Fall 2005 Meeting Highlights
Scientific Paper Sessions
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Friday, October 14, 2005
2:00pm – 3:25pm
Doug West, Doug Hodgson, and Ken Luedeke 20
minutes
"Photometry of Eta Aql" ( video, ppt )
Eta Aql is
a classical Cepheid variable of the delta Cephei type. Visually it varies
magnitude 3.5 to 4.6. In the J infrared band, the star varies from
magnitude 2.2 to 2.7 and in the H infrared band it varies from 1.9 to 2.2. This
paper reports on J (1.25 micron) and H (1.65 micron) photometry gathered using
the SSP-4 photometer by the AAVSO Infrared Photometry Group. This collection of
observations represents the most extensive consistent set of J and H band
observations reported in the literature for this star. Reduction of the
observations reveals a period of variation of 7.1760 +/- 0.0037 days. The J and
H band observations lag the visual observations by approximately 0.2 cycles.
Ronald E Zissell 15
minutes
"CY Aquarii Revisited" ( video )
The author
has been observing CY Aqr for forty years. This dwarf cepheid has undergone
over 200,000 cycles in this interval. Gross and subtle period changes are
apparent in the O-C diagram. To
paraphrase Alice, "things just get curiouser and curiouser."
Grant Foster 30
minutes
"Long-Term Light Curves of
Cepheid Variables" ( video, ppt )
We have
analyzed the light curves of 65 Cepheid variables, using visual data from the
American Association of Variable Star Observers (AAVSO). We find that Cepheid
pulsations are not nearly so constant as is often believed; half of our
well-observed sample show episodes of period change, in addition to long-term
period evolution. We derive the Fourier decomposition coefficients for the
sample, and present mean light curves for the best-observed stars. We also find
that the light curve shape is usually well approximated by a "bent sawtooth"
wave, which can account for the coefficients of the Fourier series.
John Pazmino 20
minutes
"Station at the Center of the
Universe" ( video, ppt )
Grand
Central Terminal in New York City is acclaimed by astronomers for its fabled
Sky Ceiling, the largest star map in human history. However, there are over a
dozen astronomy features of this rail hub dating from its opening in 1913
through its newest section in the 1990Ős. These were demonstrated for the first
time by NYSkies at the 2003 Earth Day show in the terminal. NYSkies had about
the most humble of booths but the very grandest of all exhibits! Slides and
handouts highlight the astronomy of Grand Central Station, station at the
center of the universe.
3:25pm – 3:55pm Coffee
Break
3:55pm – 5:30pm
Arne Henden 20
minutes
"A New Look at Johnson/Cousins
Photometric Filters" ( video, ppt )
Some of the
Schott glasses originally prescribed by Bessell in creating Johnson/Cousins
UBVRcIc photometric filters for use in CCD cameras are no longer
available. We have selected new glasses, and added interference coatings,
to create a new set of filters that accurately match the original
Johnson/Cousins bandpasses. This paper will describe the new
prescriptions and give preliminary results from on-telescope tests.
Jerry Horne 15
minutes
"V478 Lyrae Revisited: A Current
Look at Eclipses and Star Spots" ( video )
Differential
photometry of V478 Lyr is presented and analyzed, from the 2005 observing
season, spanning eighteen rotation cycles. The resulting analyses are
compared to previous published data. This study analyzed multiple eclipse
cycles and obtained photometry demonstrating additional fluctuations in the
light curve of the system. V and I band photometric observations
were fit to a two spot model using several commercially available binary star
modeling programs. Spot distributions, relative size, and
longitudinal separation have been determined.
Barry Beaman 15
minutes
"SS-AT -- A Remote Telescope
for Pretty Pictures, Science Projects, and Real Research" ( video, ppt )
ISS-AT,
International Space Station -- Amateur Telescope, is being planned to provide
amateur astronomers and students a space borne platform for imaging for
whatever purpose. The ISS-AT Alpha Scope has been established in
Arizona and is remotely operated from Dyer
Observatory in Nashville to prove the concept of operation for the proposed
space telescope. A significant block of time on the Alpha Scope is being
offered to AAVSO to help prove to NASA that amateur astronomers are capable of
doing real astronomical research from space.
Pebble Richwine, Jim
Bedient, and Dr. Timothy Slater 30
minutes
"Preliminary findings on the
impact of observing variable stars on middle school students' beliefs and attitudes toward
the nature of science" ( video, ppt )
In the
Spring 2005, middle school students in the desert southwest used the curriculum
packet "In the Hunt for Variable Stars". Preliminary results are
contributing to a larger study on how authentic research impacts studentsŐ
beliefs and attitudes toward the nature of science. The paper provides
initial and post-program data from surveys, class observations, and
interviews. Students concentrated their studies on the Right Ascension
19h45m using StarDial data available online.
Mary Ann Kadooka 15
minutes
"Deep Impact Tempel 1 Student
Projects" ( video )
Students
have been working on comet research projects using images from the 2.0 meter
Faulkes Telescope North (FTN) located on Haleakala, Maui in Hawaii. In
June, students attended sessions to do remote observing with FTN and to learn
to use image processing software in preparations for the July 4 Deep Impact
comet/impactor encounter. They operated FTN in real time during the
encounter at a teacher/ student workshop held on Maui. Images of the
comet as well as preliminary results will be shared. The mentoring provided by
an AAVSO member has been instrumental in assisting us with developing a pilot
mentor program that will utilize amateur astronomers.
Saturday, October 15, 2005
2:00pm – 3:30pm
Matt BenDaniel 30
minutes
"Remote Observing with SLOOH"
John
R. Percy, Anna Molak, Hugh Lund, Danie Overbeek, Amelia Wehlau, and Peter F. Williams 20 minutes
"V725 Sgr: Real-Time Evolution
of a Pulsating Star" ( video )
V725 Sgr is
a unique pulsating variable star, first recognized by Henrietta Swope, which
has increased its period by a factor of at least 5 in the past century.
It has also changed its amplitude and its mean magnitude. It appears that, for
the first few decades of the 20th century, its spectrum and variability were
those of a Population II Cepheid. Now, they are those of a red
semi-regular (SRa or SRb) variable. We will review V725's past
history. Unfortunately it was largely neglected through the middle of the
20th century, though there was a key paper in 1973 by Serge Demers. We
have now used visual (mostly Overbeek and Williams) and photoelectric CCD
(Lund) photometry of V725 Sgr, from 1985 to 2004, to study V725 Sgr's recent
variability -- period, amplitude, mean magnitude -- using a variety of
time-series analysis techniques (Fourier, least-squares, self-correlation),
which we shall describe. We shall then discuss possible explanations; V725
Sgr's behavior is consistent with the final stages of a thermal
"flash" in its nuclear burning shells, from the asymptotic-giant
branch and back.
J.A. Wilkerson, T.S. Brown,
and B.K. Lacoul 30
minutes
"Searching for Open Cluster
Variable Stars Using Short Duration Unfiltered Images" ( video, ppt )
As part of
an ongoing project to search for statistical evidence of isolated apparent flux
transients in stars, such as might arise from occultation by Kuiper Belt
Objects, we have acquired numerous unfiltered images from the fields containing
several open star clusters. A typical data set for a single cluster
consists of hundreds or thousands of images of a few seconds duration from each
clear night in a two to three month observing window. We have begun
assessing the viability of utilizing these data sets to search for variable
stars in these fields. Variable stars in clusters are useful for
understanding both stellar evolution and the dynamical evolution of regions of relatively
high stellar density. Cluster populations can also prove useful in
calibrating various distance estimation techniques. With so many images
from a single night, our data are particularly sensitive to variable stars with
periods less than a day (e.g., W UMa and Delta Scuti stars). Because our
data sets cover many nights over several months we can also reliably detect
longer period eclipsing binary stars. We report our technique for
identifying stellar variability given the residuals inherent in light curves
constructed from unfiltered images. We have tested our technique on the
fields containing M67 and NGC129 and we report the results of those tests as
well.
Frederick R. West 2
minute poster paper introduction
"Some recently Discovered Red
and Brown Dwarfs"
Costa et
al. (2005) recently published parallaxes obtained with the 1.5 meter telescope
at Cerro Tololo Inter-American Observatory. They reported absolute parallaxes
for 31 stars, 29 of which are red dwarfs. Four of these red dwarfs are known
flare stars; more of these red dwarfs may also be variable stars. A large
aperture telescope will be required to monitor these stars, since all of them
are between thirteenth and nineteenth visual magnitude. The red dwarf DENIS
1048-3956 (spectral type M8.0 V) is found to be only 4.00 ± 0.03 parsecs (13.06
light years) from the Sun. TeegardenŐs Star (SO 0253 + 165258, spectral type
M7.0V)is also discussed (Teegarden et al. 2003; Sinnott, 2003).
Since most
of the 63 stars now known to be closer than five parsecs (16.3 light years) are
red dwarfs (45), the completeness of the present count of red dwarfs and brown
dwarfs further from the sun is discussed on the basis of these recent papers
and The Catalog of nearby Stars by
Gliese and Jahreiss (1991).
William R. Alexander, John
Hall, Ty Nelson, and Danielle
Miller 2
minute poster paper introduction
"A Time Series of UX-UMa"
The
variable star UX-Uma (1332 +52) was observed using CCD-Visible photometry and a
0.2 meter Schmidt-Cassegrain telescope. UX-Uma is a binary star system
consisting of a white dwarf primary star and a solar-type secondary star.
Designated as a "nova-like" system, material is systematically being
transferred from the secondary star to the
primary. According to models, this material forms an accretion disc
around the primary. As the dimmer secondary star moves in front of the brighter
primary, eclipses can be observed. A sequence of two eclipses were
systematically observed and analyzed for the first time in approximately 10 years,
according to AAVSO data. The orbital period was determined to be 0.196578 +/-
0.000168 days. Preliminary results show that one of the eclipses observed
can be classified as "peculiar" and suggests that the hot spot on the accretion
disc dimmed during one of the recorded eclipse events. This could be due
to the variation of the rate of material falling onto the accretion disc from
the secondary star. These observations were conducted with the assistance
of undergraduate astronomy students.
3:30pm – 4:00pm Poster
Viewing and Coffee Break
4:00pm – 5:25pm
Paul A. Valleli 15
minutes
"Forward or Backward? Visual
brightness estimates using the MMO digital data base"
The digital scanning of plates from the Maria Mitchell
Observatory 1913- 1994 is virtually complete. The originals were taken with the
F/4.5 Cook Triplet designed by H. Dennis Taylor. The aberration pattern
of stellar images varies across the 15 degree field of view of the lens,
depending on the orientation of the central element. The author will describe the effects of the lens reversals
on stellar brightness measurements and a possible suggestion for automated
analysis.
Kerriann H. Malatesta, Sara
J. Beck, and Gamze Menali 20
minutes
"The AAVSO Data Validation
Project" ( video, ppt )
In 2002, NASA awarded the AAVSO a 2-year grant to
error check over 9.5 million observations in the AAVSO International Database
from 1911 and earlier in some cases through 2001. The purpose of
the project was not to produce "pretty" light curves devoid of
scatter, but rather to do a systematic search of the data to look for potential
and obvious errors, and to investigate and rectify any problems. In most cases,
this was done by looking at the original observation report. A project
description, outlining the stars included, common problems encountered,
procedures followed, and the accessibility of the data on the web will be
given. In addition, future data validation plans will be reported.
Edward J. Los 15
minutes
"Update on the Harvard College
Observatory Plate Digitization Project" ( video )
We are building the fastest astronomical plate scanner
in the world, capable of scanning an 8" x 10" plate to 2300 dpi in under 30
seconds. This paper presents a description of the scanner and related efforts
to put the entire Harvard College Observatory plate collection online.
Gerald P. Dyck 20
minutes
"Ormsby MacKnight Mitchel, Astronomer
and Civil War General" ( video, ppt )
A few colorful episodes from the life of O.M. Mitchel
will be presented - his ambitious efforts to found the Cincinnati Observatory, his
popular lectures in astronomy, his daring schemes and untimely demise during
the American Civil War.
Barbara L. Welther 15
minutes
"Some Notes from Annie Jump
Cannon's Notebooks" ( video )
In the mid-1890s, Annie Jump Cannon decided to return
to her alma mater, Wellesley College, to pursue graduate studies in physics and
astronomy and to assist her mentor, Professor Sarah Frances Whiting, in
teaching the undergraduate courses there. In the fall of 1896, when
Whiting sailed to Europe for a sabbatical leave, Cannon journeyed into
Cambridge to continue her graduate work at Radcliffe College and to assist in
the astronomical research at Harvard College Observatory. There,
Professor Pickering, the director of the observatory, gave her some assignments
in the fields of variable stars and stellar spectra. Along with her
scientific observations, Cannon also made some personal notations. This
paper will take a look at some of her notes and observations, especially those
of her early, impressionable years at the observatory.