Fy05 Accomplishments and Fy06 Plans Helmut A. Abt
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Appendix A NOAO SCIENTIFIC STAFF: FY05 ACCOMPLISHMENTS AND FY06 PLANS ¬New appointment in FY05 S Non-NSF (external) funding ±Term ended in FY05 HELMUT A. ABT, Emeritus Astronomer Research Interests Evolutionary stellar problems, stellar characteristics, publication studies FY05 Accomplishments Abt and C. Boonyarak (U. Thailand) studied rotation velocities of stars in binaries. It was known that those with periods shorter than several days all have synchronized rotational and orbital motions. They found that binaries with periods up to 500 days have reduced rotational velocities due to tidal interactions. Abt found that the eccentricities in binaries vary from zero in close binaries to an average of 0.5 in binaries with periods greater than 1000 days. In the initial formation of binaries, all eccentricities are equally probable. FY06 Plans Abt is trying to understand the hot inner disks that occur around, at any one time, one-quarter of the rapidly- rotating A dwarfs. These disks have no connection with the outer cool dust disks found around many stars like Vega and beta Pictoris. These disks come and go on time scales of decades. Such stars do not occur in the low-density Local Interstellar Bubble, so they are material accreted from the interstellar medium. Theoretical aspects of the physical processes is being done with M. Marlborough (U. Western Ontario). TAFT E. ARMANDROFF, Astronomer (Director, NOAO Gemini Science Center) Research Interests Stellar populations in the Galaxy and nearby galaxies; dwarf spheroidal galaxies; globular clusters FY05 Accomplishments Armandroff has been studying the dwarf spheroidal satellite galaxies of M31 in collaboration with Da Costa (RSAA/ANU), Pritzl (Macalester), and Jacoby (WIYN). This is motivated by the opportunity to increase the number of galaxies defining the properties of dwarf spheroidals, and by the fact that the somewhat different environment of the M31 dwarfs compared to those of the Galaxy allows a first look at how dwarf spheroidal galaxy properties change with environment. Recent work has concentrated on photometry from HST-WFPC2 images that yield color-magnitude diagrams and variable-star properties. Andromeda I, II, III, and VI have been surveyed for variable stars. The properties of the RR Lyrae variables and anomalous Cepheids have been analyzed and compared with those of the Galactic dwarf spheroidal galaxies. FY06 Plans Armandroff plans to construct and analyze new HST-WFPC2-based color-magnitude diagrams for the stars in Andromeda V and VI, and to prepare these for publication. JASON P. AUFDENBERG, Research Associate (Michelson Postdoctoral Fellowship, NASA) S Research Interests Stellar atmospheres, stellar winds; fundamental properties of stars; interferometry; spectroscopy; radiative transfer and modeling A-1 NOAO ANNUAL REPORT FY 2005 FY05 Accomplishments Aufdenberg and colleagues published their work on the F-type star Procyon showing the limitations of 1-D stellar atmosphere models, and the promise of 3-D models, in studying convection in stars using interferometry. He was co-author of a paper describing high-precision measurements of the classical Cepheid variable delta Cephei with the CHARA Array interferometer. Aufdenberg also obtained new interferometric measurements of hot stars Vega, Deneb, and Rigel with the CHARA Array to study these stars’ rotational distortions and/or wind mass-loss rates. He also co-authored a paper on eclipse mapping observations of the RSCVn binary star SV Cam. FY06 Plans Aufdenberg plans to finish up his interferometric studies of Vega, Deneb and Rigel in collaboration with S. T. Ridgway and the University of Paris and CHARA teams. He will also obtain additional measure- ments of Rigel with the CHARA Array. Aufdenberg will also co-author work on interferometric and spectroscopic observations of the M-type giant Alpha Ceti and work on a follow-up study of SV Cam. DMITRY V. BIZYAEV, Research Associate (Space Interferometry Mission (SIM) Grid Star Verification Program, JPL)¬S Research Interests High-resolution stellar spectroscopy, radial velocities of red giants, chemical abundances, star formation in collisional ring galaxies; structure of galaxies FY05 Accomplishments Bizyaev and V. Smith (NOAO) worked on the selection of red giants which show stable radial velocities (RV) in support of the Space Interferometer Mission (SIM). They continue to conduct high-resolution observations with the 82s telescope at the McDonald Observatory. The project is sponsored by NASA through JPL; the project moved to NOAO as of April 2005. In FY05, 106 observing nights were granted to the project; 1489 spectra have been taken, and all have been reduced. This project shows that a pre- selection of red giants based on their effective temperatures, surface gravities, and [Fe/H] helps to increase the fraction of RV-stable stars needed for the SIM operation. FY06 Plans The observations of SIM reference stars will be continued. We will complete, test, and apply our automatic pipeline to assess the stellar parameters and abundances of chemical species for all stars in our growing sample. The data will be delivered to JPL. Bizyaev, in collaboration with Special Astro- physical Observatory (Russia), will analyze IFP and long-slit spectra for a sample of collisional ring galaxies. (Their spectra were taken in 2004–2005.) Parameters of star formation induced by the propagating wave of density and the history of star formation in selected collisional rings (Cartwheel, Arp 10, etc.) will be studied. TODD BOROSON, Astronomer (Deputy Director, NOAO) Research Interests Structure of, and physical processes connected with, active galactic nuclei, stellar populations, O/IR instrumentation, analysis and mining of large astronomical data sets FY05 Accomplishments Using data from the Sloan Digital Sky Survey, Boroson completed and published a study of [O III] outflows from QSOs. This work showed that such outflows are common and are found most often in A-2 NOAO SCIENTIFIC STAFF: FY05 ACCOMPLISHMENTS AND FY06 PLANS objects emitting at a substantial fraction of their Eddington luminosity. Boroson, in collaboration with G. Richards (Princeton U.), P. Hall (York U.), and J. Shields (Ohio U.), obtained near-IR spectra of 20 moderate redshift QSOs. These will be used to explore the relationship between [O III] and C IV properties. FY06 Plans Boroson will complete the analysis of the near-IR spectra described above and continue work on an automated procedure for measuring spectral characteristics of SDSS QSOs, with the expectation of extending the principal component analysis approach to the very large SDSS samples that have now been released. KATHERINE J. BRAND, Research Associate Research Interests Multi-wavelength properties of AGN, particularly mid-IR and X-ray; accretion history of SMBHs; wide- field surveys; large-scale structure and clustering FY05 Accomplishments Brand has continued to work on the multi-wavelength properties of AGN within the NOAO Deep Wide- Field survey Boötes field. She had two papers published on the optical counterparts to the X-ray sources in the XBoötes survey and on the use of X-ray stacking to determine the nuclear accretion history of red galaxies. She also started working on the mid-IR properties of AGN, and in particular, the use of the mid- IR slope as a diagnostic in determining the fraction of AGN and star-burst dominated Ultra-Luminous Infra-Red Galaxies (ULIRGs and the nature of the extreme mid-IR bright, optically faint ULIRGs. FY06 Plans Brand intends to publish her work on the AGN contribution to the mid-IR emission of ULIRGs and continue her investigation into the nature of the extreme mid-IR bright, optically faint ULIRGs. She is obtaining IRS spectra for high redshift, X-ray loud ULIRGS and will be reducing and analyzing these data. She also intends to publish her work on the nuclear accretion history of red galaxies for the entire Boötes field and begin to extend the study to other wavelengths. SEAN D. BRITTAIN, Research Associate (Michelson Fellow, NASA)¬S Research Interests Star and planet formation, molecular spectroscopy, planet detection FY05 Accomplishments In collaboration with J. Najita (NOAO), Brittain studied gas phase diagnostics from circumstellar gas around young stars. This research will shed light on the planet formation process. In collaboration with T. Rettig and D. Balsara (U. Notre Dame), E. Gibb (U. Missouri, St. Louis), T. Simon (U. Hawaii), and C. Kulesa (U. Arizona), Brittain studied the effect of turbulence on the settling time scale of dust in Class I/II YSO’s. We find substantial gas/dust stratification in the upper atmosphere of young circumstellar disks suggestive of substantial dust settling. In collaboration with C. Kulesa, Brittain sought to measure vibrationally-excited pure rotational molecular lines around Herbig Ae/Be stars. The goal is to find high- resolution probes of the inner disk. FY06 Plans Brittain will work with J. Najita and S. Strom (NOAO) to measure the magnetic field strength of Herbig Ae stars. Herbig Ae stars are not expected to possess strong magnetic fields; however, there is considerable circumstantial evidence to the contrary. We will take CO spectra of Herbig Ae stars with A-3 NOAO ANNUAL REPORT FY 2005 known inclinations, measure the inner edge of the gas disk, and infer the magnetic field strength of the stars. Brittain will also work with T. Rettig and J. Haywood (U. Notre Dame) on a project to measure H3+ in the atmosphere of the eclipsing exoplanet HD 209458b. The observation of H3+ will provide an important tool for probing the exosphere of the planet. CHRISTINE CHEN, Research Associate (Spitzer Fellow, NASA)¬ S Research Interests Circumstellar disks FY05 Accomplishments In collaboration with M. Werner (JPL), Chen analyzed MIPS (Multiband Imaging Photometer for Spitzer) observations of 40 nearby young stars and discovered two young A-type stars which possess unusually warm dust (Chen et al. 2005, ApJ, in press). In collaboration with the IRS Disks team, she analyzed IRS 5–35 micron spectra of 75 main sequence stars with IRAS 60 micron excess and found no correlation between grain distance and stellar age as expected from self-stirred models of debris disks.