A cepheid star is located at a distance of 18.7kpc from the Earth and has an apparent visual magnitude of 13.1. Determine its pulsation period in days. Consider the following expression of the Leavitt relation MV=−2.78logPdays−1.35��=−2.78log⁡�days−1.35, where MV�� is the absolute visual magnitude and Pdays�days the pulsation period in days to 2 decimal places.

A cepheid star is located at a distance of 24.8kpc from the Earth and has an apparent visual magnitude of 13.3. Determine its pulsation period in days. Consider the following expression of the Leavitt relation My -2.78 log Pdays - 1.35, where My is the absolute visual magnitude and Pdays the pulsation period in days to 2 decimal places.

The mass of a star is 1.99·1031 kg and its angular velocity is 1.60E-7 rad/s. Find its new angular velocity if the diameter suddenly shrinks to 0.27 times its present size. Assume a uniform mass distribution before and after. Icm for a solid sphere of uniform density is 2/5 mr2.

Double stars are stars which are close enough and move slowly enough that they orbit each other.  Each star is located at the focus of the ellipse of its orbit around the other star.  Consider a binary star system which has an average angular separation of 6.1" arc and a period of 87.3 years. The annual parallax of the stars, p, is 0.192"arc.  We call the measure of the angular separation of the two stars, .  [remember that 1 degree is divided into 60 'arc (read this as 60 minutes of arc) and each 1'arc is subdivided into 60"arc (read this as 60 seconds of arc)].  The distance to the binarystar system is calculated from its parallax , p, of 0.192"arc, which has been measured carefully over a period of the last 92 years.  First we must calculate the distance to the binary system:  D  =  1/p   where p is the parallax in seconds of arc giving D in parsecs.  The distance, D =  1/p = ________ pc How many light years does this correspond to?  (remember that 1 pc = 3.26 lt yr)  D (in light…