DTIC ADA387690: University of Hawaii Institute for Astronomy

18 Pages·0.35 MB·English

by  Defense Technical Information Center

UniversityofHawaii
InstituteforAstronomy
Honolulu,Hawaii96822
This report covers the period from 1 October 1999 VisitingcolleaguesincludedMarceloEmilio,MiwaGo-
through 30 September 2000, and was compiled in October to,OlivierGuyon,MasatoshiImanishi,RolandMeier,Be´ren-
2000. ge`reParise,andBradfordSmith.
1 Introduction 2.1 NewFaculty
The Institute for Astronomy (IfA) is the astronomical In June 2000, the University of Hawaii Board of Re-
research organization of the University of Hawaii (UH). Its gents appointed Rolf-Peter Kudritzki director of the IfA be-
headquarters is located in Honolulu on the island of Oahu ginninginOctober2000. Atthetimeofhisappointment,he
near the University of Hawaii at Manoa, the main UH cam- was professor of astronomy and director of the Institut fu¨r
pus.TheIfAisresponsibleforadministeringandmaintaining AstronomieundAstrophysik(UniversityObservatory)atthe
theinfrastructureforHaleakalaObservatoriesontheislandof UniversityofMunich.
MauiandforMaunaKeaObservatories(MKO)ontheisland Haosheng Lin was appointed to an assistant astronomer
ofHawaii. position.Hehasconsiderableexpertiseininstrumentationfor
More information is available at the Institute’s World solarastronomy,andheplanstocontinuehisworkoninfrared
WideWebsite: http://www.ifa.hawaii.edu/. measurements of solar magnetic fields and precise measure-
ments of the solar cycle. He came to the IfA from the Na-
2 Staff
tional Solar Observatory/Sacramento Peak in Sunspot, New
Thescientificstaffduringthisreportperiodconsistedof Mexico, where he held the position of assistant astronomer.
Joshua E. Barnes, Ann M. Boesgaard, Wolfgang Brandner, He is based in Waiakoa on Maui and is also working at the
Douglas Burke, Kenneth C. Chambers, Antoinette Songaila MeesSolarObservatoryonHaleakala.
Cowie,LennoxL.Cowie,HaraldEbeling,IsabellaM.Gioia, EduardoMart´ınwasappointedtoanassistantastronomer
J. Elon Graves, Donald N. B. Hall, James N. Heasley, J. position. His areas of research are brown dwarfs and low-
PatrickHenry,GeorgeH.Herbig,Klaus-WernerHodapp,Es- massstars. HejoinedtheIfAaftercompletingapostdoctoral
therM.Hu,DavidC.Jewitt,RobertD.Joseph,NickKaiser, fellowshipattheCaliforniaInstituteofTechnology.
Richard Knabb, John Kormendy, Jeffrey R. Kuhn, Barry J. Szapudi was appointed to an assistant astronomer posi-
LaBonte, Jing Li, Haosheng Lin, Gerard A. Luppino, Eu- tion. Acosmologist,hecomestotheIfAfromtheCanadian
gene A. Magnier, Eduardo L. Mart´ın, Robert A. McLaren InstituteofTheoreticalPhysicsattheUniversityofToronto,
(InterimDirector),KarenJ.Meech,DonaldL.Mickey,Mal- Canada,wherehehasheldthepositionofseniorresearchas-
colmJ.Northcott,TobiasC.Owen,AndrewJ.Pickles,Nara- sociate. HeisexpectedtoarriveattheIfAinJanuary2001.
yanS.Raja,JohnT.Rayner,PuiHinW.Rhoads,A.Kathleen
2.2 HonorsandAwardsReceived
Robertson,ClaudeRoddier,Franc¸oisJ.H.Roddier,DavidB.
Sanders, Theodore Simon, Alan Stockton, David J. Tholen, SanderswontheHumboltResearchAwardforSeniorUS
AlanT.Tokunaga,JohnL.Tonry,R.BrentTully,WilliamD. Scientists. F.RoddierwontheUHBoardofRegents’Medal
Vacca,RichardJ.Wainscoat,andGarethWynn-Williams. for Excellence in Research for his work in adaptive optics.
PostdoctoralfellowsincludedHerve´Aussel(JamesClerk Chambers won the UH Board of Regents’ Medal for Excel-
MaxwellFellow), AmyBarger(Hubblefellow), PierreBau- lenceinTeaching.
doz, Nicholas Biver (James Clerk Maxwell Fellow until 30
3 MaunaKeaObservatories
June 2000), Yanga R. Fernandez, Renate Kupke, Jana Pitti-
chova(NATO-NSFPostdoctoralFellow),andGillianWilson Thetelescopesinoperationduringthereportperiodwere
(ParrentFellow). theUH2.2mand0.6mtelescopes; the3mNASAInfrared
Thefollowingstudentscompletedtherequirementsfora Telescope Facility (IRTF), operated by the UH under a con-
Ph.D.: GabrielaCanalizo,Ha˚konDahle,JamesDeane,Alex tractwithNASA;the3.6mCanada-France-HawaiiTelescope
Stephens,ChadwickTrujillo,andRobertWhiteley. (CFHT), operated by the Canada-France-Hawaii Telescope
Theothergraduatestudentsduringthereportperiodwere Corporation on behalf of the National Research Council of
James Armstrong, Elizabeth Barrett, Brian Barris, James Canada,theCentreNationaldelaRechercheScientifiqueof
Bauer, George Bendo, Peter Capak, Michael Connelley, France, and UH; the 3.8 m United Kingdom Infrared Tele-
Michael Cushing, Scott Dahm, David Donovan, Eliza Ful- scope (UKIRT), operated in Hawaii by the Joint Astronomy
ton,CyrusHall,CatherineIshida,KevinJim,DaleKocevski, Centre(JAC)basedinHiloonbehalfoftheParticlePhysics
Christopher Mullis, Michael Nassir, Megan Novicki, Daniel and Astronomy Research Council of the United Kingdom;
Potter, Barry Rothberg, Robert Thornton, Scott Sheppard, the15mJamesClerkMaxwellTelescope(JCMT),asubmil-
andWei-HaoWang. limetertelescopeoperatedbytheJAConbehalfoftheUnited
1
Form SF298 Citation Data
Report Date
Report Type Dates Covered (from... to)
("DD MON YYYY")
N/A ("DD MON YYYY")
00JAN2001
Title and Subtitle Contract or Grant Number
University of Hawaii Institute for Astronomy
Program Element Number
Authors Project Number
Task Number
Work Unit Number
Performing Organization Name(s) and Address(es) Performing Organization
University of Hawaii Institute for Astronomy Honolulu, Hawaii Number(s)
96822
Sponsoring/Monitoring Agency Name(s) and Address(es) Monitoring Agency Acronym
Monitoring Agency Report
Number(s)
Distribution/Availability Statement
Approved for public release, distribution unlimited
Supplementary Notes
Abstract
The Institute for Astronomy (IfA) is the astronomical research organization of the University of Hawaii
(UH). Its headquarters is located in Honolulu on the island of Oahu near the University of Hawaii at
Manoa, the main UH cam-pus. The IfA is responsible for administering and maintaining the infrastructure
for Haleakala Observatories on the island of Maui and for Mauna Kea Observatories (MKO) on the island
of Hawaii. More information is available at the Institutes World Wide Web site:
http://www.ifa.hawaii.edu/. In June 2000, the University of Hawaii Board of Re-gents appointed
Rolf-Peter Kudritzki director of the IfA be-ginning in October 2000. At the time of his appointment, he
was professor of astronomy and director of the Institut f ¨ ur Astronomie und Astrophysik (University
Observatory) at the University of Munich. Haosheng Lin was appointed to an assistant astronomer
position. He has considerable expertise in instrumentation for solar astronomy, and he plans to continue
his work on infrared measurements of solar magnetic fields and precise measure-ments
Subject Terms
Document Classification Classification of SF298
unclassified unclassified
Classification of Abstract Limitation of Abstract
unclassified unlimited
Number of Pages
16
Kingdom, Canada, and the Netherlands; the 10.4 m Caltech 3.2 IfAHiloFacilityandInfrastructure
SubmillimeterObservatory(CSO),operatedbytheCalifornia The35,000squarefoot(3300m2)IfAHiloFacility,com-
InstituteofTechnologyfortheNationalScienceFoundation
pleted during the summer, provides a state-of-the-art opera-
(NSF);theHawaiiantennaoftheVeryLongBaselineArray
tions base for the IfA’s activities on Mauna Kea, plus long-
(VLBA),operatedbytheNationalRadioAstronomyObser-
awaited expansion space for our research, instrumentation,
vatory (NRAO); the 10 m Keck I and Keck II telescopes of
teaching, and outreach programs. The facility is equipped
the W. M. Keck Observatory, which is operated by the Cal-
with a high-bandwidth fiber-optics link to the other base fa-
ifornia Association for Research in Astronomy for the use
cilitiesintheUHHiloUniversityParkandtothetelescopes
of astronomers from the California Institute of Technology,
on Mauna Kea for remote observing. Our Hilo-based staff
theUniversityofCaliforniasystem,NASA,andUH;the8.3
(about 30 people) moved into the new building during Au-
mSubaruTelescope,operatedbytheNationalAstronomical
gustandSeptember.
Observatory of Japan (NAOJ); and the 8.1 m Gemini North
TheMKOconnectiontotheInternethasbeenupgraded
Telescope,builtbyaninternationalpartnershipandmanaged to DS-3 capacity (45 Mbits s−1) with funding provided by
bytheAssociationofUniversitiesforResearchinAstronomy.
theNSF.Thelocalareanetworklinkingtheobservatoriesto
Construction continued on the Submillimeter Array
each other and to the base facilities has been converted to
(SMA),acollaborativeprojectoftheSmithsonianAstrophys-
asynchronoustransfermode(ATM)technology.
ical Observatory and the Institute of Astronomy and Astro-
physicsoftheAcademiaSinicaofTaiwan. 4 HALEAKALAOBSERVATORIES
3.1 MaunaKeaMasterPlan The administrative staff consisted of M. Maberry, D.
O’Gara,K.Rhoden,K.Kimura,andJ.Perreira,andthetech-
InJune,theUHBoardofRegentsapprovedanewMaster
nical staff included E. Olson, M. Waterson, R. Coulter, G.
PlanfortheUH-managedlandsonMaunaKea.Thenewplan
Nitta,J.Frey,C.Foreman,L.Hieda,B.Lindsey,K.Ventura,
provides guidelines for astronomy development for the next
andJ.Kamibayashi.
20yearsandintroducesanewmanagementstructure.
Allfuturedevelopmentwillbelocatedwithina525acre 4.1 MeesSolarObservatory
(213 hectare) Astronomy Precinct, leaving the surrounding
Mees Solar Observatory supports IfA solar scientists in
10,760 acres (4,358 hectares) as a natural and cultural pre-
data acquisition by running diverse observational programs
serve. The guidelines prohibit development on currently
with its telescope cluster. The observatory regularly co-
undisturbed cinder cones and require facility designers to
observes with the satellites Yohkoh, Solar and Heliospheric
minimize environmental impact, including visual impact.
Observatory (SOHO), and Transition Region and Coronal
Projectsforeseenthroughtheyear2020are(1)anextgenera-
Explorer (TRACE), and also participates in special satellite
tionoptical/IRtelescopeinthe25–50mrange,(2)renovation
andground-basedobservatorycampaigns. Oneoftheunique
orreplacementofuptofiveoftheolderexistingfacilities,(3)
observational capabilities at Mees is the ability to perform
expansion of the W. M. Keck Observatory with the addition
measurementsofthetemporalevolutionofphotosphericvec-
offourtosix1.8moutriggertelescopes,(4)expansionofthe
tor magnetic fields. The observatory’s complement of in-
Submillimeter Array with the addition of up to 12 more an-
strumentsincludestheImagingVectorMagnetograph(IVM),
tennas (for a total of 24), (5) one new telescope in the 4–12
Haleakala Stokes Polarimeter, Mees CCD Imaging Spectro-
mrangeatacurrentlyunusedsite,and(6)a1minstructional
graph (MCCD), Mees White Light Telescope, and Coronal
telescope.
LimbImagers.
The plan establishes a new Office of Mauna Kea Man-
Active instrumentation projects include adding rapid
agement, located at the University of Hawaii at Hilo. The
wavelength selection to the IVM to permit sequential pho-
officewillhaveadirectorreportingtotheUHHilochancel-
tospheric and chromospheric magnetic observations, and a
lor,supportstaff,andateamofguideswhowillworkonthe
new CCD camera and data system for the MCCD for high-
mountain.AlsoincludedintheplanisaMaunaKeaManage-
speed spectral imaging in collaboration with the upcoming
ment Board representing the various stakeholder constituen-
High Energy Solar Spectroscopic Imager (HESSI), a Small
cies. Thisseven-personboardwillhaveanoversightrolefor
ExplorerProgam(SMEX)mission.
allactivitiesonMaunaKea. Itwillserveastheinterfacebe-
tweentheUHandthecommunity,anditwillprovidepolicy 4.2 LUREObservatory
guidance to the Management Office. Finally, the plan calls
LURE is a satellite laser ranging (SLR) observatory.
for a panel of Hawaiian elders, the Kahu Kupuna Council,
LUREutilizesahigh-poweredpulsedlasertoobtaindistance
to provide policy recommendations and advice on Hawaiian
measurements to satellites in Earth orbit. LURE is funded
culturalmatters.
bytheSpaceGeodesyNetworksandSensorCalibrationOf-
ThenewMasterPlanistheproductoftwoyearsofhard
fice of NASA Goddard Space Flight Center. The missions
work by a great many people. There is much more work to
of the target satellites include monitoring of Earth resources
be done in the implementation phase. With this plan as a
and climate parameters, measurements of ocean levels and
framework,andwithacontinuedspiritofcooperation,itwill
temperatures,platetectonics,theimprovementoftheGlobal
be possible to balance the interests of all for whom Mauna
PositioningSystem(GPS),aswellasspecialmissionsrelated
Keaissoprecious.
to the physics of tethered satellite systems. LURE provides
2
rangedatatoNASA7daysaweek,andimprovementstothe willbetheLiverpoolTelescope,scheduledtobecomeopera-
computersystemandtotheoperationalprocedureswillsoon tionalintheCanaryIslandsinOctober2000.
allowLUREtooperateona24hourschedule. TheinitialinstrumentontheFaulkesTelescopewillbea
state-of-the-artCCDcamera.TheIfAplanstoaddaninfrared
4.3 AEOS-HaleakalaAtmosphericCharacterization
camera to the instrument complement shortly after the tele-
Project
scope is commissioned. This will allow for daytime obser-
Haleakala Observatories is under contract to the Air vationsbyschoolsinHawaii. Thecontrolsystemwillallow
Force Research Laboratories to conduct a research program observations to be made both interactively over the Internet
known as the AEOS-Haleakala Atmospheric Characteriza- orbyqueuedroboticoperation.
tion(AHAC).ThisprogramsupportstheU.S.AirForceAd- The Faulkes Telescope Project will draw upon the great
vanced Electro-Optical System (AEOS) Telescope on Hale- public interest in astronomy to teach students what science
akalabyprovidingcomprehensiveatmosphericcharacteriza- is. Astronomers in Hawaii and the United Kingdom plan to
tionandtimelypredictionofinclementweatherconditionsat engagestudentsinresearchprojectsthatwillbepublishedin
theobservatorysite. Theinstrumentsuitethatsupportsthese thescientificliterature. Theywillencouragejointprojectsin
site measurements includes a daytime/nighttime optical see- which students will collaborate over the Internet with their
ingmonitorandanetworkofremotemeteorologicalsystems counterpartshalfwayaroundtheworld.
linkedbyradiomodems. Theopticalseeingmonitorcaptures
4.6 Solar-C
star image data at high frame rates and uses a differential
image motion technique to allow the computation of seeing TheSolar-Cinstrumentisa0.5moff-axiscoronagraphic
statistics over intervals of a few seconds. Data from the re- reflecting telescope being built on Haleakala adjacent to the
mote meteorology stations are processed using an artificial MeesSolarObservatory. Thisinstrumentwill(1)allowcoro-
intelligence program to generate locally specific predictions nalobservationsthathavenotbeenrealized,evenfromspace,
ofadverseweathereventsonatimehorizonof30min. (2) develop technology that IfA scientists believe will be
usedforfuturesatelliteobservations,and(3)supportseveral
4.4 MAGNUMTelescopeProject
long-term coronal observing platforms that extend intermit-
The2mMulti-colorActiveGalacticNucleiMonitoring tentcoronalspaceobservations.Unlikemosttelescopes,light
(MAGNUM)Telescopeisdedicatedtostudyingthevariation strikes the Solar-C mirrors off-axis, at an angle to their sur-
oflightfromactivegalacticnuclei(AGNs). Theprojectisa faces. No light is blocked, reflected, scattered, or diffracted
collaboration between the University of Tokyo and the Uni- bythemirrorsortheirsupportstructureasidefromthesuper-
versity of Hawaii. The main scientific objective of MAG- polishedopticalsurfaces.
NUM is to measure distances to AGNs and quasars up to The mechanical components of the Solar-C instrument
z =1. Thetelescopeisdesignedtobeoperatedremotelyand havebeenfabricated. Theoff-axissecondarymirroriscom-
to conduct observations autonomously. The main scientific pleted, and as of fall 2000 the project awaits final polish of
instrument is a two-detector camera that can obtain images theprimarymirror.
from 0.3 to 3.4 µm. The telescope is in the final phase of
5 Instrumentation
commissioning.
5.1 AdaptiveOptics
4.5 FaulkesTelescope
The UH 36-element curvature sensing adaptive optics
On 26 June 1999, the UH-IfA and the Faulkes Tele-
system, Ho¯ku¯pa‘a, had its second commissioning run at the
scope Corporation signed a Memorandum of Understanding
Gemini North Telescope in March 2000; Ho¯ku¯pa‘a utilizes
to locate a 2 m telescope at Haleakala Observatories. This
theUHnear-infraredcamera,QUIRC.InJune2000,theopti-
professional-grade telescope will be the largest in the world
caldesignwasmodifiedtoallowdithering,andanewlenslet
dedicatedtoastronomicaleducation. Accesstothetelescope (cid:4)(cid:4)
array with a larger field of view (4 ) was installed. Also,
inHawaiiwillbeavailabletopublicandprivateschoolsand
as a part of UH graduate student D. Potter’s thesis, a Wol-
tothescienceprogramsoftheUHsystemandothercolleges
laston prism for high-contrast detection of polarized emis-
anduniversities.
sion was implemented on Ho¯ku¯pa‘a. Two observing runs
Thetelescope’sconstructionwillbefinancedbytheDill
in June/July and July/August that were part of the Gemini
Faulkes Educational Trust of the United Kingdom and will
DemonstrationScienceprogramobservedtheGalacticcenter.
benamedinhonorofDr. Martin“Dill”Faulkes,thefounder
The Gemini QuickStart science observations with Ho¯ku¯pa‘a
ofthetrust. Planscallforhavingtheinstrumentoperational
began in September 2000. A total of six science runs with
in 2002. The telescope will be housed in a state-of-the-art Ho¯ku¯pa‘aatGeminiwerescheduledfortheyear2000(∼5–
facilitywithanenclosurethatwillopenlikeaclamshelland
12nights/monthafterJuly).
that will be capable of exposing the entire telescope to the
Observations in the first half of 2000 were hampered
nightsky.
by the worse-than-average weather conditions in the Pacific
The Faulkes Telescope will be the third in a series of 2
basinduetothefadingLaNin˜aphenomenon. Nightlyprob-
m telescopes being constructed by Telescope Technologies
lems with telescope operations, as well as various problems
Limited in Birkenhead, Merseyside, in northwest England.
withHo¯ku¯pa‘a,significantlycutintothetimespentobserving
The design heritage of these telescopes comes from that of
when the weather was favorable. In September, the average
theWilliamHerscheltelescope.Thefirstoftheseinstruments
3
seeingconditionsimproved, andHo¯ku¯pa‘aconsistentlypro- to 5.6 µm. IRCS has been designed to deliver diffraction-
ducedimagecoreswithfullwidthathalf-maximum,closeto limited images from 2 to 5 µm and to provide spectroscopy
thediffractionlimitofan8mtelescopeintheK andH bands with grisms and a cross-dispersed echelle. The camera can
withStrehlratiosof∼30%. alsobeusedasaslitviewer.
Ho¯ku¯pa‘a is capable of using sources as faint as V = TokunagapreviouslyservedasthePIforthisproject.Co-
15 mag to 17 mag (depending on source color) and up to investigatorsHodappandRayner,andY.Kobayashi,T.Mai-
(cid:4)(cid:4)
45 off-axis from the science target for wavefront sensing. hara,andT.Nagata(NAOJ)haveworkedwithTokunagaand
(cid:4)(cid:4)
ThelargerfieldofviewofHo¯ku¯pa‘a’slensletarray(4 )en- Kobayashionthisproject.
ablestheuseofextendedobjects(e.g.,Neptuneorthecoreof
5.4 SpeX
M32)forthispurpose. Fordirectimaging,Ho¯ku¯pa‘aiscur-
rently capable of detecting point sources 6 mag fainter and SpeX, a new medium-resolution 0.8–5.5 µm spectro-
separated by 0(cid:4).(cid:4)3 from a bright object. For more informa- graphandimagerfortheNASAIRTF,wassuccessfullycom-
tionontheperformanceofHo¯ku¯pa‘a,consulttheWebpage, missioned during June and July 2000. Since September the
http://www.gemini.edu/sciops/instruments/uhaos. instrumenthasbeenworkingsmoothlyduringobservingtime
awardedbytheTelescopeApplicationCommittee.Over40%
5.2 TheGeminiNear-InfraredImager(NIRI)
ofobservingtimeduringthefall2000semesterwasawarded
NIRI,builtatIfA,willbethemaininfraredimagingin- toprogramsusingSpeX.Theinstrumentwasfundedprimar-
strumentonGeminiNorth. Itsfirsttaskwillbethecommis- ily by NSF with additional funding from NASA for the de-
sioning of the telescope and a characterization of its perfor- tectorarrays.
mance. Thespectrographusesgratingsandprismcross-dispers-
NIRI provides three pixel scales for scientific observa- ers to provide spectral resolving powers (R) of up to 2500
tions, the finest (0.02 arcsec pixel−1) has been chosen to simultaneouslyacross0.8–2.45µm, 1.9–4.2µm, or2.3–5.5
sampleproperlytheexpectedimagequalitydeliveredbythe µm. A low-resolution prism mode covering 0.8–2.5 µm (R
adaptiveopticssystem;themiddleone(0.05arcsecpixel−1) up to 250) and single-order long-slit modes (R up to 2500)
isbestmatchedtotheimagequalityexpectedfromtip-tiltcor- are also available. An Aladdin 3 1024 × 1024 InSb array
rected images on the best nights; and the widest field (0.12 is used in the spectrograph. The infrared imager/slit-viewer
arcsec pixel−1) fills almost the whole unvignetted science uses an Aladdin 2 512×512 InSb and covers a 60(cid:4)(cid:4) ×60(cid:4)(cid:4)
fieldofthetelescope. Thesciencedetectorarrayisa1024× field. Infrared guiding is done on objects in the field or on
1024Aladdinarraywith27µmpixels. Besidesbasicimag- spilloverfromthescienceobjectintheslit. Theimageralso
ing, NIRI provides the capability for grism spectroscopy at containsafullcomplementofscienceimagingfilters.
lowtomoderatespectralresolutions(600and2000for J, H, SpeXwasdesignedandbuiltbyIRTF/UHstaff: Rayner
and K,and1500for L). NIRIwillalsoallowcoronagraphic (PI),G.Ching(instrumenttechnician),A.Denault(software
observationsandisequippedwithaWollastonprismforpo- engineer),P.Onaka(electricalengineer),W.Stahlberger(me-
larimetricwork. chanical engineer), D. Toomey (project engineer), and D.
NIRI is using an internal on-instrument wavefront sen- Watanabe(instrumenttechnician).SupportastronomerVacca
sor(OIWFS)tokeepdifferentialflexurebetweenthescience andgraduatestudentCushingarewritingtheIDL-basedauto-
channel and the OIWFS within acceptable limits. Optical maticspectralextractionprogram,SpeXtool.Atthetelescope
wavefrontsensorsperformwellalmosteverywhereinthesky, SpeX is maintained by the IRTF day crew, and user support
butanimportantclassofscientificprojects,studiesofdeeply isprovidedbyIRTFsupportastronomers.
embedded very young stars in nearby molecular clouds, is FordetailsaboutapplyingtoIRTFandusingSpeX,visit
notabletoutilizesuchasystem. Forthisreason,andinlight theIRTFWebsiteathttp://irtf.ifa.hawaii.edu/.
ofadvancesinthenoiseperformanceofnear-infrareddetec-
tor arrays, the NIRI OIWFS uses a HAWAII 1024 × 1024 5.5 AEOSSpectrograph
HgCdTe array to allow guiding in obscured regions of the This high-resolution spectrograph being constructed for
skyandduringtwilight. theU.S.AirForceAdvancedElectro-OpticalSystem(AEOS)
In the report period, NIRI was completed and went Telescopeisnearingcompletion. Installationofthedual-arm
through the preshipment acceptance testing. It was shipped visible and near-infrared instrument into one of the AEOS
to the Gemini Hilo base facility in May 2000 and subse- coude´ rooms is about to begin. Due to the large size of this
quentlytestedthere.AfirsttestrunatthetelescopeinAugust instrument,integrationandtestingwilltakeplaceatthefacil-
2000 was successful, and NIRI is currently being fine tuned ity.
inpreparationforcommissioning. The spectrograph will employ large-format array detec-
tors to provide resolving power of up to 50,000 together
5.3 Infrared Camera and Spectrograph (IRCS) for the withwidespectralcoverageoverthe0.5–2.5µmwavelength
SubaruTelescope range. The visible arm will utilize a 4K×4K CCD mosaic
The IRCS, another IfA product, is a facility instrument beingdevelopedbyLuppino. Theinfraredarmwillutilizea
for the Subaru Telescope on Mauna Kea. It is now being 2K×2KHgCdTehybridarraybeingdevelopedbyRockwell
commissionedatthetelescopeunderthedirectionofProject Science Center. Science-grade devices of both types have
Scientist and current PI N. Kobayashi (NAOJ). It incorpo- beendeliveredandareundergoingcharacterization.
ratesa1024×1024Aladdin2arraythatissensitivefrom0.9 Fabrication of all common optical assemblies and com-
4
ponentsforthevisiblearmhasbeencompleted,andthesys- thenatureofclusterevolutionandexplorepotentialimplica-
temwillbeinstalledandtestedduringlate2000. Completion tionsforlarge-scalestructure. Fourpaperswerefinalizedfor
ofmechanicaldetailingandfabricationofIRsubsystemcom- submission to The Astrophysical Journal Letters. These pa-
ponentsisproceedinginparallel.Assemblyandtestingofthe pers give an overview of the survey and of the X-ray data.
IRarmandintegrationofthetwospectrographarmswillbe They also present evidence for a deficit of z > 0.3 clusters
completedbyJuly2001. with respect to the local universe and the existence of a su-
InstitutepersonnelresponsibleforthisprojectareMickey perclusterat z = 0.087consistingofatleast21clustersand
(PI),Stockton,Hodapp,andLuppino. groups. Follow-up observations for one of the most distant
NEP clusters at z = 0.81 with the X-ray Multi-Mirror Mis-
6 GalacticandExtragalacticStudies
sionsatellitehavebeenawarded.
Barger and Cowie have been working with collabora- Gioia is collaborating with M. Donahue (STScI) and
tors R. Mushotzky and K. Arnaud (NASA Goddard), and othercolleaguesonChandraobservationsofMS0451-03,the
E. Richards (Univ. Alabama) on identifying the hard X-ray brightestclusteratz >0.5intheEinsteinExtendedMedium
sources responsible for the extragalactic hard X-ray back- Sensitivity Survey. These data combined with other mul-
ground.TheChandrasatellitewasusedtoresolvemostofthe tiwavelength datasets will allow them to probe the density
backgroundintheHawaiifieldSSA13,andfollow-upstudies structureofgasinaclusterathighredshift.
haveshownthatthegalaxiescontainingtheAGNsproducing Gioia has an ongoing collaboration with T. Maccacaro
the X-ray sources are distributed over a wide range in red- andA.Wolter(Observ.Brera,Milan)andA.Caccianiga(Ob-
shift. BargerisnowworkingwithcollaboratorsatPennState serv.Lisbon)tosearchforradio–X-ray-selectedBLLacob-
ontheultradeepChandraimageoftheHubbleDeepFieldre- jects. Thesampletheyarebuildingalreadyconsistsofabout
gionandwithcollaboratorsatMITandCambridgeonstudies 70 BL Lacs and will be instrumental in assessing the evolu-
ofsourceslyingbehindmodestredshiftlensingclustersA370 tionarybehaviorofBLLacobjectsonarobuststatisticalba-
andA2390. sis. TheyalsoplantostudytheconnectionbetweenBLLac
Songaila, Hu, L. Cowie, and R. McMahon (IoA, Univ. objectsandotherflatspectrumradioquasarsthatsharewith
Cambridge) studied limits on the absorption due to neu- BLLacsmanyoftheirobservedproperties,suchasvariabil-
tral hydrogen clouds of the Lyman-α forest in the z = 5 ityorrelativisticeffectsbutnottheopticalproperties(i.e.,the
quasarJ033829.31+002156.3. ThisGunn-Petersontestcon- presenceofstrongemissionlines).
strains the amount of neutral hydrogen that can be present Hu,Cowie,andMcMahoncontinuestudiesofveryhigh
at high redshifts based on spectroscopic studies of absorp- redshift galaxies. They are using a combination of deep
tionofthequasar’scontinuumlightbelowtheredshiftedLy- narrowband filter imaging at the Keck telescope in long-
man break. High-resolution spectra obtained with the Keck wavelength atmospheric windows around redshift z ∼ 5.7
HIRES spectrograph were compared and calibrated against andz ∼6.5toselectobjectsviatheirredshiftedLyαemission
lower-resolution spectrophotometrically calibrated spectra linealongwithdeepmulticolorimaging. Thistechniquehas
obtained with the Keck LRIS spectrograph. Portions of the proved to be a robust and successful method of identifying
HIRESspectrareturntoneartheextrapolatedquasarcontin- the highest redshift galaxies now known, with the hydrogen
uum, yielding an upper limit of τ = 0.1 on the regions of Lyα emissionlinewidthamplifiedbytheobject’sredshift. It
minimumopacity. Thissuggestsahighmetagalacticionizing showsdistantgalaxiesinthelightoftheirearlystar-forming
background (Jν (cid:7) 4 × 10−23 erg cm−2 s−1 Hz−1 sr−1 at activity by the enhanced contrast in the line emission to the
z ∼ 4.72) for the early universe for even minimum consis- neighboring continuum starlight. Recent work has focused
tencywithnucleosynthesismeasurementsofbaryondensity, on extending the samples at redshifts ∼>5. Using observa-
even if the opacity arises in underdense regions of the inter- tionsingravitationallylensedclusters,thefirstidentifications
galacticgas. of z ∼ 6.5 galaxies have been made. High-resolution spec-
Dahle completed his thesis with supervisor Kaiser. He troscopy performed with the LRIS at Keck show the emis-
studied a large, complete X-ray–selected sample of clus- sionlineistoonarrowtobeduetoO IIemissionfromlow-
ters and obtained weak gravitational lensing mass maps for redshift, foreground galaxies, and there is no detected flux
roughly30clusters. Thisrepresentsasubstantialincreasein in the deep Keck and archival HST images at visible wave-
thetotalamountofweaklensinginformationobtainedsofar. lengths below 8200 A˚, where intervening neutral hydrogen
Some8orsoofthesewereobservedwiththeUH8Kcamera cloudsoftheLymanalphaforestabsorblightbelowthered-
andgivemassprofilesouttoalargeradius. Essentiallyallof shiftedLymanbreak. Deepmulticolorstudiesshowthatthe
theclustersweredetectedsignificantly. ThemassandX-ray brightestz >5objectscanbeselectedwithacolorbreakcri-
propertieswerecomparedandshowastrongscatterinmass terion using the optical R and Z (∼9200 A˚) bands, but that
atagivenX-rayluminosity. Acompositeclustermassprofile moretypicalhigh-zgalaxieswillbemarginallybelowcurrent
was computed and compared to the profile of the luminous Z magnitudelimits(∼25.3ABmag).
matter. Using the Cooled Infrared Spectrograph and Camera
After the completion of the optical identification of the (CISCO) on the Subaru Telescope, Hu started a program of
sources in the deepest region of the ROSAT All-Sky Survey, deep infrared imaging of the brightest z > 5 galaxies with
theso-calledNorthEclipticPole(NEP)region,Gioia,Henry, T.MaiharaandF.Iwamura(Univ.Kyoto), andK.Motohara
andMullishavecompiledawell-definedandcompletesam- (NAOJ).Thebrightz ∼5.74galaxy,SSA22-HCM1,showsa
pleofX-rayclusters. Thesampleisbeingusedtoinvestigate flat(Fν)spectrumoutto2.1µm(∼3200A˚ intherestframe),
5
and is consistent with minimal or no dust extinction. Star surementsoftheextendeddarkhaloprofilesofbrightearly-
formationestimatesbasedonultravioletcontinuumlightare typegalaxiesatredshifts0.1< z <0.9obtainedviagalaxy-
therefore consistent with the earlier estimates based on op- galaxy lensing analysis of images taken at the CFHT using
tical emission-line and Z-band (∼9200 A˚) continuum esti- theUH8KCCDMosaicCamera. TheyusedV −I colorand
mates. I magnitude to select bright early-type galaxies as the lens
Kaiser, Wilson, and Luppino presented estimates of the galaxies,yieldingasampleofmassivelenseswithfairlywell
gravitational lensing shear variance obtained from images determined redshifts. They paired these with faint galaxies
taken at the CFHT using the UH8K CCD Mosaic Camera. lying at angular distances 20(cid:4)(cid:4) < θ < 60(cid:4)(cid:4), corresponding
Sixfieldswereobservedforatotalof1hreachin V and I, to physical radii of 26 < r < 77 h−1 kpc (z = 0.1) and
resultingincatalogscontainingapproximately20,000galax- 105 < r < 315h−1 kpc(z = 0.9), andcomputedthemean
iesperfieldwithproperlycalibratedandoptimallyweighted tangential shear γ (θ) of the faint galaxies. The shear sig-
T
shearestimates.Thesewereaveragedincellsofsizesranging nal was detected at a high level of significance, and gives a
from1.(cid:4)875to30(cid:4)toobtainestimatesofthecosmicshearvari- valuefortheaveragemeanrotationvelocityofan L(cid:14) galaxy
ance(cid:8)γ2(cid:9),withuncertaintyestimatedfromthescatteramong halo atr ∼ 50–200 h−1 kpc of v(cid:14) = 238+−2370 km s−1. Sub-
theestimatesforthe6fields. Atscales∼<10(cid:4) theresultswere dividingthesampleshowedlittleevidenceforevolutionwith
foundtobeingoodagreementwiththoseofothergroupsand redshift. Thesehalomassesaresomewhatlowerthanasim-
with currently fashionable cosmological models. At larger ple perfectly flat rotation curve extrapolation from smaller-
scales the shear variance falls below the theoretical predic- scale dynamical measurements, and are considerably lower
(cid:4)
tions,withanulldetectionofshearvarianceaveragedin30 thanthemassesfoundforthebest-studiedX-rayhalos. They
cellsof(cid:8)γ2(cid:9)=(0.28±1.84)×10−5. dohoweveragreeextremelywellwiththemassesofhalosof
Tullycontinuedworkontheextragalacticdistancescale thesameabundancein(cid:16)CDMsimulations.
andstudiesofthepeculiarvelocityfieldoftheLocalSuper-
7 StarFormationandInterstellarMatter
cluster.Improvementsintheluminosity–rotationratemethod
of distance determinations have resulted from (1) better de- In 1996 Herbig published (AJ, 111, 1241) a description
termination of inclination corrections, (2) the acquisition of of the peculiar reflection nebula IC 349 (Barnard’s Merope
far larger and more complete calibration samples, and (3) Nebula), which is only 30(cid:4)(cid:4) from the bright star 23 Tauri.
many new zero-point calibrators from the HST cepheid pro- Herbig and Simon have now obtained new high-resolution
grams. Tully and M. Pierce (Indiana Univ.) now find H0 = HST/WFPC2 images of IC 349 in BVRI. With 8 times the
77±8kms−1 Mpc−1 (95%statisticalcertainty). Errorsare resolution of the best f/10 frames taken with the UH 2.2 m
nowdominatedbypotentialsystematiceffects. telescopeforthe1996paper,muchinterestingnewstructure
Tully is also collaborating with W. Saunders (AAO), B. appears.
Mobasher (STScI), and others on an observing program to HerbigandSimonhavenowexpandedinmoredetailthe
(cid:4)
acquire I and K photometry and linewidths on a sample of hypothesisthatIC349ispartofanoutlyingfragmentofthe
1300galaxiesselectedwithall-skyuniformityfromanIRAS Taurus-Auriga dark clouds that the Pleiades cluster has en-
(cid:4)
redshift survey. IRAS selection and K photometry assures counteredinitssouthwardmotion,andthatIC349asitnears
more even coverage of the sky than provided by previous 23Tauisbeingshapedbyradiationpressure. Severalobser-
studies. H Iobservationsarecontinuing, buttheopticaland vationssupportthisidea. Thecolorgradientacrossoneside
infrared observations are completed. In a companion pro- ofIC349isasexpectedifthedustisbeingsiftedbydiffer-
(cid:4)
gram, K imaging and spectroscopic follow up have made entialradiationpressureand,atthesametime,beingdragged
theIRASPointSourceCatalogue: RedshiftSurveycomplete by the H and H gas with which it is mixed. The observed
2
toverylowgalacticlatitudes. colorscanbeexplainedbyamixofsilicateandgraphitepar-
TullycollaborateswithE.J.Shaya(Raytheon),andP.J. ticles with radii between about 0.1 and 1 µm. The proper
E.PeeblesandS.Phelps(Princeton)onaleast-actionrecon- motion of IC 349 is poorly known, but it is not in conflict
structionoftheorbitsofgalaxiesintheLocalSupercluster,in with the Tau-Aur hypothesis. The radial velocity has yet to
order to understand the peculiar velocity field. Their recent bemeasuredtoeveryone’ssatisfaction;anattemptbyDeane
focushasbeenonthenearbyfield,developingmodelsthatsi- to detect IC 349 in the millimeter line of 12CO(2–1), which
multaneously take uncertainties in distance and redshift into couldhavesettledthatvexingquestion,wasunsuccessful.
account,andthatexplorethegreatimprovementspossibleif HerbigandDahmareessentiallyfinishedwiththeirpho-
measurementsofpropermotionsbecomeavailable. tometry(BVRIandJHK)andspectroscopyoftheyoungclus-
Tully is also working with N. Trentham (Cambridge terIC5146andtheadjacentclusteringaroundtheAe/Bestar
Univ.) and M. Verheijen (NRAO) in an attempt to quantify BD+46◦ 3471. The central star of IC 5146, of type B1 V,
constraintsonthefaintendofthegalaxyluminosityfunction. illuminates a large emission/reflection nebula in and around
Itisbecomingincreasinglyclearthattheluminosityfunction whichabout80Hα emissionstarsbrighterthanR=21have
is flat or even falling toward faint luminosities in moderate- beenfound. Opticalandradio-frequencyinterstellarlinesin-
tolow-densityenvironments. Theyspeculatethatthegalaxy dicate that a conical cavity is being excavated in the front
formation processes were effectively quenched in low-mass surface of the background molecular cloud, and it is in the
halosaftertheepochofreheatingoftheuniversebyearlystar outflowinggasinthiscavitythattheclusterislocated.
formationorQSOs. Similarclusteringsofemission-Hαstarshavebeenfound
Wilson, Kaiser, Luppino, and L. Cowie presented mea- inotheryoungclusters,particularlyNGC1333andIC1274.
6
Dahm has begun photometry and spectroscopy of a number This study is based on data obtained with HST/WFPC2 and
of young clusters of ages between 1 and about 15 Myr to the Infrared Spectrograph and Array Camera at the Very
determinehowclusterstructureandcompositionevolvewith Large Telescope (VLT) of the European Southern Observa-
time. tory. The deep infrared observations of NGC 3603 with the
Herbig and Dahm have used that same grism arrange- VLT confirm that there is no deficit of low-mass stars down
ment at the f/10 focus of the UH 2.2 m telescope to investi- to0.1 M(cid:13),andthatthelow-massinitialmassfunctioninthis
gatetheincidenceofHα emissionamongthebrightermem- starburstclusterisvirtuallyidenticalwiththefieldIMFinthe
bers of the cluster NGC 6611 (= M16), which has been re- massrange0.2–2 M(cid:13). Therelativescarcityofstarswithin-
ported to contain an unusually high number of Be and Ae trinsicinfraredredexcesscomparedwithalessmassivestar-
stars. The cluster is imbedded in a very bright H II region, forming region like Orion suggests that circumstellar disks
sothatpropersubtractionofthebackgroundonslitormulti- instarburstenvironmentsaretransientphenomenaandmight
object fiber-fed spectra is important. Slitless spectra are not notsurvivelongenoughtoformplanetarysystems.
subject to such contamination. Herbig and Dahm examined Sheppard,Brandner,andTokunagacompletedtheanaly-
about 40 suspected Be and Ae stars, and were able to con- sisofnear-infraredVLT/ISAACobservationsofthecircum-
firmthepresenceofHα emissionabovethecontinuumlevel stellar environment of young stars in southern star-forming
inonly4. However,about25muchfainterHα emitterswere regions. Two new edge-on circumstellar disk sources were
found in the cluster. These are probably the brightest mem- identified in the Ophiuchus star-forming region. Infrared
bers of a low-mass T Tauri population. None of these stars spectraobtainedwiththeSubaruTelescopeandanditsCIS-
are convincingly associated with the famous elephant-trunk COcamerashowthatthebipolarreflectionnebulositiesabove
structuresseeninprojectionagainsttheHIIregion. and below the disk planes exhibit featureless continua. The
Herbig published the results of his search for interstel- VLT data combined with observations obtained with the In-
larC (“buckminsterfullerene”)usingKeckHIRESspectro- frared Space Observatory nicely confirm theoretical predic-
60
grams. The laboratory data leave much to be desired, but tionsabouttheeffectofdiskgeometryandinclinationangle
whatcannowbesaidisthatneutralC couldnotbedetected on the spectral energy distribution of young stellar objects
60
inanyoftheheavilyreddenedOBstarsthatwereexamined, withcircumstellardisks.
notablyCygOB2/8A.However,giventherelevantionization Brandner,Mart´ın,G.Basri(Univ.California,Berkeley),
potentials, most interstellar C is probably singly ionized. X. Delfosse (Instituto de Astrof´ısica de Canarias), and Al-
60
Two bands at 9577 and 9632 A˚ are believed to be due to lard started a HST/WFPC2 snapshot program to survey for
+
C , and are readily detected in CygOB2/8A, a region best companions up to 50 free-floating brown dwarfs in the so-
60
observedatMaunaKeaonverydrynightsbecauseofheavy lar neighborhood. The survey studies the binary properties
atmosphericH Ostructure. Herbigalsodeterminedthecol- of free-floating brown dwarfs, which should hold important
2
umn densities of CH, CN, and C in that same star, and es- cluestotheirorigin. Asecondobjectiveistoobtaindynam-
2
timated the amount of interstellar carbon that could be tied ical mass estimates for the individual companions of brown
upinthediffuseinterstellarbands. Theconclusionwasthat dwarfbinaries.
neutralC cannotbeasignificantsinkofinterstellarC(less Magnier has continued work on “transitional” YSOs.
60
than 0.2–04% of the total amount of C available), but that His collaborators are R. Waters (Univ. Amsterdam), M. van
+
therecouldbeover100timesthatupperlimitinC . Asim- denAncker(CenterforAstrophysics),andN.McCrady(UC
60
ilarinvestigationofthefullereneC awaitsbetterlaboratory Berkeley). Theyhaverecentlyobtained L(cid:4), M(cid:4),and850µm
70
information. photometry of most of the northern objects in their sample.
Brandner, in collaboration with H. Zinnecker (Astro- This data completes the measurement of the spectral energy
physikalischesInstitutPotsdam),J.M.AlcalaandE.Covino distribution for the objects, and will be combined with the
(Osservatorio Astronomico di Capodimonte Napoli), F. Al- optical spectroscopy obtained previously to study the evolu-
lard (Univ. Lyon), S. Frink and R. Koehler (Univ. Cali- tionary state of these objects. CO (2–1) observations of the
fornia, San Diego), A. Moneti (Institut d’Astrophysique de sampleshowthatthebulkoftheobjects,nearlyallofwhich
Paris), M. Kunkel (Astronomisches Institut der Universita¨t showevidenceofoptical,ionizedoutflows,alsoshowmolec-
Wu¨rzburg), and A. Schweitzer (Univ. Georgia), completed ularoutflows. Thisservestoconfirmthetransitionalstateof
theanalysisandinterpretationofanHST/NICMOSsurveyfor theseobjects,ontheboundarybetweentheembedded(Class
substellar companions to weak-line and post–T Tauri stars. I)andtheexposed(ClassII)YSOs.
Theresultsofthesurveysuggestthatmassivesubstellarcom- C.RoddierandF.Roddiercontinuedtoobserveanumber
panionsatseparationsgreaterthan30AUareextremelyrare. of binary T Tauri stars with adaptive optics to estimate their
ISOCAM and ISOPHOT observations of the same targets projectedorbitalvelocitiesandtheircomponentvariabilities.
support the idea that small dust grains get depleted in cir- Results for T Tau were presented at IAU symposium 200,
cumstellardisksontimescalesof10Myr. Thisisverylikely “TheFormationofBinaryStars,”heldinPostdamon10–15
related to the buildup of larger dust particles and planetesi- April1999.
mals.
8 StellarAstronomy
ThestudyoftheGalacticgiantHIIregionNGC3603by
BrandnerandmaincollaboratorsE.K.Grebel(Max-Planck- Boesgaard has been studying the trio of the rare light
Institut fu¨r Astronomie), B. Brandl (Cornell Univ.), and Y.- elements—lithium, beryllium, and boron. These can be de-
H.Chu(Univ.IllinoisatUrbana-Champaign)wasextended. stroyedinsolar-typestars. Lithiumisthemostsusceptibleto
7
destruction, followedbyBeandthenB.Thelargedepletion kinematicproperties. Itisthoughtthatstarsinorbitsthatei-
of Li in the mid-F stars in the Hyades and other clusters is therpenetratetheremotehaloorexhibitlargeretrogradeve-
nowunderstoodtobeduetoslow-mixingofLiatomstodeep locitiescouldhavebeenassociatedwithassimilated(or“ac-
layers,wherethetemperatureishighenoughtodestroythem. creted”)dwarfgalaxies.Thehallmarkofanaccretedhalostar
NewresultsonthecorrelationofLiandBedepletionsinfield ispresumedtobeadeficiency(comparedwithnormalstars)
Fstarssupportsthisandarguesagainstdiffusion, massloss, oftheα-elements(O,Mg, Si, Ca, Ti)withrespecttoiron, a
andprobably,mixingbygravitywaves. Rotationallyinduced consequence of sporadic bursts of star formation within the
mixingisthemostprobablecauseoftheLiandBedepletion. diminutivegalaxies.
The G stars in the Hyades and other clusters have progres- Abundances for a select group of light metals (Li, Na,
sively less Li with decreasing surface temperature, whereas Mg,Si,Ca,Ti),iron-peaknuclides(Cr,Fe,Ni),andneutron-
thefewBeobservationsinGdwarfsshowlittleornodeple- captureelements(Y,Ba)werecalculatedusinglinestrengths
tion. RecentresultsonBshowonlysmalldepletionsinafew measuredfromhigh-resolution,highsignal-to-noisespectral
stars,andonlyinthosestarswithverylargedeficienciesinLi observationscollectedwiththeKeckIandtheKittPeakNa-
andBe. tionalObservatory4mtelescopes. Theabundancesextracted
Theabundanceofberylliumhasbeendeterminedinun- fromthespectrareveal(1)thevastmajorityofouterhalostars
evolved stars over a range metal abundances to enhance possess supersolar ([α/Fe] > 0.0) ratios; (2) the [α/Fe] ratio
the understanding of the chemical evolution of our Galaxy, appearstodecreasewithincreasingmetallicity;(3)theouter
cosmic-raytheory, andcosmology. Observationsof27stars halo stars have lower ratios of [α/Fe] than inner halo stars
have been made with Keck I with HIRES at high spectral atagivenmetallicity; (4)atthelargestmetallicities,thereis
resolution (45,000) and high signal-to-noise ratios (60–110 a large spread in the observed [α/Fe] ratios; (5) [α/Fe] an-
typically). Thereisaremarkablylinearrelationshipbetween ticorrelates with R ; and (6) only one star (BD+80 245)
APO
logN(Be/H)and[Fe/H]withaslopeof0.96(±0.04). Simi- exhibits the peculiar abundances expected of an assimilated
larly,therelationshipbetweenlogN(Be/H)and[O/H]islin- star. The general conclusion extracted from these data is
earwithaslopeof1.45(±0.04). Berylliumincreasesatthe that the formation of the nascent Milky Way was not dom-
same rate as Fe, but much faster than O. This provides con- inated by the late accretion of dwarf galaxies like the ones
straintsforandinsightsintomodelsofGalacticchemicalevo- that currently orbit the Galaxy. However, the assimilation
lution. ThereissomeevidenceforanintrinsicspreadinBeat offragmentsearlyintheevolutionoftheGalaxyisanatural
agiven[O/H]or[Fe/H].Thereisnoevidenceofaplateauin byproduct of hierarchical models of structure formation and
BeatthelowestmetallicitiesdowntologN(Be/H)=−13.5. canexplainmanypropertiesofthehalopopulation.
Boesgaard has also been determining chemical abun-
9 SolarSystemStudies
dances in globular cluster turnoff stars with Stephens, J.
King(Univ.Nevada,LasVegas),andC.Deliyannis(Indiana 9.1 Atmospheres
Univ.). Spectroscopic observations at high spectral resolu-
Owen continued studies of the ice-trapping of volatiles
tionofunevolvedstarsinglobularclustershavebeenpossible
in collaboration with Prof. Akiva Bar-Nun (Univ. Tel Aviv).
onlysincethe1993adventoftheKeckI10mtelescopeand
Thegoalofthesestudiesistorelateicyplanetesimalstoices
its high-resolution spectrometer. They have derived chemi-
in the interstellar medium and to the volatiles now found in
calabundancesoflithiumandseveralotherelementsinsome
planetaryatmospheres. Noisotopicenrichmentofdeuterium
unevolved,butidentical,starsinthreeglobularclusters. For
in HDO was detected in laboratory experiments simulating
M13 they have found a spread in Li abundances of a factor
theformationofcometaryices. Thisresultremovesoneob-
of5infourverysimilarstars. ForsixstarsinM92therange
jectiontotheideathatcometsmayhavepreservedinterstellar
isafactorof3. ThestarswiththehighestabundancesofLi
D/Hvaluesintheirconstituentmolecules.Theyalsofoundno
showvaluesthatareafactorof2abovethefieldhalostarLi
fractionationofthexenonisotopesuponincorporationofthis
plateau. The abundances of several other species—Na, Mg,
gas in ice. This result indicates that the difference between
Si, Ca, Ti, Cr, Ni, Fe, Y, and Ba—show no such star-to-star
isotopic abundances in atmospheric and solar wind xenon
variations. They compared these abundances with those of
cannot be explained by cometary delivery of this gas to the
halo field stars that were derived from Keck HIRES spectra
planets,ifthisistheonlyprocessthatcouldproducethefrac-
byStephensforhisPh.D.thesis.
tionationincomets.
Stephens completed his Ph.D. thesis on possible accre-
Further analysis of the Galileo Probe Mass Spectrome-
tion in the Galactic disk. The Milky Way disk is enveloped
terresultsbyOwen,P.Mahaffy(NASAGoddard),andother
inadiffuse,dynamicallyhotcollectionofstarsandstarclus-
membersoftheinstrumentteamledtothediscoverythatall
terscollectivelyknownasthe“stellarhalo.”Photometricand
the elements measured in the atmosphere of Jupiter (except
chemicalanalysessuggestthatthesestarsareancientfossils He and Ne) are enhanced by 3 ± 1 relative to solar abun-
of the galaxy formation epoch, yet little is known about the
dances ratioed to hydrogen. This is particularly remarkable
origin of this trace population. Is this system merely a ves-
in the case of argon and nitrogen, as these highly volatile
tige of the initial burst of star formation within the decou-
gases would not be expected to show the same enrichment
pled proto-Galaxy, or is it the detritus of cannibalized satel-
as carbon or sulfur. It appears that the only way to achieve
lite galaxies? In an attempt to unravel the history of the
this uniformity is to make the icy planetesimals that deliv-
Milky Way’s stellar halo, he performed a detailed spectro-
eredtheseelementsatextremelylowtemperatures,below30
scopic analysis of 55 metal-poor stars possessing “extreme”
8