ISO Science Legacy: A Compact Review of ISO Major Achievements

435 Pages·2005·9.731 MB·English

by  Frank Molster, Ciska Kemper (auth.), Catherine Cesarsky, Alberto Salama (eds.)

ISO SCIENCE LEGACY
A Compact Review of ISO Major Achievements
Coverfigures:
Background
ISOCAMimageoftheRhoOphiuchiCloud,
Abergeletal.AstronomyandAstrophysics315,L329
Leftinserts,fromtoptobottom:
170 μm ISOPHOT map of the Small Magellanic Cloud (40(cid:2)(cid:2) pixel size, 1(cid:2)
resolution)fromWilkeetal.,A&A401,873–893(2003).
2–200 micron composite spectrum of the Circinus galaxy obtained with the
SWS and LWS spectrometers showing a plethora of atomic, ionic and molecular
spectral,alongwithvarioussolid-statefeaturesfromdustgrainsofdifferentsizes
inVermaetal.thisvolume.
Water vapour spectral lines detected in the atmospheres of all four giant planets
andTitan,inCernicharoandCrovisier,thisvolume.
CristallinesilicatesdetectedbyISOindifferentenvironments,instars(youngand
old)andincometHale-BoppinMolsterandKemper,thisvolume.
Purerotationalhydrogenlinesobservedtowardsthemolecularhydrogenemission
peakoftheRhoOphiuchifilamentinHabart,thisvolume.
ISOSCIENCELEGACY
ACompactReviewofISOMajorAchievements
Editedby
CATHERINECESARSKY
EuropeanSouthernObservatory,
Garching,Munich,
Germany
and
ALBERTOSALAMA
EuropeanSpaceAgency,
Madrid,
Spain
ReprintedfromSpaceScienceReviews,Volume119,Nos.1–4,2005
A.C.I.P.CataloguerecordforthisbookisavailablefromtheLibraryofCongress
ISBN:1-4020-3843-7
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TABLEOFCONTENTS
Foreword vii
GENERAL
FRANKMOLSTERandCISKAKEMPER/CrystallineSilicates 3–28
JOSE´ CERNICHARO and JACQUES CROVISIER / Water in Space: The
WaterWorldofISO 29–69
EMILIEHABART,MALCOLMWALMSLEY,LAURENTVERSTRAETE,
STEPHANIE CAZAUX, ROBERTO MAIOLINO, PIERRE COX,
FRANCOISBOULANGERandGUILLAUMEPINEAUDESFOREˆTS/
MolecularHydrogen 71–91
DAVID ELBAZ / Understanding Galaxy Formation with ISO Deep
Surveys 93–119
SOLARSYSTEM
THIERRY FOUCHET, BRUNO BE´ZARD and THERESE ENCRENAZ /
ThePlanetsandTitanObservedbyISO 123–139
THOMASG.MU¨LLER,PE´TERA´BRAHA´MandJACQUESCROVISIER/
Comets,AsteroidsandZodiacalLightasSeenbyISO 141–155
STARSandCIRCUMSTELLARMATTER
BRUNELLA NISINI, ANLAUG AMANDA KAAS, EWINE F. VAN
DISHOECK and DEREK WARD-THOMPSON / ISO Observations of
Pre-StellarCoresandYoungStellarObjects 159–179
DARIOLORENZETTI/Pre-MainSequenceStarsSeenbyISO 181–199
MARIEJOURDAINDEMUIZON/DebrisDiscsAroundStars:The2004
ISOLegacy 201–214
JORIS A. D. L. BLOMMAERT, JAN CAMI, RYSZARD SZCZERBA and
MICHAELJ.BARLOW/LateStagesofStellarEvolution 215–243
INTERSTELLARMEDIUM
ALAIN ABERGEL, LAURENT VERSTRAETE, CHRISTINE JOBLIN,
RENE´LAUREIJSandMARC-ANTOINEMIVILLE-DESCHEˆNES/The
CoolInterstellarMedium 247–271
ELSPEETERS,NIEVESLETICIAMART´IN-HERNA´NDEZ,NEMESIOJ.
RODR´IGUEZ-FERNA´NDEZand XANDERTIELENS/HighExcitation
ISMandGas 273–292
EMMANUELDARTOIS/TheIceSurveyOpportunityofISO 293–310
OURLOCALUNIVERSE...
MARCSAUVAGE,RICHARDJ.TUFFSand CRISTINAC.POPESCU/
NormalNearbyGalaxies 313–353
APRAJITA VERMA, VASSILIS CHARMANDARIS, ULRICH KLAAS,
DIETERLUTZand MARTINHAAS/ObscuredActivity:AGN,Quasars,
StarburstsandULIGsObservedbytheInfraredSpaceObservatory 355–407
...ANDBEYOND
SEB OLIVER and FRANCESCA POZZI / The European Large Area ISO
Survey 411–423
LEO METCALFE, DARIO FADDA and ANDREA BIVIANO / ISO’s
ContributiontotheStudyofClustersofGalaxies 425–446
FOREWORD
Building upon pioneering work in the 1960’s and 1970’s using ground-based,
rocket- and balloon-borne systems, the realm of infrared astronomy was fully
opened by the first cryogenic telescope in space – IRAS, launched in 1983. Over
itsten-monthlifetime,IRASsurveyedalmostthewholeskyinfourbroadinfrared
bands. This survey permitted the first evaluations of the total energy emitted by
varioussystemsinourgalaxyandinthelocaluniverse.However,itcouldnotad-
dressthedetailedmechanismsandprocessesresponsiblefortheemissiondetected,
nor the exploration of the distant universe. IRAS results graphically illustrated to
astronomerstheneedforsensitiveinfraredobservatories,allowingdetailedspatial
and spectroscopic study of specific targets. All over the world, high priority was
assignedtocooledspaceinfraredtelescopes.
Following the Japanese IRTS mission, the first major satellite of this type to
fly was ESA’s Infrared Space Observatory (ISO). Launched in November 1995,
ISO completed almost 30000 scientific observations in its 2.5-year operational
lifetime. Making use of its four sophisticated and versatile scientific instruments
(acamera,aphotopolarimeterandtwospectrometers),ISOprovidedastronomers
withawealthofdataofunprecedentedsensitivityatinfraredwavelengthsfrom2.5
to240μm.ISOhasmade,andcontinuestomake,lastingcontributionstoallareas
ofastronomy,fromthesolarsystemtothefrontiersofcosmology,unravellingthe
historyoftheuniverse.Between1996and2004,over1200papersappearedinthe
refereedliteraturebasedonISOdata.
NASA’sSpitzerSpaceTelescope,launchedeightyearslater,hasenhancedcapa-
bilitiescomparedtoISOand,onceagain,infraredastronomersareofferedmatchless
observing opportunities. However, the published ISO results and the ISO archive
remainavaluableresourceforresearchwork.Theyprovideguidelinesforstudies
not only with Spitzer but also with future facilities, such as ASTRO- F, SOFIA,
Herschel,JWSTandALMA.
With the Spitzer Space Telescope now in full operations, we thought that it
would be beneficial to the astronomical community to have at hand, in a single
volume,areviewofthemaindiscoveriesowedtotheISOsatellite.Wedidnotask
theISOfoundingfathersandmotherstowritethearticles,butinsteadturnedmostly
towardsyoungerastronomerswhosecareershavebeenstronglyinfluencedbyISO.
Thearticleshavebeenrefereedbyourselvesorbyotherscientistsatourrequest.The
bookisorganisedasfollows:first,overviewsoffourmajorthemesinvestigatedwith
ISO(crystallinesilicates,molecularhydrogen,deepsurveys;waterintheuniverse),
andthenthirteenchaptersreviewingISOsciencefromthesolarsystemtothedistant
universe.ItisnotpossibletogatherinonebookalltheadvancesduetoISO,butwe
hopethatthiscompendiumofover480pageswillgivetheessenceoftheoriginal
resultsobtainedbythefirstfull-fledgedspaceinfraredobservatory.
CatherineCesarskyandAlbertoSalama
Guesteditors
GENERAL
CRYSTALLINESILICATES
FRANKMOLSTER1,∗andCISKAKEMPER2
1ESTEC/ESA,Keplerlaan1,2201AZNoordwijk,TheNetherlands
2(SpitzerFellow)DepartmentofPhysicsandAstronomy,UCLA,475PortolaPlaza,LosAngeles,
CA90095-4705;Presentaddress:UniversityofVirginia,DepartmentofAstronomy,P.O.Box3818,
Charlottesville,VA22903-0818,USA
∗
( Authorforcorrespondence:E-mail:[email protected])
(Received16July2004;Acceptedinfinalform2November2004)
Abstract. OneofthebigsurprisesoftheInfraredSpaceObservatory(ISO)hasbeendiscoveryof
crystallinesilicatesoutsideourownSolarsystem.Itwasgenerallyassumedbeforethatallcosmic
silicatesinspacewereofamorphousstructure.ThankstoISOweknownowthatcrystallinesilicates
areubiquitousintheGalaxy(exceptforthediffuseISM)andsometimeseveninverylargequantities
(>50%ofthesmalldustparticles).Theevolutionofthecrystallinesilicatesisstillnotcompletely
clarified,butthecombinationoftheoreticalmodelingandobservationshavealreadyshedlighton
theirlife-cycle.TheabsenceofcrystallinesilicatesinthediffuseISMprovidesuswithinformation
aboutthedustamorphizationrateintheISM.
Keywords: crystallinesilicates,infraredastronomy
1. Introduction
Before the Infrared Space Observatory (ISO) opened the mid- and far-infrared
rangeforhigh-resolutionspectroscopy,itwasgenerallyassumedthatcosmicdust
silicateswereofamorphousstructure.Thecrystallinesilicates,thehighlyordered
counterpartsoftheamorphoussilicates,wereonlyknowntobepresentonearth,in
thesolarsystemincomets(Hanneretal.,1994;Hanner,1996),InterplanetaryDust
Particles(IDPs)(MacKinnonandRietmeijer,1987;Bradleyetal.,1992)andinthe
dust disk of β-Pictoris (Knacke et al., 1993; Fajardo-Acosta and Knacke, 1995),
alsoacrystallineolivinefeaturewasreportedinthepolarized10μmspectrumof
AFGL2591(Aitkenetal.,1988).ApartfromthecrystallinesilicatesintheIDP’s,
that were found with the aid of transmission electron microscopy and only later
confirmed by infrared spectroscopy (Bradley et al., 1992), in all other cases the
crystalline silicate features were found by infrared spectro(polari)metry around
10μm.
Withthepresentdayknowledgeitisrelativelyeasytounderstandwhycrystalline
silicates were only discovered to be ubiquitous after ISO was operational. Before
ISO was launched the primary MIR/FIR window for observations was around
10μm. And although the crystalline silicates do have strong features in this area,
they are in general overwhelmed by emission from the much more abundant and
SpaceScienceReviews(2005)119:3–28
DOI:10.1007/s11214-005-8066-x (cid:4)C Springer2005
4 F.MOLSTERANDC.KEMPER
warmer amorphous silicates. Furthermore, most of the crystalline silicates have a
(relatively) low temperature (<150K), which suppresses the intrinsically strong
crystalline silicate features in the 10μm region. Thanks to the extended wave-
length range (up to 200μm) of the spectrographs on board ISO, the composition
of the cold (<150K) dust, which has the top of its SED at wavelengths above
15μm, could be studied in detail for the first time. With ISO, crystalline silicates
have been found around young stars (Waelkens et al., 1996), comets (Crovisier
et al., 1997), and evolved stars (Waters et al., 1996) (see Figure 2), but not con-
vincingly so in the interstellar medium. The presence of the crystalline silicates
in the different galactic environments will be discussed in Section 2. The proper-
tiesofthecrystallinesilicateswillbediscussedinSection3.InSection4wewill
discuss the crystalline silicate (trans-)formation and destruction processes based
on the ISO (and other astronomical) observations in comparison with laboratory
measurements.
2. TheUbiquitousPresenceofCrystallineSilicates
2.1. WHAT ARE SILICATES?
Silicatesarethemostcommonformofmineralsinthesolarsystem,andprobably
alsobeyond.Chemically,theyconsistofsilicatetrahedras(SiO )whicharecom-
4
bined with metal cations, such as Mg2+ or Fe2+ in a lattice structure. In ordered
(crystalline) lattice structures, the tetrahedras can share their oxygen atoms with
othertetrahedrastoformdifferenttypesofsilicates:olivines:(Mg,Fe,...) SiO ,
2 4
pyroxenes: (Mg, Fe,...)SiO or quartz: SiO . In case of unordered (amorphous)
3 2
structures,thenumberofsharedoxygen-atomsmayvaryforeachsilica-anion(see
Figure1).ThereaderisreferredtoforinstanceKleinandHurlbut(1993)formore
backgroundreadingonmineralogy.
Spectroscopically,allsilicates,amorphousandcrystallinealike,willshowres-
onances around 10 and 20 μm in the mid-infrared, due to the Si O stretching
and the O Si O bending mode arising from the silica-tetrahedras. Alignment of
the tetrahedras may cause sharp peaked resonances, whereas amorphous silicates
willshowabroadfeaturewhichcanbeseenasablendofsuchsharpresonances.
Crystallinesilicatescanalsobedistinguishedfromamorphoussilicatesduetothe
presenceoflatticemodesatλ (cid:2) 25μm,seeFigure1.
The formation temperature determines whether a silicate grain becomes crys-
talline or amorphous. If silicates are formed above the glass temperature (T ),
glass
then there is enough mobility in the silicate to from the crystalline, energetically
mostfavorable,latticestructure.However,whenthesilicatescondenseatlowertem-
peratures,suchmobilityisnotpresent,andthegrainsolidifiesinamorphousform.
Amorphous grains can become crystalline by annealing (crystallization through
heating) or vaporization and recondensation above the glass temperature. Hence,