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Structure of the Large Magellanic Cloud (LMC)
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.
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 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 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.
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.
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 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).
Show more information about my research.
Return to my home page.
Last modified May 22, 2001.
Roeland van der Marel,
marel@stsci.edu.
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