Exam 10: Characterizing Stars

By approximately how many magnitudes is the star Sirius fainter than the full Moon in our sky? (See Figure 10-2,Comins,Discovering the Essential Universe,6th ed.)

The statement that the apparent magnitude of a variable star has increased indicates that its:

If we restrict our measurements to a specific band of color or wavelength using an optical filter,what observations of a star are necessary to determine the absolute magnitude of the star at this color?

A star has a surface temperature of 6000K (see Figure 10-4b,Comins,Discovering the Essential Universe,6th ed.).Its spectrum registers a certain intensity in the green middle of the visible spectrum.Which statement characterizes the rest of the spectrum?

Stellar parallax appears because:

Use the Hertzsprung-Russell diagram (Figure 10-7)and the mass-luminosity relation (Figure 10-14)in Comins,Discovering the Essential Universe,6th ed.,to estimate the mass of Vega,an AO V main-sequence star with a surface temperature of about 10,000 K.

Which is NOT needed to compute a distance to a star by the spectroscopic parallax method?

The sequence of letters that is used to classify star surface temperatures,as determined by relative spectral absorption line strengths,in order of DECREASING temperature,is:

How do two unequal-mass stars in a binary star system move around each other,in general?

Two stars have the same spectral classification,say,M2,but one of them is a red giant while the other is a main-sequence star.To determine which is which,we look at their spectra because (see Figure 10-9,Comins,Discovering the Essential Universe,6th ed.)the absorption lines in the giant will be:

Optical glass filters are used to select certain portions of a star's light for photometry.Which filter would MOST closely match the sensitivity of our eyes,which have a peak sensitivity at about 550 nm wavelength? (See Figure 3-1,Comins,Discovering the Essential Universe,6th ed.)

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

What are the two physical parameters of stars that are plotted in the Hertzsprung-Russell diagram?

Apparent magnitude is a measure of a star's:

The Sun's luminosity is 3.83 × 10²⁶ watts.By the time this energy reaches Earth,it has spread out so that it provides only 1370 watts to each square meter.The orbit of Mars has a mean radius of 1.53 AU.How many watts of the Sun's luminosity are provided to each square meter of the surface of Mars?

Spica (in Virgo)and Hador (in Centaurus)have about the same temperature.However,Hador has roughly four times the luminosity of Spica.What can you determine about the relative radii of these two stars? Spica is about:

A star of apparent magnitude +1 appears _____ than a star of apparent magnitude +2.

A star's absolute magnitude and its apparent magnitude have the same numerical value.How far is this star from Earth?

A star shows strong hydrogen Balmer lines but weak lines of neutral sodium.Which is a likely explanation for this phenomenon?

Two stars of equal mass form a visual binary system.The separation between the two stars is 4 AU and the period of the orbital motion is 8 years.What is the mass of each star relative to the mass of the Sun?