VOL  20  ISSUE  03 

Space Telescope Science Institute

The Cycle 12 Proposal

Peer Review M. Meixner ESA,Credit: NASA, the Hubble Helix Nebula Team, NOAO, Rector (NRAO). See page 6 for more information. (STScI), and T.A. Duccio Macchetto, [email protected], Robert Williams, [email protected], & Brett Blacker, [email protected]

Overview Ongoing Features of the Hubble Peer Review ith the continuing excellent performance of the major The oversubscription of Hubble observing time and data-reduction instruments on Hubble, the science program of the funds remains high. Evaluating such a large number of proposals has telescope during Cycle 11 has been very productive. At the led to some distinctive procedures followed by the panels in identify same time there is some uncertainty over the timing of the the best proposals. We expect these procedures to apply to future  Wnext servicing mission, which will install the new Cosmic Origins proposal cycles, as follows. Spectrograph and Wide Field Camera 3. Cycle 12 observations will begin in Two-tiered TAC. In consultation with the Space Telescope Institute July 2003 on an accelerated timeline in which the Institute has shortened Council, the Director sets aside one third of the available observing the period between proposal submission and observations by four months. time (~1,000 orbits) for large (over 100 orbits) and Hubble Treasury The Institute received 1,046 proposals in late January 2003 in response to proposals, which the TAC evaluates. The remaining two thirds of

the Cycle 12 Call for Proposals. This represents an oversubscription in observing time is devoted to smaller programs, which are evaluated 2003 requested orbits by more than 6 to 1, down slightly from the 1,075 exclusively by the individual disciplinary panels. The relevant proposals received in Cycle 11. The full Time Allocation Committee (TAC) and disciplinary panels review the large and Treasury proposals, but the  11 disciplinary panels met in Baltimore in late March to evaluate the multi-disciplinary TAC performs the final assessment. proposals and to recommend programs to the Director for implementation. Twin panels. Except for the solar system panel, each disciplinary As reported in the fall 2002 Newsletter, an external review of the Institute’s panel has one or two ‘mirror’ panels that consider those proposals for TAC process was conducted last summer, which affirmed the basic integrity which its own members may have some conflict of interest. This and effectiveness of the Hubble peer review, but which recommended procedure minimizes loss of expertise in the discussion due to panelists certain changes in Cycle 12. (See http://www.stsci.edu/resources/ recusing themselves from the evaluations. In Cycle 12, the acceptance rate tac_assessment.) Among these changes were a loosening of institutional for proposals with panelist PIs was the same as that for non-panelist PIs. conflict-of-interest rules governing panelists’ review of proposals, the Progressive orbit subsidy. In order to encourage dissemination of reviewer comments to Principal Investigators (PIs) that panels to resist a tendency to favor smaller Continued reflect the panel discussions, and convening an annual workshop to programs because of the greater number of page 3 facilitate broad collaboration on Hubble Treasury proposals. them that can be approved given the limited SUMMER DIRECTOR’S PERSPECTIVE

STARS IN ASTRONOMY Steven Beckwith, [email protected]

he other day a friend of mine remarked casually, “It seems that all stellar astronomers over the age of 50 have gotten cranky.” We had noticed a certain defensiveness in one of our colleagues who thought his interests had been marginalized among more fashionable topics often featured in the popular press. Stellar astronomy dominated the study of the universe for most of the last 400 years, and astronomers who work on stars are following a rich tradition. But a lot of us got the feeling that stars are well understood and have moved on to more exotic pursuits, leaving the stellar astronomers to rethink that rich tradition.

“Stellar” brings to mind “the best and brightest,” and when I talk Bond is using similar techniques to improve our knowledge of binary about astronomers who work on “stars,” visions of Hollywood and all star masses as a check on stellar evolution theory. There has been a its glamour come to mind. Indeed, the importance of stars as a subject problem with some binary star systems whose components appear to for human inquiry is embedded in the language whenever we want to have much different ages from one another when calculated by our describe individual achievement that stands above all the rest. So why standard theory, whereas we expect them to be coeval. Initial are these “stellar astronomers” cranky? observations of Procyon revised the derived masses of the two stars in It cannot be because of any lack of success with the Hubble Space this binary system downward and brought the observations into Telescope. The Cycle 12 TAC rated a stellar proposal, Fritz Benedict’s agreement with theory for the first time. Bond’s team is continuing with (#9879) as its highest priority this year among nearly 1100 observations of several other binary systems. Stellar evolution theory is competitors. Benedict’s team will measure the distances to Cepheid one of the most important advances of 20th century astrophysics, and variables by direct parallax using the Fine Guidance Sensor (FGS1R) on its verification remains an essential underpinning for our field. Hubble; Howard Bond won time for a similar, albeit smaller program to ER 8 is the coolest known white dwarf in the Galaxy and hence the recalibrate the Cepheid zero point luminosity-period (L-p) relationship oldest. It is nearby and moving rapidly, and by chance it will pass following precise measurements of the distances to these important stars. within 50 mas of a background star in 2006 causing an apparent shift Hubble is now the most precise instrument in history for measuring in the center of light by more than 8 mas owing to gravitational lensing the positions of stars, achieving an accuracy of 0.2 milliseconds of of the star by the white dwarf. This shift is easily detectable with arc (mas), about five times better than Hipparcos, the previous FGS1R, allowing Kailash Sahu and his collaborators to measure the state-of-the-art. At that precision, several fundamental problems in mass of ER 8 to better than 5%. Knowing the mass of this cool white astronomy come into reach for the first time. For example, the l dwarf will allow them to set the best lower limit to the age of the argest uncertainty in the distance scale of the universe, expressed Galaxy yet and, by extrapolation, to the universe itself. This measure of through H0, is the zero point calibration of the L-p relation, which universal age is completely independent of the standard methods of Benedict and Bond can improve by a factor of a few to reduce the cosmology and has the potential to either confirm or deny our standard error in our knowedge of H0—and thus the age of the universe. model for the universe. This is not the sort of impact we expect from a

 2  DIRECTOR’S PERSPECTIVE

device whose main goal is to keep a spacecraft pointed in the right astrometric precision by as much as the Advanced Camera for Surveys direction, but then Hubble continues to show its superlative improved imaging. Servicing Hubble gives us a lot of bang for the buck, capabilities in unlikely areas. and since it takes a lot of bucks to do it, we are pleased to get a Sumner Starrfield and colleagues recently had their image of the correspondingly big bang. peculiar nova V838 Mon on the cover of Nature, an image so Our stellar astronomers have been flying stealthily below our radar spectacular that it could displace the Eagle Nebula as Hubble’s most screens to pick off some of the most important problems in astronomy iconic image in the public’s mind. We already have T-shirts with V838 with Hubble’s unmatched accuracy. The TAC noticed, I noticed, and Mon that are quite popular among the T-shirt wearing crowd. (I am pretty soon, someone in the science media will notice that a field thinking of getting a tie with that image or maybe another hat.) thought by its own practitioners to be less than fashionable is actually The Fine Guidance Sensors don’t get much respect these days, but cutting a wide swath through new territory and giving the more they are quietly providing opportunities to rewrite the textbooks. glamorous folks a run for their money. FGS1R, installed during servicing mission 3a, has improved the So, if you are a stellar astronomer who is feeling cranky, you may want state-of-the-art to such a degree that it opened up a number of new to take heart in the new opportunities offered by Hubble. It is going to research areas, just as all of Hubble’s new instruments have. The Cycle help you rewrite the textbooks as it has with so many other fields. 12 TAC recommended programs using the FGS for 5% of the total I, for one, will be cheering you on. Ω orbits at the same time that WFPC2—the venerable camera that is responsible for 90% of the public and more than 50% of the scientific impact of Hubble—received only 2% of the time. This change once again show how servicing Hubble has expanded the range of its scientific capabilities: FGS1R improved the state-of-the-art for

Cycle 12 Review from page 1

observing time, the Institute subsidizes the cost in orbits charged to the panel for moderate proposals (15-100 orbits). For each orbit approved above 15, an increasing fraction is charged against a pool of orbits held in reserve for the purpose. This policy has succeeded in increasing the fraction of moderate programs over the past 5 cycles. Reviewer comments. Panel feedback with information on the panel’s discussion and assessment of a proposal is highly desired by most PIs—if not always valued! Each proposal is assigned a primary reviewer, who is responsible for writing his/her own review and for incorporating comments from the other secondary reviewers. The primary reviewer leads the panel discussion and edits the written comments to reflect the panel discussion. Then others—the secondary reviewers, the panel support scientist (an Institute scientist), and the panel chair— review the comments before they are sent to the PI.

Also Notable in the Cycle 12 Peer Review Cycle 12 continued the collaboration between the Institute, the National Optical Astronomy Observatories, and the Chandra X-ray Center on the peer review of proposals requesting resources on the Hubble and either Chandra or NOAO telescopes. The Hubble peer review can approve observing time on the above facilities it deems necessary for the science objectives of the Hubble proposal. The maximum total time that can be approved in this manner is 400 ksec on Chandra and 20 nights on NOAO telescopes. For Cycle 12, the TAC and panels recommended approval of 115 ksec on Chandra and 17.5 nights on NOAO telescopes. Proposers used the Astronomer’s Proposal Tool (APT) for Phase I and Phase II submission for the first time in Cycle 12. APT enables PIs to write Continued their proposals in a variety of text editors on different platforms and page 4

 3  submit them in a way that results in a uniform format for all proposals. This feature was Cycle 12 Review from page 3 essential to our being able to shorten the time between proposal submission and scheduling observations. While we have experienced some glitches typical of the first-time use of a large software package, the Institute is committed to correcting the flaws and making APT as user friendly as possible. Specific comments on APT are welcomed and should be sent to [email protected].

Advice to Future Proposers The present Hubble review process is highly regarded and widely copied. We plan to use the same process in future cycles, which means future proposers should keep in mind the following advice drawn from experience. The scientific case should be of broad interest to your fellow astronomers. The most successful proposals describe the importance of the investigation to all astronomy in a convincing manner and include sufficient background information to provide a compelling context. Do not write proposals that are of interest to only a few experts in a narrow subdiscipline. Instead, present the big picture. This is an explicit evaluation criterion, and proposals are downgraded for failing to address it. Ask only for the resources you genuinely need. Justify your request for the number of targets and orbits and the need for Hubble observations. For example, even if you request observations in the ultraviolet, it may not be obvious to the reviewers why you cannot achieve the science aims of your proposal in a different wavelength range. In the infrared, justify your need for Hubble and NICMOS by comparison with adaptive optics systems on ground-based telescopes. Because of the limited number of orbits available in a cycle, many truly excellent proposals must be turned down. Nevertheless, remember that rejected PIs are in very good company and that many of these proposals succeed in future cycles.

Final Thoughts There is no ideal process for evaluation of proposals, and the Institute remains open to new procedures that will improve our evaluation process. We are constantly assessing our procedures in response to suggestions from the Users Committee and the community. We augment or modify some aspects of our procedures every succeeding cycle. The Cycle 12 TAC made many hard decisions, which have produced the Cycle 12 science program for the Hubble. We express our appreciation to the panelists and TAC members who participated in the recent TAC process, with special thanks to Dr. Tim de Zeeuw for serving as TAC Chair for this cycle. In the accompanying tables, we list the panel and TAC members and the programs that have been approved by the Director to receive observing time and/or data reduction and archival research funds in Cycle 12. Ω

 4  Cycle 12: TAC and Panel Members

Member Institution Member Institution

TAC Chair Extragalactic Panel Members

Tim de Zeeuw Sterrewacht Leiden Eric Agol California Institute of Technology / University of Washington Solar System Panel Members Matthias Bartelmann Max-Planck-Institut fur Astrophysik Ralf Bender (Chair) Universitats-Sternwarte Munchen / Max-Planck- Marc Buie Lowell Observatory Institut fur extraterrestrische Physik Nancy Chanover New Mexico State University Katherine Blundell University of Oxford Jean-Claude Gerard Universite de Liege Tereasa Brainerd Boston University Amanda Hendrix California Institute of Technology Elias Brinks Universidad de Guanajuato Ralph Lorenz University of Arizona Michael Brotherton University of Wyoming Karen Meech (Chair) University of Hawaii Gerald Cecil University of North Carolina at Chapel Hill Hal Weaver The Johns Hopkins University Applied Physics Renyue Cen Princeton University Laboratory Stephane Charlot Max-Planck-Institut fur Astrophysik / CNRS, Institute d'Astrophysique de Paris Galactic Panel Members Giuseppina Fabbiano (Chair) Smithsonian Institution Astrophysical Observatory Heino Falcke Max-Planck-Institut fur Radioastronomie/University Charles Bailyn (Chair) Yale University of Nijmegen Bruce Balick University of Washington Xiaohui Fan University of Arizona Thomas Bania Boston University Karl Glazebrook The Johns Hopkins University David Bennett University of Notre Dame Anthony Gonzalez University of Florida David Charbonneau California Institute of Technology Richard Green (Chair) National Optical Astronomy Observatories Roger Chevalier University of Virginia Henk Hoekstra University of Toronto / Canadian Institute for You-Hau Chu (Chair) University of Illinois at Urbana - Champaign Theoretical Astrophysics Robin Ciardullo The Pennsylvania State University Deidre Hunter Lowell Observatory Constantine Deliyannis Indiana University System William Keel University of Alabama Andrew Dolphin National Optical Astronomy Observatories Jean-Paul Kneib Observatoire Midi-Pyrynees / California Institute of Bruce Elmegreen (Chair) IBM T.J. Watson Research Center Technology Rob Fesen Dartmouth College Ken Lanzetta State University of New York at Stony Brook Ed Fitzpatrick Villanova University Simon Lilly (Chair) ETH Zurich Jules Halpern Columbia University Lynn Matthews Smithsonian Institution Astrophysical Observatory Mario Hamuy Carnegie Institution of Washington Patrick McCarthy (Chair) Carnegie Institution of Washington Pat Hartigan Rice University David Merritt Rutgers the State University of New Jersey Thomas Henning Max-Planck-Institut fur Astronomie, Heidelberg Gerhardt Meurer The Johns Hopkins University Pascale Jablonka CNRS, Institute d'Astrophysique de Paris Rafaella Morganti Stichting Astronomisch Onderzoek in Nederland Joachim Krautter Landessternwarte Heidelberg (ASTRON) Richard Larson Yale University John Mulchaey Carnegie Institution of Washington Jeff Linsky University of Colorado at Boulder Reynier Peletier University of Nottingham Peter Martin University of Toronto / Canadian Institute for Rosalba Perna Smithsonian Institution Astrophysical Observatory Theoretical Astrophysics Patrick Petitjean CNRS, Institute d'Astrophysique de Paris Phil Massey Lowell Observatory Richard Pogge Ohio State University David Meyer Northwestern University Joel Primack University of California - Santa Cruz Georges Meynet Geneva Observatory Michael Rauch Carnegie Institution of Washington Mark Morris University of California - Los Angeles Susan Ridgway The Johns Hopkins University Antonella Natta (Chair) Osservatorio Astrofisico di Arcetri Abhijit Saha National Optical Astronomy Observatories Marc Pinsonneault Ohio State University David Sanders University of Hawaii James Pringle Cambridge University Ian Smail University of Durham Tad Pryor Rutgers the State University of New Jersey Thaisa Storchi-Bergmann Universidade Federal do Rio Grande do Sul John Raymond Smithsonian Institution Astrophysical Observatory Michele Thornley Bucknell University Bo Reipurth University of Hawaii William van Breugel Lawrence Livermore National Laboratory Bradley Schaefer University of Texas at Austin Liliya Williams University of Minnesota Regina Schulte-Ladbeck (Chair) University of Pittsburgh Rogier Windhorst Arizona State University Michal Simon State University of New York at Stony Brook Donald York University of Chicago Ed Sion Villanova University Steve Zepf Michigan State University Stephen Smartt Cambridge University Tammy Smecker-Hane University of California - Irvine Verne Smith University of Texas at El Paso Alexander Tielens Kapteyn Astronomical Institute Todd Tripp Princeton University William van Altena Yale University Ted von Hippel University of Texas Don Winget University of Texas at Austin Hans Zinnecker Astrophysikalisches Institut Potsdam Ellen Zweibel University of Wisconsin

 5  Proposals By Country Summary of Cycle 12 Results

Country Submitted Approved Proposals Requested Approved % Accepted ESA Accepted ESA % Total

Australia 11 3 General Observer 819 170 20.8% 28 16.5% Austria 2 0 Snapshot 74 21 28.4% 4 19.0% Belgium 4 0 Archival Research 111 41 36.9% Brazil 2 0 Theory 42 10 23.8% Canada 13 3 Total 1046 242 23.1% 32 16.8% Chile 3 0 Primary Orbits 19674 3154 16.0% 323 10.2% France 26 3 Germany 32 8 India 2 0 Ireland 2 0 Israel 5 1 Italy 22 4 Japan 3 0 Proposal Acceptance Ratio Mexico 1 0 Norway 1 0 Russia 1 1 Spain 11 2 Sweden 4 0 Switzerland 4 0 The Netherlands 9 4 Ukraine 1 0 United Kingdom 60 9 United States 827 203 ESA Countries 190 32

The Helix Nebula Detail

his cropped version of the Helix Nebula mosaic shows cometary-filaments embedded along a portion of the inner rim of the nebula's red and blue gas ring. At a distance of 650 light-years, the Helix is one of the nearest planetary nebulae to Earth. The composite picture is a seamless blend of ultra-sharp NASA Hubble Space Telescope (HST) Advanced Camera for Surveys images combined with the wide view of the Mosaic TCamera on the National Science Foundation's 0.9-meter telescope at Kitt Peak National Observatory, part of the National Optical Astronomy Observatory, near Tucson, Arizona Astronomers at the Space Telescope Science Institute (STScI) assembled the images into a mosaic. The mosaic was blended with a wider photograph taken by the Mosaic Camera.

Credits: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: Bo Reipurth (University of Hawaii)

 6  US Proposals By State

Instrument Statistics State Submitted Approved AL 7 0 AZ 70 18 Instruments Requested Orbits % Approved Orbits % SubTotal CA 135 39 CO 41 13 ACS/HRC 1914 7.4% 251 4.7% CT 10 6 ACS/SBC 266 1.0% 19 0.4% DC 11 1 ACS/WFC 11727 45.3% 53.7% 2640 49.7% DE 9 3 54.8% FL 11 4 FGS 578 2.2% 2.2% 268 5.0% GA 10 2 5.0% HI 21 5 NIC1 427 1.6% 183 3.4% IA 1 0 NIC2 1866 7.2% 597 11.2% IL 18 4 NIC3 1471 5.7% 14.5% 342 6.4% IN 8 2 21.1% KY 4 2 STIS/CCD 1475 5.7% 333 6.3% LA 3 1 STIS/FUV 2743 10.6% 433 8.1% MA 46 11 STIS/NUV 1516 5.9% 27.8% 126 2.4% MD 155 38 23.2% MI 21 6 WFPC2 1919 7.4% 7.4% 123 2.3% MN 5 0 2.3% MO 5 0 Total 25902 100.0% 5315 100.0% NC 1 0 NE 1 1 Orbits include coordinated parallel usage NH 3 1 Excludes Pure Parallel and Snapshot Programs NJ 13 5 NM 14 3 NY 37 6 OH 11 4 OK 4 1 OR 5 2 PA 53 6 SC 4 1 TN 11 2 TX 30 8 VA 13 3 WA 14 1 Proposal and Orbit Results By Science WI 18 4 WV 1 0 WY 3 1

Cosmology 31% QAL 3%

Cool Stars 5% Star Formation 6%

Galaxies 19% Stellar Pops 11%

Hot Stars 6% Solar Systems 3%

ISM 9% AGN 7%

 7  CYCLE 12: Approved Observing Programs s galaxy the Universe at z>0.5 o 2 sts? evolution the 10 Billion Solar Mass Limit ce Scale with the Maser Galaxy NGC 4258 Extragalactic Programs Roberto AbrahamOmar AlmainiDavid Axon University of TorontoJack Baldwin Royal Observatory EdinburghAaron BarthPhilip Best Rochester Institute of Technology Michigan State UniversityJohn BirettaMichael Blanton California Institute of Technology BoekerTorsten University of Edinburgh, Institute for AstronomyGregory Bothun Science Institute Space Telescope University New York David Bowen Science Institute Space Telescope University of Oregon GO GO GO Princeton University GO ACS Imaging of the Gemini Deep Survey Fields: Galaxy Assembly at z = 1.5 A morphological study of EROs and sub-mm sources in a unique deep field GO GO Measuring Black Hole Masses in Double Peaked Broad Lined AGNs Elliptical galaxies in z~1.5 clusters GO Calibrating the Black Hole Mass Scale for Quasars Probing the High Redshift Universe with Quasar Emission Lines GO HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet AR Spiral Galaxies The Ages of Nuclear Star Clusters in Early-Type GO Comparing the ACS Ultra Deep Field to Low Redshift Galaxy Observations GO A New Member of the Local Group? The rarest of sightlines: probing the metallicity a DLA with nearby Low Surface Brightnes Michael BrothertonScott Burles University of WyomingScott BurlesRupali Chandar Massachusetts Institute of Technology Massachusetts Institute of Technology Science Institute Space Telescope AR AR GO GO forest and the intrinsic QSO continuum The low redshift Lyman-alpha A Decade of AGN SEDs Anomalous Flux Ratios in Quadruple Gravitationally Lensed QSOs Missing the Dominant Sites of Star Formation Starbur in Local UV-Bright Are We Rupali ChandarScott ChapmanAndrew Connolly Science Institute Space Telescope Steven Crawford California Institute of TechnologyRoelof de Jong University of PittsburghRenato Dupke University of Wisconsin - MadisonHarald Ebeling Science Institute Space Telescope University of Michigan University of Hawaii GO GO Age-dating Star Clusters in M101 AR A near-IR imaging survey of sub-mm galaxies with spectroscopic redshifts AR SNAP The Fate of Luminous Compact Blue Galaxies: An Environmental Approach The Dusty ISM Substructure in Nearby Spiral Galaxies The Spectral and Morphological Evolution of Galaxies GO GO A Search for the Missing Baryons in Nearby Cosmic Filaments Life in the fast lane: The dark-matter distribution most massive galaxy clusters Richard Ellis Richard Ellis Eric Emsellem Gary Ferland California Institute of TechnologyLaura Ferrarese California Institute of Technology Centre de Recherche Astronomique LyonDuncan ForbesMarijn Franx University of Kentucky Rutgers the State University of New JerseyJeffrey Gardner Swinburne University of TechnologyPeter GarnavichC. Gaskell Universiteit Leiden University of PittsburghKarl Gebhardt GO University of Notre Dame ARAlister Graham GOLincoln Greenhill GO Nailing Down M31's Central Black Hole University of Nebraska - Lincoln at Austin University of Texas Timothy Heckman The mass assembly history of early-type galaxies at z~1 University of Florida The role of dark matter and intracluster gas in galaxy formation and cluster Smithsonian Institution Astrophysical Observatory The Upper End of the Supermassive Black Hole Mass Function: Pushing GO The Johns Hopkins University AR The Globular Cluster Systems of Spiral Galaxies along the Hubble Sequence Numerical simulations of outflows in quasars: the microphysics BAL winds GO AR GO GO AR and Robust Calibration of the Extragalactic Distan Accurate GO Resolving Galaxy Formation and Evolution for Interpretation of HST Observations ESSENCE: Measuring the Dark Energy Equation of State Deep NICMOS imaging of HDF-South: restframe optical morphologies high redshift galaxies A Detailed Photoionization Study of the Broad Line Region NGC 5548 AR Search for Black Holes in M31 Globular Clusters AR The Astrophysics of Star Formation & Galaxy Building in the "Middle Ages": z ~ 0 t Measurements of core sizes in luminous early-type galaxies Name Institution Type Title Name Institution Type

 8  CYCLE 12: Approved Observing Programs Dusty Universe h Material z=0.83 DS-N Images and Keck DEIMOS Spectra again Radio Galaxy 3C236 sters ch galaxy clusters ous X-ray Sources a-Deep Field 6 Mpc Jeffrey KenneyAnton KoekemoerDavid Koo University Yale David Koo Science Institute Space Telescope Konrad KuijkenKonrad Kuijken University of California - Santa CruzKenneth Lanzetta Universiteit Leiden University of California - Santa Cruz Universiteit Leiden at Stony Brook State University of New York AR AR Morphology and Evolution of the Largest Complete Sample X-ray Selected AGN AR AR GO Relation of High Redshift z > 1 Disks Using GOO Evolution of the Tully-Fisher Photometry and Photometric Redshifts of Faint Galaxies in the Ultr The Ages of Distant Field Galaxy Spheroids Ram Pressure Stripping in the Virgo Spiral NGC 4522 GO GO Proper motion kinematics in Galactic bulge/bar fields orbits for Leo I and II The mass of the Milky Way: Luis HoRolf Jansen Carnegie Institution of Washington Arizona State UniversityIgor KarachentsevDaniel KelsonObs.Astrophysical Special Sciences, of Academy Russian Carnegie Institution of Washington SNAP SNAP The local Hubble flow and the density field within A Narrow-band Snapshot Survey of Nearby Galaxies SNAPAri LaorSoren Larsen H-alpha Snapshots of Nearby Galaxies observed Quantifying Star Formation in a in F300W: GO European Southern Observatory - Germany Institute of Technology Technion-Israel Large Cluster Radii: The Outskirts of MS1054-03 at Galaxy Populations at Very GOEric Perlman GOBradley Peterson Massive Clusters in Spiral Galaxies and the Connection with Open Clu Young Bradley PetersonBradley Peterson Reverberation Mapping of the Least Luminous Seyfert 1 Galaxy NGC 4395 University of Maryland Baltimore County Ohio State UniversityAndrew Phillips Ohio State UniversityDaniel Proga Ohio State UniversityDouglas Richstone University of California - Santa CruzSusan RidgwayBassem Sabra University of Michigan University of Colorado at BoulderVicki Sarajedini GO The Johns Hopkins UniversityJames Schombert University of FloridaEdward Shaya The Structure and Physics of Extragalactic Jets University of FloridaGeorge Sonneborn University of OregonS. Stanford GO AR Services Company Raytheon Technical NASA Goddard Space Flight Center GO SNAP AGN Black Hole Masses from Stellar Dynamics AR Nature & Evolution of Compact Galaxies in the GOODS-N Field University of California - Davis Structure of the Accretion Disk in NLS1 NGC 4051 Host Galaxies of Reverberation-Mapped AGNs GO GO AGN Radiation-Driven Outflows: Models vs. Observations Black Holes in Big Galaxies with Small Bulges The Evolution of the Host Galaxies Radio-Quiet Quasars AR GO GO AR AR Optimization of the Tip Red Giant Branch Distance Estimator AALs in Quasars: Diagnostics of the Environment Supernovae Probing the Halo and ISM of Low-Redshift Galaxies with Young Spectroscopy and Morphology Variability, AGN in the GOODS fields: A Study of Short-Term Morphological and Structural Study of the Galaxies in Distant Cluster CL1322.5+3028 AR The Construction of Elliptical Galaxies at High Redshifts Sebastian JesterKelsey JohnsonInger Jorgensen Fermilab University of Wisconsin - Madison Northern Operations Gemini Observatory, GO AR Galaxy Evolution During Half the Age of Universe: ACS imaging ri Study of Super Star Clusters as They Emerge From Their Birt A Multi-Wavelength Karen LeighlyBarry Madore GOBarry Madore University of Oklahoma NormanPatrick McCarthy Campus The Nature of the UV Excess in Jet 3C273 Carnegie Institution of WashingtonJon Miller Carnegie Institution of WashingtonEdward Moran Carnegie Institution of WashingtonJohn MulchaeyChristopher O'Dea University Smithsonian Institution Astrophysical Observatory Wesleyan Carnegie Institution of Washington GO Science Institute Space Telescope AR UV Spectroscopic Observations of Luminous Narrow-line Seyfert 1 Galaxies GO GO AR Morphological Evolution of Galaxies from the Present to z = 0.3-0.5 Observations of Intermediate Mass Black Hole Candidate Ultra-Lumin M83: Calibrating the Cepheid PL Relation Archival Study of Red Galaxies in the Chandra Deep Field South GO GO GO The Role of Groups in the Evolution Galaxies at Intermediate Redshifts Star Formation, and AGN Fueling in the Born- Time Scales for Gas Transport, X-ray-Bright, Optically Normal Galaxies: The "Hidden" Truth Name Institution Type Title Name Institution Type

 9  CYCLE 12: Approved Observing Programs tion and their LF ulation in late-type galaxies. Stars First-Overtone Galactic Cepheids opulations of high redshift E/S0 galaxies rby Dwarf Galaxy IC 2574 A Rich Early Release Dataset gh Spectral Resolution and Abundances Taft ArmandroffTaft Philip ArmitageFrancesca Bacciotti Optical Astronomy Observatories, National AURA JILA Osservatorio Astrofisico di Arcetri GO Dwarf Elliptical Galaxies in Nearby Groups: Stellar Populations GO Stars: investigating NUV lines with very hi Rotation in Jets from Young AR of Disk Accretion in Cataclysmic Variables Variability Turbulent Yujin YangYujin Stephen Zepf ZhengWei ZhengWei University of ArizonaBodo Ziegler Michigan State University The Johns Hopkins UniversityGalactic Programs The Johns Hopkins University Universitats-Sternwarte GottingenHector Arce California Institute of TechnologyJohn BahcallCharles Bailyn GO GO GOJohn Bally GO SNAPMartin Barstow Institute For Advanced Study The Age and Mass Function of the Intermediate Age Globular Cluster System of NGC 4365 University Yale Galaxy Evolution in Action: The Detailed Morphology of Post-Starburst Luciana Bianchi Properties of the Intergalactic Medium near Epoch HeII Reionization Confirmation of New Candidates for the Study Intergalactic Helium Evolution of Scaling Relations Field Spiral Galaxies at Intermediate Redshift Luciana Bianchi University of Leicester University of Colorado at BoulderLuciana Bianchi The Johns Hopkins UniversityAnn Boesgaard AR The Johns Hopkins UniversityHoward Bond The Johns Hopkins UniversityHoward Bond The Impact of Infall and Outflow Motions on the Circumstellar Envelope Young University of Hawaii Science Institute Space Telescope GO Science Institute Space Telescope GO Observing the Next Nearby Supernova GO AR An ACS/WFC H-alpha Survey of the Orion Nebula GO GO GO The Planetary Nebula K648 in the Globular Cluster M15 (NGC104) Archival Studies of Main Sequence Binaries in 47 Tucanae the White Dwarf Mass-Radius Relation with Sirius B Verifying UV extinction by dust in unexplored LMC environments GO Massive Clusters in M33 Young GO GO HST Observations of Astrophysically Important Visual Binaries Calibration of the Period-Luminosity Relations for Fundamental and Trigonometric Boron in F Stars the Hyades - Insights into Li-Be Dip Massimo StiavelliLisa Storrie-Lombardi Science Institute Space Telescope California Institute of Technology GO GO The environment of QSOs at the reionization epoch First Look Survey: Morphologies of EROs and Field Galaxies in SIRTF's David WittmanHaojing Yan Bell Labs Arizona State University GO AR NIC3 Imaging of z~6 Candidates in a Deep ACS Parallel Field: Finding the reionizing popula Probing the Mass Distribution at High Redshift in UDF Michael Strauss TreuTommaso Jason Tumlinson Princeton UniversityWil van Breugel California Institute of TechnologySylvain Veilleux University of ChicagoBart Wakker Lawrence Livermore National LaboratoryFabian Walter University of MarylandRachel WebsterRichard White University of Wisconsin - Madison National Radio Astronomy ObservatoryBradley Whitmore University of MelbourneGerard Williger Science Institute Space Telescope Rogier Windhorst Science Institute Space Telescope AR GO The Johns Hopkins University GO Arizona State University The Lenses Structure and Dynamics (LSD) Survey: mass distribution and stellar p Halos Around High Redshift Radio Galaxies Giant Lya SNAP II Quasars The Host Galaxies of Type GO GO with New SDSS QSOs Probing IGM Phases, Metals, and the Cosmic Web GO Investigating the Powering Sources of Expanding Supergiant Shells in Nea Intergalactic O VI absorption at redshift <0.004 GO The Fundamental Plane of Massive Gas-Rich Mergers GO GO Alpha Galaxy at z=5? Leaky IGM at z=6 or Lyman ACS, NICMOS, and STIS Observations of Three Ongoing Mergers GO Microarcsecond Imaging of a Gravitationally Lensed QSO: 2237+0305 SNAP A test of the foreground proximity effect at z=1.2 the remarkable cool stellar pop NIC3 SNAPs of nearby galaxies imaged in the mid-UV: Name Institution Type Title Name Institution Type

 10  CYCLE 12: Approved Observing Programs h NICMOS c survey of cataclysmic variables ts mation t s at Kiloparsec Scales Francois BoulangerHerve Bouy Institut d'Astrophysique Spatiale BridgesTerry Timothy BrownAdam Burgasser European Southern ObservatoryNuria Calvet Anglo-Australian Observatory University Corporation For Atmospheric ResearchStefan Cartledge University of California - Los AngelesRoger ChevalierOrsola De Marco Smithsonian Institution Astrophysical Observatory Louisiana State University & Agricultural Medical CollegeJohn Debes The University of Virginia GO GO American Museum of Natural History GO a Quiescent Molecular Cloud SMC Extinction Curve Towards SNAP in the Atmosphere of an Extrasolar Plane Vapor A Search for Water Pennsylvania State University GO Exploring Interstellar Krypton Abundance Variation GO GO Multiplicity among brown dwarfs in the Pleiades cluster Search for Core-disrupting Wide-Angle Winds T Dwarf Companions: Searching for the Coldest Brown Dwarfs Search For Metallicity Spreads in M31 Globular Clusters GO AR A tailored survey of proplyds with the ACS GO Stellar wind interactions around binary stars: models for planetary nebulae Finding Planets in the Stellar Graveyard: A Faint Companion Search of White Dwarfs wit Andrew DolphinAndrew DolphinBryan Dorland National Optical Astronomy Observatories, AURAGordon Drukier National Optical Astronomy Observatories, AURAReginald Dufour United States Naval ObservatoryDouglas Duncan University Yale Steven Federman Rice University ARAnnette Ferguson University of Colorado at Boulder GOGary Ferland University of ToledoRobert Fesen Kapteyn Astronomical Institute CTE Corrections for WFPC2 and ACS Boris Gaensicke ACS Photometric Zero Point Verification Peter Garnavich University of KentuckyDonald Garnett Dartmouth College University of Southampton GODouglas Gies University of Notre DameDouglas Gies University of Arizona The Kinematics and Dynamics of the Material Surrouding Eta Carinae Gerard Gilmore GOJohn Gizis Georgia State University Research FoundationJohn Gizis GO Georgia State University Research Foundation GO Experimental Proof of the Neutrino Process in SN from Boron Isotope Measuremen University of Cambridge SNAPJohn Gizis ARBertrand Goldman Shooting Stars: Looking for Direct Evidence of Massive Central Black Holes in Globular Clusters Stellar Populations in the Outskirts of M33: A Unique Probe Disk Galaxy For CIII] Imagery of Planetary Nebulae and HII Regions -- A Snap Program University of DelawareKarl Gordon University of Delaware Surveying Interstellar Carbon Monoxide Via Ultraviolet Absorption ARGraham Harper New Mexico State University GO SNAP University of DelawareWilliam Harris GO GO ARPatrick Hartigan a global understanding of accretion physics - Clues from an UV spectroscopi Towards Calculation of Fe II atomic data required for the modeling HST observations University of Arizona The Masses of the O-type Binary 15 Monocerotis University of Colorado at BoulderCarole Haswell in the Black Hole Binary Cyg X-1 Wind Accretion and State Transitions GO McMaster University Probing the Dynamics and Shock Physics of Cas A Supernova Remnant William Herbst in the Ultra-Deep Field Transients Rice UniversityGregory Herczeg Open UniversityJeff Hester Structure in Planetary Nebulae Recombination Lines and Temperature SNAP University Wesleyan University of Colorado at Boulder A snapshot survey of rich stellar clusters in the Large and Small Magellanic Clouds GO GO GO Arizona State University AR SNAP Brown Dwarf Ultraviolet Observations Young of a Very Brown dwarf atmospheric variability observations NICMOS Observations of Cool Brown Dwarf Doubles Binaries A Snapshot Search for Halo Very-Low-Mass GO New Insights into Betelgeuse's Inhomogeneous Wind GO of Extended Red Emission The Exciting Wavelength AR GO Establishing the Metallicity Distribution in Normal Giant Ellipticals GO GO Stars Models of Gas in Disks Classical T Tauri Ultraviolet Emission from Protostellar Accretion Disks GO Microquasars: Outbursts and Outflows in Black Hole Accretion Flows Natural Coronagraphic Imaging of KH 15D ACS Monitoring of the Polarization Crab Nebula Name Institution Type Title

 11  CYCLE 12: Approved Observing Programs tem HS1136+6646 ival Study n the Andromeda Galaxy ster core A parallax & proper motion ormation netesimal disks a r PSR J0537-6910 hite dwarf PG1031+234 Dean HinesJay Holberg Space Science Institute University of Arizona GOJohn Krist GOJames Lauroesch Enabling Coronagraphic Polarimetry with NICMOS Alex Lazarian in the Unique Post-Common Envelope Sys STIS Observations of Orbital and Rotational Variations LewinWalter Northwestern University Science Institute Space Telescope Michael LiuRoberto Maiolino University of Wisconsin - MadisonPhilip Massey Massachusetts Institute of Technology Osservatorio Astrofisico di Arcetri University of Hawaii Lowell ObservatoryBernard McNamaraS. Megeath New Mexico State UniversityMichael Meyer GORoberto Mignani AR AR GO MomanyYazan Smithsonian Institution Astrophysical Observatory and HH 30 Stellar Outflows: XZ Tauri Evolution of Young University of ArizonaJon Morse European Southern Observatory - Germany and Mixing Flows, Turbulence, SNAP Archival HST Studies of Six Globular Clusters Jose Munoz The Physical Character of the Smallest-Scale Interstellar Structures Universita di PadovaEdmund Nelan A NICMOS search for obscured supernovae in starburst galaxies M. Sean O'Brien GO University of Colorado at Boulder GORobert O'Dell Universidad de Valencia Science Institute Space Telescope Robert O'Dell AR University Yale GO How do Brown Dwarfs Form? Planetary-Mass Companion NICMOS Confirmation of a Young GOGeorge Pavlov UniversityGeorge Pavlov Vanderbilt Low Mass Objects in M35 Using the HST/FGS Archive Searching for Very The Physical Parameters and Stellar Winds of Hot, Massive Stars at High Metallicity: O-stars i University Vanderbilt Timing of the proposed optical counterpart of the 16 ms LMC X-ray pulsa The Pennsylvania State University The Pennsylvania State University GO GO GO The Origins of Sub-stellar Masses: Searching for the 'End' IMF GO the Homunculus and Outer Ejecta of Eta Carinae Tracking GO SagDIG: a benchmark for understanding star formation in extreme low-metallicity galaxies Dynamical Masses and Radii of Four White Dwarf Stars A Survey of Extinction Curves to Redshift z=1 GO GO AR GO GO Far-UV Spectrum and Pulsations of PSR 0656+14: Thermal vs. Nonthermal The Distance and Mass of the Neutrino-Luminous White Dwarf PG 0122+200 What's The Point? Deep NICMOS Imaging of the Central X-ray Point Source in Cas Analysis of Helix Nebula Observations During the Leonids Encounter of 2002 Calibration of the ACS Emission Line Filters J. HowkChristopher Johns-KrullChristopher Johns-Krull Rice UniversityChristopher Johns-Krull University of California - San Diego Rice UniversityStefan Jordan Rice UniversityPaul KalasPaul Kalas Institut fur Astronomie & Astrophysik Universitat Tubingen, Charles KeyesIvan King University of California - BerkeleyChristian Knigge GO University of California - Berkeley Science Institute Space Telescope Christian Knigge AR University of Southampton The field structure of the most strongly magnetized w University of Washington University of Southampton for Understanding High-Redshift Star F Interstellar Cooling in the SMC: a Template AR GO GO Stars Accretion Shocks in Classical T-Tauri GO The Distance to the Pleiades GO GO Stars Separating Activity and Accretion in T Tauri Philip Massey ACS Imaging of beta Pic: Searching for the origin rings and asymmetry in pla Bruce McCollum Fomalhaut and beta Pic via ACS detection of sub-stellar companions around Vega, Multi-wavelength Observations of Symbiotic Stars in Outburst GO Lowell Observatory GO GO California Institute of Technology Curing the SW Sex Syndrome NGC 6791 The Bottom of the Main Sequence in Old, Metal-Rich Cluster, Uncovering the CV population in M15: a deep, time-resolved, far-UV survey of the clu SNAP Stars in the Orion Nebul First Spectroscopic Study of a Unique Set Young GOLaura Penny A He-rich O2-3 star in the LMC: Freakish Relic or Paradigm Shifter? Geraldine Peters College of Charleston University of Southern California SNAP Stars A SNAPSHOT Survey of Sharp-Lined Early B-Type AR of O-type Stars at Low Metallicity Projected Rotational Velocities Jimmy Irwin University of Michigan AR The Globular Cluster-Low Mass X-ray Binary Connection in Nearby Early-type Galaxies: An Arch Name Institution Type Title Name Institution Type

 12  CYCLE 12: Approved Observing Programs Interaction of the Oldest Stars va Remnant sses Through Multiplicity Microlensing irradiated accretion discs ite dwarfs in the Hyades rona and Local Group ain Sequence Stars in the Large Magellanic Cloud vs. neutrino spallation Snapshot Study of NGC 6388 rs Giampaolo PiottoSteven PravdoFrancesca Primas Università di Padova Jet Propulsion Laboratory European Southern Observatory - Germany GO Boron in stars of same O and Li, but different Be: testing cosmic-ray GO GO Geometric Distances of the Galactic Globular Clusters NGC2808 and NGC6752 NICMOS Observations of the Gl 164 Companion Barton Pritzl National Optical Astronomy Observatories, AURA SNAP The Second Parameter Effect in Metal-Rich Globular Clusters: A Kenneth SembachJanet Simpson Science InstituteStephen Smartt Space Telescope John Stocke NASA Ames Research CenterRoeland van der Marel University of Cambridge DykSchuyler Van Science Institute Space Telescope Don Vandenberg University of Colorado at Boulder California Institute of Technology University of Victoria GO Gas in the Distant Galactic Co The Properties of Highly Ionized High Velocity GO AR GO GO A Search for the Exciting Sources in OMC-1 through NICMOS Polarization Measurements AR Stellar Dynamical Models for HST Proper Motion Datasets Probing Outflowing Winds from the Galactic Center Direct imaging of the progenitors massive, core-collapse supernovae The Local Environments of Supernovae in Archival HST Images GO Parallaxes of Extreme Halo Subgiants: Calibrating Globular Cluster Distances and the Ages Bo ReipurthMichael RichMartino RomanielloPilar Ruiz-Lapuente University of Hawaii European Southern Observatory - GermanySteven Saar University of California - Los Angeles University of BarcelonaRaghvendra SahaiRaghvendra SahaiKailash Sahu Jet Propulsion Laboratory Smithsonian Institution Astrophysical ObservatoryKarin Sandstrom Jet Propulsion LaboratoryRavi Sankrit GODivas Sanwal Science Institute Space Telescope University of California - BerkeleyAta Sarajedini SNAP GO Low Mass Star Formation at Low Metallicity: Accretion Rates of Pre-M Dimitar Sasselov The Johns Hopkins University A Snapshot Survey of Galactic Bulge Globular Clusters The Pennsylvania State UniversityMatthias Schreiber GO Whirling Dervish Dynamos: Magnetic Activity in CV Secondaries University of Florida Harvard University GO Observatoire de Strasbourg HH110: Collision between a Jet and Cloud GO Ia SNe through HST astrometry Probing the nature of Type SNAP GO GO V Hydrae High-Speed Jet in the Carbon Star, the Evolution of a Knotty, Tracking post-AGB stars? A NICMOS Imaging Survey Are OH/IR Stars the Youngest Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric UV Spectroscopy of the Hot, Helium-Core White Dwarf Companion in HR 1608 GO GOFrederick WalterBarry Welsh Optical Counterpart of the Neutron Star 1E 1207.4-5209 in PKS 1209-51/52 Superno - Circumstellar Medium Kepler's Supernova Remnant: an Imaging Study of the Blast Wave Daniel Welty at Stony Brook State University of New York GOKlaus Werner GO GORussel White University of California - Berkeley Detecting the hottest white dwarf in a dwarf nova: V446 Her as a laboratory for University of Chicago Ages For Second Parameter Clusters in M33 Main Sequence Turnoff Institut fur Astronomie & Astrophysik Universitat Tubingen, Planet OGLE-TR-56b: The Most Interesting Transiting California Institute of Technology GO GO The Parallax of Geminga deficiency in hot hydrogen-deficient post-AGB sta Iron GO Where is the Local Hot Gas? GO GO Binary Brown Dwarfs: Constraining Formation Scenarios and Ma A Search for Young Abundances, Dust, and Physical Conditions in the LMC ISM Robert WilliamsBrian WoodRosemary Wyse Science Institute Space Telescope Hans Zinnecker University of Colorado at Boulder The Johns Hopkins University Astrophysikalisches Institut Potsdam GO AR Integrated Absorption- and Emission-Line Analysis of Nebulae GO AR Absorption Detections in the HST Archive Searching for Astrospheric Lyman-alpha A NICMOS direct imaging search for giant planets around the seven single wh An astrometric standard field in omega Cen Name Institution Type Title Name Institution Type

 13  CYCLE 12: Approved Observing Programs Jupiter the WFPC2-ACS Link at R=28-60 mag. r summer oung Dynamical Families in the Main Asteroid Belt r Mass Function Mark Lemmon MajeedTariq Jean-Luc Margot A & M Research Foundation Texas William Merline University of Michigan California Institute of Technology Southwest Research Institute GO GO From molecules to aerosols: observing the haze creation process during Titan's pola AR SNAP Binary systems in the Kuiper Belt An Imaging Survey of the Statistical Frequency Binaries Among Exceptionally-Y Using STIS Observations Alpha Line Profiles to Map High-Altitude Winds on of Auroral Lyman Solar System Programs James BellRichard FrenchErich Karkoschka Cornell University College Wellesley University of ArizonaJoel ParkerMark ShowalterWilliam SparksAnne Verbiscer NASA Ames Research Center Southwest Research InstituteHarold Weaver Science Institute Space Telescope Rogier Windhorst The University of Virginia The Johns Hopkins University Arizona State University GO GO GO Spectroscopy and Polarimetry of Mars at Closest Approach The Long-term Observational Record of Uranus' Atmosphere, its Rings, and Satellites: Saturn's rings and small moons on the eve of Cassini GO GO GO Ceres: High-Resolution Mapping and Determination of Physical Properties Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons Lightning on the Jovian Dayside AR GO AR UVBRI Photometry Abundances and the D/H Ratio in Long-Period Comets of Janus and Epimetheus Volatile All-Sky Archival Zodiacal Background Measurements: Constraints to Kuiper Belt Objects Large Programs Fritz BenedictMichael GreggChristopher Kochanek at Austin University of Texas Sangeeta Malhotra Smithsonian Institution Astrophysical Observatory University of California - DavisMatthew Malkan Science Institute Space Telescope Saul PerlmutterAdam Riess University of California - Los AngelesKailash Sahu Lawrence Berkeley National Laboratory GO Science Institute Space Telescope HST Imaging of Gravitational Lenses Science Institute Space Telescope GO SNAP GO GO An Astrometric Calibration of the Cepheid Period-Luminosity Relation The Next Generation Spectral Library GO The Grism-ACS Program for Extragalactic Science (GRAPES) The NICMOS Parallel Observing Program Exploration of the SN Ia Hubble Diagram at z > 1.2 GO GO Ia Supernovae the History of Cosmic Expansion to z~2 with Type Tracing Survey Deep Stella and Very The Galactic Bulge Deep Field: A Planetary Transit Hubble Treasury Programs Hubble Treasury Nicholas ScovilleRodger Thompson California Institute of Technology University of Arizona GO The COSMOS 2-Degree ACS Survey GO Deep Near IR Images in the Chandra Field South Ultra Name Institution Type Title Name Institution Type

 14  Hubble Fellowship Program

Michael Fall, [email protected]

ubble Fellowships are awarded annually to outstanding young scientists engaged in research related to the Hubble mission. The research may be observational—either space-based or ground-based—or theoretical. The Fellowships provide three years of salary and other support at U.S. host institutions of a Fellow’s choice (subject to a Hmaximum of one new Hubble Fellow per institution per year). A selection committee met at the Institute in January 2003 to review about 100 applications for Hubble Fellowships to start in September 2003. The new Fellows are listed in the table below. Hubble Fellows present the results of their research each year at a Hubble Fellows Symposium held at the Institute. The most recent Symposium was held on March 6 and 7, 2003. We plan to select approximately 12 new Hubble Fellows in winter 2003/4 for positions to start in fall 2004. The Announcement of Opportunity, available at http://www.stsci.edu/ stsci/hubblefellow/ao.html, provides instructions for the application process. Ω

2003 New Hubble Fellows

Name Ph.D. Institution Host Institution

Avishay Gal-Yam Tel Aviv, 2003 Caltech Marla Geha Santa Cruz, 2003 Carnegie Jason Harris Santa Cruz, 2000 Arizona Wynn Ho Cornell, 2003 Stanford Marc Kuchner Caltech, 2000 Princeton Darren Madgwick Cambridge, 2002 LBNL Michael Muno MIT, 2002 UCLA Jeffrey Newman Berkeley, 2000 LBNL Nathan Smith Minnesota, 2002 Colorado Tommaso Treu Pisa/STScI, 2001 UCLA Risa Wechsler Santa Cruz, 2001 Chicago Qingjuan Yu Princeton, 2002 Berkeley

The Dumbbell Nebula - M27 n aging star’s last hurrah is creating a flurry of glowing knots of gas that appear to be streaking through space in A this close-up image of the Dumbbell Nebula, taken with NASA's Hubble Space Telescope. The Dumbbell, a nearby planetary nebula residing more than 1,200 light-years away, is the result of an old star that has shed its outer layers in a unique display of color.

Image Credit: NASA and the Hubble Heritage Team (STScI/AURA) Acknowledgment: C.R. O’Dell (Vanderbilt University)

 15  The Local Group: The Universe In A Nutshell

Mario Livio, [email protected]

his year’s May Symposium was on the topic of “The Local Group as an Astrophysical Laboratory.” The Symposium took place May 5-8, 2003, and it attracted about 130 participants. The choice of topic reflected the fact that observations of the Local Group have reached the point where they can provide a closer look at processes characterizing Tthe universe at large. From observations of the cosmic microwave background by the Wilkinson Microwave Anisotropy Probe (WMAP), we know that the energy density of the universe is dominated by ‘dark energy’ (about 73%) and non-baryonic dark matter (about 22%). Originally it was thought that the mass in the halos of galaxies might be dominated by Massive Compact Halo Objects (MACHOs), such as brown dwarfs. Microlensing observations towards the Magellanic Clouds revealed that even in the most optimistic case, MACHOs could not constitute more than 5% of the dark matter in the universe, in agreement with the WMAP results. Furthermore, 4 out of the 17 observed microlensing events, for which additional information about location exists, seem to be due to self lensing by Magellanic Clouds stars rather than by MACHOs. Thus, the fraction of mass in MACHOs could be even much smaller. Structure formation is a second topic to which Local Group observations have contributed and will continue to contribute significantly. Current models indicate that the growth of structure in the universe occurred by hierarchical accretion and merger of dark-matter halos. Since galaxy halos should simply be scaled versions of galaxy clusters, a few hundred satellites should accompany galaxies like the Milky Way. The number observed is only a few tens. This increases the importance of studies of high velocity clouds in the Local Group (as potential satellites) and of processes within galaxies, such as feedback from star formation. At the same time, observations of the halo of M31 reported at the Symposium support the idea of past mergers. These observations reveal the presence of a significant population of stars with ages of 6-8 billion years, in contrast to the halo of the Milky Way, where all the ages are between 11 and 13 billion years. This result suggests that M31 may have undergone a major merger some 6 to 8 billion years ago, which threw younger stars from the disk into the halo. Central black holes are a third topic for which observations within our cosmic backyard are important. Black holes have already been discovered at the centers of many galaxies, and collapse into a black hole may be inevitable at the center of very dense stellar systems. The center of the Milky Way afforded a very special treat at the Symposium, with the report that full orbits have now been determined for a few stars around the Galactic black hole, Sgr A∗. Furthermore, evidence suggests the existence of intermediate-mass (a few thousands to a few tens of thousands solar masses) black holes at the centers of the Galactic globular cluster M15 and the M31 cluster G1. Finally, the Local Group allows a glimpse at star formation in different environments, with different metallicities. Theory suggests that in a hot, metal-free universe, the Initial Mass Function was strongly biased towards massive stars. Starburst regions in the Local Group offer the opportunity to test some of these ideas. Observational and theoretical tools can both now be used on the Local Group to place meaningful constraints on our understanding of the universe. Ω

 16  Advances with ACS

Roeland P. van der Marel, [email protected]

igure 1 provides a spectacular illustration of the powerful capabilities of the Advanced Camera for Surveys (ACS). In a large Cycle 11 program, Tom Brown and collaborators used the Wide Field Channel (WFC) to take deep images of a field in the halo of the Andromeda galaxy (Messier 31). The panels in the figure show cut-outs that each cover about 1% of Fthe total WFC field of view. Each panel shows a stunning combination of Andromeda halo stars and background galaxies. The results of this program provide the deepest image obtained with Hubble to date. Objects are detected to a limiting magnitude of 31 and there are 300,000 stars in a single ACS/WFC field. The color-magnitude diagram of the stars indicates that approximately one-third of the Andromeda halo stars formed only 6 to 8 billion years ago, which is much younger than the 11-to-13 billion-year age of the stars in the Milky Way’s halo. This finding provides important new clues to the formation of galaxy halos (http://hubble.stsci.edu/ newscenter/archive/2003/15/). On Astronomy Day, May 10, the Institute released a beautiful mosaic of the Helix nebula (NGC 7293; see http://hubble.stsci.edu/newscenter/archive/2003/11/) in conjunction with a variety of other outreach activities. ACS obtained the data for this image during the Leonids

Figure 1: Advanced Camera for Surveys images of fields in the halo of the Andromeda galaxy (Messier 31). Each panel covers about 1% of the total field of view of the Wide Field Channel and shows a stunning combination of Andromeda halo stars and background galaxies. Tom Brown and his collaborators are using these data to study the formation of galaxy halos.

meteor shower in November 2002. At that time we pointed Hubble in the anti-radiant direction of the meteor shower to minimize the risk for potential damage to the telescope. The Helix nebula happens to lie close to this anti-radiant direction. This provided an opportunity for a group of Institute staff and astronomical community members to observe the nebula in a non-proprietary campaign. The Hubble Heritage Team used data from a program aimed at calibration Continued of the ACS polarizer filters to create a spectacular image of the Egg page 18 nebula (http://hubble.stsci.edu/newscenter/archive/2003/09).  17  ACS will continue to be a focus of attention in Cycle 12. The Institute Director announced the Advances with ACS from page 17 approved programs in April 2003. They are listed on page 8 in this newsletter. ACS observations again make up more than half the accepted programs. The Treasury program of Scoville and collaborators is of particular interest. These investigators will perform a 2 square degree imaging survey (the Cosmic Evolution Survey—COSMOS) with ACS. The survey will study an equatorial field that is accessible to all ground-based telescopes. The data will be non-proprietary and will be available for use by the entire astronomical community. The Cycle 12 TAC also approved four ACS calibration proposals from the astronomical community. We are looking forward to the results from these programs and the improved understanding that they will provide of the instrument. At the Institute, we are continuing to analyze Cycle 11 ACS calibration data. Sixteen supported modes of the ACS High Resolution Channel (HRC) lie in the wavelength regime below 4000 Å. We have now created improved flat field reference files for these modes. For those filters that do not have significant red leaks, we used observations of the bright Earth (http://www.stsci.edu/hst/acs/documents/isrs/isr0302.pdf). While the bright Earth is a poor flat field source at optical wavelengths because of structure in the cloud cover, it is a uniform source of diffuse light at shorter wavelengths due to the high optical depth above the cloud layer. Observations of Wolf-Rayet stars are useful for the wavelength calibration of the ACS/WFC G800L grism. Dispersion solutions were derived from such data (http://www.stsci.edu/ hst/acs/documents/isrs/isr0301.pdf). The results were incorporated into the extraction software ‘aXe’ (http://www.stecf.org/software/aXe/), which is maintained by the Space Telescope European Coordinating Facility. We completed a variety of checks and tests of ACS. We photometrically verified the stability of the shutters for short exposure times and found that they operate within the pre-launch specifications. We also monitored for a potential decrease of ultraviolet sensitivity due to contamination but found none. Photometry of star fields revealed that the point-spread function (PSF) on WFC shows mild variations over the field of view. We found that this is the result of small spatial variations in the thickness of the detector, which affect the charge diffusion properties of the CCD. John Krist developed a model for this effect and included it in the new release of his PSF modeling software Tiny Tim (http://www.stsci.edu/software/tinytim/). We are now analyzing the first external calibration data taken on ACS to measure the effects of Charge Transfer Efficiency (CTE) degradation on stellar photometry. Preliminary results match expectations. For typical observing backgrounds and stellar fluxes, CTE losses on WFC are typically 1 to 2% far from the readout amplifier and readily correctable. However, in worst-case scenarios—faint sources observed with narrow-band filters—CTE losses can be significantly larger. No measurable CTE effects are seen for the HRC at this time. As for other CCD detectors in space, the CTE of ACS is expected to degrade with time. The advent of the Aft Shroud Cooling System (ASCS) during the next servicing mission should mitigate this degradation. The thermal vacuum testing of the ASCS was just completed successfully at Goddard Space Flight Center. Investigators preparing WFC observations for Cycle 12 should pay particular attention to the anticipated growth of hot pixels (see: http://www.stsci.edu/hst/acs/documents/isrs/isr0209.pdf). Proper dithering strategies are required to correct for hot pixels during data reduction, as described in the most recent ACS newsletter (http://www.stsci.edu/hst/acs/ documents/newsletters/stan0302.html). This newsletter also provides other important information for those preparing Phase II programs. For example, we are now providing full bias calibrations for the non-default gain settings 2 on WFC and 4 on the HRC, in addition to the default settings (1 and 2, respectively). Also, selection of general subarrays will be available in Cycle 12 and, in some cases, supported. In this context, supported means that bias frame calibrations will be supplied by the Institute for a predefined set of subarrays. Many papers on the calibration of ACS, both from Institute staff and members of the astronomical community, can be found in the proceedings of the 2002 HST calibration workshop, which are now available on-line (http://www.stsci.edu/hst/HST_overview/documents/ calworkshop/workshop2002). As always, the latest news about ACS can be found at http://www.stsci.edu/hst/acs/. Ω

 18  JWST Mission Replan

Nino Panagia, [email protected]

purred by a better understanding of the mission costs and available funding, NASA management began an end-to-end examination of the program in November 2002. The ‘replan’ teams involved members from all the development partners and the recently selected Science Working Group (SWG). SOn January 15, the replan teams reported their conclusions to the JWST project manager Phil Sabelhaus and NASA Headquarters (HQ). If the plan is implemented, the greatest savings will be achieved by ESA providing an Ariane V for the launch vehicle. Northrop Grumman Space Technology (NGST) will develop the integration and test system and the flight software and hardware for the observatory instead of NASA. Integration and test of the science instrument module remains a NASA responsibility. NASA will supply the detectors and support electronics for the ESA near infrared spectrograph. All other instrument projects will procure their own detectors and associated electronics. The observatory-level integration and test plan was simplified to provide additional time for the development and delivery of the science instruments. To further reduce risk, the project decided to reduce the effective area of the primary mirror to 25 square meters (down from 29.4 in the original TRW/Ball proposal). The smaller size meets the baseline science requirements and can be achieved with larger but fewer segments (18 instead of 36). For additional savings, the Canadian Space Agency (CSA) contribution of tunable filters cameras was removed from the Near Infrared Camera (NIRCam) and combined with the Fine Guidance System. While this step did not significantly reduce U.S. costs, it simplifies the working arrangements between CSA and other JWST partners and reduces technical risk in the NIRCam. The Mid-Infrared Instrument (MIRI) team proposed reductions in U.S. contributions to the MIRI development by reducing detector and cryocooler development costs and by increasing software contributions from the European team. The replan is on its way to becoming reality. ESA has proposed to provide the Ariane V launcher for JWST. NASA HQ has reviewed the replan and the cumulative savings and has given approval to move forward. Anne Kinney, the director of the Astronomy and Physics Division at NASA HQ, has repeated her endorsement of the basic JWST instrument capabilities (NIRCam, Near Infrared Spectrometer, and MIRI). With these steps, the Project will complete the replanning exercise and prepare for the key reviews that are required before the JWST team can begin detailed design and development planning (Phase B). Ω

News from the Multimission Archive at STScI (MAST)

Paolo Padovani on behalf of the MAST team, [email protected]

n early June 2003, Hubble data archive contains 13.8 terabytes of data in about 312,000 science data sets. The archive ingestion rate set another record in February 2003 at almost I 19 gigabytes per day. The retrieval rate also set a record the same month, reaching almost 60 gigabytes per day. New MAST Search Interface Features We have added three new features to the MAST search interfaces: • Multiple input targets. This feature allows users to search MAST on a list of sky positions or astronomical names, providing a quick and easy way to look for sources having MAST data in an arbitrary catalog. • New preview page for Hubble data. This feature now conforms to the preview pages of other missions by including not only the data preview but also essential information on the observation and the original proposal and Continued links to published papers. page 20  19  • High Level Science Products (HLSP) column. The MAST search output page now has an Mast from page 19 extra column for HLSP, which is for the fully processed images and spectra. A number in this column shows if and how many HLSP related to a given dataset are available and provides links to an HLSP page where one can download the data and access information about them. As usual, send any comments/questions/suggestions/praises you might have to [email protected].

Cycle 12 Treasury, Large, & Legacy Archival (TALL) Programs At the MAST, we are making plans to archive sets of contributed data coming from TALL programs recently awarded time in Cycle 12. As we are doing for the Cycle 11 TALL programs, we will be ingesting into MAST HLSP for these projects as soon as they are made available. The full lists of Cycle 11 and Cycle 12 TALL programs, along with links to the available HLSP and individual program World Wide Web sites, are available at http://archive.stsci.edu/hst/tall.html.

NICMOS Added to the Hubble ‘Pointings’ Interface By now readers should be familiar with the MAST ‘pointings’ interface (http://archive.stsci.edu/cgi-bin/point), a tool that allows users to make advanced searches by position and by ranges of the sky in Galactic latitude, ecliptic latitude, right ascension, and declination to which Hubble has been ‘pointed’. We are pleased to announce that this tool now includes Near Infrared and Multi-Object Spectrometer (NICMOS) data. An example of the queries that are now possible: “How many regions of the sky have been observed at least twice in the J and H band for longer than 1,000 s?” (Answer: 98). Future versions of this tool will include Advanced Camera for Surveys (ACS) data. StarView News We recently released StarView 7.2. Current users of StarView are upgraded automatically through the self-update feature. This version of StarView’s most prominent new feature is the Vizier catalog interface. Vizier is the astronomical catalog system supported by SIMBAD at the Centre de Donnees astronomiques de Strasbourg (CDS). Users can now make queries of any catalog available through Vizier and then search for corresponding Hubble observations. We have also simplified user preferences and enabled a ‘right-click’ option to retrieve specific files. For example, when looking at the reference or On-The-Fly-Reprocessing screen results for a dataset and wanting to retrieve a single reference file, one can now simply ‘right click’ on the name to request that file. Users can also request specific files by their file name directly from the Retrieval window. StarView is also ready to work with the new Hubble data distribution system, which will be opened to the public in late summer or early fall. We have also included a new and improved version of SpecView for spectral data preview exploration. Ingest and Distribution Systems Redesign For the last couple of years, the Institute has been developing a Unix-based replacement for the Data Archive and Distribution System (DADS). As storage and CPU requirements intensified, the Institute also invested in a massive ‘spinning disk’ storage system, an EMC Symmetrix 8830, and a multi-CPU, multi-domain Sunfire 15K server. Once the software solution for DADS retrievals is operational, users will be able to retrieve subsets of the data (e.g., just the raw data or just the calibrated data). They will also have guest privileges for public data, which means that registration will no longer be necessary for non-proprietary data. DADS should work more reliably and faster because it will retrieve most of the basic data from spinning disk rather than jukeboxes of platters. Internally, we will be able to manage queues more sensibly than ‘first-come, first-served’, which is the only mode currently available. MAST to Archive Galaxy Evolution Explorer Data On April 28 the Galaxy Evolution Explorer (GALEX) satellite was successfully launched on a Pegagus XL rocket. Its mission is to survey the whole sky for ultraviolet-bright stars and galaxies to constrain the history of star formation and galaxy evolution back to a redshift of 2. It will also conduct a number of deeper probes over smaller areas. GALEX will provide images and intermediate-resolution spectra of ultraviolet-bright objects in both near- and far-ultraviolet bandpasses. The GALEX Project at JPL (http://www.galex.caltech.edu) will release its data in three stages: an initial (‘samplers’) Data Release 0 (DR-0) in September 2003, a DR-1 perhaps in late summer of 2004, and a DR-2 at the end of the mission, some 29 months after launch. MAST will be the sole host of GALEX data and serve them at the http://archive.stsci.edu/galex. At this writing, the site is populated with a limited amount of simulated data to allow users to  20  become familiar with it. Initially the site will allow the retrieval and browsing of specific data sets, but we expect its primary use to be to permit complex queries (either by point-and-click or Structured Query Language) as well as cross-correlations with Sloan Digital Sky Survey data. By the time of DR-0, we expect to provide the on-line overplotting capability of “ION” (IDL On Line). We look forward to your exercising this system and becoming skillful in manipulating GALEX data in the coming months. Ω

Supernova Shock Wave Paints Cosmic Portrait emnants from a star that exploded thousands of years ago created a celestial abstract portrait, as captured in this NASA Hubble Space Telescope image of the Pencil Nebula. Officially known as NGC R 2736, the Pencil Nebula is part of the huge Vela supernova remnant, located in the southern constellation Vela. Discovered by Sir John Herschel in the 1840s, the nebula's linear appearance triggered its popular name. The nebula's shape suggests that it is part of the supernova shock wave that recently encountered a region of dense gas. It is this interaction that causes the nebula to glow, appearing like a rippled sheet.

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: W. Blair (JHU) and D. Malin (David Malin Images)

 21  Starburst99 & Mappings —A Perfect Match Claus Leitherer, [email protected]

he Starburst99 evolutionary synthesis code (Leitherer et al. 1999) and its associated website at http://www.stsci.edu/science/starburst99/ are premier tools for modeling star-forming regions containing hot massive stars. Evolutionary and population synthesis codes aim to simulate as many observed properties of resolved and Tunresolved stellar populations for a predefined set of input parameters, such as the chemical composition, the star-formation history, and the stellar initial mass function. Starburst99 is one of several synthesis codes developed over the past decade, such as GISSEL (Bruzual & Charlot 1993), SED@ (Cerviño & Mas-Hesse 1994), Dial-A-Model (Worthey 1994), PÉGASE (Fioc & Rocca-Volmerange 1997), Alexandre Vazdekis’ models (Vazdekis 1999), Alberto Buzzoni’s database (Buzzoni 2002), or GALEV (Anders & Fritze-v. Alvensleben 2003), to name a few. Links to these and other models are compiled on the website of IAU Commission 35, Stellar Constitution, at http://iau-c35.stsci.edu. The concept of evolutionary synthesis dates back to an influential paper by Tinsley (1968), who pioneered the field of utilizing and testing the predictive power of stellar evolution and atmosphere models.

Figure 1: Starburst99 portal. The link to the new Mappings interface is highlighted in red.

Starburst99 is an ongoing effort at the Institute and owes its capabilities to the contributions of numerous undergraduate and graduate students, postdocs, and collaborators. Its main focus is on hot, massive stars and their main observables. While Starburst99 is a stellar and not a nebular code, there is strong interest in predicting nebular star-formation tracers as well. Star-formation indicators such as the Hα luminosity of HII regions are widely used as a proxy for the emitted stellar light at far-ultraviolet (far UV) wavelengths (Kennicutt 1998). Predictions for nebular recombination lines are, of course, trivial and are included in the standard Starburst99 application. Modeling non-recombination lines, such as collisionally excited [OIII] 5007 Å is outside the scope of Starburst99 and can only be accomplished in combination with photoionization codes. Stasi´nska & Leitherer (1996) made a first attempt in linking Starburst99 to the photoionization code PHOTO. Comparison between predicted and observed emission-line strengths in a sample of HII galaxies suggested ionizing stellar populations with a mass spectrum with close to a Salpeter (1955) slope. Kewley et al. (2001) fed Starburst99 into the Mappings code and pointed out shortcomings of current stellar models when the ionizing radiation field is tested in HII regions. Such tests are particularly revealing when the stellar content is known independently, e.g., from UV spectroscopy. Leitherer et al. (2001) and Robert et al. (2002) discussed how the

 22  strength and in particular the blueshift of the UV stellar-wind lines can be used to infer the age and mass spectrum of the ionizing stellar population. The underlying physical mechanism is the tight relation between stellar-wind properties (i.e., the line shape and velocity) and luminosity, which is an immediate consequence of a radiatively driven wind. This method has become the standard tool to study stellar populations in the UV (Leitherer 1998). Applying this technique and using the CLOUDY code to model the nebular lines, González Delgado et al. (2002) discussed the potential of simultaneous nebular and stellar modeling and identified areas requiring improvement. We felt the time was finally ripe for developing a simple, robust, and astrophysically sound interface between Starburst99 and a major photoionization code. We opted for Mappings (Sutherland & Dopita 1993), both for physical and practical reasons. Mappings accounts for thermal and non-thermal (shock) energy input, eventually allowing us to link the stellar wind and supernova energy release predicted by Starburst99 with the Mappings shock modeling. On the practical side, a lot of preparatory work had already been done in Lisa Kewley’s thesis, thereby minimizing our effort spent on designing the interface code. Alternatively, Gary Ferland’s widely used CLOUDY photoionization code (Ferland et al. 1998) would be an excellent match for Starburst99. Starburst99 and Mappings are mature, independent codes. Therefore we decided to leave the codes on their existing servers at the Institute and CfA and design an interface that would provide an automatic file transfer between the two domains at http://www.stsci.edu and http://www.-cfa.harvard.edu. A new button was added to the familiar Starburst99 portal at the Institute, giving access to the new interface (see Figure 1). The link leads to the new Mappings portal, where the user can specify the model parameters from the input page (Figure 2). This initiates the calculation of a stellar spectral energy distribution with the Starburst99 code at the Institute. Upon completion, the Starburst99 output is automatically transferred to the Mappings

Figure 2: Mappings input page. The user can interactively specify a wide range of stellar, nebular, and dust parameters. server at CfA and a photoionization model is initialized. Once finished, the Continued photoionization output is returned to the Institute by ftp, and an email page 24 notification is sent to the user. The destination directory at the Institute

 23  contains both the nebular output from Mappings and the stellar spectra from Starburst99. While Starburst99 from page 23 this may sound quite complicated, users do not have to worry about the file transfer between the Institute and CfA. This process occurs entirely behind the scenes. All that needs to be done is to specify the input parameters and wait for an email notification. The Starburst99-Mappings interface became fully operational in December 2002 and has since been widely used by us and by the community at large. An application is shown in Figure 3, where Dopita et al. (2000) computed a grid of diagnostic line ratios to constrain abundances and ionization parameters in HII regions. Those particular calculations made use of older, unblanketed Wolf-Rayet model atmospheres by Schmutz et al. (1992), which produced an overly hard ionizing radiation field for metal-rich Figure 3: Diagnostic plot of [OIII]/Hb vs. [NII]/Ha. stellar populations. In the meantime, a Instantaneous zero-age starburst models computed with new set of fully blanketed models has Starburst99-Mappings. The theoretical grids of ionization parameter and chemical abundance are shown as well become available and was implemented (Dopita et al. 2000). into Starburst99 (Smith et al. 2002). With this upgrade, Starburst99 uses the most advanced stellar model atmospheres currently available for massive, hot stars. We are particularly excited about the prospects of using Starburst99- Mappings for the interpretation of infrared spectra of dust-embedded starbursts that will be provided by the upcoming SIRTF mission. Ω

Acknowledgements Julia Chen’s expertise in developing the Starburst99™-Mappings interface is deeply appreciated. My collaborator Lisa Kewley supported the back-end work at CfA and provided expert advice on issues related to photoionization modeling. We are grateful to the Institute computer support, whose friendly staff helped us overcome numerous roadblocks. This work was made possible by funding from the Director’s Discretionary Research Fund.

References Anders, P., & Fritze-v. Alvensleben, U. 2003, A&A, 401, 1063 Leitherer, C., Leão, J. R. S., Heckman, T. M., Lennon, D. Bruzual A, G., & Charlot, S. 1993, ApJ, 405, 538 J., Pettini, M., & Robert, C. 2001, ApJ, 550, 724 Buzzoni, A. 2002, AJ, 123, 1188 Leitherer, C., Schaerer, D., Goldader, J. D., González Cerviño, M., & Mas-Hesse, J. M. 1994, A&A, 284, 749 Delgado, R. M., Robert, C., Foo Kune, D., de Mello, D. Dopita, M. A., Groves, B. A., Sutherland, R. S., & Kewley, F., Devost, D., & Heckman, T. M. 1999, ApJS, 123, 3 L. J. 2003, ApJ, 583, 727 Robert, C., Pellerin, A., Aloisi, A., Leitherer, C., Hoopes, Dopita, M. A., Kewley, L. J., Heisler, C. A., & Sutherland, C., & Heckman, T. M. 2003, ApJS, 144, 21 R. S. 2000, ApJ, 542, 224 Salpeter, E. E. 1955, ApJ, 121, 161 Ferland, G. J., Korista, K. T., Verner, D. A., Ferguson, J. Schmutz, W., Leitherer, C., & Gruenwald, R. 1992, PASP, W., Kingdon, J. B., & Verner, E. M. 1998, PASP, 110, 761 104, 1164 Fioc, M., & Rocca-Volmerange, B. 1997, A&A, 326, 950 Smith, L. J., Norris, R. P. F., & Crowther, P. A. 2002, González Delgado, R. M., Leitherer, C., Stasi´nska, G., & MNRAS, 337, 1309 Heckman, T. M. 2002, ApJ, 580, 824 Stasi´nska, G., & Leitherer, C. 1996, ApJS, 107, 427 Kennicutt, R. C. 1998, ARA&A, 36, 189 Sutherland, R. S., & Dopita, M. A. 1993, ApJS, 88, 253 Kewley, L. J., Dopita, M. A., Sutherland, R. S., Heisler, Tinsley, B. 1968, ApJ, 151, 547 C. A., & Trevena, J. 2001, ApJ, 556, 121 Vazdekis, A. 1999, ApJ, 513, 224 Leitherer, C. 1998, in Stellar Astrophysics for the Local Worthey, G. 1994, ApJS, 95, 107 Group: VIII Canary Islands Winter School of Astrophysics, ed. A. Aparicio, A. Herrero, & F. Sanchez (Cambridge: CUP), 527  24  A Surprise from the Andromeda Halo Thomas Brown, [email protected]

ur textbook concept of giant spiral galaxies is largely driven by our own Milky Way, which has an old1, metal-poor2 halo of stars, and a younger3, chemically-enriched4 stellar disk. However, within the Local Group of galaxies, the Andromeda galaxy offers an important contrast to this picture. Although it is of similar size and Hubble type to Othe Milky Way, its halo population has a relatively high metallicity5, as indicated by the colors of its bright red giant stars. These stars offer a good indication of the halo's metallicity, but they tell us little about its age distribution. Thus, without better evidence, the Andromeda halo was assumed to be an old population that underwent more rapid chemical enrichment than the halo of the Milky Way. Accurate ages for stellar populations come from photometry reaching the subgiant branch and main sequence, but these fainter stars have always been beyond the reach of both space-based and ground-based telescopes. However, with the installation of the Advanced Camera for Surveys (ACS) in 2002, we can now resolve these stars in an observing program of reasonable duration. Early in the proposal process, we realized that a detailed observing strategy would be critical to the success of this project. We first considered the required exposure depth. Some team members wanted to resolve stars two magnitudes below an old main sequence turnoff, because that is the level used historically to determine accurate ages in Galactic globular clusters. The halo population of a giant galaxy would be more complicated than that of a globular cluster (where all the stars are the same age and chemical composition), so it made sense that one would want photometry at least as deep as that used to study star clusters. However, the hundreds of Hubble orbits needed to reach that depth seemed unreasonable, even for a scientific goal we felt to be very important. Instead, we chose a goal of 1.5 mag below the turnoff and decided that a large sample of stars could compensate for depth. While accurate photometry requires that images have no more than one star per tens of resolution elements, with the large ACS format we could still comfortably include hundreds of thousands of stars in our halo images. Figure 1: A 25.5 by 36.4 arcsecond subsection of an ACS image We produced artificial ACS images realistically simulating a showing distant background galaxies through the Andromeda halo. broad range of conditions: the effects of the Hubble point-spread function, sky background, detector noise, and various stellar population mixes. From these simulations, we found the level of crowding where we could blindly recover our input population from the photometry. This level of crowding defined a limiting elliptical annulus around Andromeda. We then picked a field along the southeast minor axis within this annulus that also included the globular cluster GC312, thus enabling a secondary goal of studying the age of Andromeda's halo relative to that of one of its clusters. A review of previous Hubble imaging of the chosen field6 ensured accurate predictions of the crowding. Because we were concerned about the systematic errors that might be introduced by

1 VandenBerg, D.A., 2000, ApJS, 129, 315 2 Ryan, S.G., & Norris, J.E. 1991, AJ, 101, 1865 3 Fontaine, G., Brassard, P., & Bergeron, P. 2001, PASP, 113, 409 4 Soubiran, C., Bienaymé, O., & Siebert, A. 2003, A&A, 398, 141

5 Mould, J., & Kristian, J. 1986, ApJ, 305, 591 Continued 6 Holland, S., Fahlman, G.G., & Richer, H.B. 1996, AJ, 112, 1035 page 26  25  using a new Hubble camera, we included images of five Galactic globular clusters with the same Andromedea Halo from page 25 ACS filters in order to produce empirical isochrones of old stellar populations, and to calibrate the theoretical isochrones, which could be used to model younger populations. The observations of our Galactic clusters were scattered over the second half of 2002, while the main program in Andromeda executed from 2 Dec 2002 to 11 Jan 2003, obtaining 250 exposures with a total integration time of 3.5 days. The final drizzled images are beautiful (Figure 1), showing thousands of background galaxies through a veil of ~300,000 stars in the halo of Andromeda. The big surprise came from comparisons of our Andromeda color-magnitude diagram to those of the clusters. These show that the Andromeda halo population spans a wide range in both metallicity and age (Figure 2). The metal-poor stars Andromeda are about as old as the stars in M92 (13 Gyr), but those at higher metallicity in Andromeda are younger than those in the clusters. The age spread is indicated by the subgiant branch and main sequence turnoff, which are increasingly brighter in Andromeda than those in the clusters as one moves to higher metallicity. To quantify this further, we used the cluster data to calibrate a library of isochrones7 in the Hubble bandpasses and then fit Figure 2. Left panel: The color-magnitude diagram of the Andromeda halo as observed with the the Andromeda data using the ACS. Completeness limits are marked (the data are 50% complete at Johnson V = 30.7 mag). StarFish code8. This code takes Right panel: Comparison to the ridge lines of five Galactic globular clusters shows that the metal-rich the isochrones, scatters them to populations in Andromeda are significantly younger than those in the clusters. match the photometric errors in the data, and then tries to reproduce the data using a linear combination of the isochrones. We find that no combination of old isochrones (11.5 to 13.5 Gyr) can reproduce the Andromeda data. Instead, a wide range in age (6 to 13.5 Gyr) is required. The best-fit model puts approximately 30% of the Andromeda halo at young ages (6 to 8 Gyr) and high metallicity ([Fe/H] > -0.5). Because the gas in a young giant galaxy rapidly falls into the disk, it seems very unlikely that this newly revealed intermediate-age population can be explained by star formation continuing unassisted in the halo for more than 6 Gyr. A more plausible explanation is a merger with a large satellite galaxy when the universe was approximately half of its present age—or a series of mergers with smaller satellites. The resulting halo would be a mix of stars originally formed in the halo, disrupted disk stars, disrupted satellite stars, and stars formed during the merger(s). It remains to be seen whether halos typically form in a relatively quiescent process, like that in our own Galaxy, or a violent one, like that in Andromeda. Ω

7 VandenBerg, D.A., & Clem, J.L. 2003, AJ, in press. 8 Harris, J., & Zaritsky, D. 2001, ApJS, 136, 25  26  The Omega Nebula esembling the fury of a raging sea, this image actually shows a bubbly ocean of glowing hydrogen gas and small amounts of R other elements such as oxygen and sulfur. The photograph, taken by NASA's Hubble Space Telescope, captures a small region within M17, a hotbed of star formation. M17, also known as the Omega or Swan Nebula, is located about 5,500 light-years away in the constellation Sagittarius.

Credit: NASA, ESA and J. Hester (ASU)

Contact STScI:

The Institute’s website is: http://www.stsci.edu Assistance is available at [email protected] or 800-544-8125. International callers can use 1-410-338-1082. For current Hubble users, program information is available at: ST-ECF http://presto.stsci.edu/public/propinfo.html. The current members of the Space Telescope Users Committee (STUC) are: Newsletter Debbie Elmegreen (chair), Vassar College, [email protected] he Space Telescope - European Coordinating Facility Debbie Elmegreen, (CHAIR) Karen Meech, Institute for publishes a newsletter which, although aimed Vassar College Astronomy principally at European Space Telescope users, contains David Axon, U. of Hertfordshire Peter Nugent, Lawrence Berkeley articles of general interest to the HST community. If Marc Davis, U.C. Berkeley Laboratory you wish to be included in the mailing list, please James Dunlop, U. Edinburgh Karl Stapelfeldt, JPL Tcontact the editor and state your affiliation and specific Martin Elvis, Harvard-Smithsonian John Stocke, U. Colorado involvement in the Space Telescope Project. Holland Ford, JHU Lisa Storrie-Lombardi, Caltech Richard Hook (Editor) The Space Telescope Science Institute Newsletter is edited by Robert Brown, [email protected], who invites comments and suggestions. Space Telescope - Technical Lead: Christian Lallo, [email protected] European Coordinating Facility Design: Krista Wildt, [email protected] Karl Schwarzschild Str. 2 D-85748 Garching bei München To record a change of address or to request receipt of the Newsletter, Germany please send a message to [email protected]. E-Mail: [email protected]

 27  Contents: Calendar Cycle 12 Cycle 12 Results ...... 1 JWST Science Working Group at the Institute ...... October 1-2, 2003 Cycle 12: TAC and Panel Members ...... 5 Cycle 12: Statistics ...... 6 STUC at Institute ...... November 6-7, 2003 Cycle 12: Approved Observing Programs ...... 8

Institute News Director’s Perspective ...... 2 Hubble Fellowship Program ...... 15 The Local Group: The Universe in a Nutshell ...... 16 Advances with ACS ...... 17 JWST Mission Replan ...... 19 MAST News at STScI ...... 19

Institute Science Starburst99 & Mappings—A Perfect Match ...... 22 A Surprise from the Andromeda Halo ...... 25

Contact STScI ...... 27 Calendar ...... 28

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