Name ____________________ Block __________ Date ___
E3 Stellar Distances
Found a great new video site called Studynova.
http://www.studynova.com/videos/subject.php?id=7
Found great site with example MATH problems. This site will go through
all the topics for this sections of Astrophysics. Keep referring back to it as you make your way
through the standards. http://sci.esa.int/sciencee/www/object/index.cfm?fobjectid=35616&fbodylongid=1659
Stellar Parallax
E.3.1 Define the parsec
E.3.2 Describe the stellar parallax method of determining the distance to a star.
E.3.3 Explain why the method of stellar parallax is limited to measuring stellar distances less than several
hundred parsecs.
E.3.4 Solve problems involving stellar parallax.
The standards are task. Use the following three sites to do the task and answer the question
inside of the sites.
1) There are several good videos here at khanacademy.org that look at all these standards.
http://www.khanacademy.org/science/cosmology-and-astronomy/stellar-life-topic/stellar-parallaxtutorial/v/parsec-definition
2) Here is a good definition and explanation of Newton’s model and idea of the universe.
https://sites.google.com/site/anrosphysics/ib-physics/astrophysics-option/2-astronomicaldistances
3) Answer the following questions from an old IB exam.
https://docs.google.com/file/d/0B6JZ47ZkMM5NmU3NDAxZGItMDRmYy00OTg4LTkyNGYtMTEwYzNkNGQxOWEy/edit?pli=1
Absolute and apparent magnitudes
E.3.5 Describe the apparent magnitude scale. Students should know that apparent
magnitude depends on luminosity and the distance to a star. They should also know
that a magnitude 1 star is 100 times brighter than a magnitude 6 star.
E.3.6 Define absolute magnitude.
E.3.7 Solve problems involving apparent magnitude, absolute magnitude and distance
E.3.8 Solve problems involving apparent brightness and apparent
magnitude.
http://sci.esa.int/sciencee/www/object/index.cfm?fobjectid=35616&fbodylongid=1868
Anrophysics – Gives example walk through of practice problems.
https://sites.google.com/site/anrosphysics/ib-physics/astrophysics-option/3-themagnitude-of-stars
Questions:
1. A certain type of variable star are known to have a average absolute magnitude of 0.0. Such stars are
observed in a particular star cluster to have an apparent magnitude of +16.0. What is the distance to the star
cluster?
2. The star Procyon in Canis Minor (the Small Dog) is a prominent star in the winter sky, because it's apparent
magnitude is +0.37. It is also one of the closest stars, being only 3.51 parsecs from Earth. What is the
absolute magnitude of Procyon? How many times brighter or dimmer than the Sun is it?
3. Barnard's star can only be seen with a telescope because its apparent magnitude is +9.54. Its distance from
Earth is only 1.81 pc. How much closer to the Earth would Barnard's star need to be for it to be visible to the
naked eye?
Spectroscopic Parallax
E.3.9 State that the luminosity of a star may be estimated from its spectrum.
E.3.10 Explain how stellar distance may be determined using apparent brightness and
luminosity.
E.3.11 State that the method of spectroscopic parallax is limited to measuring stellar
distances less than about 10Mpc.
E.3.12 Solve problems involving stellar distances, apparent brightness and luminosity.
Pg 925 -926 (Giancoli-White with a Mountain) – Challenge yourself with some practice from pg 944 and 945
Ringo is back!
http://www.youtube.com/watch?v=Q7kVEwkG58A&list=PL7FD7F1082F45C268&index=7&safety_mode=tru
e&persist_safety_mode=1
Teacher’s web site. This has practice problems at the end. Try them with out looking at the
answer first.
http://cde.nwc.edu/SCI2108/course_documents/stars/stellar_distances/spectroscopic_parallax/
spectroscopic_parallax.htm
Cepheid Variables
E.3.12 Outline the nature of a Cephid variable
E.3.14 State the relationship between period and absolute magnitude for Cepheid variables.
E.3.15 Explain how Cepheid variables may be used as “standard candles”.
E.3.16 Determine the distance to a Cepheid variable using the luminosity – period relationship.
Cepheid Variables Video https://www.youtube.com/watch?feature=player_embedded&v=E9gvk_OkrPw#
Ringo again!
http://www.youtube.com/watch?v=djLNBNFQSd8&list=PL7FD7F1082F4
5C268&safety_mode=true&persist_safety_mode=1