nubecula major adric riedel in glorious. outline basic facts discovery morphology its place in the...
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Nubecula Major
Adric Riedel
IN GLORIOUS
Outline• Basic Facts• Discovery• Morphology• Its place in the Local Group
– Relation to the Small Magellanic Clouds– As compared to other galaxies
• The Past and Future of the LMC– Dark Nebulae– Terminal spiral into Milky Way
• What we’ve learned from the LMC• Star-forming regions
– Spiral Nebula– Superbubbles!– 30 Doradus
• SN 1987a– Where SN1987a is
History of the LMC
Discovered in 1519 by Ferdinand Magellan
Discovered in 1503 by Amerigo Vespucci
Discovered in 964 by Abd-Al-Rahman Al Sufi
Discovered even earlier by everyone who lived in the southern hemisphere
Basic Facts• 50 kpc distant in the constellation
Dorado• Tidal radius 15 ± 4.5 kpc (van der Marel et al.
2002, ApJ 124, 2639)
• Actual distance is not known (despite supernova studies) because the LMC is thick.
• Actual distance is not known (despite supernova studies) because the LMC has depth.
Wei-Hao Wang (IfA, U. Hawaii)
Basic Facts
• Third closest galaxy to the Milky Way (thus discovered)
Canis Major Dwarf Elliptical 25 kly
Sagittarius Dwarf Elliptical
Large Magellanic Cloud
Small Magellanic Cloud
Basic Facts
• Fourth most massive galaxy in the Local Group
M31 Andromeda 3.1x1011
Milky Way 1.3x1011
M33 Triangulum 3.9x109
LMC 6x109
M32
NGC 6822 1.4x109
NGC 205
`SMC 1.5x109
Harwit, M. “Astrophysical Concepts”. 3rd ed. Springer-Verlag 1998
Things we can do with the LMC
• Calibrate Distance scales (Hubble 1925, Obs, 48, 139H )
• Find the age of the universe• Study stellar evolution from a top down perspective• Find Dark Matter between the LMC and us
(microlensing)• Constrain the size of the Milky Way dark halo• Study supernova evolution• Study ISM from a top down perspective• Give seminar presentations• Develop galaxy formation models• Develop galactic chemical evolution models• Find more massive and rare stars
Obligatory
Morphology
• Often considered irregular• Prototype SBm barred Magellanic Type spiral
“Mediocre Design”
Morphology
• The LMC has globular clusters of its own, in disk-like orbits (reason unknown)
The Brothers Magellanic
The Parkes HI telescope
Brüns et al. 2005 (A&A, 432, 45)
The Large and Small Magellanic Clouds are interacting with each other (but not actually bound to each other).
The Magellanic stream contains 630×106 Msun of gas. (Brüns et al. 2005 A&A, 432, 45)
The Eventual Fate of the LMC
• Slowly spiraling into Milky Way
• According to Mastropietro et al. (2005, MNRAS 363, 509) the LMC has lost its dark matter halo already
• Has lost large quantities of gas Mastropietro et al. 2005, MNRAS 363, 509
The Eventual fate of the LMC
• Mastropietro et al. assume the LMC started as a small spiral galaxy
• ‘Arms’ form naturally from the tidal forces and gas/halo ram pressure
The Eventual Fate of the LMC
• Final state of the simulation results in a ring of matter around the Milky Way
• Simulation intentionally ignores SMC
• Simulation ignores the potential collision with Andromeda 3-4 Gyr from now
Stars: Those pretty pointy things
• Despite tidal and gravitational forces, the LMC has plenty of gas
• Was a ‘dark galaxy’ until relatively recently- few if any clusters between 4 and 10 Gyr old (van den Bergh 2000 PASP 112, 529) DEM L 130a (LMC N119) (NGC 1910)
An honest-to-goodness spiral nebula
SuperCOSMOS Red plate
400 Ly ×600 Ly
OB associations in the LMC
• Difficult to date• The LMC is
uniformly low metallicity, so Pop I and Pop II are irrelevant
The SN1987a OB associationBlue= >6Msun, Green=2-6Msun, Red=<2Msun
http://heritage.stsci.edu/1999/04/nino/nino_ctr.html
30 Doradus (Tarantula Nebula)
280 parsecs
9 parsecs
Orion Nebula (M42)NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA)
30 Doradus: King of the Star Forming Regions
HST, John Trauger (JPL), James Westphal (Caltech), Nolan Walborn (STScl), Rodolfo Barba' (La Plata Observatory), NASA
R136
How we can see Superbubbles
• Holes in HI, shells of HII (fainter as you go outward)
• Purple is Hα, Cyan is OIII.
350 ly
Superbubble N44Gemini Observatory GMOS Image/Travis Rector - University of Alaska Anchorage
SN 1987a (1997)Hubble Heritage Team (AURA/STScI/NASA/ESA)
SN 1987a (2006)NASA, ESA, P. Challis & R. Kirshner (Harvard-Smithsonian Center for Astrophysics)
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