Astronomy Quiz 10

Questions and Answers

What is the class of the most elongated elliptical galaxies?

What is the class of the most circular elliptical galaxies?

What type of galaxy has a mix of young and old stars, an abundant amount of gas and dust, ongoing star formation, and a definitive shape?

Spiral Galaxies

What type of galaxy has only old stars, little to no gas and dust, and no star formation?

Elliptical galaxies Signup and view all the answers

A(n) type galaxy is _______ with elongated central regions.

SB; a spiral galaxy Signup and view all the answers

_ galaxies contain mostly Population II stars, while __ galaxies contain both Population I and Population II stars.

Elliptical; spiral Signup and view all the answers

_ galaxies have smaller nuclei and loosely wound arms compared to _ galaxies.

Sd; Sc Signup and view all the answers

The accurate determination of star distances by the method of standard candles requires accurate knowledge of the __________________ of the standard candle.

luminosity Signup and view all the answers

Hubble's law implies that the _ galaxies have larger __ in their spectral lines.

more distant; redshift Signup and view all the answers

Hubble's law is not applicable to __ because the motion of these galaxies is affected by .

galaxies in the Local Group; gravitational interaction with the Milky Way Signup and view all the answers

What are the main differences between spiral and barred spiral galaxies? What are irregular galaxies?

Spiral galaxies have 2 or more arms winding out from the center; Barred galaxies have arms that emerge from ends of an elongated central region; Irregular galaxies show no arms or uniform appearance, having stars and gas clouds. Signup and view all the answers

List two methods for determining the distances to galaxies and discuss their limitations.

Astronomers use cepheid stars which have luminosity that is proportional to the light variation; by measuring the light variation and apparent luminosity, it is possible to determine distance. A star's recession velocity is proportional to its distance and is measured by its redshift. Using Hubble's law, the distance can be found. Signup and view all the answers

Study Notes

Types of Elliptical Galaxies

E7 class represents the most elongated elliptical galaxies.
E0 class represents the most circular elliptical galaxies.

Spiral Galaxies

Characterized by a mix of young and old stars, rich in gas and dust.
Ongoing star formation is present, and they exhibit a defined spiral shape.

Elliptical Galaxies

Composed primarily of old stars with minimal gas and dust.
Lack ongoing star formation and generally appear more uniform.

Spiral and Barred Spiral Galaxies

Spiral galaxies have two or more arms winding out from the center.
Barred spiral galaxies feature arms that extend from the ends of a central elongated bar.

Population of Stars in Galaxies

Elliptical galaxies predominantly contain Population II stars.
Spiral galaxies feature both Population I and Population II stars.

Structural Differences in Spiral Galaxies

Sd galaxies have smaller nuclei and loosely wound arms compared to Sc galaxies, which possess tightly wound arms.

Determining Star Distances

The method of standard candles requires precise knowledge of the luminosity of the standard candle for accurate distance measurement.

Hubble's Law

Suggests that more distant galaxies exhibit larger redshifts in their spectral lines.
Hubble's law is not applicable to galaxies in the Local Group due to gravitational interactions with the Milky Way.

Irregular Galaxies

Lack distinct arms or uniform shape, containing a mix of stars and gas clouds.

Distance Measurement Methods

Cepheid variable stars have luminosity proportional to their light variation, allowing distance determination through observed light changes.
A star's recession velocity is tied to its distance, measurable through redshift, and can be utilized with Hubble's law to ascertain distance.

Description

Test your knowledge of galaxy classifications with this Astronomy Quiz 10. From elliptical to spiral galaxies, this quiz covers essential concepts and terminology in astronomy. Challenge yourself and see how well you understand the different types of galaxies!