11.____ a form of electromagnetic radiation produced by rapidly moving : 1777245
11.____ is a form of electromagnetic radiation produced by rapidly moving electrons spiraling through magnetic fields.
12.The Crab nebula is
A.a planetary nebula.
B.a Bok globule.
C.an open cluster.
D.an absorption nebula.
13.Star clusters are important to our study of stars because
A.all stars formed in star clusters.
B.the sun was once a member of a globular cluster.
C.they give us a method to test the our theories and models of stellar evolution.
D.they are the only objects that contain Cepheid variables.
E.all of the above
14.What is the approximate age of the star cluster in the HR diagram below? (Hint: Main Sequence Stars of spectral between types A and B core supply of hydrogen is sufficient to last about 250 million years. Between A and F about 2 billion years. Type G about 10 billion years. Between K and M about 30 billion years..)
A.200 million years
B.2 billion years
C.10 billion years
D.30 billion years
E.The age of the cluster can not be estimated from an HR diagram of the cluster.
15.The triple alpha process
A.controls the pulsations in Cepheid variable stars.
B.is the nuclear fusion of hydrogen to helium in massive stars.
C.is the process that produces the neutrinos we receive from the sun.
D.requires a temperature of about 5,000,000 K to operate
E.occurs during helium flash.
16.Which of the following nuclear fuels does a one solar mass star use over the course of its entire evolution?
B.hydrogen and helium
C.hydrogen, helium and carbon
D.hydrogen, helium, carbon, and neon
E.hydrogen, helium, carbon, neon, and oxygen.
17.Helium flash occurs
A.because helium is very explosive and cannot be controlled when the nuclear reactions occur.
B.because degenerate electrons in the core do not allow the core to expand as it heats up.
C.in Cepheid variables.
D.in stars with masses less than 0.4 M.
E.none of the above
18.Stars in a star cluster
A.all have the same age.
B.all have the same chemical composition.
C.all have the same luminosity.
D.all of the above
E.a and b above
19.If the stars at the turnoff point of a cluster have a mass of 3 M¤, what is the age of the cluster?
A.3.0 ´ 1010 years
B.3.3 ´ 109 years
C.6.4 ´ 108 years
D.1.6 ´ 1011 years
E.The age of a star cluster can not be determined from the mass of stars at the turnoff point.
20.In the diagram below, which point indicates the location on the HR diagram of a one solar mass star when it undergoes helium flash?