Constantine P. Deliyannis - US grants

Deliyannis, Constantine AST 98-12735 Dr. Deliyannis will carry out a program of observations of open star clusters that will address a number of issues in stellar and chemical evolution, by tracing the behavior of the stellar lithium abundance. Observations will be made with the Wisconsin-Indiana-Yale-NOAO telescope using its multi-object spectrograph which can provide large samples of stars within each cluster. A sample of up to 10 clusters, selected to span the relevant parameter space in age and metallicity, will allow the investigation of : a) mechanisms for Li depletion in main-sequence stars, b) tests of theoretical explanations for the behavior of Lithium abundance with temperature, and c) the galactic evolution of Lithium and its relation to 'primordial' Li abundance. The research plan focuses on using the behavior of Lithium abundance in unevolved stars as probes of stellar structure and evolution, but the results would have implications for the determination of globular cluster ages, big bang nucleosynthesis, and cosmology.

AST-0206202
Deliyannis, Constantine


Dr. Deliyannis is awarded funds at Indiana University in Bloomington, Indiana to study the abundance of lithium (Li) in the members of open star clusters. He will use the multi-object spectrograph on the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5m telescope to make spectroscopic observations of up to 100 stars simultaneously. Dr. Deliyannis is participating in the WIYN Open Cluster Study (WOCS), a collaboration already underway by WIYN Consortium members.

This study will make detailed observations of the Li abundance of stars of different ages in an attempt to understand the failures of our current stellar structure and evolution models. Observations of 6 to 10 clusters of different ages will be made. Dr. Deliyannis will work to determine the metallicity dependence of Li depletion, the development of the Li "gap" with age, and the Li peak and plateau.

AST-0139617
Honeycutt

Dr. Honeycutt is awarded funds to establish a Research Experiences for Undergraduates site in astronomy at Indiana University in Bloomington, Indiana. The site will host six students per year for three years. Recruitment will target students from small colleges and state universities without astronomy Ph.D. programs. The focus of the student projects will be observational stellar astronomy using ground-based photometric and spectroscopic data. The students will be organized into three research groups in the areas of variable stars, open cluster color-magnitude diagrams, and high dispersion spectroscopy. Student activities will include a week-long trip to Kitt Peak to use the 0.91-m WIYN (Wisconsin-Indiana-Yale-NOAO) telescope, an internal research symposium in the final week of the program, and the preparation of abstracts and posters for presentation at a professional meeting.

REU SITE: An REU Site at Indiana University in Stellar Astrophysics and Beyond

ABSTRACT

AST 0452975 Deliyannis

The PI, Constantine Deliyannis and collaborators will continue the operation of the Research Experiences for Undergraduates (REU) site at Indiana University. The program brings incoming juniors seniors to Bloomington, IN for 10 weeks during the summer to undertake research with faculty and graduate student mentors. Students also participate in a weeklong observing run on the Wisconsin-Indiana-Yale-NOAO (WIYN) 0.9-meter telescope at Kitt Peak, AZ. Research projects include studies of the properties of star clusters, searches for, and studies of, variable stars, and determination of the chemical composition of stars and star clusters. All students present their results at meetings of the American Astronomical Society.

The broader impact of this program includes the opportunity for promising young scientists to experience research in astronomy, and the resulting encouragement to pursue careers in science. The program aims to recruit underserved minorities and women, and provide them with research experience that can help as they move on to graduate school.

AST-0607567

INSTITUTION: Indiana University
PI: Constantine Deliyannis
TITLE: Lithium and Metallicities of Older Open Clusters

ABSTRACT

Dr. Constantine Deliyannis, at Indiana University, will study the abundance of the chemical Lithium (Li) in 7 primary and several secondary open star clusters, to address key issues in stellar structure and evolution that might ultimately have significant implications for light element chemical evolution, globular cluster ages, big bang nucleosynthesis, dark matter and cosmology. Specific areas of research address issues that follow from Dr. Deliyannis' work with the Wisconsin-Indiana-Yale-NOAO (WIYN) Open Cluster Study.

Two graduate students and at least six undergraduates will be trained and encouraged to pursue careers in science. Dr. Deliyannis has a record of recruiting women and minorities, and this is expected to continue. Dr. Deliyannis will also conduct exit and later interviews for assessment of student training, and he will incorporate his research results in classrooms, and give various public talks based, in part, on the research.

AST-0618157
Constantine P. Deliyannis
Indiana University

The WIYN 0.9-meter Consortium will a) build a modern, half-degree imager ("HDI") for the WIYN 0.9m telescope at Kitt Peak, b) make associated observatory upgrades for this imager, and c) carry out new outreach initiatives. This imager will feature a monolithic, 4-amplifier, fast-readout 4Kx4K CCD with 15 micron (=0.4") pixels that yield a 29'x29' field with high (and flat) U-response. HDI will replace the 15-year-old S2KB CCD, whose performance has been degrading and is vulnerable to complete failure. The return to the US Community includes a 10-20% share (Section7) of the observing time on the new imager for five full years, access to all archived data after a modest proprietary period, and access to WITN's special queues, including the long-term monitoring queue and the "opportunity" queue.

The WIYN 0.9-meter Observatory is operated by WIYN Observatory, Inc. and serves a consortium of ten partner institutions from across the nation. W09 supports highly diverse short and long-term scientific projects, educational activities with undergraduate and graduate students including three REU programs and a major outreach program to K-12 teachers (Teacher Leaders in Research Based Science Education). Most basically, this new imager will permit continued operations of this very successful and vital facility; failure of the present CCD would be the end of operations. HDI will also increase significantly the quality of observations and the observing efficiency, it will enable new and more ambitious scientific endeavors, and it will enable us to continue our current educational/outreach initiatives and goals and to improve and expand them.

This award will help to ensure a future for the WIYN 0.9m observatory (including continued access to the community of MOSAIC on the 0.9m, which has been oversubscribed by an average factor of 1.83 during the past 7 semesters). HDI will enable a number of diverse short term and long term programs and surveys, including fundamental precision open cluster UBVRI and Stromgren photometry using multiple photometric nights per cluster to reduce systematic calibration errors; a comprehensive survey of all northern open clusters; surface photometry and Halpha photometry of galaxies, broad-band and narrowband Halpha optical studies of the ALFALFA-HI survey galaxies, studies of starburst and normal galaxies; long-term monitoring of stellar periods in open clusters and star forming regions, and of long period variables in globular clusters; monitoring of cataclysmic variables and activity in open clusters; extensive surveys of of the stellar populations in M31 and M33 and of Milky Way spiral arms through OB associations; and coordinated photometric/spectroscopic observations with other telescopes such as the WIYN 3.5.

The WIYN Consortium has a track record of using the telescope to train numerous undergraduate students and graduate students. The survival of the observatory through HDI will allow these activities to continue, and the participants' experiences will be enhanced by the superior pedagogy enabled from use of HDI's state-of-the-art technology: introductory-level students, teachers, and Tohono O'odham tribe members will get a better glimpse of high-level astronomy, while advanced undergraduate and graduate students will receive superior training to prepare them for a career in astronomy.

This award is funded by the Division of Astronomical Sciences and the Office of Multidisciplinary Activities.

In this project, previously obtained observational data are analyzed to determined the oxygen and iron abundances in solar-type dwarf stars of 15 open clusters of known age and different metallicity (i.e., the contents of the heavy chemical elements relative to hydrogen). The samples range by nearly a factor of ten in their iron-to-hydrogen ratios and cluster ages span from about 30 million to about 8 billion years. This study expands previous abundance data sets to cover about three times as many clusters, a higher sample of stars in each cluster, and a wider range in metallicity and age.

The abundances of oxygen and iron trace the galactic chemical evolution - the enrichment of the interstellar medium in chemical elements produced in stars. This study addresses whether the iron and oxygen abundances in clusters depend on cluster age and how iron and oxygen abundances relate to each-other. This is of interest because oxygen and iron productions vary among different types of massive stars that explode as supernovae. An additional study here checks on the relation of the alpha element (such as Mg and Si) production with age. Such relations may place constraints on the processes in stars and stellar nucleosynthetic yields of heavy elements that are released into the interstellar medium by massive stars.

This project provides a venue to attract many undergraduate and graduate students to scientific research as have previous projects by the principal investigator.

In this collaborative project, the PI's will use spectroscopy and photometry to measure the abundances of Li and other elements for hundreds of stars in seven open clusters, in order to constrain models of interior stellar structure. The collaborative component of the project will bring together photometry and spectroscopy expertise so that the investigators can address the mystery of anomalous Li abundances, which may indicate that additional, as yet unknown, physical mechanisms act in stars. Both PI?s have institutional access to appropriate observatories (WIYN and Mt. Laguna). The work will have broader impacts to Galactic evolution and cosmology, and the PI?s will train undergraduate and graduate students in research at two universities.

The abundance of Lithium, relative to Hydrogen, is a key prediction of Big Bang models of the early universe. Abundances of the elements can be measured using the absorption lines in stellar spectra. But Lithium can also be destroyed in stars when convection mixes surface material with the hotter stellar interiors. Low abundance of Lithium in stellar atmospheres is seen among stars where processes that deplete Lithium would not be expected to occur, and abundances are far lower than predicted for stars where such depletion processes are expected to be operating. This team will measure the abundance of Lithium in the atmospheres of a carefully selected sample of stars in order to better understand physical processes inside stars. They hope to determine whether the Sun is a normal or abnormal star for its mass and age, whether there is variation in Lithium destruction among supposedly identical stars, and better understand the disagreement between the Big Bang Lithium abundance inferred from the microwave background observations and that seen in stellar atmospheres. This is a collaborative effort among astronomers at four universities, including a predominantly undergraduate institution. This project will lead to at least one PhD thesis and extend the educational opportunities for undergraduates at the individual schools by integrating a team of students in a large-scale research program, using astronomical observatories in Arizona, California, and Australia.

The research team will extend and expand its spectroscopic studies of stars in open and globular clusters, emphasizing the old open clusters M67 and NGC188, and the nearest globular cluster, NGC6397. Their goals are (a) determine whether the Sun is a normal or abnormal star for its mass and age, (b) determine if there is variation in the physical mechanisms controlling Li destruction among supposedly identical stars, (c) pioneer studies on the role of stellar metal content in determining the level of Li-depletion, and (d) study the potential impact of stellar evolution on metal deficient stars of the halo, with implications for the true level of disagreement (if any) between the value of the Big Bang Li abundance inferred from the microwave background versus that inferred from halo dwarf surface Li abundances.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.