Nubecula Major

Adric Riedel

IN GLORIOUS

Outline

• Discovery• Its place in the Local Group• The LMC as a whole• Gas• Stars• Supernovae

History of the LMC

Discovered in 1519 by Ferdinand MagellanDiscovered in 1503

by Amerigo VespucciDiscovered 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.

Wei-Hao Wang (IfA, U. Hawaii)

Basic Facts

http://www.astronomy.com/asy/objects/images/local_group_0305_diagram_800.jpg

Basic Facts

• Third closest galaxy to the Milky Way (thus discovered)

Canis Major Dwarf Irregular (d. 2003) 7.6 kpc

Sagittarius Dwarf Elliptical (d. 1994) 30 kpc

Large Magellanic Cloud 50 kpc

Small Magellanic Cloud 60 kpc

Ursa Minor Dwarf Spheroidal (d. 1954) 60 kpc

Sculptor Dwarf Spheroidal (d. 1937) 90 kpc

Draco Dwarf Spheroidal (d. 1954) 80 kpc

Sextans Dwarf Elliptical (d. 1990) 90 kpc

Carina Dwarf Spheroidal (d. 1977) 100 kpc

Fornax Dwarf Spheroidal (d. 1938) 140 kpc

Van den Bergh, 2000 PASP 112, 170

Discovery dates from http://www.seds.org/~spider/spider/LG/lg.html

Basic Facts

• Fourth Largest Galaxy in the Local group M31 (Andromeda) 7.5x1011 Msun

(Brunthaler, 2007 A&A, 462, 101)

Milky Way 1.3x1012 Msun (Bellazini, 2004 MNRAS, 347, 119)

M33 (Triangulum) 1.29x1010 Msun (Lohmann, 1974 Ap&SS, 29, 62)

LMC 8.7x109 Msun (Van der Marel 2002, AJ, 124, 2639)

M32

NGC 6822 1.4x109 Msun (Harwit, Astrophysical Concepts)

NGC 205

SMC 2.4x109 Msun (Stanimirovic 2004, AJ, 604, 176)

NGC 185

NGC 147

I have no idea

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 via microlensing• Constrain the size of the Milky Way dark halo• Study supernova evolution• Study Giant Molecular Clouds• Examine ISM from an external perspective• Give seminar presentations• Develop galaxy formation models• Develop galactic chemical evolution models• Enlarge sample sizes of rare stars

Obligatory

Morphology

• Often considered irregular• Prototype SBm barred Magellanic Type spiral

“Mediocre Design”

The Brothers Magellanic

The Parkes HI telescope

•The Large and Small Magellanic Clouds are interacting with each other.

•Bekki et al. (2004 ApJL,

610, L93) suggest they may be colliding

•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

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

• ‘Bar’ forms naturally from the tidal forces and gas/halo ram pressure

Mastropietro et al. 2005, MNRAS 363, 509

The Eventual Fate of the LMC

• LMC eventually breaks up and merges with our galaxy

• This simulation intentionally ignores SMC

• Simulation ends before the potential collision with Andromeda 3-4 Gyr from now Mastropietro et al. 2005, MNRAS 363, 509

The LMC ISM

• The LMC still has plenty of gas

• May have been a ‘dark galaxy’ until relatively recently- van den Bergh (2000

PASP 112, 529) found few clusters between 4 and 10 Gyr old (also Bekki et al. 2004 ApJL, 610, L93)

DEM L 130a (LMC N119) A spiral nebulaESO 2.2m/WFI

C. Smith, S. Points, the MCELS Team and NOAO/AURA/NSF

The LMC ISM

http://www.astro.uni-bonn.de/~miralles/hyperz/hyperz_manual1/node10.html.gif

The LMC ISM

Grocholski et al. 2006 AJ 132, 1630

The LMC ISM

Grocholski et al. 2006 AJ 132, 1630

Stars in the LMC

• Difficult to date• The LMC is

uniformly low metallicity, so Pop I and Pop II are irrelevant

• Two distinct epochs

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

Hodge 301

R136

HST, John Trauger (JPL), James Westphal (Caltech), Nolan Walborn (STScl), Rodolfo Barba' (La Plata Observatory), NASA

6x104 Msun (Townsley et

al 2006, AJ 131, 2140)

Supernovae

Supernovae

Anglo-Australian Observatory, photograph by David Malin.

How we can see Superbubbles

• Holes in HI, shells of HII (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)