The University of Wisconsin-Madison Department of Astronomy Madison, WI 53706

This description covers the Department’s activ- was at Lick Observatory (Santa Cruz) and is inter- ities from October 1, 2003, through September 30, ested in instrumentation and the nature of QSOs. 2004. It only refers to papers that were published Prof. Christopher Anderson retired at the end of the within this period. It ignores research that is under spring semester and was appointed Emeritus Pro- way and papers that are in press or submitted. fessor. Linda Sparke completed three ’ duty Gallagher will assume full editorship of the As- as Chair and was replaced in that capacity by John tronomical Journal on 1 January 2005, following Hoessel. Barger and Lazarian were promoted to his selection in May. Associate Professor. The faculty consist of Pro- The Southern African Large Telescope (SALT) fessors Cassinelli, Churchwell, Gallagher, Hoes- will undergo engineering tests in 2005. Its Prime sel (Chair), Mathieu, Nordsieck, Reynolds, Savage, Focus Imaging Spectrograph (Nordsieck, PI; Burgh, Sparke, Zweibel, and Associate Professors Barger, scientist) will be shipped to South Africa in early Bershady, Lazarian, and Wilcots. Bless and Mathis 2005. The Spitzer Space Telescope Legacy Sci- are Professors Emeriti residing in Madison. Robert ence project GLIMPSE, a near-infrared imaging Benjamin is an Assistant Professor of Physics at survey of the inner Galactic plane (Churchwell, PI), UW-Whitewater and served in Madison as Pro- is producing excellent scientific results. Other ma- gram Director of the Summer Research Opportu- jor thrusts include studies of formation, extra- nities Program. Percival is a Scientist; Wakker, an galactic structure and evolution, properties of inter- Associate Scientist. Burgh, Haffner, Ignace, and stellar and intergalactic gas, and studies of magne- Lehner were Assistant Scientists. tized turbulence. Kelsey Johnson went to the Univ. of Vir- WIYN refers to the Wisconsin-Indiana-Yale- ginia as an Assistant Professor. D. Harbeck went NOAO 3.5-m telescope on Kitt Peak. WHAM to UC-Berkeley as a Charles Townes Fellow, and refers to the Wisconsin H-Alpha Mapper, a sen- R. Indebetouw is at U. Virginia as a postdoctoral sitive Fabry-Perot spectrometer operating on Kitt researcher. R. Ignace joined the faculty at East Peak. FUSE denotes the Far-Ultraviolet Spectro- Tennessee State University. K. Stassun left for a scopic Explorer, a satellite that provides spectra faculty job at Vanderbilt University. B. Pichardo from 90 nm to 120 nm. HST is the Hubble Space moved to a postdoctoral research position at U. Telescope. Kentucky W. Harris left for a faculty job in the De- The description of research that follows em- partment of Earth and Space Sciences at U. Wash- phasizes the contribution of UW personnel, but in ington. Orio is a Visiting Associate Scientist. J. almost every case there are several authors from Marche´ served as Lecturer. outside that have contributed in various amounts, Prof. Ron Reynolds received the Beatrice M. often taking the lead in the project being described. Tinsley Award of the American Astronomical So- Space and style do not permit a complete list of col- ciety, given on a worldwide basis every two years leagues and collaborators for each project. The list for research of and exceptionally creative or inno- of papers at the end of the report lists authors in the vative character. Amy Barger received the David correct order in the published paper. and Lucile Packard Fellowship for Science and En- gineering. 1 Personnel Cassinelli was honored at a workshop entitled Dr. Andrew Sheinis accepted a position as “Massive : From Photospheres to V-infinity”. Assistant Professor, to begin in Fall, 2005. He Barger edited a book “Supermassive Black Holes in

1 the Distant Universe”, published by Kluwer Aca- nal Hα during the 1997 - 2001 solar cycle. It is demic Press in its Astrophysics and Space Science about 45% higher at solar maximum than at mini- Library series. mum. Bershady continues to serve as the Board Di- Gallagher began work on a program with W. rector of SALT, with Nordsieck as the Science Harris (U. Washington) to search for comets around Working Group representative. Wilcots and Sparke a young star using FUSE to detect UV line absorp- are on the WIYN Board of Directors. Barger is tion associated with cometary gas. on the WIYN Science Advisory Committee. Math- ieu continued as Director of the NSF Center for 3 Stars and Novae the Integration of Research, Teaching, and Learn- Cassinelli showed that the long-standing prob- ing. Reynolds served as Interim Director of the lem of supplying enough momentum to the strong Space Astronomy Lab. Wilcots served as Wiscon- winds of Wolf-Rayet stars is not solved by assum- sin’s representative to the U.S. Square Kilometer ing optically thick clumps. The rate of mass loss Array Consortium and as a member of the Inter- is reduced, but the amount of momentum extracted national Science Advisory Committee of the SKA by scattering the stellar radiation is reduced. He radio telescope project. and others took into account the variations of mass A. Fox received a University Teaching Assis- loss rate with latitude for the magnetically torqued tant award. N. Homeier, now at Johns Hopkins disk model for hot star disks. He and Ignace used University, presented a PhD thesis, “Behind Closed the infrared free-free continuum of the Wolf-Rayet Curtains: The Hidden Population Of Massive Stars WR 136, plus the widths of several He II emission In The ”, supervised by J. Gallagher. G. lines, to determine that the amount of clumping is Madsen’s PhD thesis (Reynolds, supervisor) was small in the outer parts of the wind. “An Exploration of the Heterogeneous Nature of Cassinelli, Reynolds, and colleagues used the the Warm Ionized Medium”. He continued at UW- Chandra X-ray satellite to observe the emission Madison but has accepted a 2-yr NSF Mathemat- lines in τ Sco and Spica (α Vir) from ions such as ical and Physical Sciences “Distinguished Inter- Ne IX and O VII. The lines of both are rather nar- national Postdoctoral Research Fellowship” at the row rather than being Doppler broadened by the ex- Anglo-Australian Observatory, to begin in January pansion of the stellar wind. The spectra suggest a 2005. A. Steffen presented his thesis “A Wide Field production by shocks caused by instabilities in the Chandra Survey of the Lockman Hole” (Barger, winds. supervisor) and is now a postdoctoral fellow at A team including Gallagher found a linear re- Penn State. C. Watson presented his thesis “Hot lation between the equivalent width of the Ca II Cores and Entrainment in Massive, Bipolar Out- triplet absorption lines and [Fe/H] in red giants. flows” (Churchwell, supervisor) and is an Assistant No age effect is observed. The [Fe/H] = −0.56 Professor of Physics at Manchester College in In- for Trumpler 5, lower than about 0.3 dex from the diana. color-magnitude diagram. The method is applica- ble to red giants in . 2 The Solar System Ignace, Nordsieck, and Cassinelli studied the Anderson contributed to a kinetic model of the Hanle effect that involves the polarization of reso- comae of comets. It examines the chemistry of nance line radiation scattered by atoms aligned by OH, O I(3P) and O I(1D) in detail, and the role of a circumstellar a magnetic field. The effect diag- these species in the destruction of CO and other noses the field in the outer parts of typical hot star molecules. winds. For high surface fields, both the Hanle and Reynolds, Madsen, and colleagues determined Zeeman effects can be used. the kinematics of zodiacal dust by observing Mg I Lazarian considered the superluminal ejections λ5184 with WHAM. The are eccentric and in microquasars (binary stars with a compact mem- have a broad distribution of orbital planes. WHAM ber and a relativistic jet) that might be caused by was used to monitor variations in the solar geocoro- violent magnetic reconnection events during super-

2 critical disk mass . Accreting stars show harder x-ray spectra but are Tidal circularization of binary systems has been not more luminous than the non-accreting objects, a major thrust in Mathieu’s research. He and stu- possibly because of attenuation by the circumstel- dents determined that the period of spectroscopic lar gas. The X-rays arise from the chromospheres, binaries below which the orbits are circularized in not from accretion. the old Galactic cluster NGC 188 is longer than Zweibel considered magnetic field evolution in in younger clusters. Contrary to theory, tidal cir- neutron star crusts due to the Hall effect (dominant cularization is more effective in solar-type main- in isolated objects) and ohmic decay (dominant for sequence binaries for times longer than 1 Gyr than accreting objects). The team gives expressions for currently predicted by tidal models. The team also the evolution of the field, both internal and external considered M35 and NGC 6819. Mathieu worked to the star, with several examples. on precision from old plates of the open Orio used FUSE and HST to observe the spec- cluster NGC 188, using recent CCD Mosaic Imager trum of the dwarf nova EY Cyg during quiescence. frames to calibrate the optical distortions for var- The best models have a temperature of 22 kK, ious telescopes and field correctors. The method log(g) = 9, and an accretion belt with T = 36 kK. provided a new catalog of proper motions and po- Photometry of the polar V1062 Tau showed two sitions for stars in the cluster. He used K-band periods (orbital and spin), plus their beat period. imaging polarimetry to resolve T Tauri binary and There was an outburst of the object during the ob- multiple system stars and determine the relative servations. orientation of the circumstellar disks. In the bi- By means of the CN and CH band strengths, nary systems the disks tend to be parallel to each Harbeck determined the C and N abundances in other. In multiple systems, the disk orientations are the giant stars in three globular clusters. Deple- randomly oriented to the polarization angle of the tions of C with increasing evolutionary state are widest pair. Contamination by interstellar polariza- evident. There seems to be an extra-mixing pro- tion is problematic. AK Sco has been analyzed in cess during the later stages of ascent of the Red Gi- some detail, including the structure of its dusty cir- ant Branch. He has investigated the C/Fe and N/Fe cumstellar disk and variable inflow and outflow. abundances of main sequence stars in the globular Sparke and postdoc Pichardo used a new dy- cluster 47 Tuc. The ratios are strongly anticorre- namical method to calculate the sizes and shapes of lated and are similar to those in the giants. The test-particle disks around stars in eccentric binary results rule out simple surface pollution and sug- , where the gravitational potential changes pe- gest that substantial fractions of the stars’ masses riodically in time. They found that the “observer’s are mixed. recipe” of using the Roche lobe for a circular or- Whitney and Indebetouw used 3D Monte-Carlo bit at pericenter gives a good approximation to the radiative transfer models to explore the effects of size of the circumstellar disk. The circumbinary stellar temperature on the infrared spectral energy disks are significantly elliptical and off-center such distribution of young stellar objects. that the inner edge of the disk keeps almost con- stant distance from the smaller star. 4 The Interstellar Medium Stasson and Mathieu determined dynamical The Spitzer Space Telescope’s legacy program masses of pre-MS stars in a binary system in the GLIMPSE (Churchwell, PI) is very successful. The Orion Cluster, 1.01 and 0.73 M , to ∼1% team includes local members Meade, Indebetauw, accuracy. No theoretical models predict both lumi- Watson, Mathis, B. Whitney (resident scientist), nosities simultaneously, although the mass-radius student Devine, and as well as others from sev- relationship is recovered. There seems to be ineffi- eral institutions. The project is a survey of the cient convection within the stellar interiors. Galactic plane from |l| = 10 − 65◦, |b| ≤ 1◦, in Using the Chandra satellite, Stasson and Math- the Infrared Array Camera filters at wavelengths ieu analyzed the X-ray properties of the pre-main- of 3.6, 4.5, 5.8, and 8.0 µm. The filters include sequence stars in the Orion Nebula cluster. The emission from interstellar polycyclic aromatic hy- LX /Lbol is anticorrelated with the rotation rates.

3 drocarbon (PAH) features and Brα. Pa- and star formation. pers have been accepted on results describing the With a 3D photoionization code, Mathis showed massive star formation region RCW49 and show- that the increase of some nebular line ratios with ing fascinating images of fine filaments, pillars, height above the Galactic midplane results from knots, and bubbles of diffuse emission, as well as at hardening of the ionizing radiation of the exciting least 300 stars with infrared excesses, presumably stars by clumped gas, in excess of the increase from very young stars in the making, within the RCW49 smooth gas density distributions. region. Whitney and Indebetouw used 3D Monte- The WHAM team (Reynolds, Haffner, Mad- Carlo radiative transfer models to explore the ef- sen, Percival, and others) published its survey of fects of stellar temperature on the infrared spectral the distribution and kinematics of ionized gas in energy distribution of young stellar objects. Inde- the Milky Way above −30◦. There betouw and the team found that interstellar extinc- are 37,565 spectra within 100 km s−1 of the Local tion is not very dependent on wavelength in both Standard of Rest, with 3σ intensities ≥3 Rayleighs. the field and in the RCW49 region. A tight clus- Many intermediate- and high-velocity clouds are ter, probably a globular, was found in the Galactic detected. This is a trove of information regarding plane. the Diffuse Ionized Gas. Churchwell surveyed 6-cm emission from H2CO Savage and Wakker, using FUSE to study O VI emission and absorption towards massive young in the Milky Way halo, found it in a plane-parallel stellar objects. The emission is confined to small patchy absorbing layer with an exponential scale regions. The team resolved the distance ambigui- height of ∼2.3 kpc, with an excess in the north- ties and mapped the Galactic locations of 44 Galac- ern hemisphere. Approximately 60% of the sky is tic H II regions by H radio recombination line and covered with high-velocity O VI, tracing outflow- H2CO measurements. Ignace and Churchwell ex- ing material, accretion of gas onto the , and plained the unusual power-law spectral slope of ra- tidal interactions with the Magellanic Clouds. In dio flux from hypercompact H II regions vs. fre- another study they find that Complex C, a high- quency by optically thin clumps with little shad- velocity cloud far out of the plane of the Milky owing. The distribution of the optical depths of Way, has O/H ∼1/6 solar. Its D/H is consistent the clumps determines the spectrum. Sewilo and with the Wilkinson Microwave Anisotropy Probe Churchwell found broad H radio recombination measurement of the fluctuations of the cosmic mi- lines in six massive star formation regions, pos- crowave background combined with simple models sibly broadened by several separate mechanisms. relating metallicity and D/H. Simple photoioniza- Churchwell performed high angular resolution ob- tion models of Complex C fail to predict the distri- servations on the “hot core” (thermal emission dom- bution of its various stages of ionization. Possibly inated by warm dust) object G29.96-0.02 and found the cloud is interacting with a hot halo medium. a density and temperature gradients consistent with Lehner, Savage, and Wakker investigated the accretion onto a massive rotating disk. cooling of the diffuse gas using far-UV observa- Lazarian studied the cascade timescale and an- tions of C II absorption or emission with FUSE and isotropy of freely decaying strong MHD turbu- HST in the spectra of 43 objects. On average, 50% lence with by means of 3D numerical studies. His of the cooling is in the warm ionized phase. For a team considered stochastic reconnection in a mag- cloud at ∼ 1 kpc above the galactic plane the cool- netized, partially ionized medium. The speed of ing is a factor 2 lower than near the plane, and for reconnection is determined by the ability of the two clouds > 5 kpc from the plane the rate drops ejected plasma to diffuse away from the current to 10% of that in the plane, similar to those in a sheet structure. They find the turbulent cascade sample of damped Lyα absorbers. can extend to well below the viscous cutoff scale. Using FUSE, Lehner and Howk (UC San Diego) The scalings and anisotropy of compressible mag- studied O VI absorption toward four hot stars in the netohydrodynamic turbulence were investigated by globular cluster NGC 6752. On spatial scales of 2 numerical simulations, with applications to cosmic – 10 pc there are no detectable variations in the O ray acceleration of cosmic rays, gamma ray bursts, VI column density and velocity distribution. The

4 hot gas with O VI is quite patchy at larger scales. region of the field covered by the Hubble Space Lehner and Savage are studying O VI toward white Telescope’s Great Observatories Origins Deep Sur- dwarfs 10 − 200 pc from the Sun, relating the vey (GOODS)-North. She and student Steffen amounts of hot gas to cool in order to test model participated in a wide-area, deep, synoptic survey predictions of their mixing. at X-ray (using the Chandra X-ray Observatory) Watson, with Zweibel and Churchwell, exam- and optical (using WIYN and the Japanese tele- ined the Kelvin-Helmholtz instability in a shear scope Subaru) wavelengths of the “Lockman Hole- flow of a stellar wind outflowing past partially ion- Northwest” field, where the Galactic H I emission ized circumstellar material with an embedded mag- is at a minimum. Many of the X-ray sources netic field. There should be detectably narrower showed variability. They found a definite lack of lines in ionized species tracing the outflow as com- luminous, high accretion rate sources at z < 1. She pared to the neutrals. The field is not tangled by and student Steffen also constructed the hard X-ray turbulence in the boundary layer. luminosity function of AGNs at z = 0.1 − 1 to de- Bethell, Zweibel, Heitsch, and Mathis calcu- termine the change of the relative fraction of AGNs lated the radiation field and grain temperature within with luminosity. Barger participated in a study of dark clouds illuminated from outside by interstel- the evolution of the ultraluminous infrared galaxy lar radiation. The cloud is significantly brighter population from nearby space to redshifts of 1.5 throughout most of its volume than it would be if and found that the number of objects without clear uniform. Zweibel also determined the instability of AGN signatures varies as (1 + z)7. a vertical magnetic field in a planar flow on ellip- Bershady has been concerned with the Tully- tical streamlines, always unstable without a field. Fisher relation between the masses of galaxies and There is still instability, although with a slower rate the spread in velocity of various spectral signa- of growth. Heitsch and Zweibel considered turbu- tures. He has discussed the scaling relations in lent ambipolar diffusion and found that the turbu- barred and unbarred galaxies and how they relate lence rapidly diffuses the magnetic flux to mass ra- to the virial properties. He and Andersen (MPI- tio. Heidelberg) constructed the first “face-on” Tully- Indebetouw and others surveyed high stages of Fisher relation by measuring velocities fitted to the ionization (O VI, N V, and C IV) in the Galactic optical spectrum, using the integral-field echelle halo with FUSE and HST. These ions are produced spectrometer on WIYN. The inclinations are as low by collisions in non-equilibrium gas by processes as 4∼15◦. Asymmetries make an important contri- such as shocks or evaporative interfaces. No single bution to the scatter in the T-F relation. Bershady model can explain the observations. conducted a spectroscopic study of compact blue Weitenbeck published interstellar polarization galaxies with the HST, finding supergiant H II re- data on stars obtained at the Pine Bluff Observa- gions. He studied kinematics in the cores of low tory during 1995-2003. Several cases are found for surface brightness galaxies in order to measure the which the wavelength dependence is anomalous. inner slope of the dark matter distribution. Con- stant density cores and ones with r−1 profiles are 5 Extragalactic Astronomy and Cosmology consistent with the data. Noncircular and random Barger surveyed the Hubble Deep Field (North) motions make the determination of the inner dark region at 850 µm. The detected submillimeter matter slope difficult. He compared nearby H II sources account for 24 – 34% of the far-infrared galaxies in the far-UV, using HST, with blue com- extragalactic background light. The positions of pact galaxies in the near-UV and with z ∼ 3 lumi- ∼60% of the submillimeter sources were accu- nous blue galaxies, all at the same rest-frame wave- rately located using deep radio and X-ray data. In lengths. There are many similarities between the addition, she participated in a deep multicolor sur- distant and local objects. The asymmetry of the vey of the field and measured the density of ob- images in the Hubble Deep Field North provides jects in the range 3 ≤ z ≤ 7. She also obtained direct evidence for hierarchical galaxy assembly at a large sample of spectroscopic redshifts for the z ∼ 3. Gallagher has engaged in programs with many

5 collaborators to determine the star formation his- in NGC 4395, determining a distance of 4.0 0.18 tory and age-metallicity relations in galaxies, us- or 4.30.3 Mpc, depending on the choice of period- ing color-magnitude diagrams. They applied the luminosity relationship. Hoessel and Gallagher ex- method to IC 1613, a dwarf irregular, and found amined short-period variable stars in the halo of that the rate of star formation has been depressed in M31. The RR Lyrae stars have lower metallicity the last Gyr. The massive star clusters in NGC 1140 than the average of the halo. show that most of the star formation activity was Nordsieck determined the wavelength depen- induced 35 – 55 Myr ago, consistent with their dence of the interstellar polarization toward glob- spectral energy distributions. With WIYN, he per- ular clusters in M31. The relation was similar to formed a photometric survey of carbon stars in that in the Galaxy, although suggesting somewhat M31 and dwarf spheroidal galaxies. These larger grains. objects are ancient, without substantial populations Savage studied the structure of the dust above of intermediate-age stars. Photometry of bright the plane of the edge-on spiral NGC 4217 with the clusters of stars in nearby starburst galaxies (es- HST. Some structures extend to 2 kpc and have 5 pecially NGC 6240) provides ages and metallici- masses of ∼ 2 × 10 M . The work to lift them ties, and therefore constraints on the star forma- is the energy output of several supernovae. Using tion histories. With HST, Gallagher and Home- the FUV satellite FUSE and the HST spectrograph ier investigated the small- and intermediate-scale STIS, Savage studied intergalactic absorption to- structure and the fraction of mass in the ISM in wards the QSO PG 1259+593 (zem = 0.478.) The a sample of local starburst galaxies, including the team achieved high spectral resolution and inves- giant starburst M83. They could obtain a full bud- tigated 78 absorption line components, including get for various ions and the mechanical energy in- heavy ions in four. From the O VI lines they find put. The times of ongoing star formation are in the that a substantial fraction of the baryons in the lo- range 107 − 108 yr. The X-ray sources in starburst cal universe are in intergalactic gas. galaxies are preferentially located near but signifi- With P. Erwin (IAC Tenerife), Sparke pub- cantly displaced from the star clusters. Gallagher, lished images from Erwin’s 2001 PhD thesis, show- Harbeck, and Grebel (MPI-Heidelberg) worked on ing that nuclear bars and disks are common in the chemical evolution of dwarf spheroidal sys- early-type barred galaxies. This shows that the tems. Even the oldest display extended periods of light of the inner galaxy comes mainly from a flat star formation and evolve to gas-free stellar fossil disklike component, not from a round and dynami- galaxies. Their early period of formation may ac- cally “warm” bulge. count for their metals content. Sparke used near-IR, optical and H I data to With B. Pritzl, P. Knezek (WIYN), and oth- study how the kinematics of Polar Ring galaxies fit ers Gallagher found that the dwarf galaxy HIPASS into the Tully-Fisher relation. They appear not to fit J1321-31, with a distinctive plume of red stars in the relation for normal spirals exactly, which may its color-magnitude diagram, probably represents be related to the shape of the dark halos. However, an episode of rapid star formation followed by rel- it is surprising that these merger products fall any- ative quiescence that is unusual in galactic evolu- where close to the normal relation! She also used tion. Reionization in early phases of the universe infrared images to show that the apparent bar in seems to have no clear effect on the star formation ESO 235-G58 is in reality an edge-on disk galaxy, in nearby dwarf galaxies. NGC 1275, the central surrounded by a polar ring of low surface bright- galaxy of the Perseus cluster of galaxies, is sur- ness. rounded by Hα filaments that are also bright in Wilcots surveyed Magellanic spiral galaxies in X-rays, possibly due to conduction and mixing of H I and found that four of 13 have confirmed neigh- hot and comparatively cool gas. There is a radio bors, and only 2 that have their morphology af- bubble seen as a hole in the X-ray emission, and fected by the neighbor. The interactions cannot further studies of the ionized gas kinematics are in be responsible for the lopsided morphology, which progress. must be a long-lived characteristic. Wilcots and Hoessel continued WIYN studies of Cepheids Wakker used H I emission and FUSE observations

6 of ionic absorption lines, from both hot and cool has concluded, and optical design is nearing com- gas, to search for the intragroup ISM in two loose pletion. The time scale for project completion is groups of galaxies. They detected a small mass of 1-1.5 years from the time of this report. The device gas of rather loosely constrained extent. employs volume-phase holographic (VPH) high- K. Johnson, Indebetouw, Watson, and Kobul- throughput, holographically produced transmission nicky investigated the young starburst in the Wolf- gratings. Rayet galaxy Haro 3 by radio and infrared imag- The halfwave polarimeter (HPOL), Nord- ing. There are very young star clusters. The mass sieck, PI, resided on the 0.9m telescope at Pine 6 associated with the starburst is ∼ 10 M . John- Bluff Observatory. HPOL obtained observations of son mapped the radio spectral energy distribution Be stars, luminous red variables, hot supergiants, of very young super-starclusters in Henize 2-10. interacting binaries,Herbig Ae/Be stars, planets, The masses of ionized gas are relatively low and comets, asteroids, novae, Wolf Rayet stars, sym- the pressures 103 − 106 times that in the plane of biotic stars, and other objects. Broadband polari- the Milky Way. Indebetouw and Johnson imaged metric results of HPOL observations are at infrared-selected compact H II regions in the Mag- www.sal.wisc.edu/HPOL/. ellanic Clouds in radio continuum and found prop- Star Tracker, Percival, PI. The ST5000 tracker erties of star and cluster formation similar to those provides pitch, yaw, and roll control for sounding of compact HII regions in the Galaxy. rockets, but can also do a full attitude determination without gyros for both sounding rockets and satel- 6 SALT, WIYN, and Instruments lites. The ST5000 has been adopted by NASA’s SALT: The Southern African Large Telescope Sounding Rocket program and will replace the cur- (SALT) is an 11-meter optical telescope modified rent complement of trackers. The ST5000 had from the Hobby-Eberly Telescope design, located a successful commissioning flight in April 2004. in Sutherland, South Africa. Engineering and inte- Two more commissioning flights are scheduled for gration has proceeded during 2004, with commis- late 2004 and early 2005. sioning scheduled to begin in late 2004 into early Spatial Heterodyne Spectrometer. Reynolds 2005. The dedication of the telescope is expected and colleagues used their newly built Spatial Het- in November, 2005. Nordsieck (PI), Burgh, and erodyne Spectrometer at the Pine Bluff Observa- Percival are completing the Prime Focus Imaging tory to detect for the first time diffuse interstellar Spectrograph, the primary first-light instrument. It [O II] 3726 and 3729 emission from the warm, ion- is scheduled to ship to Cape Town in January 2005, ized medium (WIM) extending out 20 degrees from with acceptance and commissioning activities to the Galactic plane. These [O II] lines are a princi- commence directly thereafter. First-science is ex- pal coolant for the WIM and a potential tracer of pected in early 2005. temperature variations within the gas. The GLIMPSE Legacy Science program on the Spitzer Space Telescope satellite (Churchwell, 7 Outreach PI) has completed 3/8 of its survey on both sides In conjunction with the African Studies Pro- of the Galaxy center from |b| = 10◦ − 65◦, l = gram and the Wisconsin Teacher Enhancement Pro- 1◦. Images and photometry of stars are avail- gram, the Department brought 10 South African able in four filters centered at 3.6, 4.5, 5.8, and science teachers to spend several weeks taking part 8.0 µm. A summary of the GLIMPSE Legacy Sci- in teacher enhancement programs on campus. ence program is in Benjamin et al. (2003, PASP, This summer, UW-Madison hosted another REU 115, 953), and several papers that have already (Research Experiences for Undergraduates) pro- been produced by the team are on the Web site at gram. A diverse group of ten students from around /www.astro.wisc.edu/sirtf/glimpsepubs.html. the country joined us for a summer of research. In The WIYN Bench Spectrograph upgrade (Ber- 2002-4 we hosted 33 students with NSF and UW shady, PI), with gains of factors of 3 in throughput, Graduate School funds; 42The program was di- continues. A successful preliminary design review rected by R. Benjamin. Pictures of the group and

7 the results of their research projects are on the REU Bellamy, M.J., Tadhunter, C.N., Morganti, R., website: Wills, K.A., Holt, J., Taylor, M.D., Watson, C.A. http://wisp.physics.wisc.edu/reu. 2003, “Near-infrared spectroscopy of PKS 1549- The eighth of the successful Universe in 79: a protoquasar revealed?”, Monthly Notices of the Park outreach program was directed by Wilcots. the Royal Astronomical Society, 344, L80-L84. There were nearly 50 sessions at 27 state parks Benjamin, R.A., and 19 colleagues 2003, and forests throughout Wisconsin, reaching nearly “GLIMPSE. I. An SIRTF Legacy Project to Map 4000 people. the Inner Galaxy”, Publications of the Astronomi- Mathieu is Co-Director the Center for Integra- cal Society of the Pacific, 115, 953-964. tion of Research, Teaching, and Learning (CIRTL), Bershady, M.A. 2003, “Galaxy Formation and an NSF Center for Learning and Teaching project the GTC” (eds. J.M.R. Espinoza, F.G. Lopez, V. in collaboration with Michigan State University Melomartin). Revista Mexicana de Astronomia y and Pennsylvania State University. Its mission is to Astrofisica (Serie de Conferencias), 16, 203-208. produce a future science, technology, engineering Bershady, M.A., Andersen, D.R., Harker, J., and mathematics (STEM) college faculty that is ef- Ramsey, L.W., Verheijen, M.A.W. 2004, “SparsePak: fective in both research and teaching. The empha- A Formatted Fiber Field Unit for the WIYN Tele- sis in the first year was the Delta Program in Teach- scope Bench Spectrograph. I. Design, Construc- ing and Learning, comprising a suite programs at tion, and Calibration”, Publications of the Astro- the University of Wisconsin in which STEM grad- nomical Society of the Pacific, 116, 565-590. uate students apply their research skills to the im- Bethell, T.J., Zweibel, E.G., Heitsch, F., provement of student learning. More on the CIRTL Mathis, J.S. 2004, “Dust Heating by the Interstel- project can be found at www.cirtl.net and on Delta lar Radiation Field in Models of Turbulent Molec- at www.delta.wisc.edu. ular Clouds”, Astrophysical Journal, 610, 801-812. Briley, M.M., Harbeck, D., Smith, G.H., Grebel, 8 Publications E.K. 2004, “On the Carbon and Nitrogen Abun- The following are the publications appearing in dances of 47 Tucanae’s Main-Sequence Stars”, As- refereed journals or invited presentations to scien- tronomical Journal, 127, 1588-1593. tific meetings. Departmental members have their Brogan, C.L., Devine, K.E., Lazio, T.J., Kas- names in bold face. sim, N.E., Tam, C.R., Brisken, W.F., Dyer, K.K., Alencar, S.H.P., Melo, C.H.F., Dullemond, C.P., Roberts, M.S.E. 2004, “A Low-Frequency Survey Andersen, J., Batalha, C., Vaz, L.P.R., Mathieu, of the Galactic Plane Near l=11deg: Discovery of R.D. 2003, “The pre-main sequence spectroscopic Three New Supernova Remnants”, Astronomical binary AK Scorpii revisited”, Astronomy and As- Journal, 127, 355-367. trophysics, 409, 1037-1053. Brown, J.C., Telfer, D., Li, Q., Hanuschik, Andersen, D.R., Bershady, M.A. 2003, “A R., Cassinelli, J.P., Kholtygin, A. 2004, “The ef- Face-on Tully-Fisher Relation”, Astrophysical Jour- fect of rotational darkening on magneti- nal, 599, L79-L82. cally torqued Be star discs.” Monthly Notices of the Barger, A.J. 2003, “High-Redshift Galaxies”. Royal Astronomical Society, 352, 1061-1072. Maps of the Cosmos. IAU Symposium 216. Calzetti, D., Harris, J., Gallagher, J.S., Smith, Barger, A.J. 2003, “The X-Ray Background”, D.A., Conselice, C.J., Homeier, N., Kewley, L. Revisita Mexicana de Astronomia (Serie de Con- 2004, “The Ionized Gas in Local Starburst Galax- ferencias), 17, 226-229. ies: Global and Small-Scale Feedback from Star Barger, A.J., Cowie, L.L., Capak, P., Alexan- Formation. Astronomical Journal, 127, 1405-1430. der, D.M., Bauer, F.E., Fernandez, E., Brandt, Chapman, S.C., Windhorst, R., Odewahn, S., W.N., Garmire, G.P., Hornschemeier, A.E. 2003, Yan, H., Conselice, C. 2003,“Hubble Space Tele- “Optical and Infrared Properties of the 2 Ms Chan- scope Images of Submillimeter Sources: Large Ir- dra Deep Field North X-Ray Sources”, Astronom- regular Galaxies at High Redshift’,’ Astrophysical ical Journal, 126, 632-665. Journal, 599, 92-104. Cho, J., Lazarian, A. 2003, “Angular spectra

8 of polarized Galactic foregrounds”, New Astron- 127, 3137-3145. omy Review, 47, 1143-1149. Cumming, A., Arras, P., Zweibel, E. 2004, Cho, J., Lazarian, A. 2003, “Compressible “Magnetic Field Evolution in Neutron Star Crusts magnetohydrodynamic turbulence: mode coupling, Due to the Hall Effect and Ohmic Decay”, Astro- scaling relations, anisotropy, viscosity-damped regime physical Journal, 609, 999-1017. and astrophysical implications’,’ Monthly Notices de Grijs, R., Smith, L.J., Bunker, A., Sharp, of the Royal Astronomical Society, 345, 325-339. R.G., Gallagher, J.S., Anders, P., Lancon, A., Cho, J., Lazarian, A., Vishniac, E. T. 2003, O’Connell, R.W., Parry, I.R. 2004, “CIRPASS near- “MHD Turbulence: Scaling Laws and Astrophysi- infrared integral-field spectroscopy of massive star cal Implications” (eds E. Falgarone and T. Passot). clusters in the starburst galaxy NGC 1140” Monthly Lecture Notes in Physics, 614, 56-98. Notices of the Royal Astronomical Society, 352, Cho, J., Lazarian, A., Vishniac, E. T. 2003, 263-276. “Ordinary and Viscosity-damped Magnetohydro- Dolphin, A.E., Saha, A., Olszewski, E.W., Thim, dynamic Turbulence”, Astrophysical Journal, 595, F., Skillman, E.D., Gallagher, J.S., Hoessel, J. 812-823. 2004, “Short-Period Variable Stars in the M31 Halo”, Clayton, G.C., Wolff, M.J., Gordon, K.D., Smith, Astronomical Journal, 127, 875-896. P.S., Nordsieck, K.H., Babler, B.L. 2004, “Inter- Fabian, A.C., Sanders, J.S., Crawford, C.S., stellar Polarization in M31” Astronomical Journal, Conselice, C.J., Gallagher, J.S., Wyse, R.F.G. 2003, 127, 3382-3387. “The relationship between the optical H-alpha fil- Code, A.D. 2003, “Albert Edward Whitford aments and the X-ray emission in the core of the (1906-2002)” Publications of the Astronomical So- Perseus cluster” Monthly Notices of the Royal As- ciety of the Pacific, 115, 1020-1022. tronomical Society, 344, L48-L52. Cole, A.A., Smecker-Hane, T.A., Tolstoy, E., Feline, W.J., Dhillon, V.S., Marsh, T.R., Steven- Gallagher, J.S. 2004, “Abundance Patters of the son, M.J., Watson, C.A., Brinkworth, C. S. 2004, Large Magellanic Cloud Disk and Bar” Edited by “ULTRACAM photometry of the eclipsing cata- A. McWilliam and M. Rauch. Origin and Evolu- clysmic variable OU Vir” Monthly Notices of the tion of the Elements, from the Carnegie Observato- Royal Astronomical Society, 347, 1173-1179. ries Centennial Symposia. Fox, A. J., Savage, B.D., Wakker, B.P., Richter, Cole, A.A., Smecker-Hane, T.A., Tolstoy, E., P., Sembach, K.R., Tripp, T.M. 2004, “Highly Ion- Bosler, T.L., Gallagher, J.S. 2004, “The effects of ized Gas Surrounding High-Velocity Cloud Com- age on metallicities derived from the near- plex C”, Astrophysical Journal, 602, 738-759. infrared CaII triplet” Monthly Notices of the Royal Gallagher, J.S., Grebel, E.K., Harbeck, D, Astronomical Society, 347, 367-379. 2004, “Spheroidal Dwarfs and Early Chemical Evo- Conselice, C.J., Bershady, M.A., Dickinson, lution of Galaxies” Edited by A. McWilliam and M., Papovich, C. 2003, “A Direct Measurement of M. Rauch. Origin and Evolution of the Elements, Major Galaxy Mergers at z¡ 3” Astronomical Jour- from Carnegie Observatories Centennial Symposia. nal, 126, 1183-1207. Glinski, R.J., Ford, B.J., Harris, W.M., An- Courteau, S., Andersen, D.R., Bershady, M.A., derson, C.M., Morgenthaler, J.P. 2004, “Oxygen/ MacArthur, L.A., Rix, H. 2003, “The Tully-Fisher Hydrogen Chemistry in the Inner Comae of Active Relation of Barred Galaxies” Astrophysical Jour- Comets”, Astrophysical Journal, 608, 601-609. nal, 594, 208-224. Gomez, M., Stark, D.P., Whitney, B.A., Church- Cowie, L.L., Barger, A.J., Fomalont, E.B., well, E. 2003, “Jets and Herbig-Haro Objects in Capak, P. 2004, “The Evolution of the Ultralumi- the rho-Ophiuchi Embedded Cluster”, Astronomi- nous Infrared Galaxy Population from Redshift 0 cal Journal, 126, 863-886. to 1.5”, Astrophysical Journal, 603, L69-L72. Grebel, E.K., Gallagher, J.S. 2004, “The Im- Cowie, L.L., Barger, A.J., Hu, E.M., Capak, pact of Reionization on the Stellar Populations of P., Songaila, A. 2004, “A Large Sample of Spectro- Nearby Dwarf Galaxies”, Astrophysical Journal, scopic Redshifts in the ACS-GOODS Region of the 610, L89-L92. Hubble Deep Field North”, Astronomical Journal, Haffner, L.M., Reynolds, R.J., Tufte, S. L.,

9 Madsen, G.J., Jaehnig, K.P., Percival, J.W. 2003, Indebetouw, R., Shull, J.M. 2004, “O VI, N “The Wisconsin H-alpha Mapper Northern Sky Sur- V, and C IV in the Galactic Halo. I. Velocity- vey”, Astrophysical Journal Supplement Series, 149, Dependent Ionization Models”, Astrophysical Jour- 405-422. nal, 605, 205-215. Harbeck, D., Gallagher, J.S., Grebel, E.K. Indebetouw, R., Shull, J.M. 2004, “O VI, N 2004, “WIYN Survey for Carbon Stars in the M31 V, and C IV in the Galactic Halo. II. Velocity- and Cetus Dwarf Spheroidal Galaxies: Evolution- Resolved Observations with the Hubble Space Tele- ary Implications.”, Astronomical Journal, 127, 2711- scope and Far Ultraviolet Spectroscopic Explorer”, 2722. Astrophysical Journal 607, 309-332. Harbeck, D., Smith, G.H., Grebel, E.K. 2003, Iodice, E., Arnaboldi, M.,Sparke, L.S., Buta, “CN variations in NGC 7006”, Astronomy and As- R., Freeman, K.C., Capaccioli, M. 2004, “Photo- trophysics, 409, 553-561. metric structure of the peculiar galaxy ESO 235- Harris, J., Calzetti, D., Gallagher, J.S., Smith, G58”, Astronomy and Astrophysics, 418, 41-52. D.A., Conselice, C.J. 2004, “The Recent Cluster Jensen, E.L.N., Mathieu, R.D., Donar, A.X., Formation Histories of NGC 5253 and NGC 3077: Dullighan, A. 2004, “Testing Protoplanetary Disk Environmental Impact on Star Formation” Astro- Alignment in Young Binaries” Astrophysical Jour- physical Journal, 603, 503-522. nal, 600, 789-803. Heitsch, F., Zweibel, E.G., Slyz, A.D., De- Johnson, K.E., Kobulnicky, H.A. 2003, “The vriendt, J.E.G. 2004, “Turbulent Ambipolar Diffu- Spectral Energy Distributions of Infant Super-Star sion: Numerical Studies in Two Dimensions”, As- Clusters in Henize 2-10 from 7 Millimeters to 6 trophysical Journal, 603, 165-179. Centimeters”, Astrophysical Journal, 597, 923-928. Hodapp, K.W., Walker, C.H., Reipurth, B., Kaaret, P., Alonso-Herrero, A., Gallagher, J.S., Wood, K., Bally, J., Whitney, B.A., Connelley, Fabbiano, G., Zezas, A., Rieke, M.J. 2004, “Dis- M. 2004, “A Disk Shadow around the Young Star placement of X-ray sources from star clusters in ASR 41 in NGC 1333”, Astrophysical Journal, starburst galaxies” Monthly Notices of the Royal 601, L79-L82. Astronomical Society, 348, L28-L32. Hoffman, J.L., Whitney, B.A., Nordsieck, K.H. Lazarian, A., Cho, J. 2004, “Magnetic Re- 2003, “The Effect of Multiple Scattering on the Po- connection and Turbulent Mixing: From ISM to larization from Envelopes. I. Self- and Clusters of Galaxies.” Astrophysics and Space Sci- Externally Illuminated Disks”, Astrophysical Jour- ence, 289, 307-318. nal, 598, 572-587. Lazarian, A., Finkbeiner, D. 2003, “Microwave Ignace, R., Churchwell, E. 2004, “Free-Free emission from aligned dust” New Astronomy Re- Spectral Energy Distributions of Hierarchically view, 47, 1107-1116. Clumped H II Regions”, Astrophysical Journal, Lazarian, A., Vishniac, E.T., Cho, J. 2004, 610, 351-360. “Magnetic Field Structure and Stochastic Recon- Ignace, R., Nordsieck, K.H., Cassinelli, J.P. nection in a Partially Ionized Gas” Astrophysical 2004, “The Hanle Effect as a Diagnostic of Mag- Journal, 603, 180-197. netic Fields in Stellar Envelopes. IV. Application Lebovitz, N. R., Zweibel, E. 2004, “Magne- to Polarized P Cygni Wind Lines” Astrophysical toelliptic Instabilities” Astrophysical Journal, 609, Journal, 609, 1018-1034. 301-312. Ignace, R., Quigley, M.F., Cassinelli, J.P. 2003, Lehner, N., Jenkins, E.B., Gry, C., Moos, “Constraints from Infrared Space Observatory Data H.W., Chayer, P., Lacour, S. 2003, “Far Ultraviolet on the Velocity Law and Clumpiness of WR 136”, Spectroscopic Explorer Survey of the Local Inter- Astrophysical Journal, 596, 538-555. stellar Medium within 200 ”, Astrophysical Indebetouw, R., Watson, C., Johnson, K.E., Journal, 595, 858-879. Whitney, B., Churchwell, E. 2003, “Detection of Lipkin, Y.M., Leibowitz, E.M., Orio, M. 2004, a Near-Infrared Counterpart to the Massive Pro- “Photometry of V1062 Tau: low states, short out- tostar G192.16-3.82”, Astrophysical Journal, 596, bursts and period switching”, Monthly Notices of L83-L86. the Royal Astronomical Society, 349, 1323-1330.

10 Mathieu, R.D., Meibom, S., Dolan, C. J. 2004, C.A., Buckley, D.A. H., Phillips, A. 2004, “Stokes “WIYN Open Cluster Study. XVIII. The Tidal Cir- imaging, Doppler mapping and Roche tomography cularization Cutoff Period of the Old Open Clus- of the AM Herculis system V834 Cen” Monthly ter NGC 188” Astrophysical Journal, 602, L121- Notices of the Royal Astronomical Society, 348, L123. 316-324. Mewe, R., Raassen, A.J.J., Cassinelli, J.P., van Pritzl, B.J., Knezek, P.M., Gallagher, J.S., der Hucht, K.A., Miller, N.A., Gudel, M. 2003, Grossi, M., Disney, M.J., Minchin, R.F., Freeman, “High-resolution XMM-Newton X-ray spectra of K.C., Tolstoy, E., Saha, A. 2003, “Anomalous Evo- tau-SCORPII”, Advances in Space Research, 32, lution of the Dwarf Galaxy HIPASS J1321-31” As- 1167-1173. trophysical Journal, 596, L47-L50. Nossal, S.M., Roesler, F.L., Mierkiewicz, E.J., Ramachandran, R., Backer, D.C., Rankin, J.M., Reynolds, R.J. 2004, “Observations of solar cycli- Weisberg, J.M., Devine, K.E. 2004, “Effect of cal variations in geocoronal Hα column emission Quasi-Orthogonal Emission Modes on the Rotation intensities”, Geophysical Research Letters, 31, 6110. Measures of Pulsars”, Astrophysical Journal, 606, Olmi, L., Cesaroni, R., Hofner, P., Kurtz, S., 1167-1173. Churchwell, E., Walmsley, C.M. 2003,“High res- Reynolds, R.J. 2004, “Warm ionized gas in the olution observations of the hot core in G29.96- local interstellar medium”, Advances in Space Re- 0.02‘” Astronomy and Astrophysics, 407, 225-235. search, 34, 27. Orio, M., Hartmann, W., Still, M., Greiner, Richter, P., Savage, B.D., Tripp, T.M., Sem- J. 2003, “An XMM-Newton Observation of Nova bach, K.R. 2004, “FUSE and STIS Observations LMC 1995: A Bright Supersoft X-Ray Source” As- of the Warm-hot Intergalactic Medium toward PG trophysical Journal, 594, 435-442. 1259+593”, Astrophysical Journal Supplement Se- Palmer, P., Goss, W.M., Devine, K.E. 2003, ries, 153, 165. “Phase-Referenced Very Long Baseline Array Ob- Savage, B. 2003, “Ultraviolet absorption line servations of OH Masers at 4765 Mhz” Astrophys- studies of the Galactic interstellar medium with the ical Journal, 599, 324-334. Goddard High Resolution Spectrograph” (eds. M. Pasquali, A., Gallagher, J.S., de Grijs, R. 2004, Livio, K. Noll, M. Stiavelli). STSci Symposium “Nuclear star formation in NGC 6240” Astronomy Series, 14, 101. and Astrophysics, 415, 103-116. Savage, B., Helmberger, D. V. 2004, “Com- Pasquali, A., de Grijs, R., Gallagher, J.S. 2003, plex Rayleigh waves resulting from deep sedimen- “On the formation of star clusters in the merger tary basins” Earth and Planetary Science Letters, NGC 6240” Monthly Notices of the Royal Astro- 218, 229. nomical Society, 345, 161-174. Savage, B.D., Wakker, B.P., Sembach K.R., Pentericci, L., Rix, H.W., Prada, F., Fan, X., Richter, P., Meade, M. 2003, “The FUSE Survey Strauss, M.A., Schneider, D.P., Grebel, E.K., Har- of O VI in and near the Milky Way” Edited by P.A. beck, D., Brinkmann, J., Narayanan, V.K. 2003, Duc, J. Braine, and E. Brinks. IAU Symposium “The near-IR properties and continuum shapes of 217, 147. high redshift quasars from the Sloan Digital Sky Sefako, R.R., de Jager, O.C. 2003, “Constraints Survey”, Astronomy and Astrophysics, 410, 75-82. on Pulsar Magnetospheric and Wind Parameters for Pisano, D.J., Wakker, B.P., Wilcots, E.M., the Compact Nebulae of Vela and PSR B1706-44”, Fabian, D. 2004, “Searching for the Intragroup Astrophysical Journal, 593, 1013-1023. Medium in Loose Groups of Galaxies”, Astronom- Sewilo, M., Churchwell, E., Kurtz, S., Goss, ical Journal, 127, 199-212. W.M., Hofner, P. 2004, “Broad Radio Recombina- Platais, I., Kozhurina-Platais, V., Mathieu, R.D., tion Lines from Hypercompact H II Regions”, As- Girard, T.M., van Altena, W.F. 2003,“WIYN Open trophysical Journal, 605, 285-299. Cluster Study. XVII. Astrometry and Membership Skillman, E.D., Tolstoy, E., Cole, A.A., Dol- to V=21 in NGC 188”, Astronomical Journal, 126, phin, A.E., Saha, A., Gallagher, J.S., Dohm-Palmer, 2922-2935. R. C., Mateo, M. 2003, “Deep Hubble Space Tele- Potter, S.B., Romero-Colmenero, E., Watson, scope Imaging of IC 1613. II. The Star Formation

11 History” Astrophysical Journal, 596, 253-272. T., Bjorkman, J.E., Whitney, B. 2004, “The struc- Stanimirovic, S., Weisberg, J.M., Hedden, A., ture of brown dwarf circumstellar discs” Monthly Devine, K.E., Green, J.T. 2003, “Does Tiny-Scale Notices of the Royal Astronomical Society, 351, Atomic Structure Exist in the Interstellar Medium?”, 607-616. Astrophysical Journal, 598, L23-L26. Watson, C., Zweibel, E.G., Heitsch, F., Church- Stassun, K.G., Mathieu, R.D., Vaz, L.P.R., well, E. 2004, “Kelvin-Helmholtz Instability in a Stroud, N., Vrba, F.J. 2004, “Dynamical Mass Con- Weakly Ionized Medium”, Astrophysical Journal straints on Low-Mass Pre-Main-Sequence Stellar 608, 274-281. Evolutionary Tracks: An Eclipsing Binary in Orion Watson, C.A., Dhillon, V. S. 2004, “The ef- with a 1.0 M Primary and a 0.7 M Secondary”, fect of star-spots on eclipse timings of binary stars” Astrophysical Journal Supplement Series, 151, 357- Monthly Notices of the Royal Astronomical Soci- 385. ety, 351, 110-116. Stassun, K.G., Ardila, D.R., Barsony, M., Basri, Watson, C.A., Dhillon, V.S. 2004, “Roche G., Mathieu, R.D. 2004, “X-Ray Properties of Pre- tomography of the secondary stars in Cvs”, As- Main-Sequence Stars in the Orion Nebula Cluster tronomische Nachrichten, 325, 189-192. with Known Rotation Periods”, Astronomical Jour- Weisberg, J.M., Cordes, J.M., Kuan, B., Devine, nal, 127, 3537-3552. K.E., Green, J.T., Backer, D.C. 2004, “Arecibo 430 Steffen, A.T., Barger, A.J., Cowie, L.L., Mu- MHz Pulsar Polarimetry: Faraday Rotation Mea- shotzky, R.F., Yang, Y. 2003, “The Changing Ac- sures and Morphological Classifications”, Astro- tive Galactic Nucleus Population” Astrophysical physical Journal Supplement Series, 150, 317-341. Journal, 596, L23-L26. Weitenbeck, A.J. 2004, “Stars with ISM Po- Thim, F., Hoessel, J.G., Saha, A., Claver, J., larization Observed with HPOL. II”, Acta Astr. 54, Dolphin, A., Tammann, G. A. 2004, “Cepheids and 87 Long-Period Variables in NGC 4395” Astronomi- Whitney, B.A., Wood, K., Bjorkman, J.E., Co- cal Journal, 127, 2322-2343. hen, M. 2003, “Two-dimensional Radiative Trans- Thompson, T.W.J., Howk, J.C., Savage, B.D. fer in Protostellar Envelopes. II. An Evolution- 2004, “ Imaging of Extra- ary Sequence”, Astrophysical Journal, 598, 1079- planar Dust Structures in the Edge-On Spiral NGC 1099. 4217”, Astronomical Journal, 128, 662-673. Wilcots, E.M., Prescott, M.K.M. 2004, “H I Verheijen, M.A.W., Bershady, M.A., Ander- Observations of Barred Magellanic Spirals. II. The sen, D.R., Swaters, R.A., Westfall, K., Kelz, A., Frequency and Impact of Companions” Astronom- Roth, M.M. 2004, “The Disk Mass project; science ical Journal, 127, 1900-1916. case for a new PMAS IFU module”, Astronomis- Wood, K., Mathis, J.S., Ercolano, B. 2004, che Nachrichten, 325, 151-154. “A three-dimensional Monte Carlo photoionization Vishniac, E.T., Lazarian A., Cho, J. 2003, code for modelling diffuse ionized gas” Monthly “Problems and Progress in Astrophysical Dynamos” Notices of the Royal Astronomical Society, 348, (eds E. Falgarone, T. Passot). Lecture Notes in 1337-1347. Physics, 614, 376-401. Zweibel, E.G., Heitsch, F., Fan, Y. 2003, “Nu- Wakker, B.P. 2004, “Recent Developments merical Simulations of Magnetic Fields in Astro- Concerning High-Velocity Clouds”, Astrophysics physical Turbulence” (eds E. Falgarone and T. Pas- and Space Science, 289, 381-390. sot). Lecture Notes in Physics, 614, 101-126. Wakker, B.P., Richter, P. 2004, “Our grow- ing, breathing Galaxy” Scientific American, 290, 28-37. Waldron, W.L., Cassinelli, J.P. 2002. “Chan- dra Observations of O Stars” (eds E.M. Schlegel and S.D. Vrtilek). ASP Conference Proceedings, 262, 69. Walker, C., Wood, K., Lada, C.J., Robitaille,

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