Transcript The Milky Way Galaxy

The Milky Way Galaxy
The Milky Way Galaxy
By: Rachel Williams
&
Deidre Vaughters
Size
• The Milky Way is about
100,000 light years in
diameter
• It is said to be about
1,000 light years
thickness.
• It was estimated that The
Milky Way contains at
least about 200 billion
stars possibly even 400
billion.
• The stellar disk is a much
thicker disk of gas.
• The gaseous disk has a
thickness of 12,000 light
years.
Age
• Scientist said that it is
extremely difficult to
define the age of which
Milky Way was formed.
• The age of the oldest star
was discovered yet about
13.2 billion years ago.
• Astronomers Luca
Pasquini, Piercarlo
Bonifacio, Sofia Randich,
Daniele Galli, and
Raffaele G. Gratton used
the UV-Visual Echelle
Spectrograph of the Very
Large Telescope to
measure the beryllium
content of two stars in
globular cluster NGC
6397.
Compositions and structure
• Spitzer Space
• In the disk region are
Telescope in 2005
several arm
backed up previously
structures that spiral
collected evidence
outward in a
that suggested the
logarithmic spiral
Milky Way is a barred
shape. The mass
spiral galaxy.
distribution within the
Galaxy closely
• Consists of a barresembles the Sbc
shaped core region
Hubble .
surrounded by a disk
of gas, dust and stars.
Sun’s Location
• It takes the Solar System
about 225–250 million
years to complete one
orbit of the galaxy (a
galactic year),[33] so it is
thought to have
completed 20–25 orbits
during the lifetime of the
Sun and 1/1250th of a
revolution since the origin
of humans.
Environment
• The Milky Way and the
Andromeda Galaxy are a
binary system of giant
spiral galaxies.
• Together with their
companion galaxies they
form the Local Group, a
group of some 50 closely
bound galaxies. The
Local Group is part of the
Virgo Supercluster.
• The Milky Way is orbited
by two smaller galaxies
and a number of dwarf
galaxies.
• The largest is the Large
Magellanic Cloud with a
diameter of 20,000 lightyears.
• It has a close
companion, the Small
Magellanic Cloud. The
Magellanic Stream.
Velocity
• Many astronomers
believe the Milky Way
is moving at
approximately 600 km
per second relative to
the observed
locations of other
nearby galaxies.
• The recent estimates
range from 130 km/s
to 1,000 km/s.
• The Galaxy is moving
at 600 km/s, Earth
travels 51.84 million
km per day, or more
than 18.9 billion km
per year, about 4.5
times its closest
distance from Pluto.
Discovery
• A Greek philosopher
Democritus was the first
known person to propose
that the Milky Way might
consist of distant stars.
• proof came in 1610 when
Galileo Galilei used a
telescope to study the
Milky Way and
discovered that it was
composed of a huge
number of faint stars.
• Thomas Wright,
speculated that the Milky
Way might be a rotating
body of a huge number of
stars, held together by
gravitational forces akin
to the Solar System but
on much larger scales.
• A disk of stars would be
seen as a band on the
sky from our perspective
inside the disk.
Facts
•
All the stars that we can see at
night are part of our own Milky
Way Galaxy.
•
Like other spiral galaxies we can
view from space, the Milky Way
Galaxy is disk-shaped spiral with a
central bulge. The diameter of the
disk is approximately 100,000 light
years; the central bulge is about
16,000 light years.
•
Our solar system is located on a
spiral arm of the Milky Way
Galaxy, about two thirds of the
way out from the center.
•
The center of the Milky Way is
surrounded by a spherical halo of
about 150 globular clusters.
A globular cluster is a densely
packed ball of stars containing
hundreds of thousands or even
millions of stars.
The stars of globular clusters are
low in metals and were thus
formed when the Galaxy was
young and less highly evolved.
•
•
Facts
• The central region of the
Galaxy contains old stars
and little in the way of
dust and gas.
• The disk of the galaxy
contains gas, dust,
younger stars with more
complex chemical
compositions, and active
regions of star formation
like the Orion nebula.
Facts
• 90% of the matter in the
universe is nonluminous.
• Our Galaxy is centered in
a halo of nonluminous
dark matter that may be
ten times larger than the
visible portion of the
spiral disk.
• It takes our Sun about
200 million years to
complete one orbit of the
center of the Milky Way.
• Like other distant
galaxies, our own Milky
Way Galaxy is a flat spiral
with dark lanes.
• We can see dark lanes
from inside the galaxy.
• In this time exposure, the
dark rift in the Milky way
can be seen starting in
the constellation of
Cygnus.
Facts
• Under dark summer
skies, it is possible to see
this dark rift in our own
galaxy with the naked
eye.
• A band of dust and other
nonluminous matter that
cuts a visible rift in the
plane of a galaxy by
obscuring the light from
stars.
• Many fuzzy objects
(nebula) are visible in the
night sky, and are
included in the catalog of
Messier Objects, which
the 18th century French
astronomer Charles
Messier compiled to aid
him in his search for
comets.
Facts
• Diameter of M.W. Disk
120,000 light years
• Radius of Central Bulge
6,000 light years
• Thickness of M.W. Disk
1,000 light years
• Distance (Earth to
Galactic Nucleus) 30,000
light years
• Period for Solar System
(sun, earth, etc.) to circle
M.W. 225,000,000 years
• Number of Stars in the
Milky Way
100,000,000,000 (1011)
• Total Mass of Milky Way
7.2 X 1011MSUN or
1012MSUN
Facts
• We cannot see the
center of the Milky
Way with visible light,
but infrared, radio,
and x-rays show
much.
• It is likely that a giant
black hole lives at the
center.
Facts
• The light year is a measure of distance.
• Light travels 186,282 miles in one second.
• A light year is the distance that light travels
in one year, or 5,880,000,000,000 miles.
Milky Way