Ryan Rubenzahl

University of Rochester Physics and Astronomy




Projects

Here are some papers/projects I have completed for various courses I have taken so far.

PHY 243W: Advanced Experimental Techniques -- Fall 2017 (Senior)

RR Lyrae Stars and Stellar Evolution in the Globular Cluster M15
We present lightcurves for 30 RR Lyrae variable stars identified in the globular cluster M15 using observations recorded at the University of Rochester’s C.E.K. Mees Observatory. The periods of the variables are compared to observations of the brightest RR Lyrae star, RR Lyrae itself, whose proximity is such that its distance is accurately determined by parallax measurements. From this we estimate the distance to M15 to be 9000 ± 370 pc. Further, we perform photometry for the stars in the cluster in three wavelength bands and present a HR diagram of M15. We discuss the evolution of the stellar members of M15 by comparison of the HR diagram to that of nearby stars.
Here is a blinking gif of M15 - how many variable stars can you find?

The Franck-Hertz Experiment
We conduct the classic Franck-Hertz experiment in which electrons are accelerated through a mercury vapor and inelastically collide. We find the energy required to initiate inelastic collisions between electrons and mercury atoms to be 4.69 ± 0.05 eV, in agreement with the lowest excited state of mercury (63P0). The dependence of the Franck-Hertz curve on the tube temperature is explored, and we find a decrease in average peak spacing with increased temperature. We find the measurement of the lowest excited state to be stable with temperature if derived from minima spacings, and inconsistent if derived from the maxima spacings, in agreement with previous studies.


PHY 413: Gravitation (Graduate) -- Spring 2017 (Junior)

Gravitational Wave Radiation by Binary Black Holes
Derivation of gravitational waves from the Einstein field equations under the linearized theory, derivation of the quadrupole formula for energy radiated from a system in the form of gravitational waves, equations describing gravitational wave radiation for a binary system: power radiated, rate of orbital decay, waveform of emitted gravitational waves. Comparison of linearized gravitational waves to the first LIGO detection "chirp" and waveform.


PHY 235W: Classical Mechanics -- Fall 2016 (Junior)

Small Oscillations of the n-Pendulum and the "Hanging Rope" Limit n → ∞
Solving for the equations of motion and frequencies of small oscillations for a n-link pendulum and exploring the limit in which the pendulum becomes a dangling rope of continuous mass density. This is explored from four different approaches: using Newtonian mechanics from a discrete setup (n-pendulum) and then taking the limit, as well as starting with the continuous case (rope) and solving, as well as using Lagrangian mechanics for the discrete and continuous cases. This term paper partially satisfies the upper-level writing requirement of the Physics and Astronomy major at UR.

Interactive Mathematica notebooks: Enter a value of n and watch the pendulum swing!
Numerical solution for full n-pendulum: npendulum.nb
Small-oscillations (fully solved): smalloscillationsnpendulum.nb


AST 142: Elementary Astrophysics -- Spring 2016 (Sophomore)

Black Hole Mergers and Gravitational Wave Astronomy
Basic concepts of gravitational wave emission from binary black holes: inspiral, merger, ringdown phases. Basic properties of gravitational waves and their ability to be detected, principles of gravitaitonal wave astronomy: interferometry, noise-reduction techniques, what kind of science can be accomplished by measuring gravitational waves, future observatories in development.


AST 111: The Solar System and Its Origin -- Fall 2014 (Freshman)

Measuring The Mass of Uranus by Observing the Revolution of the Moons Using Kepler's Third Law
Final project involving observations from the C.E.K. Mees Observatory's 24 inch Cassegrain telescope and 4k CCD camera. The positions of the moons and their separation from the planet are measured in order to determine the mass of Uranus via Kepler's Third Law. However, only three nights of data were acquired during the semester, and so fitting a sine curve to the three data points was impossible. Instead, I develop my own method that is able to determine an excellent approximation given the orbital geometry of the Uranus system relative to our line-of-sight. Periods of the moons Titania and Oberon are found to 4% and 1% accuracy respectively, and the mass of Uranus is determined to 11% accuracy. Largest sources of error come from the following assumptions: (1) the orbit of the moons are circular and (2) the Uranus system is viewed exactly pole-on. The magic of conservation of momentum does the rest.