Quelques explications sur l'évènement d'aujourd'hui à bord de l'ISS.
Le problème se situe dans la Chambre Intermédiaire (PrK) du module russe Zvezda. C'est le petit espace à l'arrière du module qui donne accès à la pièce d'amarrage où arrivent les vaisseaux Progress. 1/n
The Small Magellanic Cloud, one of the Milky Way’s closest galactic neighbours, appears to be expanding rather than rotating like a stable disk.
A new analysis based on more than a decade of near-infrared observations from the VISTA Survey of the Magellanic Clouds has mapped the proper motions of millions of stars inside the galaxy with much higher precision than before. Instead of showing a clean, ordered rotation pattern, the stellar motions reveal that stars are moving away from the galaxy’s centre, especially along a southeast-northwest direction.
This matters because the Small Magellanic Cloud has long been treated, at least in simplified models, as a small galaxy with some kind of internal rotation. The new map suggests that this picture is too simple. Its internal motion is dominated by tidal disturbance. The main gravitational culprit is the Large Magellanic Cloud, its more massive companion, which has repeatedly interacted with it over billions of years. Those encounters have stretched and distorted the Small Magellanic Cloud, leaving it dynamically out of equilibrium.
The study used a longer observational baseline, around 6 to 11 years, from VISTA data release 7. That longer baseline allowed the researchers to measure stellar proper motions with about three times better precision than previous VMC-based studies. After correcting for the overall motion of the galaxy and for perspective effects, the residual motion map showed clear signs of large-scale expansion. The researchers also found no convincing evidence for normal disk-like rotation once those corrections were applied.
Another important point is that the disturbance is not only visible in the outer regions, where tidal stripping might be expected, but also in the central parts of the Small Magellanic Cloud. That suggests the whole galaxy has been strongly affected by its interaction with the Large Magellanic Cloud. Older red giant stars also show a coherent northward motion away from the centre, which the authors interpret as a possible kinematic fossil of an interaction that happened more than two billion years ago.
The broader implication is that the Small Magellanic Cloud is not a calm nearby dwarf galaxy, but a galaxy being reshaped in real time by gravitational encounters.
Because it is close enough for astronomers to measure individual stellar motions, it becomes a valuable laboratory for studying how small galaxies are disrupted, stretched, and transformed by larger companions. The result also warns that using simple rotating-disk models for disturbed dwarf galaxies can give a misleading picture of their structure and evolution.
👉 https://t.co/cj8NP9yhDj