scholarly journals A collision between the Large and Small Magellanic Clouds 2×108 years ago

1985 ◽  
Vol 106 ◽  
pp. 471-476
Author(s):  
M. Fujimoto ◽  
T. Murai
Keyword(s):  
Triple System ◽  
Gravitational Interaction ◽  
Magellanic Clouds ◽  
The Past ◽  
Model Galaxy ◽  
Binary State ◽  
The Galaxy ◽  
Magellanic Stream

A number of orbits are obtained for the Large and Small Magellanic Clouds (LMC and SMC) revolving around a model Galaxy with a massive halo. It is suggested that the SMC approached the LMC as close as 3 to 7 kpc about 200 million years ago, if these clouds have been in a binary state for the past 1010 years, and the Magellanic Stream (MS) is due to the gravitational interaction among the triple system of the Galaxy, LMC, and SMC.

scholarly journals Review of N-Body Models of Tidal Interactions

1999 ◽  
Vol 190 ◽  
pp. 480-486
Author(s):  
L. T. Gardiner
Keyword(s):  
Star Formation ◽  
Triple System ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Magellanic Clouds ◽  
Considerable Progress ◽  
Tidal Interactions ◽  
The Galaxy ◽  
Magellanic Stream ◽  
Made In

Considerable progress has been made in the current decade with the help of N-body simulations towards a deeper understanding of the nature of the dynamical relationship between the Large and Small Magellanic Clouds and the Galaxy. The origin of such features as the Magellanic Stream, the inter-Cloud Bridge, the Wing and large extension in depth of the SMC has come to be interpreted in the context of the tidal interactions among the members of the LMC-SMC-Galaxy triple system. The inclusion of gas-dynamical effects and star formation in the latest models has added further refinements to this picture and confirmed the enhancement of the star formation rate in the SMC as a result of the recent LMC-SMC encounter.

scholarly journals The Magellanic Stream

1974 ◽  
Vol 60 ◽  
pp. 617-624
Author(s):  
D. S. Mathewson ◽  
M. N. Cleary ◽  
J. D. Murray
Keyword(s):  
Galactic Plane ◽  
Gravitational Interaction ◽  
Great Circle ◽  
Magellanic Clouds ◽  
The Other ◽  
Small Magellanic Cloud ◽  
Velocity Range ◽  
Sky Survey ◽  
The Galaxy ◽  
Magellanic Stream

A southern sky survey of Hiin the velocity range − 340 km s−1 to + 380 km s−1 has shown that a long filament of H iextends from the Small Magellanic Cloud (SMC) region down to the South Galactic Pole and connects with the long Hifilament discovered recently by Wannier and Wrixon (1972) and van Kuilenberg (1972). There is also some evidence that this continues on the other side of the Magellanic Clouds and crosses the galactic plane at l = 306°. This filament, which follows very closely a great circle over its entire 180° arc across the sky, is given the name ‘The Magellanic Stream’. It may have been produced by gravitational interaction between the SMC and the Galaxy during a close passage (20 kpc) of the SMC some 5 × 108 yr ago, although it is impossible to account for the observed radial velocities along the Stream unless some force other than gravity is invoked to act on the Stream as well.

scholarly journals The Magellanic Stream: theoretical considerations

1979 ◽  
Vol 84 ◽  
pp. 557-566 ◽  
Author(s):  
M. Fujimoto
Keyword(s):  
Local Group ◽  
Galactic Disk ◽  
Magellanic Clouds ◽  
Particle Simulation ◽  
The Past ◽  
Local Supercluster ◽  
New Models ◽  
The Galaxy ◽  
Magellanic Stream ◽  
Theoretical Considerations

The tidal and the primordial theories for the Magellanic Stream are examined in a frame of test-particle simulation for the interacting triple system of the Galaxy, the Large and Small Magellanic Clouds (LMC and SMC). Difficulties of the radial velocity of the Stream still beset these two theories. Several new models for the Stream and the Clouds are briefly discussed in relation to the bending of the galactic disk, the past binary orbits of the LMC and SMC and also the Local Group and the Local Supercluster of galaxies.

scholarly journals The Magellanic Stream

1974 ◽  
Vol 58 ◽  
pp. 367-374 ◽  
Author(s):  
D. S. Mathewson ◽  
M. N. Cleary ◽  
J. D. Murray
Keyword(s):  
Galactic Plane ◽  
Gravitational Interaction ◽  
Great Circle ◽  
Magellanic Clouds ◽  
The Other ◽  
Small Magellanic Cloud ◽  
Velocity Range ◽  
Sky Survey ◽  
The Galaxy ◽  
Magellanic Stream

A southern sky survey of H I in the velocity range — 340 km s−1 to +380 km s−1 has shown that a long filament of H I extends from the Small Magellanic Cloud (SMC) region down to the South Galactic Pole and connects with the long H I filament discovered recently by Wannier and Wrixon (1972) and van Kuilenburg (1972). There is also some evidence that the feature continues on the other side of the Magellanic Clouds and crosses the galactic plane at l = 306°. The whole filament, which follows very closely a great circle over its entire 180° length, is given the name ‘The Magellanic Stream’. It may have been produced by gravitational interaction between the SMC and the Galaxy during a close passage (20 kpc) of the SMC some 5 × 108 yr ago although it is impossible to account for the observed radial velocities along the Stream unless some force other than gravity is invoked to act on the Stream as well.

scholarly journals The properties of early-type stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 325-336
Author(s):  
Christopher J. Evans
Keyword(s):  
Physical Properties ◽  
Mass Loss ◽  
Temperature Scale ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Early Type ◽  
The Past ◽  
The Galaxy ◽  
Stellar Temperature ◽  
Early Type Stars

AbstractThe past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.

scholarly journals The Magellanic Stream and the Magellanic Cloud System

1999 ◽  
Vol 186 ◽  
pp. 31-38 ◽  
Author(s):  
M. Fujimoto ◽  
T. Sawa ◽  
Y. Kumai
Keyword(s):  
Gravitational Force ◽  
Narrow Band ◽  
Hydrogen Gas ◽  
Tidal Model ◽  
Common Envelope ◽  
Binary State ◽  
The Galaxy ◽  
Flat Rotation Curve ◽  
Magellanic Stream ◽  
Hubble Time

A tidal model has been introduced to the triple system of the Galaxy, Large and Small Magellanic Clouds (the LMC and SMC hereafter) and successfully reproduced the Magellanic Stream (Murai and Fujimoto 1980; Lin and Lynden-Bell 1982; Gardiner et al. 1994; Gardiner and Noguchi 1995; Lin et al. 1995), a narrow band of diffuse atomic hydrogen gas emerging from the SMC region, passing by the South Galactic Pole along an overhead great circle spanning over 100° (Wannier and Wrixon 1972; Mathewson et al. 1974). The LMC and SMC have a hydrogen bridge and common envelope (Hindman 1964; McGee and Milton 1966) and, therefore, we can consider that they have been in a binary state for the Hubble time, revolving together around the Galaxy with a halo whose mass is larger than 1012M⊙ if the flat rotation curve extends up to more than 100 kpc. The strong gravitational force due to this heavy halo attracts the Magellanic Stream and produces the high negative radial velocities (Murai and Fujimoto 1980).

scholarly journals Some Lessons from the Past and Thoughts on the Future of Spectral Classification

1979 ◽  
Vol 47 ◽  
pp. 337-346 ◽  
Author(s):  
N. R. Walborn
Keyword(s):  
Magellanic Clouds ◽  
External Information ◽  
Spectral Classification ◽  
New Techniques ◽  
The Past ◽  
Spectroscopic Examination ◽  
The Galaxy ◽  
The Many ◽  
Large Telescopes ◽  
New Phenomena

AbstractThe importance of maintaining the greatest possible independence of spectral classification from theoretical or other external information is emphasized anew, with reference to some historical discussions now seen with the benefit of hindsight. This ideal requirement applies equally to the development and to the application of a classification system, although in practice some well-established information may guide one’s intuition in the initial hypothetical formulation. The fundamental position of this principle in the MK approach to classification is a major reason for the value of its spectral types, and for its continuing success in uncovering new phenomena. The ability of a particular technique to produce interesting or useful results is surely the most significant criterion of its value, and from this viewpoint it appears that new techniques and methods will complement rather than replace traditional spectral classification. Finally, the unique importance at this time of applying both new and traditional methods to spectral classification in the Magellanic Clouds is stressed; they provide the only current opportunity for detailed spectroscopic examination of numerous stars in external systems. It is essential that large telescopes be utilized for this work so that the best attainable observational quality may be maintained, and the many fascinating phenomena revealed by spectral classification in the Galaxy can be comparatively investigated to the maximum extent praticable in the Magellanic Clouds

scholarly journals How to Model the Chemical Evolution of Galaxies

1993 ◽  
Vol 155 ◽  
pp. 557-566
Author(s):  
Joachim Köppen
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Time Scale ◽  
Life Time ◽  
Magellanic Clouds ◽  
Formation Time ◽  
List Type ◽  
The Galaxy ◽  
H Ii Region ◽  
Magellanic Stream

For a first interpretation of the comparison of observational data, the crude “Simple Model” of chemical evolution is quite useful. Since it has well been described in the literature (e.g. Pagel and Patchett 1975, Tinsley 1980), let us here just review the assumptions and whether they are satisfied: 1.The galaxy is a closed system, with no exchange of matter with its surroundings: For the solar neighbourhood this probably is not true (the infamous Gdwarf-“problem”, Pagel 1989b). For the Magellanic Clouds this is most certainly wrong, because of the presence of the Inter-Cloud Region and the Magellanic Stream, and evidence for interaction with each other and the Galaxy as well (cf. e.g. Westerlund 1990).2.It initially consists entirely of gas (without loss of generality of primordial composition): This is good approximation also for models with gas infall, as long as the infall occurs with a time scale shorter than the star formation time scale.3.The metal production of the average stellar generation (the yield y) is constant with time: Initially, it is reasonable to make this assumption. For tables of the oxygen yield see Koppen and Arimoto (1991).4.The metal rich gas ejected by the stars is completely mixed with the ambient gas. To neglect the finite stellar life times (“instantaneous recycling approximation”) is appropriate for elements synthesized in stars whose life time is much shorter than the star formation time scale, such as oxygen, neon, sulphur, and argon.5.The gas is well mixed at all times: We don't know. The dispersion of H II region abundances may give an indication. In the Magellanic Clouds Dufour (1984) finds quite a low value (±0.08 dex for oyxgen).

scholarly journals The Kinematics of the Magellanic Clouds

1995 ◽  
Vol 166 ◽  
pp. 273-282
Author(s):  
B.E. Westerlund
Keyword(s):  
Galactic Halo ◽  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Great Promise ◽  
Common Envelope ◽  
The Past ◽  
Ram Pressure ◽  
Long Time ◽  
Magellanic Stream ◽  
Magellanic System

It is essential for our understanding of the evolution of the Magellanic System, comprising the Large and the Small Magellanic Cloud, the Intercloud or Bridge region and the Magellanic Stream, to know its motions in the past. The Clouds have a common envelope of neutral hydrogen; this indicates that they have been bound to each others for a long time. The Magellanic System moves in the gravitational potential of our Galaxy; it is exposed to ram pressure through its movement in the galactic halo. Both effects ought to be noticeable in their present structure and kinematics. It is generally assumed, but not definitely proven, that the Clouds have been bound to our Galaxy for at least the last 7 Gyr. Most models assume that the Clouds lead the Magellanic Stream. The interaction between the Clouds has influenced their structure and kinematics severely. The effects should be possible to trace in the motions of their stellar and gaseous components as pronounced disturbances. Recent astrometric contributions in this field show a great promise for the future if still higher accuracy can be achieved.

scholarly journals Michigan 160: a precursor to the LMC?

1991 ◽  
Vol 148 ◽  
pp. 376-377
Author(s):  
L. Staveley-Smith
Keyword(s):  
Star Formation ◽  
Dynamical Evolution ◽  
Stellar Populations ◽  
Detailed Comparison ◽  
Elliptical Galaxies ◽  
Magellanic Clouds ◽  
Formation Processes ◽  
Stellar Formation ◽  
The Galaxy ◽  
Magellanic Stream

The tidal interaction between the Magellanic Clouds and the Galaxy is an important factor in influencing the physical and dynamical evolution of the Clouds (e.g. the Magellanic Stream) as well as the genesis and evolution of their respective stellar populations. However, how important is the influence of the Galaxy? This is a key question since we know that relatively isolated, magellanic-type galaxies do exist (e.g. NGC 3109 and NGC 4449) and have been just as efficient at star-formation as the LMC. It is possible in fact that the star formation in the clouds is primarily stochastic in nature and is relatively insensitive to the global forces which seem to have shaped stellar formation processes in massive spiral and elliptical galaxies. Unsupported by a massive bulge or halo component, cold gas disks are inherently susceptible to radial and bar-like instabilities (Efstathiou et al. 1982) which are very efficient at creating the dynamical pressures required for rapid star-formation. With this in mind, a detailed comparison of 'field' magellanic-type galaxies with the LMC and SMC is of some importance.

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