Breathing in, I calm myself

Breathing out, I smile Breathing in, I calm myself Living in the present moment This is a wonderful moment --Thick Nhat Hanh

SOAR 2014: Galaxies Aileen A. O’Donoghue Priest Associate Professor of Physics

Galaxies • 9/9/14 • Milky Way Galaxy Contents & Motions • 9/16/14 • Milky Way Environment & the Local Group • 9/23/14 • Other Galaxies & Clusters of Galaxies • 9/30/14 • Expansion, History & Evolution of the Universe

SOAR: Galaxies The Milky Way Environment & the Local Group Aileen A. O’Donoghue Priest Associate Professor of Physics

The Local Group • The Milky Way’s Galaxy Cluster > 54 galaxies within 5 million light years Triangulum (M110) Milky Way Andromeda (M31) & Satellites M32 & M33

The ‘Hood

Milky Way’s Environment • IntraCluster Medium (ICM) • Did galaxies form from this gas?

Milky Way’s Environment • Galaxies emit and absorb gas

Milky Way’s Environment • Milky Way’s Lumpy Halo • Stars, Globular Clusters, Gas, Dwarf Galaxies Being studied by RAdial Velocity Experiment by Institutions from 11 nations

Galactic Cannibalism • Galaxies grow by eating their neighbors • MW has 9 dwarf companion galaxies • Halo stars from disrupted dwarfs

The Milky Way Growing? • Galaxies merge with other galaxies “Galactic Cannibalism” • Milky Way has two known merging galaxies • Dwarf Elliptical Galaxy in Sagittarius • Dwarf Galaxy in Canis Minor • Closest galaxy in process of merging • Researchers expect to find more!

Sagittarius Dwarf Elliptical • Part of the “Sagittarius Stream” of gas & stars • 52 klyc from galactic center • Has passed through MW 10 times • Dark Matter indicted by lack of disrupton! SgrDEG on far side of galactic center Stars of SgrDEG have different speeds than MW stars

Sagittarius Stream • Stars & gas stripped from SgrDEG APOD image of Sagittarius Stream “Flyaround” of Milky Way with Sagittarius Stream

Sagittarius Stream • Simulations of tidal stripping of SgrDEG ~ 2 billion BCE to 500 million CE Color indicates stellar density Color indicates time of tidal stripping Simulations by Kathryn V. Johnston, Wesleyan University

Canis Minor Dwarf • Discovered in 2003, 25 kly from MW center

CMi Dwarf • Discovered in 2003 • 42 kly from MW center • Merging with MW

Milky Way Ring • Thick ring of stars beyond disk

Milky Way Ring • Due to past galactic collision? Star formation in ring of shocked gas Which of these galaxies passed through one to left?

The Local Group • More than 54 galaxies • Mostly dwarfs, including those merging with the Milky Way • 3 Major spiral galaxies • Milky Way, Andromeda & Triangulum http://www.atlasoftheuniverse.com/

The Sky Tonight Enif Little Dipper Cepheus Big Dipper Pegasus  Cephei Scheat Polaris Markab Great Square of Pegasus Pointer stars point to … Cassiopeia Alpheratz Andromeda Galaxy Algenib Andromeda Almach Triangulum Galaxy Perseus Rasalmothallah Triangulum Algol Aries Capella

Finding Galaxies Andromeda Galaxy Alpheratz Andromeda Almach Triangulum Galaxy Rasalmothallah Triangulum

Andromeda Galaxy • Local Group’s Largest Galaxy • One Trillion Stars (1012) • 2.5 million light-years away • 1.5 x 1019 mi (1 ly = 5.88 x1012 miles ~ 6 trillioin) • 200,000,000 M black hole in center • Approaching us at 300 km/s (190 miles/sec) • Should collide with Milky Way in ~4 billion years

M32 – Dwarf Galaxy M110 – Dwarf Galaxy

Triangulum Galaxy • Pinwheel Galaxy (M 101) • 40 Billion Stars (1010) • 3 million light-years away • 1.5 x 1019 mi (1 ly = 5.88 x1012 miles ~ 6 trillioin) • Linked to Andromeda by streams of stars and neutral hydrogen  interacted with Andromeda 2-8 by ago  will have more violent interaction in 2.5 my  may participate in collision with MW

http://www.nasa.gov/topics/universe/features/molecule-fingerprints.htmlhttp://www.nasa.gov/topics/universe/features/molecule-fingerprints.html

The Coming Collision http://www.nasa.gov/mission_pages/hubble/science/milky-way-collide.html

Breathing in, I calm myself