Question

h - r diagram, life cycle, and nucleosynthesis of stars quiz

1. what is the primary information used to classify and place a star on the h - r diagram?

(1) its mass and its solar radius
(2) its age and elemental composition
(3) its distance from earth and its apparent brightness
(4) its true brightness and its surface temperature
base your answers to questions 2 through 4 on the diagram below and on your knowledge of earth science. the diagram represents some of the inferred stages in the life cycle of stars according to their original mass.

1. which star may once have been similar to our sun in mass and luminosity?

(1) spica
(2) procyon b
(3) proxima centauri
(4) deneb

1. energy is produced in the cores of main sequence stars when

(1) cosmic background radiation is released
(2) cosmic background radiation is absorbed
(3) heavier elements undergo fusion into lighter elements
(4) lighter elements undergo fusion into heavier elements

1. the final stage in the life cycle of the most massive stars is a

(1) white dwarf (2) black hole (3) black dwarf (4) supergiant

Explanation:

1)

The Hertzsprung - Russell (H - R) diagram plots stars based on their luminosity (true brightness) on the y - axis and surface temperature (related to spectral class) on the x - axis. Mass and solar radius are not the primary axes for the H - R diagram. Age and elemental composition are not the axes. Distance and apparent brightness are not the axes for classifying stars on the H - R diagram.

Proxima Centauri is a low - mass star. Spica is a massive star. Procyon B is a white dwarf (a later stage, not similar to the Sun in mass during its main - sequence stage). Deneb is a supergiant (a massive star). The Sun is a main - sequence star of a certain mass, and low - mass stars (like Proxima Centauri in its main - sequence stage) can have a similar mass - related life - cycle path as the Sun (before the Sun became a giant).

In the cores of main - sequence stars, nuclear fusion occurs. Cosmic background radiation is not involved in energy production in star cores. Heavier elements do not fuse into lighter elements (fusion in main - sequence stars is mainly hydrogen (lighter) fusing into helium). Heavier elements are formed in more massive stars in later stages. Lighter elements (like hydrogen) undergo fusion into heavier elements (like helium) in main - sequence star cores, releasing energy.

Answer:

(4) its true brightness and its surface temperature

2)