Exam 10: Characterizing Stars

Two stars,one classified A4 V and the other F8 V,have the same apparent magnitude.There is no significant amount of absorption of starlight by interstellar material.From this information we know that the A4 V star is _____ the F8 V star.

The spectrum of a very distant star shows spectral absorption lines of ionized helium,He II,and molecular absorption bands from titanium oxide,TiO.What could you conclude about this star?

Two stars are found to have the same luminosity.However,one star has twice the surface temperature of the other.From this information,what can you determine about their radii?

In a particular binary star system,only one star is visible because the other star is too faint to see at that distance.An astronomer measures the size (semimajor axis)and period of the orbit of the visible star.From this information,the astronomer:

Which sentence describes the relationship between mass and luminosity of stars on the main sequence?

Parallax of a nearby star is used to estimate its:

You are observing a binary system with two stars of masses M₁ and M₂.You determine a,the semimajor axis (also the average distance between the stars)and P,the period of their motion.Using this information in Kepler's third law,you can calculate:

The ancient Greek astronomer Hipparchus introduced the magnitude scale on which he called the brightest stars first magnitude.Today,the brightest star in the night sky is Sirius,with a magnitude of -1.4,considerably brighter than first magnitude.Why the discrepancy?

The star Arcturus is classified as K2 III,which means that it is a:

Which atom or ion produces the strongest absorption lines in the spectra of stars with the highest surface temperatures?

Which important stellar parameter can be derived from the study of binary stars mutually bound to each other by gravitational forces?

The Sun's spectrum peaks in the green region (i.e.,green is the most intense color in its spectrum).The spectrum of Rigel (the knee of Orion)peaks in the short-wavelength end of the visible spectrum.Compared with the Sun,Rigel is:

Absorption lines in the spectra of some binary stars are seen to change periodically from single to double lines and back again.Explain.

A star of apparent magnitude +5 appears _____ than a star of apparent magnitude +3.

The Hertzsprung-Russell diagram is a plot of:

The light intensity from a particular star remains essentially constant,except for short and regular decreases and increases by a fixed amount.What is the explanation for this phenomenon?

The luminosity of a star is:

Where are the MOST massive stars to be found in the main sequence of a Hertzsprung-Russell diagram?

The star ɛ Canis Majoris has an absolute magnitude of -4.1 and a spectral class of B2.Using Figures 10-7 and 10-8 of Comins,Discovering the Essential Universe,6th ed.,how would Canis Majoris be classified?

Looking at the clock face on a distant steeple,the clock subtends an angle of 275 arcseconds.How far away is it?