We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert galaxy. The observations were made with INTEGRAL, a fiber based system operating at the WHT. The intensity map of the ...Hβ emission line represents a spiral or ring-like pattern of HII regions. On the contrary, the OIII intensity map morphology is markedly anisotropic. The strong morphological differences imply that the OIII emitters represent highly ionized gas illuminated by the central source. The OIII map morphology is compatible with a biconical structure of ionization induced by strong extinction in the galaxy disc that also obscures half of the spheroidal stellar bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the presence of Hβ broad emission lines. This spectrum is located in a region where strong extinction is expected but exhibits the bluest spectral energy distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the stellar rotation center. This result has been also found in other Seyfert galaxies and interpreted in terms of a past merger. The offcentering could indicate the presence of nonsymmetric departures in the gravitational potential which could be fueling the active nucleus. The kinematics of the OIII emitters show important deviations at a kpc scale with respect to the stellar velocity field and show features related to the asymmetrical morphology of the high ionization region.
We propose a hypothesis of the truncation of stellar discs based on the magnetic model of the rotation curve of spiral galaxies. Once the disc had formed and acquired its present structure, ...approximately, three balanced forces were acting on the initial gas: gravity and magnetic forces, inwards, and centrifugal force. When stars are formed from this gas, the magnetic force is suddenly suppressed. Gravitation alone cannot retain the newly-formed stars and at birth places beyond a certain galactocentric radius they escape to intergalactic space. This radius is the so-called “truncation radius”, which is predicted to be at about 4–5 disc radial scale lengths, in promising agreement with observations.
We present a first study of truncation of the stellar disks of spiral galaxies in the near infrared. Observations of NGC 4013, NGC 4217, NGC 6504 and NGC 5981 were made with the CAIN NIR camera on ...the CST in Tenerife. This wavelength range provides the best description of the phenomenon, not only because extinction effects are minimized, but also because the distribution of the old stellar population is directly obtained. The four galaxies are edge-on and an inversion method was developed to obtain the deprojected profiles. We did not assume any model of the different galactic components. The "truncation curve" , i.e. $T(R) = \mu(R)- \mu_{\rm{D}}(R)$, where μ is the actual surface brightness in $\rm{mag} /\rm{arcsec}^2$ and $\mu_{\rm{D}}$ the exponential disk surface brightness, has been obtained with unprecedented precision. It is suggested that $T(R)$ is proportional to $(R_{\rm{t}}-R)^{-1}$, where $R_{\rm{t}}$ is the truncation radius, i.e. the radius beyond which no star is observed.
From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high ...amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii is there no correlation with asymmetry. c) A third anticorrelation appears in a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show the same dependence.
New Integral Field Spectroscopy of the central region of NGC 7331 reveals strong Hα emission in the well-known CO and HI ring of NGC 7331. The NII/Hα ratio indicates that a large scale stellar ...formation process is taken place at the ring in agreement with previous hypothesis about the exhaustion of gas in the inner to the ring region. The dynamics of stars and gas are not coupled. There is a ring of peculiar velocities in the ionized gas velocity map. These peculiar velocities can be well interpreted by the presence of an axisymmetric inflow of 40 km s-1 at the inner boundary of the large-scale gaseous ring. We infer an inwards total flux of 1.6 $M_{\odot}$ yr-1. This value is typical of the accretion rates in hypothetical large nuclear black holes. Despite the large differences in the scales of the nucleus and the gas ring of NGC 7331, we suggest that this inwards flux is feeding the nucleus.
Blasts and shocks in the disc of NGC 4258 Jiménez-Vicente, J.; Mediavilla, E.; Castillo-Morales, A. ...
Monthly notices of the Royal Astronomical Society,
07/2010, Letnik:
406, Številka:
1
Journal Article
A study was made of the stability of crude hog kidney
d-amino acid oxidase (
d-AAO) under different experimental conditions of temperature, enzyme concentration, buffer, and in the presence of ...flavine adenine dinucleotide (FAD)_ and glycerol. A deactivation mechanism is proposed.
The kinetic deactivation studies were performed in a buffer at pH over a temperature range of 277-327K (4–54°C). The activity for
d-AAO at 1 U/ml at 277 K in potassium phosphate and potassium pyrophosphate buffer remains almost constant for 20 days. For
d-AAO at 0·02 U/ml at 303 K (30°C) in phosphate buffer, the presence of FAD and glycerol causes the deactivation constant to decrease, while the initial activity and the half-life time increase, the latter doubling on passing from buffer alone to buffer with FAD and 10% glycerol. In the case of
d-AAO at 0·2 U/ml, the stability increases considerably with respect to 0·02 U/ml. Both FAD and glycerol enhance this stabilization.
For temperatures above 313 K (40°C), the deactivation of
d-AAO at 0·2 U/ml showed values of the thermodynamic variables for the overall deactivation constant and for the deactivation constant due to the loss of FAD that indicate that the dissociation of FAD is the main deactivation mechanism. Finally, deactivation due to the loss of FAD is higher for
d-AAO at 0·1 U/ml as compared with a concentration of 0·2 U/ml.
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