Nubecula Major Adric Riedel IN GLORIOUS. Outline Basic Facts Discovery Morphology Its place in the...
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Transcript of Nubecula Major Adric Riedel IN GLORIOUS. Outline Basic Facts Discovery Morphology Its place in the...
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)