LMC size (APOD 4 Sep 2006)

[aquataine]

In the Sept. 4 explanation about the LMC, it is stated that it spans 70,000 light years. In the May 10 explanation about the LMC it is stated that it spans only 15,000 light years. Which is correct?

[harry]

Hello All


Re: The Large Magellanic Cloud in Infrared
http://antwrp.gsfc.nasa.gov/apod/ap060904.html

The LMC is a satellite galaxy to our own Milky Way Galaxy, spans about 70,000 light years, and lies about 160,000 light years away toward the southern constellation of the Swordfish (Dorado).

10 may
The Large Cloud of Magellan
http://antwrp.gsfc.nasa.gov/apod/ap060510.html

The Large Magellanic Cloud (LMC) pictured above is only about 180,000 light-years distant in the constellation Dorado. Spanning about 15,000 light-years

Have a look at this link,,,,,,,,,hope its right.

The Local Group
http://www.astro.uu.se/~ns/mwsat.html
Galaxy Distance Year M(V) Diameter Type

Canis Major (CMa) 40 000 2003 ? 5000? dIrr
Sagittarius (Sgr) 60 000 1994 -15.0 10 000? dSph
Large Magellanic Cloud (LMC) 160 000 ---- -18.5 20 000 dIrr
Small Magellanic Cloud (SMC) 200 000 ---- -17.1 15 000 dIrr
Bootes (Boo) 210 000 2006 -5.7 500? dSph
Ursa Minor (UMi) 220 000 1954 -8.9 1000 dSph
Draco (Dra) 260 000 1954 -9.4 500 dSph
Sextans (Sex) 280 000 1990 -9.5 3000 dSph
Sculptor (Scl) 290 000 1938 -9.8 1000 dSph
Ursa Major (UMa) 330 000 2005 -7.0 3000 dSph
Carina (Car) 305 000 1977 -9.4 500 dSph
Fornax (For) 450 000 1938 -13.1 3000 dSph
Leo II 670 000 1950 -10.1 500 dSph
Canes Venatici (CVn) 720 000 2006 -7.9 3000? dSph
Leo I 880 000 1950 -11.9 1000 dSph


You may need to look at the link

[astro_uk]

The figure of 15000 ly is probably much closer to the correct number. The MW is only about 100 000 ly in diameter, and the LMC is much smaller (like 20 times smaller in mass but is also less concentrated).

Of course it does depend on whether you measuring the visual extent of the stars or the DM potential, in which case the LMC is actually within the galaxies potential.