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)