What are 3 characteristics of spiral galaxies?
Most spiral galaxies contain a central bulge surrounded by a flat, rotating disk of stars. The bulge in the center is made up of older, dimmer stars, and is thought to contain a supermassive black hole. Approximately two-thirds of spiral galaxies also contain a bar structure through their center, as does the Milky Way.
What are the properties of a Seyfert galaxy?
Seyfert Galaxies are spiral galaxies with unusually bright, tiny cores that fluctuate in brightness. They do not have radio lobes. Most are powerful sources of infrared radiation. In addition, some emit intensely in the radio, X ray, and gamma ray regimes.
What is meant by an elliptical galaxy?
Definition of elliptical galaxy : a galaxy that has a generally elliptical shape and that has no apparent internal structure or spiral arms. — called also elliptical. — compare spiral galaxy.
What is an example of elliptical galaxy?
Examples. M87 (NGC 4486), whose supermassive black hole is the first black hole to be imaged by the Event Horizon Telescope. IC 1101, one of the largest galaxies in the observable universe. Maffei 1, the closest giant elliptical galaxy.
What are 5 characteristics of a spiral galaxy?
Structure
- A flat, rotating disc of stars and interstellar matter of which spiral arms are prominent components.
- A central stellar bulge of mainly older stars, which resembles an elliptical galaxy.
- A bar-shaped distribution of stars.
- A near-spherical halo of stars, including many in globular clusters.
How do you classify spiral galaxies?
Spiral galaxies are classified as Sa/SBa, Sb/SBb or Sc/SBc (classic/barred) according to the tightness of their spiral, the clumpiness of their spiral arms, and the size of their central bulge. These differences can be traced back to the relative amounts of gas and dust contained within the galaxies.
What does a Seyfert galaxy evolve into?
Type II Seyfert galaxies are very bright sources of infra-red and visible light. Type II Seyfert galaxies evolve into Type I Seyfert galaxies. Seyfert galaxies make up about 10% of all galaxies.
What’s the difference between a Seyfert galaxy and a quasar?
Quasars are brighter and more distant objects (that is, they are older) than Seyfert galaxies. Quasars are detected without observing the underlying galaxies, whereas Seyfert galaxies are detected both by the energetic core and by the entire galaxy radiation.
What is the difference between spiral and elliptical galaxies?
Spiral galaxies have a central bulge of stars surrounded by a disk that contains arms, which form a spiral structure. Elliptical galaxies don’t show any structure, but have a smooth ellipsoidal shape, appearing as a large spherical or elliptical ball of stars.
What is elliptical galaxy made of?
Elliptical galaxies are made up of mostly old stars, and do not have much gas and dust. There is very little new star formation in these galaxies. Elliptical galaxies also come in many sizes. The largest galaxies we see are ellipticals, but, elliptical galaxies can also be small.
What do elliptical galaxies contain?
Elliptical galaxies are ellipsoidal in shape, contain no spiral arms, contain little interstellar gas or dust, and are found mostly in rich clusters of galaxies. Elliptical galaxies appear typically yellow-red, as opposed to spirals which have spiral arms that appear quite blue.
Why are elliptical galaxies red?
Because star-forming activity in many giant elliptical galaxies has shut down to very low levels, these galaxies mostly house long-lived stars with low masses and red optical colors. Astronomers have therefore called these galaxies “red and dead”.