# 2011 - PJAS state meeting astronomy projects

Hubble's Constant and the Age of the Universe
Christian Jay Snyder (Riverview Jr/Sr High School)

Project Description:

Hubble's Constant and the Age of the Universe is the title of an experiment conducted by me - Christian Snyder. Many people ask me how I came up with this idea for the experiment, and I always say the same thing; I have always had an interest in astronomy, and this was a perfect way for me to express that. But coming up with the idea for the research was the easy part, I actually had to conduct the experiment. I began by reading more and learning about the Hubble constant. Then, I began measuring and calculating the angular size of each of my 15 choice spiral galaxies and by using the angular size I calculated the distance to each galaxy. Because the Hubble constant is a relationship between the distance away a galaxy is from us and the velocity at which it is receding, I then needed to determine the velocity at which each galaxy is traveling. I used emission and absorption spectra to measure the amount of Doppler shift, which in turn would give me the velocity at which it was traveling. I then simply graphed the average galaxy velocity versus the distance to each galaxy and used the slope of that graph as my value for the Hubble Constant. Lastly, I determined the age of the universe. My value for the Hubble Constant was roughly 81.2 km/sec/Mpc, which would put the age of the Universe at roughly 11.7 billion years old. Using the scientifically accepted value for the Hubble Constant, which is 74.2 km/sec/Mpc, the age of the Universe is roughly 13.2 billion years old. Being as current findings have put the value for the age of the Universe anywhere from 10-15 billion years old using different methods, my value for the age of the Universe (and therefore the Hubble Constant) are considered accurate.

An Extended Study of Frequency Precursors to Cataclysmic Variable Star Outbursts in type U Geminorum Dwarf Novae
Nicole Melso (Springfield High School)

Project Description:

The purpose of this experiment was to search for the existence of an outburst precursor in a broader star category. Since SS Cygni is a subtype of U Geminorum stars, the prototype star U Gem was chosen for study. U Gem is an eclipsing binary system in which the white dwarf accretes matter from its companion star. Dwarf novae outbursts occur when unstable material in the accretion disk falls inward releasing large amounts of gravitational potential energy. During outburst, dwarf novae greatly increase in brightness and then return to a quiescent state. A telescope grant from the GRAS Observatory was received for this project, and scripts were written to control the observatory via the Internet. Data was collected in the form of photometry images using a CCD telescope, and the magnitude of U Gem in each image was obtained using the program VPHOT. It was hypothesized that if U Gem was monitored throughout quiescence, it would exhibit frequency precursors similar to those observed in SS Cygni. Data was analyzed by making frequency graphs in the program Peranso. These graphs represented the activity within the accretion disk. It was anticipated that high frequency peaks would appear close to the start of the outburst, signifying that material had become unstable and fallen inward. My results did not support the existence of a precursor. Because U Gem is an eclipsing binary, its orientation with earth prevents astronomers from viewing the center of the accretion disk, and therefore, the elevation in frequency.

The Orbit Determination of 4055 Magellan
Tara Jain (Moravian Academy Upper School)

Project Description:

The purpose of my project was to calculate the orbital elements of the asteroid 4055 Magellan, and to compare these elements to those predicted by JPL's Horizon Database. My hypothesis was that orbital elements that I calculated would not differ greatly from the elements predicted by the database. I used Gauss's Method, with which I could use three measurements of Right Ascension (RA) and Declination (Dec) of 4055 Magellan on three separate nights to determine the six classic orbital elements. With a 14 inch Meade Telescope connected to a CCD camera, I found the (x,y) positions of the asteroid and eight background stars on the CCD image and used these measurements in a program I wrote in Python using the LSPR model to find the RA and Dec of the asteroid on that observation night. After three observation nights spaced about twelve days apart, I wrote a program using Gauss's Method that would output the position vector, velocity vector, and the orbital elements of 4055 Magellan. I then compared these elements to those calculated by JPL's Horizon Database, and found that my hypothesis was supported- the elements I calculated did not differ greatly from those predicted by the database.

Preventing a Deep Impact
Vikas Aragam (Methacton High School)

Project Description:

The goal of my project was to determine whether nuclear weapons can divert near-Earth asteroids. I hypothesized that nuclear weapons of appropriate explosive energies can divert asteroids of various radii. I built a simulation of Earth and several incoming asteroids using the software package Interactive Physics. The nuclear explosives were represented by moving steel spheres that carried equivalent kinetic energies to the blast energies released by each explosive. I manually calculated the radius that each sphere would require to yield the necessary kinetic energies. Each steel sphere was collided perpendicularly to an incoming near-Earth asteroid, and the asteroid's modified trajectory was observed. I discovered a strong logarithmic relationship between the largest asteroid radius successfully diverted and the corresponding explosive energy. From this relationship, I concluded that nuclear explosives can successfully prevent asteroids from impacting the Earth. However, the experiment can be repeated in the future using software with three-dimensional rendering capabilities to verify this conclusion.