Unit 6 Galaxies *Basic Galaxy Info. *Types of Galaxies -Characteristics of The Milky Way (Spiral Galaxies) *Red Shift & Hubble’s Law

Basic Galaxy Info. Vocab Words for “Basic Galaxy Info.” Galaxy Gravitational Lens Active Galaxy Galactic Cannibalism Pulsating/Variable Star

Basic Galaxy Info. A Galaxy is a group of stars, gas, dust and other interstellar matter all gravitationally bound together Can be bound together in different patterns We live in the Milky Way Galaxy!

Basic Galaxy Info. Galaxies behave as a Gravitational Lens A Gravitational Lens is a body that refracts passing by light Our galaxy is currently an Active Galaxy An Active Galaxy a galaxy that is alive and has young and forming stars as a part of it. An active galaxy may be growing or decreasing in number of stars. An active galaxy may be performing Galactic Cannibalism. An active galaxy may contain Pulsating or Variable Stars.

Basic Galaxy Info. Galaxies (including the Milky Way) sometimes perform Galactic Cannibalism. Galactic Cannibalism is when larger galaxies consume smaller galaxies to become larger! Galaxies also contain a special type of star, a Pulsating or Variable Star. A Pulsating or Variable Star is a rotating neutron stars with beams of radiation coming out of its poles

Types of Galaxies Vocab. words for “Types of Galaxies” Spiral Galaxy Barred Spiral Galaxy Elliptical Galaxy Irregular Galaxy

Types of Galaxies Spiral Galaxy – In a Spiral Galaxy, the gas, dust & interstellar matter is all gravitationally bound together in a spiral pattern

Types of Galaxies Special Type of Spiral Galaxy…. In a Barred Spiral Galaxy gas, dust & interstellar matter is all gravitationally bound together in a spiral pattern with a barred, instead of circular center

Types of Galaxies Elliptical Galaxy – In an Elliptical Galaxy, gas, dust & interstellar matter is all gravitationally bound together in an elliptical pattern

Types of Galaxies Irregular Galaxy In an Irregular Galaxy, gas, dust & interstellar matter is all gravitationally bound together with no rhyme or reason its shape

Types of Galaxies Characteristics of the Milky Way (Spiral Galaxies) Vocab Words for “Characteristics of the Milky Way (Spiral Galaxies) Spiral Arm Galactic Bulge Galactic Disk Globular Cluster Galactic Halo Local Group

Types of Galaxies Characteristics of the Milky Way (Spiral Galaxies) The Milky Way is a spiral galaxy, so we know a lot about spiral galaxies. We know they contain… A Galactic Bulge A Galacitc Halo A Galactic Disk Globular Clusters Spiral Arms

Types of Galaxies Characteristics of the Milky Way (Spiral Galaxies)

Types of Galaxies Characteristics of the Milky Way (Spiral Galaxies) The Galactic Bulge is the group of stars surrounding the immediate center of a spiral galaxy The Galactic Disk is the portion of a spiral galaxy that contains most of the interstellar matter, the nucleus and the spiral arms are a part of it The Spiral Arm is the winding offshoot from the center of a spiral galaxy The Globular Cluster is the group of thousands of stars tightly packed together lying outside the galactic disk, but within the galactic halo The Galactic Halo is the imaginary sphere surrounding a spiral galaxy that contains ALL of the interstellar matter of that galaxy

Types of Galaxies Characteristics of the Milky Way (Spiral Galaxies) The Milky Way galaxy is part of a cluster of galaxies called the Local Group The Local Group is the cluster of the Milky Way and more than 30 other nearby galaxies Two of these nearby galaxies are: Andromeda Triangulum

Red Shift & Hubble’s Law Vocab Words for “Red Shift & Hubble’s Law” Red Shift Hubble’s Law Dark Matter

Red Shift & Hubble’s Law All the galaxies put together makes up our Universe! Red Shift is the idea that the universe is expanding outward. The idea is that the galaxies are getting further and further away from each other.

Red Shift & Hubble’s Law Red Shift does NOT mean everything is turning red! It means that the Doppler Effect is occurring with light waves and radiation is shifting towards the red end of the visible light spectrum.

Red Shift & Hubble’s Law This demonstrates what Red Shift means and how it implies, objects (galaxies) are moving away! Remember - - there are wavelengths assigned to each of these colors!

Red Shift & Hubble’s Law Hubble’s Law takes this idea of Red Shift a step further Hubble’s Law states that the universe is expanding outward and accelerating as it expands It can be demonstrated by an equation of… V = H 0 D, where V is velocity, H 0 is Hubble’s constant and D is Distance.  For our purposes, we will use Hubble’s constant as 60.

Red Shift & Hubble’s Law This is a graph of the relationship between a Galaixy’s distance from us and the Velocity of that Galaxy.

Red Shift & Hubble’s Law What is causing the galaxies to accelerate as they move outward? Astronomer’s believe Dark Matter is causing these galaxies to accelerate. We don’t really know what dark matter is. We call dark matter, matter that emits and reflects minimal to no light. We know its there, because it does have a gravitational influence that is causing the galaxies to accelerate.

Red Shift & Hubble’s Law Picture of a Black Hole!

Red Shift & Hubble’s Law There is a picture of “Dark Matter” on the left and a picture of “Not Dark Matter” on the right!