NAIC/AO Newsletter, November 1997
The NSF Research Experience for Undergraduates (REU) program sponsored eight undergraduates; the NASA Capability Enhancement program (administered by the University of Puerto Rico Resource Center for Science and Engineering) funded one student; and the program administered by the Puerto Rico Community Foundation supported former Arecibo summer students, Antonio Algaze, Luis Wilkes and Sven Schrecker, who were continuing their research at the Observatory as part of senior or master's theses.
Due to the presence of a number of people involved in the completion of the Upgrade and some large groups performing experiments, the Visiting Scientist Quarters (VSQ's) were full and could not accommodate the students this summer. We were fortunate in finding a large rental house not far from the Observatory which the students could use. The house had banana trees in the back yard and a large porch with a view of the hills. Although they dealt with cramped quarters and plumbing problems cheerfully, most felt that living on site would be better in future summers. A group of the students from the mainland rented a car for the summer and were very adventurous about exploring. Many of them had family and friends visit, with whom they took excursions to Ponce, El Yunque, and Vieques.
An extension of the summer student research experience is the opportunity to attend scientific meetings. Brent Grime attended the CEDAR meeting in Boulder, CO, in June. Francisco Acevedo, Amanda Birmingham, Chris Hardin, Zoe Leinhardt, Melissa Nysewander, and Anil Seth are planning on presenting posters on their summer projects at the winter AAS meeting in Washington, D.C. This experience allows the students to discuss their projects with other scientists and to learn more about the most recent scientific developments in the fields of astronomy and atmospheric science.
As usual, the entire staff of the Observatory enjoyed the stimulus of this annual infusion of young, enthusiastic students.
Albin Alonso Rosario and Arturo Yanez Navarrete (both of UPR - Mayaguez) worked under the supervision of Edgar Castro and Craig Tepley to develop a remote control system for the Arecibo Observatory Ionosonde. The Ionosonde transmits a vertical pulse of radio frequencies from 3 MHz to 20 MHz. When the frequency of the pulse equals the electron plasma frequency in the ionosphere, the wave is reflected down to Earth. The output (ionograms) maps the electron density (derived from the plasma frequency) as a function of height. The user-friendly system which the students developed allows a scientist in the control room to operate the ionosonde and display the resulting ionograms which track the overall changes of the ionosphere and its component layers.
Amanda Birmingham (Amherst College), with Jo Ann Eder, determined the molecular gas content of three star-forming S0 galaxies, previously detected in HI with the Arecibo telescope. The goal of the project was to compare the ratio of molecular to atomic gas in these early-type galaxies with that for normal spiral galaxies reported in the literature. Amanda became the local Unipops expert in order to reduce NRAO 12 meter CO spectra from which she inferred the total molecular gas content of each galaxy. Then she tackled AIPS to deal with VLA velocity cubes of HI maps. She divided both data sets into velocity bins so that she could calculate the total gas mass in each and compare this to the critical gas density necessary for star formation.
Brent Grime (Pennsylvania State Univ.) worked with Jonathan Friedman and the new Sodium Resonance Lidar system to study temporal and spatial variations in the sodium density in the mesopause; variations which carry information about gravity wave dynamics. Brent learned how to operate a complex system and stayed up many nights accumulating data. On several occasions he witnessed the rise and decay of a sporadic layer. He also developed signal processing and plotting routines with IDL to analyze the data. Brent will return this winter to use the Na Resonance Lidar during the upcoming rocket campaign, the resulting data to be used for his master's thesis.
Chris Hardin (Amherst College), a math major working with José Alonso, designed a Web page for the Visitor Center which included an interactive 3-D tour of the telescope, 3-D models of different reflecting systems (including the new Gregorian), a pulsar model with its period controlled by the viewer, and a "virtual museum" through which a visitor can wander. Chris not only learned several new languages (VRML, AWK, and JavaScript), but learned a lot about astronomy and the functioning of the telescope as well.
Zoe Leinhardt (Carlton College), with Kiriaki Xilouris, studied pulsar fluctuation spectra at high frequencies (1.4, 4.7, 8.3 and 10.5 GHz) using single pulse data from the 20 brightest pulsars observable from the northern hemisphere. They resolved the components of the fluctuation spectra in order to determine the relationship between the fluctuation properties and the origin of the emission in the magnetosphere (whether from a "core" or a "hollow cone"). They found that the fluctuation behavior of their sample was frequency independent. Their analysis also suggested that different modes of emission are associated with slightly different fluctuation spectra.
Melissa Nysewander (Agnes Scott College) investigated high density gas in far infrared (FIR) and megamaser galaxies with Willem Baan. She reduced spectra taken for two samples of galaxies, one with maser emission and one without, and compared the line ratios of each group. From the relative abundances of the observed molecules (CO, HCN, HCO+, CS, and CN), the general chemistry and processes of the galaxies could be inferred.
Anil Seth (Wesleyan Univ.) worked with Chris Salter studying the distribution of Rotation Measure (RM) and magnetic-field orientation over the supernova remnant (SNR), G41.1-0.3. This was achieved using frequency-spaced C-band VLA continuum observations. Using AIPS, Anil made full Stokes-parameter maps at the opposite ends of the C Band, and for various resolutions, constructed the polarized intensity, position angle of the plane of polarization and percentage polarization distributions. The derived RM distribution was used to recover the intrinsic position-angle distribution, giving the magnetic field orientation within the object. This showed that the magnetic field had considerable structure, indicating filamentary structures and a distorted barrel shape. This SNR also displays a wide range of polarization percentages, and evidence of very faint structural "plumes". Anil plans to use the results for this remnant and for SNR G11.2-0.3, plus interpretation of the results, for his senior thesis.