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Scientific Paper Session Schedule  

Saturday, October 28, 2006

 

1:00pm - 3:30pm

 

John R. Percy, Kaushala Bandara, and Pietro Cimino 15 minutes

"Random Cycle-to-Cycle Period Fluctuations in Pulsating Variable Stars"

 

Eddington and Plakidis (1929 MNRAS 90, 65) showed that the times of maximum brightness of Mira and chi Cyg (both Mira stars) could be understood in terms of (i) random cycle-to-cycle fluctuations in period, and (ii) random errors in measuring the times of maximum brightness. In later papers, Plakidis drew the same conclusion for 21 more Miras. Percy and Colivas (1999 PASP, 111, 94) used the AAVSO International Database to detect and study period fluctuations in 391 Miras over 75 years. These fluctuations dominate the (O-C) diagrams of these stars, and make it difficult (but not impossible: Percy and Au 1999 PASP 111, 98) to detect evolutionary period changes in Mira stars. Similar fluctuations dominate the (O-C) diagrams of RV Tauri stars and yellow semi-regular variables, and have been found in at least one classical (Population I) Cepheid and one Population II Cepheid.

 

Here, we report on the search for period fluctuations in three SX Phe stars (CY Aqr, XX Cyg, DY Peg) and one delta Scuti star (VZ Cnc). See Templeton (2006 JAAVSO 34, 1) for a description of delta Scuti and SX Phe stars and their period changes. We explain why it is much more difficult to study period fluctuations in these short-period stars than in long-period variables like Miras. And we speculate about what might be the cause of period fluctuations in different kinds of variables.

 

We are beta-testing a program, written in C, to test for period fluctuations in datasets of either (O-C)s or times of maximum or minimum brightness. This program will eventually be made publicly and freely available on our website: http://www.astro.utoronto.ca/~percy/index.html

 

We thank NSERC Canada for research support, and the many AAVSO and other observers whose measurements have made our studies of period fluctuations possible.

 

Mary Ann Kadooka 20 minutes

"Fun Physics Demonstrations for Astronomy Outreach"

 

Here are fun ways to motivate attendees at your star parties. You can excite your audience with simple inertia demonstrations using raw eggs and paper tubes plus an orbiting nerf ball activity. Simple explanations on how these physics concepts are applied to astronomy phenomenon will be given.

 

Michael Saladyga 25 minutes

"A History of AAVSO's Headquarters"

 

This paper is a survey of the physical locations from which the AAVSO has operated, with discussion of the circumstances surrounding each of the AAVSO's moves.

John Pazmino 20 minutes

"Sunshine at Ground Zero"

 

The site of the late World Trade Center in New York is under development. The new World Trade Center, although itself a substantial project, differs significantly from the late one. One feature is to dedicate a section in the campus where the Sun shines during the memorial hours, 08:46 thru 10:29 EDST, on every September 11th. This astronomy feature is the 'Wedge of Light'. But will it work? Is there a true 'wedge of light' at Ground Zero?

 

Vladimir Strelnitski 20 minutes

"10-Year BVRI Monitoring of the Unique Hydrogen Maser Star MWC349"

 

The variable emission-line star MWC349 is the only known source of high-gain hydrogen maser and laser emission, which seems to arise in the ionized "skin" of the flaring neutral circumstellar disk seen almost edge-on. The uniqueness of this object prompts a short, transitory evolutionary state. Up to the end of 1990s, the data on the optical variability of the star were scarce and controversial. We have monitored it in B,V,R and I with the 31-in CCD telescope of Lowell Observatory for the past 10 years. Two modes of variability emerge from our data: (1) a secular decline of 0.03-0.05 mag per year (depending on the color band) and (2) possible periodic component, with a period of 3 A+/- 0.3 years and an amplitude of 0.1-0.2 mag. More frequent observations of masing hydrogen radio lines, carried out with the 12-m ARO radio telescope on Kitt Peak, revealed a general correlation with the optical, but also strong independent variations on shorter time scales. Preliminary interpretation of these results will be presented. More frequent optical observations of MWC349 in optical domain are obviously needed.

 

Roger Kolman and Barry Beaman 20 minutes

"Progress and Prospects - The AAVSO-AL Observing Venture"

 

Progress is reported here on the prospect of a cooperative observing venture between the AAVSO and the Astronomical League. Several proposals are suggested and strategies for implementation are discussed.

 

Steve Brady 25 minutes

"Real Time Photometry & Follow-up of Variable Stars"

 

An automated system for variable star observation with real time photometry and closed loop telescope scheduling is described. This new 'AutoPhotometry' tool has demonstrated new opportunities for observatory productivity and discovery.

 

The system uses a predefined observing strategy which may schedule the telescope for immediate:

* Time-series observations

* Additional filter sequence observations

 

A system for 'off-line' automated photometry of CCD images is described:

* Format observations for AAVSO submission

* Write observations to database for further data analysis

* Generate light curves

 

Edward Los 2 minute poster paper introduction
"Harvard Plate Digitization Progress Report"

 

We have built a high speed digitizer with the goal of putting most of the 500,000 plates in the Harvard plate stacks online. The digitizer is now operational and undergoing qualification testing.  A pilot project is underway to study variables in M44 as a demonstration of the scientific usefulness of the digitizer output.

 

3:30pm - 3:55pm Coffee Break

3:55pm - 5:45pm

 

Pebble Richwine and Dr. Timothy F. Slater 25 minutes

"Astronomy Teaching Resources from Great Explorations in Math and Science (GEMS)"

 

The Great Explorations in Math and Science (GEMS) curriculum guide books developed by Lawrence Hall of Science (LHS) support teachers in implementing inquiry in their classrooms.  The guides are easy to use and provide extensive background information for teachers.  In addition, several GEMS guides/activities are appropriate for Star Parties and other educational outreach opportunities for supporting the study of variable stars.  They include:  Earth, Moon, and Stars; Invisible Universe; Living with a Star; Messages from Space; Moons of Jupiter; The Real Reasons for the Seasons; Color Analyzers, and More than Magnifiers.  During this session, each of the astronomy GEMS guides will be summarized and some of the hands-on inquiry activities will be demonstrated to build AAVSO members' awareness of these valuable resources.

 

Christopher L. Watson, Arne A. Henden, and Aaron Price 25 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.

 

Grant Foster 10 minutes

"Effect of Finite Resolution on Magnitude Estimates"

 

We consider the effect of finite resolution of visual magnitude estimates on the limiting precision and accuracy of visual light curves.

 

Ronald E Zissell 10 minutes

"Secular Variations in CCD Transformation Coefficients"

 

How often should one redetermine your CCD transformation coefficients?  Data obtained over an interval of eleven years show nightly scatter greater than the error statistics and a small but real secular change in the coefficients.

 

Theo Jones and Pebble Richwine 15 minutes

"In the Hunt for Variable Stars: Digging into the Data Mine"

 

My name is Theo Jones I'm thirteen years old and currently in 7th grade. I'm a finalist in the 2006 Discovery Channel Young Scientist Challenge. I have a strong interest in astronomy and physics, as well as computer programming. I've attended several astronomy camps facilitated by the Conceptual Astronomy and Physics Education  Research (CAPER) team at the University of Arizona.

 

I'm currently working with the Pebble Richwine, a member of the CAPER team, at the University of Arizona using the curriculum packet "In the Hunt for Variable Stars". I am presenting data results from studying the following variables: V558 AQL, NSV 12374, and GX Aql Software applications utilized include: Fitsview , Astrometrica, and Mira 6.

 

Michael Mattei 25 minutes

"Digital Novae Searching"

 

Using a simple 35mm camera lens attached to a CCD camera mounted piggyback on a telescope one can image large areas of the sky to look for novae.