Possible formation scenarios for the giant H i envelope around the NGC 4490/4485 system     

M. S. Clemens  P. Alexander  & D. A. Green 《Monthly notices of the Royal Astronomical Society》1998,297(4):1015-1020

We present observations of H i in the nearby interacting galaxies NGC 4490 and 4485 made with the VLA in both C and D arrays. The galaxies are embedded in an extensive envelope of neutral hydrogen which is elongated in a direction approximately perpendicular to the plane of NGC 4490, with an extent of about 56 kpc. We argue that this distribution of neutral hydrogen can best be explained by a galactic-scale bipolar outflow of H  i driven by supernovae in NGC 4490. The flow from the disc appears to be reasonably well collimated and has probably persisted for approximately 6 × 10⁸ yr. The implications for galaxy evolution when such mass loss occurs are briefly discussed.  相似文献   

Tidally induced star formation in Abell 1367     

C. Moss  M. Whittle  & J. E. Pesce 《Monthly notices of the Royal Astronomical Society》1998,300(1):205-220

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The interaction of positive streamers with charged and uncharged water drops in vertical electric fields     

E. O. Oladiran 《Pure and Applied Geophysics》1981,119(5):966-977

Investigation was carried out to study the interaction of positive streamers with charged and uncharged drops in a vertical electric field configuration. Results obtained for vertical and horizontal positions of the photographic films show that streamer interactions with neutral and negative drops are similar and further confirmed earlier results byPhelps (1972). It showed that indirect streamer interaction with droplets is effected by branches being sent to the drops from the main channel. The visibility of the branches on the Lichtenberg figures and the degree of interaction of streamers with drops depend on the drop size, its initial charge and shape, and/or the separation of the drops from the main channel. Suppression of streamer propagation among the positively charged drops was observed.  相似文献   

Topographically forced three-wave quasi-esonant and non-resonant interactions among barotropic rossby waves on an infinnite beta-plane     

Luo Dehai 《大气科学进展》1998,15(1):83-98

In this paper, we first apply the assumption h = εh′ of topographic variation (h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant and non-resonant interactions among Rossby waves for zonal wavenumbers 1—3 over a wavenumber-two bottom topography (WTBT). Some numerical calculations are made with the fourt-order Rung-Kutta Scheme. It is found that for the case without topographic forcing, the period of three-wave quasi-resonance (TWQR) is found to be independent of the zonal basic westerly wind, but dependent on the meridional wavenumber and the initial amplitudes. For the fixed initial data, when the frequency mismatch is smaller and the meridional wavelength is moderate, its period will belong to the 30–60-day period band. However, when the wavenumber-two topography is included, the periods of the forced quasi-resonant Rossby waves are also found to be strongly dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind reaches a moderate extent, intraseasonal oscillations in the 30–60-day period band can be found for zonal wavenumbers 1–3. On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction over a WTBT can occur in this case. When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the presence of a WTBT, the three Rossby waves oscillate with the identical period. The period, over a moderate range of the zonal basic westerly wind, is in the intraseasonal, 30–60-Day range.  相似文献   

Steepened inner density profiles of group galaxies via interactions: an N-body analysis     

Benjamin M. Dobke  Lindsay J. King  Michael Fellhauer 《Monthly notices of the Royal Astronomical Society》2007,377(4):1503-1510

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The environments and clustering properties of 2dF Galaxy Redshift Survey selected starburst galaxies     

Matt S. Owers  Chris Blake  Warrick J. Couch  Michael B. Pracy  Kenji Bekki 《Monthly notices of the Royal Astronomical Society》2007,381(2):494-510

We investigate the environments and clustering properties of starburst galaxies selected from the 2dF Galaxy Redshift Survey (2dFGRS) in order to determine which, if any, environmental factors play a role in triggering a starburst. We quantify the local environments, clustering properties and luminosity functions of our starburst galaxies and compare to random control samples. The starburst galaxies are also classified morphologically in terms of their broad Hubble type and evidence of tidal merger/interaction signatures. We find the starburst galaxies to be much less clustered on large (5–15 Mpc) scales compared to the overall 2dFGRS galaxy population. In terms of their environments, we find just over half of the starburst galaxies to reside in low to intermediate luminosity groups, and a further ∼30 per cent residing in the outskirts and infall regions of rich clusters. Their luminosity functions also differ significantly from that of the overall 2dFGRS galaxy population, with the sense of the difference being critically dependent on the way their star formation rates are measured. In terms of pin-pointing what might trigger the starburst, it would appear that factors relating to their local environment are most germane. Specifically, we find clear evidence that the presence of a near neighbour of comparable luminosity/mass within 20 kpc is likely to be important in triggering a starburst. We also find that a significant fraction (20–30 per cent) of the galaxies in our starburst samples have morphologies indicative of either an ongoing or a recent tidal interaction and/or merger. These findings notwithstanding, there remain a significant portion of starburst galaxies where such local environmental influences are not in any obvious way playing a triggering role, leading us to conclude that starbursts can also be internally driven.  相似文献   

Abundance diagnosis of E+A (post-starburst) galaxies   总被引：1，自引：0，他引：1  

Tomotsugu Goto 《Monthly notices of the Royal Astronomical Society》2007,377(3):1222-1228

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The Galaxy Evolution Explorer UV emission in shell galaxies: tracing galaxy 'rejuvenation' episodes     

R. Rampazzo  A. Marino  R. Tantalo  D. Bettoni  L. M. Buson  C. Chiosi  G. Galletta  R. Grützbauch  R. M. Rich 《Monthly notices of the Royal Astronomical Society》2007,381(1):245-262

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On the origin of the dichotomy of early-type galaxies: the role of dry mergers and active galactic nucleus feedback     

X. Kang  Frank C. van den Bosch  A. Pasquali 《Monthly notices of the Royal Astronomical Society》2007,381(1):389-400

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Wave driven free surface motion in the gap between a tanker and an FLNG barge     

《Applied Ocean Research》2015

When two vessels are moored side-by-side with a narrow gap between them, intense free surface motions may be excited in the gap as a result of complex hydrodynamic interactions. These influence the motions of the two vessels, and the forces in any moorings. The present paper uses first and second order wave diffraction analysis to investigate this phenomenon. Key theoretical aspects of the numerical analysis are first summarised, including the vital need to suppress “irregular frequency” effects; and results are given to validate the code used. The case of a tanker alongside a large floating FLNG barge is then considered in detail.  相似文献