Exam 12: Characterizing Stars

If the intrinsically brightest stars in Earth's sky have absolute magnitudes of -10, how bright (in terms of total energy output per second) are these stars compared with the Sun, whose absolute magnitude is +4.8?

For MOST stars, the

What is a star's luminosity?

The Hipparcos satellite was able to measure parallax for stars out to about 150 pc. This distance includes roughly 2.5 million stars. What is the average number of stars in 1 cubic parsec?

Suppose the distance between an observer and a lightbulb is doubled. How does its final brightness compare with its initial brightness?

What will be the intrinsic brightness or luminosity of a white dwarf star that has the same temperature as the Sun? See Figure 12-7 in the text.

Why are Balmer absorption lines very weak in the spectra of stars with low surface temperatures-significantly below 10,000 K, for example?

How many eleventh magnitude stars are required to equal the brightness of one first magnitude?

When comparing two stars, the one with the _____ must have the greater luminosity.

Absolute magnitude is defined as the apparent magnitude that a star would have if

A particular star is at a distance of 20 pc from Earth. For this star, the apparent magnitude will have

How many times brighter than a magnitude +4.0 star is a magnitude +3.0 star?

What condition is necessary on Earth to see eclipses of stars in binary star systems?

The absolute magnitude of a star is the brightness the star would appear to have if it were placed at what distance from Earth?

Astronomers originally classified the spectra of stars according to the strengths of their hydrogen lines. What new physical insight enabled a reinterpretation of these patterns in terms of surface temperature during the 1920s?

Which important property of stars can be BEST determined by observations of binary stars systems?

Which of these MOST plausibly explains why the star Bellatrix in Orion looks bluish to the naked eye?

In the spectral classification scheme, what designation is given to a star just a little hotter than an F8 star?

Which of these statements can be used to define stellar parallax?

A particular star appears approximately equally bright when viewed through a blue filter and through a yellow filter. What is the approximate surface temperature of this star?