Ata Sarajedini - US grants

ABSTRACT

Sarajedini, Ata
"Collaborative Project: Deep Astrometry and Photometry of Key Open Clusters: A New Foundation for Stellar Astrophysics"
AST-9819768

This is a multi-pronged collaborative investigation of stellar open clusters with Imants Platais at Yale University (AST-9819777). The goal is to provide useful clues and constraints on a variety of astrophysical problems such as: (1) the shape of the Initial Mass Function and its universality; (2) the extent of convective overshoot in stellar cores; and (3) the metallicity gradient in the Galaxy. The project will also result in a database of high quality astrometric, photometric and spectroscopic data for a carefully chosen sample of open clusters that will provide a benchmark for many unrelated future studies.

This grant supports the photometry portion of this investigation. UBVRI apparent magnitudes and color indices for cluster members will be obtained to ~1% internal precision for all stars in the astrometric database, as well as for fainter stars in these 8 clusters and 6 additional clusters. The collaborating team will conduct the astrometry portion of this investigation. Positional information, proper motions and cluster membership determinations will be acquired for 8 key open clusters to at least 6 apparent magnitudes (~250x) fainter than previous surveys, while maintaining current limits of proper motion accuracy (~0.005 "/yr). From this data, the present distribution of stars by mass will be determined for a wide range of cluster ages, richness, galactic position and metallicity.

Dr. Sarajedini will carry out a study of the stellar populations of galaxies in the local neighborhood of the Milky Way out to about 5 Mpc, with the aim of understanding the star formation and chemical evolutionary histories of galaxies with a range of morphological types. Particular attention will be paid to the interplay of dynamical interactions, star formation, and chemical enrichment in these galaxies. Work in a number of research areas will provide observational data to study the effects of environment on galaxy formation and evolution. His research plan includes studies of clusters in the galaxy and nearby Magellanic Clouds to develop a grid of color-magnitude diagrams that cover a range of metallicity and age. These will be used as fiducials against which the stellar populations of dwarf galaxies can be determined. He will also investigate the effects of dynamical interactions on star formation by studying the local examples of the Sagittarius dwarf and the Magellanic Clouds. He also plans to compare and contrast the stellar populations in the Milky Way, M33, and M31 using a variety of data. As larger and more efficient telescopes become available, these techniques and types of observations will be extended further into and beyond the local group.

He will also carry out a suite of educational and outreach activities over the next 5 years, which range from outreach to local K-12 classrooms and public talks for the Gainesville area, to designing a new undergraduate course. His research program naturally includes opportunity for undergraduates and graduate students to be highly involved and significant contributors.

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.

The research to be carried out here is an extension and expansion of a previously NSF supported program of open cluster photometry as part of the WIYN Open Cluster Study (WOCS). The goals of the WOCS in general are to create a database of high quality open cluster astrometry, photometry, and spectroscopy which in turn can be applied to investigate a range of astrophysical questions. Examples include the shape of the initial mass function and its universality, the extent of convective overshoot in stellar cores, the determination of precise cluster ages, the metallicity gradient in the Galaxy, and the extragalactic distance scale. In addition to continued use of the WIYN 3.5 and 0.9-meter telescopes to obtain precision photometry in support of WOCS, additional activities will be undertaken to extend the photometric component of WOCS. First, in collaboration with Chilean astronomer Dr. Doug Geisler at the Universidad de Concepcion, imaging/photometry will be extended to a sample of southern hemisphere open clusters in the 3rd and 4th Galactic quadrants. Second, near-infrared photometry will be obtained of WOCS clusters in order to develop color-magnitude diagrams with the largest color baseline possible. Third, WOCS clusters will be surveyed for variable stars using the University of Florida's Rosemary Hill Observatory. The resulting photometric database will be made freely available to the community. The work will also help establish an international collaboration between a US and Chilean university. An educational component is included in which undergraduate and graduate students will be trained in observing and data reduction. Moreover, the variable star survey will be carried out in large part by high school students using a CCD imaging system on the 30-inch telescope at the Rosemary Hill Observatory (thereby enhancing the local infrastructure for research, education, and training).

Dr. Sarajedini (University of Florida) will reduce and analyze archival imaging data from the Canada-France-Hawaii and Subaru telescopes in order to derive positions, magnitudes and colors for field stars, cluster stars, and the clusters themselves in M33. The resultant catalog will contain the deepest and widest-field ground-based photometry for M33 to-date. The field color-magnitude diagrams (CMDs) will be analyzed with synthetic CMD techniques to derive the star formation and chemical enrichment history of the field, while the cluster CMDs will be analyzed by comparison to theoretical isochrones and empirical cluster fiducials in order to estimate their ages and metallcities. These results will be used in conjunction with the integrated colors of the clusters to further constrain their ages and metallicities. The positions will be used to help characterize the structure of M33 and to search for substructure in its outer parts.

In addition to disseminating all of the results of the catalog of M33 photometrry and astrometry via a searchable web interface, Dr. Sarajedini and his group will also write a cook book for the analysis performed on the data. Undergraduate and graduate students will also be trained by working on certain aspects of this project.