The Classification of Stellar Spectra Started with the Amount of Hydrogen

question 27

Multiple Choice

The classification of stellar spectra started with the amount of hydrogen in the star's spectrum; however, now a better scheme uses the star's _____.

• A) mass
• B) diameter
• C) radius
• D) temperature
• E) luminosity

---

Definitions:

Just Noticeable Threshold

The minimum level of stimulus intensity needed for a person to detect its presence or a change in its presence, approximately 50% of the time it is present.

Physical Stimulation

Any external or internal stimulus that elicits a sensory or physiological response in the body.

Sensation

The method through which sensory receptors and the nervous system detect and depict energies from stimuli in our surroundings.

ESP Effects

Refers to supposed "extrasensory perception" phenomena where individuals claim to have abilities beyond the known human senses, such as telepathy or clairvoyance.