Astronomy Chapter 25- The Milky Way Galaxy

dwarf galaxy

A small galaxy containing 100 million up to several billion stars, a small number compared to the milky ways 200-400 billion stars

Globular Clusters

A spherically collection of stars that orbits a galactic core. They are very tightly bound by gravity which gives them their spherical shapes and relatively high stellar densities toward their centers

barred spiral galaxy

A spiral galaxy with a central bar-shaped structure composed of stars.

unbarred spiral galaxy

A spiral galaxy without a central bar-shaped structure composed of stars.

Pueblo building

American Indian settlement of the southwestern US, especially one consisting of multistoried adobe houses built by the pueblo people.

collision of the milky way w/ Andromeda

In the billion years these two galaxies will begin a long process of colliding separating and then coming back together to form an elliptical galaxy.

The galactic center

Rotational center of the Milky Way Galaxy

Galactic year

The time it takes for the Sun to revolve once around the center of Milky Way galaxy,

SagIttarius A

The very strong source of radio waves at the center of our galaxy.. near the border of the constellations Sagittarius and Scorpius about 5.6 degrees south of the ecliptic

We are in the disk of the galaxy, about 3/5 of the way from the center

What have we learned from the work of Harlow Shapley and others about the location of the sun in the milky way galaxy

Thin disk

a structural component of spiral composed of stars gas and dust

bulge

a tightly packed group of stars within a larger formation

Two micron all-sky survey /2MASS

an astronomical survey of the whole sky in the infrared and one of the most ambitious such projects

Sagittarius dwarf spherodial Galaxy

an elliptical loop shaped satellite galaxy of the milky way. consists of four globular clusters, the main cluster discovered in 1994

galactic halo

an extended, roughly spherical component of a galaxy that extends beyond the main, visible component. several distinct components of galaxies compromise the halo: the stellar halo. the galactic corona(hot gas i.e. a plasma)

Galileo

built his telescope in 1609. All astronomical discoveries before galileos time were made w/o the aid of a telescope. With the telescope, Galileo was able to view the universe in a new way.

Gravitational forces

caused the gas in the thin disk to fragment into clouds or clumps w/ masses like those of star clusters

Andromeda galaxy

closest galaxy to the Milky Way and approximately 2.537 million light years from earth. the name stems from the area of the earths sky in which it appears, the constellation andromeda

Spiral galaxies

consist of a flat, rotating disc containing stars, gas and dust, and a central concentration of stars known as the bulge. these are often surrounded by a much fainter halo of stars, many if which reside in globular clusters

Herschel's Diagram of the Milky Way

constructed this cross section of the galaxy by counting stars in various directions

William Herschel

discovered uranus, built giant telescopes, and made measurements of the Suns place in the galaxy, the suns motion through space, and the comparative brightness of the stars

central region

milky way has a modest bar in its

Halo stars

name given to the ancient formation of the stars which encircle the outer edge of the milky way galaxy representing the last stellar clusters to be encountered before one enters the eternal, frigid night of the intergalactic void

halo

nearly spherical population of field stars and globular clusters. it surrounds most dick galaxies as well as some elliptical galaxies

Shapleys diagram of the milky way

shows the location of the globular clusters, with the position of the Sun also marked.

milky way galaxy

the galaxy that contains the solar system with the name describing the galaxy's appearance from Earth. a hazy band of light seem in the night sky formed from the stars that cannot be individually distinguished by the naked eye.

Orion Spur

the solar system is on this and between the two longer adjacent arms Perseus and carina Sagittarius

Scutum-Centaurus and perseus

two spiral arms of the milky way