dominated galaxies, for which
dynamical modeling allows the comparison between the gas velocity and the
circular speed.Comment: 1 single page, 1 encapsulated figure. Poster contribution at the
Euroconference "The Evolution of Galaxies. I- Observational clues.", held in
Granada (Spain), May 23-27 2000. To be published as a special issue of
Astrophysics and Space Scienc
Evidences of volcanic unrest on high-temperature fumaroles by satellite thermal monitoring: The case of Santa Ana volcano, El Salvador
International audienceOn October 1st, 2005, Santa Ana volcano (El Salvador) underwent a VEI 3 phreatomagmatic eruption after approximately one century of rest. Casualties and damages to some of the local infrastructures and surrounding plantations were followed by the evacuation of the nearby communities. The analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) infrared data reveals that the main explosion was preceded by a one-year-long thermal unrest, associated to the development of a fumaroles field, located at the western rim of the summit crater lake. By combining space-based thermal flux and ground-based measurements (seismicity, sulfur emissions and lake temperatures), we suggest that the activity observed at Santa Ana between 2004 and 2005 was driven by the gradual intrusion of an undegassed magma body at a very shallow depth. Magma injection induced thermal anomalies associated with sustained degassing from the fumaroles field and promoted the interaction between the magmatic-hydrothermal system and the overlying water table. This process culminated into the VEI 3 phreatomagmatic eruption of October 2005 that strongly modified the shallow structure of the crater area. The subsequent three-years-long activity resulted from self-sealing of the fracture system and by the opening of a new fracture network directly connecting the deeper hydrothermal system with the crater lake. Our results show that satellite-based thermal data allow us to detect the expansion of the high-temperature fumarolic field. This may precede an explosive eruption and/or a lava dome extrusion. In particular, we show that thermal records can be analyzed with other geochemical (i.e. SO2 emissions) and geophysical (seismicity) data to track a shallow magmatic intrusion interacting with the surrounding hydrothermal system. This provides a remarkable support for volcano monitoring and eruption forecasting, particularly in remote areas where permanent ground data acquisition is hazardous, expensive and difficult
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