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 The Effect of Drag from the Galactic Hot Halo on the Magellanic Stream and Leading Arm

2011 ◽  
Vol 28 (2) ◽  
pp. 117-127 ◽  
Author(s):  
Jonathan Diaz ◽  
Kenji Bekki
Keyword(s):  
Density Gradient ◽  
Column Density ◽  
Numerical Models ◽  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Negative Effects ◽  
Global Properties ◽  
Ram Pressure ◽  
Magellanic Stream ◽  
Drag Term

AbstractWe study the effect of drag induced by the Galactic hot halo on the two neutral hydrogen (HI) cloud complexes associated with the Large and Small Magellanic Clouds: the Magellanic Stream (MS) and the Leading Arm (LA). In particular, we adopt the numerical models of previous studies and re-simulate the tidal formation of the MS and LA with the inclusion of a drag term. We find that the drag has three effects which, although model-dependent, may bring the tidal formation scenario into better agreement with observations: correcting the LA kinematics, reproducing the MS column density gradient, and enhancing the formation of MS bifurcation. We furthermore propose a two-stage mechanism by which the bifurcation forms. In general, the inclusion of drag has a variety of both positive and negative effects on the global properties of the MS and LA, including their on-sky positions, kinematics, radial distances, and column densities. We also provide an argument which suggests that ram-pressure stripping and tidal stripping are mutually exclusive candidates for the formation of the MS and LA.

scholarly journals The interacting Magellanic System

1991 ◽  
Vol 148 ◽  
pp. 447-452 ◽  
Author(s):  
S. R. Wayte
Keyword(s):  
Magellanic Clouds ◽  
Entire Length ◽  
Tidal Model ◽  
The Past ◽  
Multi Phase ◽  
Magellanic Stream ◽  
Insight Into ◽  
Magellanic System ◽  
Anomalous Velocity

The Magellanic System is viewed focusing on the global interactions in the System. These give insight into its history and structure. The past orbits of the Magellanic Clouds (MCs) are examined. A tidal encounter between the Large and Small Magellanic Clouds (LMC, SMC) has almost certainly occurred within the last 109 yrs. This hypothesis is supported by the observed structure of the Magellanic System, and so is accepted. The Magellanic Stream is an indirect result of the tidal encounter which is crucial to understanding the Magellanic System. It is a complex interacting gas feature, bifurcated along its entire length with many anomalous velocity H I clouds alongside. The possible models for the Magellanic Stream are examined and here I propose that its origin is due to the collision of a multi-phase halo with the vast region of gas between the LMC and the SMC. In this respect the polar subsystem around our Galaxy is seen to be particularly important. The popular tidal model for the origin of the Magellanic Stream fails to satisfy key observational features, and is thus rejected.

The ‘High Velocity Cloud’ Origin of the Magellanic System

1987 ◽  
Vol 7 (1) ◽  
pp. 19-25 ◽  
Author(s):  
D. S. Mathewson ◽  
S. R. Wayte ◽  
V. L. Ford ◽  
K. Ruan
Keyword(s):  
High Velocity ◽  
Galactic Halo ◽  
Magellanic Clouds ◽  
The One ◽  
Magellanic Stream ◽  
Gaseous Halo ◽  
Velocity Cloud ◽  
High Velocity Cloud ◽  
Magellanic System

AbstractIt is believed that the splitting of the SMC into two fragments and the production of the Inter-Cloud gas and the Magellanic Stream occurred in the one event 4 × 108 years ago. This event was a collision between the LMC and SMC. This time is too short for the Stream to be tidal, or be the result of stripping of the Inter-Cloud gas by a diffuse gaseous halo. It is proposed that the clouds in the Stream are the results of collisions between the Inter-Cloud gas and HVCs in the Galactic halo. A model of this process accounts for all of the observational features of the Stream. Observations of HVCs in the path of the Magellanic Clouds are used to predict the development of the Stream. The HVCs in our halo are thought to be a result of a collision of a galaxy with our Galaxy 6 × 109 years ago.

The Magellanic System

1985 ◽  
Vol 6 (1) ◽  
pp. 104-109 ◽  
Author(s):  
D. S. Mathewson
Keyword(s):  
Globular Clusters ◽  
Neutral Hydrogen ◽  
Close Encounter ◽  
Polar Ring ◽  
Ram Pressure ◽  
Cepheid Variables ◽  
Ultimate Fate ◽  
Magellanic Stream ◽  
Gaseous Halo ◽  
Magellanic System

AbstractThis review concentrates on observations of neutral hydrogen in the Magellanic System, and what they reveal about the structure, dynamics, evolution and ultimate fate of the LMC and SMC. Some recent observations of 161 Cepheid variables in the SMC are used together with the HI observations to determine the geometry of the SMC. These show that it has an amazing depth of at least 30 kpc. To explain the results it is proposed that the SMC had a close encounter with the LMC which has warped the disk of the LMC, produced the bridge between the two galaxies and tidally fissioned the SMC. The SMC is in the process of irreversible disintegration. It is believed that the Magellanic Clouds are not bound to our Galaxy and approached us from the direction of Andromeda. They may have had a close encounter with Andromeda 3 x 109 years ago, which may explain the massive starburst which occurred in the LMC and SMC at that time. It is believed that the Magellanic Stream has been swept out of the inter-Cloud region by the ram pressure of the gaseous halo of our Galaxy. If dynamic friction is sufficient for the Clouds to be captured and to eventually collide with our Galaxy, a polar ring will be formed similar to that observed in some other galaxies. The polar ring of dwarf spheroidals and outlying globular clusters at present encircling our Galaxy may be the remnants of a previous collision with some other galaxy 6 x 109 years ago.

scholarly journals Models for the dynamical evolution of the Magellanic System

2008 ◽  
Vol 4 (S256) ◽  
pp. 105-116
Author(s):  
Kenji Bekki
Keyword(s):  
Galactic Halo ◽  
Dynamical Evolution ◽  
Magellanic Clouds ◽  
Young Stars ◽  
Proper Motions ◽  
Self Consistent ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Magellanic Stream ◽  
Magellanic System

AbstractI discuss the following five selected topics on formation and evolution of the LMC and the SMC based on fully self-consistent chemodynamical simulations of the Magellanic Clouds (MCs): (1) formation of bifurcated gaseous structures and young stars in the Magellanic bridge (MB), (2) formation of the Magellanic stream (MS) due to the tidal interaction between the LMC, the SMC, and the Galaxy within the last 2 Gyrs, (3) origin of the observed kinematical differences between H i gas and stars in the SMC, (4) formation of stellar structures dependent on their ages and metallicities in the LMC, and (5) a new common halo model explaining both the latest HST ACS observations on the proper motions of the LMC and the SMC and the presence of the MS in the Galactic halo. I focus exclusively on the latest developments in numerical simulations on formation and evolution of the Magellanic system.

scholarly journals Young stars raining through the galactic halo: the nature and orbit of price-whelan 1

2019 ◽  
Vol 490 (2) ◽  
pp. 2588-2598 ◽  
Author(s):  
Michele Bellazzini ◽  
Rodrigo A Ibata ◽  
Nicolas Martin ◽  
Khyati Malhan ◽  
Antonino Marasco ◽  
...  
Keyword(s):  
Galactic Halo ◽  
Stellar System ◽  
Young Stars ◽  
Stellar Content ◽  
Velocity Difference ◽  
Ram Pressure ◽  
Magellanic Stream ◽  
Gas Cloud ◽  
Velocity Cloud ◽  
High Velocity Cloud

ABSTRACT We present radial velocities for five member stars of the recently discovered young (age ≃ 100−150 Myr) stellar system Price-Whelan 1 (PW 1), which is located far away in the Galactic Halo (D≃ 29 kpc, Z≃ 15 kpc), and that is probably associated with the leading arm (LA) of the Magellanic Stream. We measure the systemic radial velocity of PW 1, Vr = 275 ± 10 km s−1, significantly larger than the velocity of the LA gas in the same direction. We re-discuss the main properties and the origin of this system in the light of these new observations, computing the orbit of the system and comparing its velocity with that of the H i in its surroundings. We show that the bulk of the gas at the velocity of the stars is more than 10 deg (5 kpc) away from PW 1 and the velocity difference between the gas and the stars becomes larger as gas closer to the stars is considered. We discuss the possibilities that (1) the parent gas cloud was dissolved by the interaction with the Galactic gas, and (2) that the parent cloud is the high-velocity cloud (HVC) 287.5+22.5 + 240, lagging behind the stellar system by ≃ 25 km s−1 and ≃10 deg ≃ 5 kpc. This HVC, which is part of the LA, has metallicity similar to PW 1, displays a strong magnetic field that should help to stabilize the cloud against ram pressure, and shows traces of molecular hydrogen. We also show that the system is constituted of three distinct pieces that do not differ only by position in the sky but also by stellar content.

scholarly journals The Magellanic Stream as a probe of the galactic halo

1979 ◽  
Vol 84 ◽  
pp. 574-574
Author(s):  
R. J. Cohen ◽  
R. D. Davies ◽  
I. F. Mirabel
Keyword(s):  
Galactic Halo ◽  
Neutral Hydrogen ◽  
The Sun ◽  
Typical Size ◽  
Stellar Component ◽  
Large Velocity ◽  
The Galaxy ◽  
Magellanic Stream

Recent observations of the Magellanic Stream can be used to set limits on a possible hot halo surrounding the Galaxy. The observations are described in detail elsewhere (Mirabel, Cohen & Davies, submitted to Mon. Not. R. astr. Soc.). Briefly, the neutral hydrogen in the northern end of the Magellanic Stream is concentrated in narrow filaments which contain small elongated clouds of typical size 0°.4 × 0°.6. These clouds have a large velocity halfpower width (25 km s−1 and are gravitationally unstable, unless there is a massive low luminosity stellar component. If we consider only the observed gas the expansion age of a typical cloud is 6 × 105 D years, where D is the distance in kpc from the Sun, and this falls at least a factor of ten short of the age of the Stream predicted by current models. This strongly suggests that some containment mechanism is operating.

scholarly journals Group pre-processing versus cluster ram-pressure stripping: the case of ESO156−G029

2019 ◽  
Vol 490 (1) ◽  
pp. L6-L11 ◽  
Author(s):  
Robert Džudžar ◽  
Virginia Kilborn ◽  
Chandrashekar Murugeshan ◽  
Gerhardt Meurer ◽  
Sarah M Sweet ◽  
...  
Keyword(s):  
Rapid Evolution ◽  
Neutral Hydrogen ◽  
Current Data ◽  
Cluster Galaxy ◽  
The Past ◽  
Gas Kinematics ◽  
Ram Pressure ◽  
The Galaxy ◽  
A Minor ◽  
Projected Distance

ABSTRACT We report on observations of ESO156−G029, member of a galaxy group which is positioned at the virial radius of cluster Abell 3193. ESO156−G029 is located ∼1.4 Mpc in projected distance from the brightest cluster galaxy NGC1500. We show that ESO156−G029 has disturbed gas kinematics and a highly asymmetric neutral hydrogen (H i) distribution, which are consequences of group pre-processing, and possibly of ram pressure. Based on the current data we propose a scenario in which ESO156−G029 had a minor gas-rich merger in the past and now starts to experience ram pressure. We infer that the galaxy will undergo rapid evolution once it gets closer to the cluster centre (less than 0.5 Mpc) where ram pressure is strong enough to begin stripping the H i from the galaxy.

scholarly journals THE MAGELLANIC STREAM SYSTEM. I. RAM-PRESSURE TAILS AND THE RELICS OF THE COLLISION BETWEEN THE MAGELLANIC CLOUDS

2015 ◽  
Vol 813 (2) ◽  
pp. 110 ◽  
Author(s):  
F. Hammer ◽  
Y. B. Yang ◽  
H. Flores ◽  
M. Puech ◽  
S. Fouquet
Keyword(s):  
Magellanic Clouds ◽  
Ram Pressure ◽  
Stream System ◽  
Magellanic Stream

scholarly journals N-Body Simulations of the Magellanic System Including Gas Dynamics and Star Formation

1999 ◽  
Vol 186 ◽  
pp. 60-60
Author(s):  
A.M. Yoshizawa ◽  
M. Noguchi
Keyword(s):  
Star Formation ◽  
Gas Dynamics ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Small Magellanic Cloud ◽  
Tidal Distortion ◽  
Formation And Evolution ◽  
Magellanic Stream ◽  
Magellanic System

The system of the Magellanic Clouds is considered to be dynamically interacting among themselves and with our Galaxy. This interaction is thought to be the cause of many complicated features seen in the Magellanic Clouds and the Magellanic Stream (see Westerlund 1990, A&AR, 2, 27). In order to better understand the formation and evolution of the Magellanic System, we carry out realistic N-body simulations of the tidal distortion of the Small Magellanic Cloud (SMC) due to our Galaxy and the Large Magellanic Cloud (LMC).

Sign in / Sign up

Export Citation Format

Share Document