Nubecula Major

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Nubecula Major

• Adric Riedel

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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 weve learned from the LMC
• Star-forming regions
• Spiral Nebula
• Superbubbles!
• 30 Doradus
• SN 1987a
• Where SN1987a is

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History of the LMC
Discovered even earlier by everyone who lived in
the southern hemisphere
Discovered in 1519 by Ferdinand Magellan
Discovered in 964 by Abd-Al-Rahman Al Sufi
Discovered in 1503 by Amerigo Vespucci
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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)
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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




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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
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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

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Obligatory
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Morphology

• Often considered irregular

• Prototype SBm barred Magellanic Type spiral

Mediocre Design
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Morphology

• The LMC has globular clusters of its own, in
  disk-like orbits (reason unknown)

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The Brothers Magellanic
The Large and Small Magellanic Clouds are
interacting with each other (but not actually
bound to each other). The Magellanic stream
contains 630106 Msun of gas. (Brüns et al. 2005
AA, 432, 45)
The Parkes HI telescope Brüns et al. 2005 (AA,
432, 45)
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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
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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

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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

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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
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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 association Blue gt6Msun,
Green2-6Msun, Redlt2Msun http//heritage.stsci.e
du/1999/04/nino/nino_ctr.html
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30 Doradus (Tarantula Nebula)
280 parsecs
9 parsecs
Orion Nebula (M42) NASA,ESA, M. Robberto (Space
Telescope Science Institute/ESA)
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30 Doradus King of the Star Forming Regions
HST, John Trauger (JPL), James Westphal
(Caltech), Nolan Walborn (STScl), Rodolfo Barba'
(La Plata Observatory), NASA
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How we can see Superbubbles

• Holes in HI, shells of HII (fainter as you go
  outward)
• Purple is Ha, Cyan is OIII.

350 ly
Superbubble N44 Gemini Observatory GMOS
Image/Travis Rector - University of Alaska
Anchorage
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SN 1987a (1997) Hubble Heritage Team
(AURA/STScI/NASA/ESA)
SN 1987a (2006) NASA, ESA, P. Challis R.
Kirshner (Harvard-Smithsonian Center for
Astrophysics)