Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk 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 of which reside in globular clusters. Spiral galaxies are named by their spiral structures that extend from the center into the galactic disc. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disc because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin. The proportion of barred spirals relative to barless spirals has likely changed over the history of the universe, with only about 10% containing bars about 8 billion years ago, to roughly a quarter 2.5 billion years ago, until present, where over two-thirds of the galaxies in the visible universe (Hubble volume) have bars. The Milky Way is a barred spiral, although the bar itself is difficult to observe from Earth's current position within the galactic disc. The most convincing evidence for the stars forming a bar in the galactic center comes from several recent surveys, including the Spitzer Space Telescope. Together with irregular galaxies, spiral galaxies make up approximately 60% of galaxies in today's universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters. (Wikipedia).
Astronomy - Ch. 29: Galaxies (5 of 14) Spiral Galaxies
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn about the spiral galaxy. Spiral galaxies make up 72% of observed galaxies, 25% of all galaxies, but in our local group
From playlist ASTRONOMY 29 GALAXIES
Astronomy - Ch. 29: Galaxies (6 of 14) Barred Spiral Galaxies
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn about 2/3 of all spiral galaxies are barred spirals, the Milky Way, and over time (billions of years) spiral galaxies b
From playlist ASTRONOMY 29 GALAXIES
Astronomy - Ch. 29: Galaxies (3 of 14) Comparing Galaxy types
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will compare the different characteristics of spiral, barred spiral, elliptical, and irregular galaxies. Previous video in this s
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From playlist Courses and Series
Teach Astronomy - Formation of Spirals
http://www.teachastronomy.com/ When a large primordial gas cloud has a large amount of rotation or angular momentum the collapse will occur preferentially along the rotation axis leading to a disc-like formation. The disc will subsequently shear, and gas pockets will collapse within the d
From playlist 20. Galaxy Interaction and Motion
Teach Astronomy - Spiral Galaxies
http://www.teachastronomy.com/ We are very familiar with spiral galaxies because the Milky Way is a spiral, and M31 is a prominent nearby example. The main components of spiral galaxies are disks, bulges, and halos. Spirals may also have a bright nucleus or stellar bar. When viewed face
From playlist 19. Galaxies 2
Astronomy - Ch. 29: Galaxies (9 of 14) Irregular Galaxies
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn irregular galaxies tend to be small and irregular in size. They are rich in interstellar gas and dust and active star f
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Astronomy - Ch. 29: Galaxies (7 of 14) Elliptical and Lenticular Galaxies
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn elliptical galaxies are the most common galaxies in the universe (1/3 to ½). They vary in size from a few million stars
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Astronomy - Ch. 29: Galaxies (2 of 14) What Type of Galaxies are There?
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 We will learn there are 4 types of galaxies: spiral, barred spiral, elliptical, and irregular galaxies. Previous video in this serie
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The Grand Designs In Outer Space | Hubble's Canvas | Spark
This episode focuses on the forces that drive the creation of the universe. Also, by the studying of galaxy rotation, we are introduced to the theory of dark matter and dark energy. Subscribe to Spark for more amazing science, tech and engineering videos - https://goo.gl/LIrlur Follow u
From playlist How The Hubble Telescope Opened Our Eyes
Unexplained Mystery of Red Spiral Galaxies Found By James Webb Telescope
Get a Wonderful Person Tee: https://teespring.com/stores/whatdamath More cool designs are on Amazon: https://amzn.to/3wDGy2i Alternatively, PayPal donations can be sent here: http://paypal.me/whatdamath Hello and welcome! My name is Anton and in this video, we will talk about the stranges
From playlist Galaxies, Quasars, Blazars
The Andromeda galaxy is on a direct collision course with The Milky Way. Fortunately, it's more than two million light years away and is coming pretty slowly. Everybody, walk for your lives! Or just see the future of the Milky Way—no time-traveling DeLorean required. This video is lectur
From playlist Science
Galaxies, part 1: Crash Course Astronomy #38
The Milky Way is our neighborhood in the universe. It’s a galaxy and there are many others out there. Galaxies contain gas, dust, and billions of stars or more. They come in four main shapes: elliptical, spiral, peculiar, and irregular. Galaxies can collide, and grow in size by eating each
From playlist Astronomy
We Just Found The Oldest Spiral Galaxy in the Universe
You can buy Universe Sandbox 2 game here: http://amzn.to/2yJqwU6 Hello and welcome to What Da Math! In this video, we will talk about the oldest spiral galaxy in the universe. Support this channel on Patreon to help me make this a full time job: https://www.patreon.com/whatdamath Space
From playlist Space Engine
M81 - Bode's Galaxy - Deep Sky Videos
Professor Mike Merrifield discusses Bode's Galaxy, known as M81 or NGC 3031. More links and info in full description ↓↓↓ More Messier Object videos: http://bit.ly/MessierObjects More with Professor Merrifield: http://bit.ly/Merrifield_Playlist Testing Density Wave Theory with Resolved
From playlist Messier Objects
Astronomy - Chapter 1: Introduction (5 of 10) How Did The Galaxy Form?
Visit http://ilectureonline.com for more math and science lectures! In this video I will examine "How did the galaxy form?”
From playlist ASTRONOMY 1 INTRODUCTION