answer for part A,B,C The original Small Magellanic Cloud Cepheid Period-Luminos
ID: 106630 • Letter: A
Question
answer for part A,B,C
The original Small Magellanic Cloud Cepheid Period-Luminosity relation from Leavitt and Pickering (left panel) and a contemporary Cepheid Period-Luminosity relation from Benedict et al. (right panel). For both plots the x-axis is log_10 period in days. The y-axis for the Leavitt and Plickering plot (left) is in apparent magnitude while the y-axis for the Benedict et al. (2007) plot is absolute magnitude. (a) Why were Leavitt and Pickering able to observe a Cepheid Period-Luminosity relation using apparent magnitudes, rather than absolute magnitudes? (b) What three measurements (and from what data) do you need to produce a plot of absolute magnitude as a function of period for Cepheids? (c) Using the lower relation from Leavitt and Pickering (left panel) and the contemporary Cepheid Period-Luminosity relation from Benedict et al. (right panel), determine the approximate distance to the Small Magellanic Cloud. (d) What is the Tully-Fisher relation and how is it used to measure distances? (e) What is the principal advantage of the Tully Fisher relation relative to Cepheid distances?Explanation / Answer
a)Apparent magnitudes were used to observe luminosity relation because apparent magnitudes do not take the leakage values into account whereas absolute magnitudes plot the leakage lumimous values which leads to complex calculations.
b)The three main measurements are
The value of 'a' found in the plot
The value of 'b' found in the graph
The log value of p plotted
These value are taken from the panel on the right side in order to find the absolute value as it takes into account all the side leakage values into account.
c)The approximate distance to the Small Magellanic Cloud is calculated as,
Distance =(a*b)/logp
The log p value is taken at the center point and is equal to 1.
distance=(-4.07*-2.55)/1=10.37
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