Nubecula Major Adric Riedel IN GLORIOUS
Dec 13, 2015
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
• 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
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
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)
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