Skip to main content

95th Spring Meeting of the AAVSO: Scientific Paper Session Abstracts

The 95th Spring Meeting of the AAVSO
Rockford, Illinois
May 4-6, 2006

Scientific Paper Session Schedule
and Powerpoint Presentations (when available)

Friday, May 5, 2006
2:30pm - 3:30pm

Gary Billings        30 minutes
Period changes of the Algol-type eclipsing binary LS Persei
Period changes of the Algol-type eclipsing binary LS Persei (quicktime .mov)

Archival observations using the Harvard College Observatory Photographic Plate Collection have provided 251 magnitude estimates, and 18 timings of minima for LS Persei, back to 1889. Data from 1889 - 1935 (I series plates), and 1931 - 1950 (RH series plates) show different periods, which are different again from the GCVS (1960s and 70s) and later periods. In addition, two CCD times of minima were obtained in late 2005 that confirm a period increase, suggested by 1990s visual timings, of about 0.003% since 1990. Overall, the period of LS Per has decreased by 0.025% between 1889 and 2005. The O-C data can be fit by assuming intervals of constant period separated by abrupt period changes. Alternatively, if continuous period decrease is assumed, the residuals show cyclic variations of alternating sign. Possible mechanisms for this will be discussed.

Paula Szkody        10 minutes
Using XMM and Optical Photometry to Figure out CVs

X-ray light curves from XMM combined with optical data from the satellite and ground-based observers provide distinctive shapes and periodicities that provide information on the type of cataclysmic variable. Our recent data on 3 SDSS sources with strong He emission are used to identify a highly magnetic system (a polar), the spin of the white dwarf in an intermediate polar, and a typical disk accreting system.

Matthew Beaky        15 minutes
Detecting Extrasolar Planetary Transits Through Photoelectric Photometry (ppt)
Detecting Extrasolar Planetary Transits Through Photoelectric Photometry (quicktime .mov)

Observations of extrasolar planetary transits are crucial to determining specific information about the planet, such as mass and radius. Most observations are made using a CCD camera, but in this project we demonstrate that a solid-state photoelectric photometer can yield comparable precision. In this study, an Optec SSP-3A photoelectric photometer was used at the Truman State University Observatory in Kirksville, Missouri to observe transits of extrasolar planets. The precision of this system is demonstrated by observing a transit of HD209458, a well-known transiting planet with an associated stellar magnitude decrease of 0.017. Other attempts at observing planetary transits will also be reported.

3:30pm - 3:45pm Coffee Break

3:45pm - 5:10pm

Pebble Richwine, James Bedient, and Dr. Timothy F. Slater        30 minutes
Uncovering High School Students' Initial Understanding and Beliefs about the Nature of Science Prior to Studying Variable Stars (ppt)
Uncovering High School Students' Initial Understanding and Beliefs about the Nature of Science Prior to Studying Variable Stars (quicktime .mov)

Through the Spring of 2006, high school students' initial conceptual understanding and attitudes were systematically measured prior to using the curriculum packet "In the Hunt for Variable Stars." Students were about to investigate long-period variable stars on Stardial images of a 26 square degree area in Aquila, under the guidance of their science teacher in a high school integrated science classroom. This study builds upon previous work and provides important baseline information to measure cognitive and affective changes resulting from an authentic scientific research experience for high school students. As such, this educational research project represents an iterative step toward developing a comprehensive picture of students' conceptual understanding of the scientific enterprise of astronomy and students' attitudes about the nature of science.

Mario Motta, MD        15 minutes
Update on New 32-inch Scope (ppt)
Update on New 32-inch Scope (quicktime .mov)

Update on the almost completed, new 32-inch telescope.

Jerry Horne        15 minutes
Automated Extraction of Photometric Data: A demonstration project using MaximDL on CV images (ppt)
Automated Extraction of Photometric Data: A demonstration project using MaximDL on CV images (quicktime .mov)

The intrinsic photometric functions and scripting capability of the image processing software MaximDL is used to automate the extraction of photometric data from images of Cataclysmic Variable stars using standard AAVSO comparison stars. The resulting photometric data is then formatted for inclusion in the AAVSO variable star database. This automated technique is compared with manual data extraction methods and other photometric software.

Karen Meech        25 minutes
Observing a Lunar Impact (ppt)
Observing a Lunar Impact (quicktime .mov)

In view of the highly successful NASA Deep Impact mission (July 4, 2005), the technique of controlled impacts as a remote sensing space experiment is receiving wide interest. The SMART-1 mission is a European Space Agency mission for advanced research in technology. Launched in late September 2003, it headed for the Moon using solar-electric propulsion, arriving in lunar orbit mid November 2004. In addition to the technology demonstration component of the mission, the SMART-1 is exploring the moon to make a comprehensive chemical inventory of elements on the surface, in part to investigate the theory that the moon formed from a violent collision. After exhausting the Xe fuel onboard the spacecraft, the gravitational perturbations by the Earth and Sun would cause a collision with the lunar surface in mid August 2006. ESA has approved an extended mission, and beginning June 26 hydrazine thrusters will be fired to extend the mission at low altitude to allow for an impact on the near side of the moon, on the dark part near the lunar terminator under good observing conditions from Earth. The present date and time that the impact will occur are 3 September 2006, 02:00 UT. The impact mass will be 290 kg at 2 km/sec. Cratering predictions suggest that the thermal flash could be as bright as 7.4 if half of the kinetic energy of the impact were converted into heat, although if less efficient, the flash could be as faint as magnitude 16. The ESA SMART-1 Project Scientist, B. Foing, is soliciting an observing campaign at the time of impact. Because this event may be visible to the public and accessible by small telescopes, this talk will briefly describe the types of observations requested and the possible effects of the impact.

Saturday, May 6, 2006

2:00pm - 3:30pm

Vance Petriew and Aaron Price        25 minutes
The Comparison Star Database and the Automated Chart Plotter (PDF)
The Comparison Star Database and the Automated Chart Plotter (QuickTime .MOV video - 38MB)

The AAVSO is working towards an electronic charting system in order to eliminate the manual task of creating paper-based charts. The Comparison Star Database Working Group has taken the first step by documenting all the charts into a database. This database will be queried by the Automated Chart Plotter which is currently under development. This presentation will discuss what has been accomplished to date and what future initiatives need to be explored.

Aaron Price        20 minutes
Preparing For the NGC 6811 AAVSO Deep and Wide Field Campaign (PDF)
Preparing For the AAVSO Deep and Wide Field Campaign (Quicktime .MOV video - 27MB)

Prepare for the most ambitious AAVSO observing campaign ever. The AAVSO is planning a visual + PEP JHBVR + CCD BVRI observing campaign over a full degree of the late summer sky. Coordinating with the Case-Western Schmidt Telescope at Kitt Peak, we aim to cover the field from magnitudes 0-20 with intensive time resolution and high precision over the course of 30-60 days. In this talk we will discuss planning, coordination, observing strategies and the scientific goals of the campaign.

Aaron Price        20 minutes
SS Cyg Like You've Never Seen Her Before (PDF)
SS Cyg Like You've Never Seen Her Before (Quicktime .MOV video - 30MB)

An international group of AAVSO CCD observers watched SS Cyg nightly for many hours during most of the 2005 observing season. Over six months, they compiled over 100,000 observations of SS Cyg which resulted in the most detailed and comprehensive light curve of SS Cyg yet obtained. The goals, challenges, side benefits, and preliminary analysis results will be presented.

John R. Percy and Rohan Palaniappan        20 minutes
Analysis of AAVSO Visual Observations of T Tauri Stars

T Tauri stars are complex variable stars, with unique spectra, which are sun-like stars in the final stages of birth: they are still accreting gas and dust from a surrounding disc. They vary on timescales of minutes to decades, with amplitudes of up to several magnitudes. The variability can arise from variable accretion, from flaring, rotation and, in a few cases, binarity. AAVSO observers have made tens of thousands of visual observations of dozens of T Tauri stars over the decades, but most of these observations have not yet been validated, because their scientific value was not clear. The purpose of this project is to begin to investigate their scientific potential.

We have analyzed the visual observations of some of the stars, using a combination of light-curve, Fourier, and self-correlation analysis. In some cases, we have been able to compare our results with those from long-term CCD observations of the same stars, by William Herbst (Wesleyan University) and his collaborators. So far, we have determined the "variability profiles" (degree of variability versus time scale) for the stars. In some cases, we have also determined the rotation period.

Rohan Palaniappan is a participant in the University of Toronto Mentorship Program, which enables outstanding senior high school students to work on research projects at the university. We thank the AAVSO observers for their measurements, and AAVSO Headquarters Staff for checking and providing them to us.

3:30pm - 4:00pm Coffee Break

4:00pm - 5:00pm

Christopher L. Watson        30 minutes
The International Variable Star Index (VSX)

Now available at the AAVSO web site is a new utility: The International Variable Star Index (VSX). This program serves two distinct functions: an easy portal to access information about variable stars that is far more extensive than the GCVS; and a method of uploading variable star information. The information access includes all known cross references, basic parameters such as period and variability type, and finding charts. The upload feature permits information update on known variables (such as a new period) as well as entering new variable stars into the system. This paper will show examples of how to use VSX and describes the vetting guidelines.

Walter MacDonald II        30 minutes
A Dome on a Home: The Story of Winchester Observatory

In early 2003, a robotic rooftop observatory was built on the speaker's home. The 6-foot diameter dome houses a 10" f/6.3 LX-200 and is used almost exclusively for variable star work. Using only readily available, off-the-shelf hardware, the observatory is sufficiently automated to allow long, unattended observing runs. This presentation will discuss the construction and automation of Winchester Observatory and the adventures experienced during its first three years of operation.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484