Our Milky Way in Space and Time Caty

Our Milky Way in Space and Time Caty Pilachowski Mini-University 2013

Our Journey… v. Where in the Galaxy Are We? v. The Local Neighborhood v. Top Milky Way Destinations! v. The Dark Heart of the Galaxy v. Formation of the Milky Way v. Our Galaxy in the Cosmos

Where Are We? ? ?

100, 000 Light Years A Thin Disk of Stars 100, 000 Light Years

What Is a Light Year? v. The distance light travels in one year (about 6 trillion miles) v. Light travels at 186, 000 miles per second The Moon is 1 The Sun is 8 light-second The Earth nearest star, light-minutes from Proxima Centauri, is from Earth four light years from the Sun

Our Home The Sun Dust Lanes Spiral Arms Disk Hot Young Stars Halo Bulge Galactic Center Light takes 100, 000 years to cross the Milky Way

Meet the Neighbors v Proxima Centauri v Alpha/Beta Centauri v Most nearby stars are small, dim and cool

100 Light Years

Polaris 500 Light Years

Orion Nebula Distance: ~1300 light years X

Orion Nebula Distance: ~1300 light years X

Pillars of Creation X Eagle Nebula with Hubble Lower density gas has been eroded away, leaving pillars of higher density gas where stars are forming

Crab Nebula ESO X v. The remnant of an exploded star v. The explosion was recorded in 1054 CE

Ring Nebula WIYN X v. The remnant of a dying star v. The ring will fade, and the central star will become a white dwarf

Globular Cluster X v. Messier 3 v. Age – 13 billion years v 500, 000 stars WIYN

Cygnus X-1 X v. A binary star containing a black hole v. Mass from the star is pulled into the black hole

The Galactic Center! In visual light, this region is hidden from us by gas and dust that dim the light by a factor of 10 billion!

The Galactic Center in Infrared Light The dust is transparent to infrared light, and we can see through the gas and dust to observe the Galactic Center

The Galaxy massive black v. Orbits of stars around the central mass is consistent with a 4 million solar mass object at the Galactic Center hosts a superhole at its heart!

Massive Black Hole! v Detected in infrared, radio, and x-ray light v Mass 4 million times the Sun’s mass v Growing slowly through accretion v All big galaxies host central black holes

A Gas Cloud Approaches the Black Hole! v The cloud will pass within 36 light hours next month (July) v~3 Earth masses v~2000 miles per sec Animation!

The Universe Contains Many Spiral Galaxies We learn about our Milky Way from other galaxies

Forming the Milky Way Galaxies like the Milky Way form from the consolidation of many primordial gas clouds Collisions of gas clouds create bursts of star formation to shape the Galaxy

The Milky Way Is Still Growing v Nearby dwarf galaxy discovered in 1994 in the direction of Sagittarius v Distance about 88, 000 light years v Merging with the Milky Way

Galaxy’s “New” Tidal Stream v. Sagittarius orbits the Milky Way v. The orbital period is about a billion years v“Tidal stream” of stars from Sagittarius circles the Milky Way

The Local Group 2. 5 million light years v. The Milky Way is v. Andromdea Galaxy part of a small group v. Milky Way Galaxy of galaxies known as v. Triangulum Galaxy the local group v. Many small ones

Galaxy Collision!

The an Local Group Is EVEN BIGGER Part of Group v. The Local Group is part of the Virgo Super Cluster of Galaxy Groups

Newly Discovered Galaxy! v. The Leo P galaxy was just discovered here at IU using the WIYN Telescope v. Five million light years from the Milky Way v. Undisturbed, in an empty part of nearby space

Our Home in the Cosmos