Caty Pilachowski Mini-University 2013 Our Milky Way in Space and Time.
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Caty PilachowskiMini-University 2013
Our Milky Way in Space and Time
Our Journey…Where in the Galaxy Are We?The Local NeighborhoodTop Milky Way Destinations!The Dark Heart of the GalaxyFormation of the Milky WayOur Galaxy in the Cosmos
A Thin Disk of Stars
100,000 Light Years
100,0
00 L
igh
t Years
What Is a Light Year?
The distance light travels in one year (about 6 trillion miles)
Light travels at 186,000 miles per secondThe Moon is
1 light-second from
Earth
The Sun is 8 light-minutes
from Earth
The nearest star, Proxima Centauri,
is four light years from the Sun
Disk
Bulge
Halo
Hot Young Stars
Spiral Arms
Dust Lanes
Galactic Center
The Sun
Light takes 100,000 years to cross the Milky Way
Our Home
Meet the Neighbors
Proxima Centauri Alpha/Beta Centauri Most nearby stars are
small, dim and cool
100 Light Years
500 Light YearsPolaris
Orion Nebula
Distance: ~1300 light years
X
Orion Nebula
Distance: ~1300 light years
X
Pillars of Creation
Lower density gas has been eroded away, leaving pillars of higher density gas where stars are forming
Eagle Nebulawith Hubble
X
Crab Nebula
The remnant of an exploded star
The explosion was recorded in 1054 CE
ESO
X
Ring Nebula
The remnant of a dying star
The ring will fade, and the central star will become a white dwarf
X
WIYN
Globular Cluster
Messier 3Age – 13
billion years500,000 stars
WIYN
X
Cygnus X-1
A binary star containing a black hole
Mass from the star is pulled into the black hole
X
The Galacti
c 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
LightThe dust is transparent to infrared light, and we can see through the gas and dust to observe the Galactic Center
The Galaxy hosts a super-massive black hole at its
heart!
Orbits of stars around the central mass is consistent with a 4 million solar mass object at the Galactic Center
Massive Black Hole!
• Detected in infrared, radio, and x-ray light
• Mass 4 million times the Sun’s mass
• Growing slowly through accretion
• All big galaxies host central black holes
A Gas Cloud
Approaches the Black Hole!
The cloud will pass within 36 light hours next month (July)
~3 Earth masses~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
Nearby dwarf galaxy discovered in 1994 in the direction of Sagittarius
Distance about 88,000 light yearsMerging with the Milky Way
Galaxy’s
“New”Tidal
Stream
Sagittarius orbits the Milky WayThe orbital period is about a billion years“Tidal stream” of stars from Sagittarius
circles the Milky Way
The Local Grou
pThe Milky Way is
part of a small group of galaxies known as the local group
Andromdea GalaxyMilky Way GalaxyTriangulum GalaxyMany small ones
2.5 million light years
Galaxy Collision!
The Local Group Is Part of an EVEN BIGGER Group
The Local Group is part of the Virgo Super Cluster of Galaxy Groups
Newly Discovered Galaxy!
The Leo P galaxy was just discovered here at IU using the WIYN Telescope
Five million light years from the Milky Way
Undisturbed, in an empty part of nearby space
Our Home in the Cosmos
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