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Structure of the Large Magellanic Cloud (LMC)

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The near-IR data from 2MASS (Two Micron All Sky Survey) and DENIS (Deep Near-Infrared Southern Sky Survey) are ideally suited for studies of the structure of the LMC, because of the large statistics and insensitivity to dust absorption. The following images show some of the main results from my recent work on this subject.
Near-IR RGB/AGB LMC star count map on the sky Deprojected (face-on) near-IR RGB/AGB LMC star count map
Left Panel (Figure 2c of van der Marel 2001): Surface number density distribution on the sky of RGB and AGB stars in the LMC, extracted from 2MASS and DENIS data. The image is 23.55 x 21.55 degrees (2400 times the area of the full moon!); North is to the top and East is to the left.

Right Panel (Figure 2d of van der Marel 2001): The deprojected view of the LMC, as it would appear when viewed face-on. The image is 20.95 x 19.18 kpc. The deprojection was done using the viewing angles determined by van der Marel & Cioni (2001). The line of nodes (the intersection of the plane of the galaxy and the plane of the sky) is indicated by white line segments. It lies at the same angle in the panel on the left. The sky projection map on the left is obtained conceptually from the face-on map on the right by rotating the latter around the line of nodes through an angle i=34.7 degrees (the inclination angle), such that the top left part of the map is tilted out of the screen. Note the important new result that the LMC disk is not circular in the disk plane, but considerably elongated. Most likely, this is due to the tidal force from the Milky Way.



Image Gallery & Further Reading


Optical image of the LMC central bar Optical image of the LMC bar. North is to the top and East is to the left. Compare to the images at the top of your screen; the scale should be roughly the same. Click the image for a bigger view, and check out the accompanying description and links provided by the `Astronomy Picture of the Day' web site.

Near-IR 2MASS image of the LMC
central bar Near-IR 2MASS image of the LMC bar. North is to the top and East is to the left. Compare to the images at the top of your screen; the scale should be roughly the same. Also, compare to the optical image above. Note how the morphology in the optical image is much more influenced by dust absorption and young stellar populations. Click the image for a blow-up view. Also, check out the other cool pictures in the 2MASS Picture of the Week Archive Index.

Large angle view of the LMC+SMC system Wide-angle view of the Large and the Small Magellanic Cloud (SMC) on the sky. North is approximately to the top left. Click the image for a bigger view, and check out the accompanying description and links provided by the `Astronomy Picture of the Day' web site. Note that the image shows only the central bar region of the LMC, due to its short exposure time. Comparison to the images at the top of your screen shows that the LMC is actually much bigger; it has a radius of about 10 degrees. So it extends nearly halfway to the SMC, which is 21 degrees away.

Large angle view of the southern sky with
CTIO 4m Telescope Another wide-angle view of the LMC (bottom left) and the SMC (top left) on the sky, with part of the luminous band of the Milky Way visible as well (right). This image has the 4-meter Blanco Telescope of the Cerro Tololo Inter-American Observatory (CTIO) in Chile on the foreground. Click the image for a bigger view, and check out the accompanying description and links provided by the `Astronomy Picture of the Day' web site.

Schematic View of the Magellanic
Stream Schematic view of the LMC and SMC as they move around the Milky Way galaxy. Click the image for a bigger view, and check out the accompanying description and links provided by the `Astronomy Picture of the Day' web site. A large stream of gas detected in radio waves, the Magellanic Stream, has been pulled out of the LMC/SMC system due to its interaction with the Milky Way. The same tidal force believed to be responsible for the Magellanic Stream may also be responsible for the fact that the LMC is not circular, but elongated (see top of the page).

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Last modified May 22, 2001.
Roeland van der Marel, marel@stsci.edu.
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