University:
University of Michigan
Course:
ASTRO 127 | Naked Eye Astronomy
Academic year:

2024
Views:

472

Pages:

2
Author:

Ann Arbor

💫 The Milky Way Created by Created time Eesha Ray @December 4, 2024 11:48 PM done Galaxy (formal): a bound system of gas, dust, stars, and dark matter, usually all orbiting a large black hole at the center The MW is also flat (like the SS) like a pancake, ~100 times as wide as it is thick The Milky Way represents a preferred location for stars on our sky, indicating that the Sun is located within a giant disk of stars MW is spinning too fast. Hence, there is unseen matter causing the fast spin We call this unseen matter “dark matter” (because does not interact with light, only gravity) The Galactic disk contains not only stars, but also almost all the gas and dust in our Galaxy. Since stars form out of this gas, the youngest stars are located closest to the plane of the disk The gas and young stars are organized into spiral arms. The entire disk is rotating at 220 km/s. We now know that the disk is about 100,000 LY (light-years) across and only 1000 LY thick When compressed, the gas will be heated, and trigger star formation, causing blue spiral arms Globular clusters are dense, giant star clusters (red stars) Stars in globular clusters are ancient, low-mass stars, and were probably among the earliest stars to form in our Galaxy The Milky Way 1 The globular clusters are found in a sparse and vast spherical Galactic halo of stars surrounding the Galactic disk This halo with globular clusters allowed astronomers to identify the Sun's location in our Galaxy, by mapping their positions and estimating their distances *interstellar dust can create illusion of fainter, farther away clusters tho Today, we know that the Sun is about 26,000 LY from the Galactic center, or slightly more than half way out The relative size and luminosity of a galaxy's bulge relative to its disk is an important criterion for classifying its galaxy type. The Milky Way is an SBb galaxy, and has a mid-sized bulge, composed of billions of stars The bulge is about 15,000 LY in radius. It is also associated with the Galactic bar, which is an elongated stellar structure of similar size Baade's Window, located at 18h 03m, -30º 02'. The dust-free, observable"window" is about 1° in diameter on the sky In the Galactic coordinate system, the Galactic equator is defined by the plane of the Milky Way, and it includes both the Galactic Center and the Sun The Galactic poles represent the coordinate system's axis, perpendicular to the Galactic disk Galactic longitude and Galactic latitude are abbreviated as (l, b) 0 Longitude is longitude of Galactic Center *Measured in degrees on parallel to galactic equator The Galactic anticenter is the point on the sky diametrically opposite the Galactic Center (180, 0) Galactic latitude is measured in degrees of arc from the Galactic equator toward the Galactic poles The Milky Way 2

The Milky Way

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