PMF's Research Page

"Exploring Halo Substructure with Giant Stars: Spectroscopy of Stars in the Galactic Anticenter Stellar Structure" Crane, Jeffrey D.; Majewski, Steven R.; Rocha-Pinto, Helio J.; Frinchaboy, Peter M.; Skrutskie, Michael F.; Law, David R., ApJL, 594, 119 (PDF)

"Star Clusters in the Galactic Anticenter Stellar Structure and the Origin of Outer Old Open Clusters" Peter M. Frinchaboy, Steven R. Majewski, Jeffrey D. Crane, I. Neill Reid, Helio J. Rocha-Pinto, Randy L. Phelps, Richard J. Patterson, and Ricardo R. Munoz. 2004, ApJL, 602, L21 (PDF)

``A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: II. Swope Telescope Spectroscopy of M Giant Stars in the Dynamically Cold Sagittarius Tidal Stream'', Majewski, S. R., Kunkel, W. E., Law, D. R., Patterson, R. J., Polak, A. A., Rocha-Pinto, H. J., Crane, J. D., Frinchaboy, P. M., Hummels, C. B., Johnston, K. V., Rhee, J., Skrutskie, M. F., \& Weinberg, M. 2004, AJ, 128, 245 (PDF)

``The Fan Observatory Bench Optical Spectrograph'', Crane, J. D., Majewski, S. R., Patterson, R. J., Skrutskie, M. F., Adams, E. Y., Frinchaboy, P. M. 2005, PASP, 117, 526 (PDF)

``Exploring Halo Substructure with Giant Stars. IV. Extended Distributions of Giant Stars Around the Carina Dwarf Spheroidal Galaxy -- How Reliable are They?'', Majewski, S. R., Frinchaboy, P. M., Kunkel, W. E., Link, R., Munoz, R. R., Ostheimer, J. C., Palma, C., Patterson, R. J., & Geisler, D. 2005, ApJ, in press (astro-ph/0503627)(PDF)

``Exploring Halo Substructure with Giant Stars. VIII. The Extended Structure of the Sculptor Dwarf Spheroidal Galaxy'', Westfall, K.B., Ostheimer, J. C., Majewski, S. R., Patterson, R. J., Frinchaboy, P. M., Link, R. & Kunkel, W. E. 2005, ApJ, in press (astro-ph/0508091)(PDF)

``Exploring Halo Substructure with Giant Stars: The Velocity Dispersion Profiles of the Ursa Minor and Draco Dwarf Spheroidals At Large Angular Separations'', Munoz, R. R., Frinchaboy, P. M., Majewski, S. R., Kuhn, J. R., Chou, M.-Y., Palma, C., Sohn, S., Patterson, R. J. & Siegel, M. H, 2005, ApJL, in press (astro-ph/0504035) (PDF)

``Chemodynamics of Outer Disk Star Clusters: Berekey 29, Saurer 1 and BH176'', Frinchaboy, P. M., Munoz, R. R., Phelps, R. L., Majewski, S. R. & Kunkel, W. E. 2005, AJ, submitted

``Exploring Galactic Disk Tracers: I. Survey Methods & Orbits of Southern Clusters'', Frinchaboy, P. M. & Majewski, S. R. 2005, ApJ, in preparation

More publications... (from ADS)

To determine the rotation curve outside the solar circle, at minimum one must obtain proper motions and reliable distances for a suitable stellar tracer population. Past analyses have included studies of HII regions (Fich et al. 1989), Cepheid variable stars (Pont et al. 1994), and Asymptotic Giant Branch (AGB) stars and planetary nebulae (Amaral et al. 1996), but each have shortcomings. For example, gaseous tracers (planetary nebulae and HII regions) have an inherent distance scale uncertainty, AGB stars are difficult to obtain accurate photometric parallaxes for in isolation, while pulsational variability complicates RV determination for Cepheids. Star clusters offer many advantages over these other tracers as compared to an isolated field star at the same location in the Galaxy, the distance, metallicity, age, and kinematics of a cluster are much easier to establish. The 3-D kinematics of individual stars or clusters requires both proper motions and RVs, but the ability to average over an ensemble of cluster members lowers the required per star precision. Our radial velocities will be combined with proper motions from SIM to yield orbits of outer Galactic clusters that will be used as dynamical probes of the Milky Way's gravitation potential.

For my thesis, I am working with my advisor Dr. Steven Majewski on a project to using photometry, proper motion, and spectroscopy, to investigate Galactic structure through the use of open clusters. The project will yield space motions of numerous open clusters outside the solar circle at a precision to make tangible improvements in the determination the mass of the galaxy. The project will also provide the best derived bulk RVs for these clusters with errors of ~ 1 km/s. Deriving detailed velocity fields of clusters will also yield valuable insights into the dynamical evolution of open clusters. "For free" we obtain spectroscopic metallicites of open cluster stars. Thus, the survey will provide age-dated tracers with good distances and [Fe/H] suitable for investigating the chemodynamical evolution of the Galactic disk.

The University of Virginia Galactic Structure Group has been investigating various tidal streams from Milky Way dwarf satellites, including Sagittarius, the Magellanic Clouds, GASS, Carina, Leo I and II, Ursa Minor, and Sculptor. We have also been investigating the dwarf satellites of the Andromeda Galaxy (M31) as well.

I have been investigating star clusters associated with the Galactic Anticenter Stellar Structure "GASS", also know as the "Ring", that may be associated with the proposed "Argo" or "Canis Major" dwarf galaxy. Some of the results from this project were presented in a poster at the conference "Chemical Abundances and Mixing in Stars in the Milky Way and its Satellites", held September 12-17, 2004 near Grosseto, Italy. Additional work is being completed.

Frinchaboy, P.M., Munoz, R. R., Majewski, S. R., Friel, E. D., Phelps, R. L., & Kunkel, W. E. 2005, in ``Chemical Abundances and Mixing in Stars in the Milky Way and its Satellites'', eds. L. Pasquini & S. Randich, ESO Astrophysics Symposia (astro-ph/0411127)

The University of Virginia Galactic Structure Group has been using the three filter Washington + DDO51 photometric system to identify distant giant stars as a means to search for substructure in the Milky Way's halo. A targeted search for "extra-tidal" stars associated with the present family of dwarf satellite galaxies and globular clusters. First results on the Carina dwarf spheroidal show an extended distribution of giant stars beyond the nominal tidal radius for the galaxy. I am working on the membership verification of giant stars of in dSph galaxies to beyond the tidal galaxy's tidal radius. We are using the CTIO 4-meter / Hydra mulit-fiber spectrograph and the WIYN 3.5-meter / Hydra mulit-fiber spectrograph to verify galaxy membership through radial velocity discrimination. Current work is being done on the Carina, Sculptor, Ursa Minor, and Sagittarius dwarf spheroidals and a number of globular clusters. We are investigating whether the velocities of these stars imply they are unbound tidal debris (implying a substantial mass loss rate), or represent some kind of bound halo population.

The Grid Giant Star Survey (GGSS) is designed to find stars needed for the Astrometric Grid of the NASA Space Interferometry Misson (SIM), with a strategy to identify the most distant, $V<13$, giants in 1302 ``bricks'' each covering ~0.5 deg2, distributed over the entire sky. The photometric observations with the Washington M, T_2 and the (gravity sensitive) DDO51 filters have been performed in 99% of these bricks at the Las Campanas 1-m telescope, the 0.8-m telescope of McDonald Observatory, and the WIYN 0.9-m telescope.

I have helped obtain low-resolution spectroscopic follow-up observations with the CTIO 4-meter / Hydra mulit-fiber spectrograph for scientifically interesting stars for many projects, including tracing the extent of the Sagittarius Dwarf Galaxy and stars found in the Magellanic Stream.

The University of Virginia Galactic Structure Group has been accumulating a large database on the globular cluster Omega Centauri. This data base includes a ~1 degree photometric survey using Washington + DDO51, and radial velocities of giant stars and suspected giant stars of the cluster. Additionally, we are measuring metallicites for the star for which we have spectra. We have compiled this database with other previously published work.

I investigated the metallicity distribution function of omega Centauri for my Masters project here at UVa. The results of this project was presented in a poster at the conference "Omega Centauri, a unique window into astrophysics", held August 13-16, 2001 in Cambridge, England.

"The Metallicity Distribution Function of Omega Centauri" Frinchaboy, P.M., Majewski, S.R., Ostheimer, J.C., Smith, V.V., Patterson, R.J., Kunkel, W.E., Rhee, J., Johnson, W.Y., Dinescu, D., Palma, C., & Westfall, K.B., Omega Centauri, A Unique Window into Astrophysics. ASP Conf. Ser. Vol. 265. eds. Floor van Leeuwen, Joanne D. Hughes, & Giampaolo Piotto 2002. (astro-ph/0112169)

As an undergrad working with Dr. Randy Phelps, we completed a paper on a subset of PLCON clusters that had not been investigated before and were first discovered in 1994. The "Saurer et al." clusters are a set of open clusters for which V,I photometry was obtained to provide preliminary determinations of the clusters' ages, distances, and reddenings. Five of these clusters were found to be true clusters, with ages older than 1 Gyr, based on the ``morphological age index'' (MAI) of Janes & Phelps [AJ, 108, 1773 (1994)], while effects of differential extinction made the identification of another as a true cluster inconclusive. The derived ages of the clusters range between a low of about 1 Gyr to a high of 7-8 Gyr for Cluster A. Based on the derived parameters, Cluster A is one of the oldest and the most distant of any Galactic open clusters studied to date. These results were published in May 2002 (see Publications). Additional work is being conducted on these and other distant old open clusters.