Department of Astronomy Annual Report 2001

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University of Helsinki

Annual Report 2001

Observatory P.O. Box 14, FIN-00014 University of Helsinki, Finland

http://www.astro.helsinki./

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Thefractionof externalfunding hasagainexceeded

80%inourlastyears'budget. Thisandthehighnumber

of publishedpapersclearlyshowthehigh qualityofre-

search ofoursta. Startingin March2001 threemajor

spaceresearchprojectsreceived3-yearsfundingfromthe

Academy of Finland and National Technology Agency

ResearchProgrammeforSpaceresearch(ANTARES).

Anewcomputerclassroomforthestudentswascom-

pleted in August 2001. The renovation of the 70 m 2

workshop facilities as workspacefor postgraduateswill

also soon be completed. Since spring 2001, each stu-

dentmajoringin Astronomyhasbeenappointedaper-

sonalteachertutorinthestaoftheObservatory. These

teachertutorshelpthestudentsinvariousstudy-related

problemsandquestions.Thesemeasureshavebeentaken

toreachourlong-termaimtoincreasetheannualnum-

berofcompleteddegreesto3M.Sc. and1-2.Ph.D. de-

grees. According to the atmospheresurveycarried out

in autumn 2001, our department has a good teaching

andresearch atmosphere. Ourexcellentteachingatmo-

spherewasalsorecentlynotedbytheinternationalpanel

invitedtoevaluatetheteaching oftheexactsciencesat

theUniversityofHelsinki.

Majorpublicoutreachprojectsduring2001included

the pressconferencesrelatedto the launch of theOdin

Satellite on Feb 20th and to the progress of the High

Energy Astrophysics (HESA) consortium on June 8th.

Three research groupsfrom the Observatory had their

compartmentsattheSpace2001Exhibitionorganizedby

the URSA Astronomical Assocation at Kaapelitehdas,

Helsinki onNovember2nd-4th. About20personsfrom

thestaof ourObservatoryparticipatedin thisexhibi-

tion.

To some extent the year 2001 resembled the previ-

ousoneinbeingadministrativelyademandingone. The

yearbeganwiththedecisionoftheSenateoftheUniver-

sityonJanuary17thstatingthat theObservatoryshall

continue as an independent department and shall not

bemergedtothenewDepartmentofPhysicalSciences.

Thisdecisionwaspreceded byawhole yearofadminis-

trativeworkbytheObservatorysta,lledwithreports,

meetings,appealsetc. ThedecisionenabledtheObser-

vatorystaanddirectortoreturnfulltimebacktotheir

maintasks;researchandteaching. However,inOctober

2001the verysameideaofmergingtheObservatoryto

the Department Physical Sciences emerged again, this

timeaspartoftheplantoreorganizethewholeUniver-

sity administration in accordance with its locations at

dierentcampuses. Anotherhalfayearlledwithmeet-

ings,appeals,reportsandotheradministrativeworkfol-

lowed. Bythetimeof thiswriting, decisionshavebeen

madewhichsecure thecontinuationof theObservatory

It hasbeenaprivilegeto bethedirectoroftheOb-

servatoryduring thepasttwoyears. I acknowledge the

supportoftheBoardoftheObservatoryandthestudent

associationMeridian,andtheworkbythestaand the

students in maintaining the high level of research and

educationoftheDepartmentofAstronomy.

LauriJetsu

DirectoroftheObservatory

Helsinki,June6th,2002

Contents

1 StrategyoftheObservatory 1

2 Researchofinterstellarmediumandstarformation 2

2.1 Researchactivities . . . 2

2.2 Progress . . . 2

2.3 Moneyandresources . . . 5

2.4 Testsoflearning. . . 5

2.5 Visitsabroad . . . 5

2.6 Visitingacademics . . . 6

2.7 Papersreadatscienticconferences,symposia, meet- ingsetc. . . 6

2.8 Membershipinscienticandscholarlysocieties. . . 7

2.9 Additionalinformation . . . 7

3 PlanetaryAstronomy 8 3.1 Researchactivities . . . 8

3.2 Progress . . . 8

4 HighEnergyAstrophysics 10 4.1 Researchactivities . . . 10

4.2 Progress . . . 10

4.2.1 Missionsunderdevelopment . . . 10

4.2.2 Missionsunderplanning . . . 10

4.7 ActingasOpponentand pre-examinationsofdoctoral dissertations . . . 11

5 Stellar-planetaryAstronomy 13 5.1 Researchactivities . . . 13

5.2 Progress . . . 13

5.4 Testsoflearning. . . 15

5.6 Visitingacademics . . . 15

5.9 ActingasOpponentand pre-examinationsofdoctoral dissertations . . . 17

6 Publications 18 6.1 Scienticmonographs. . . 18

6.2 Articlesinrefereedjournals . . . 18

6.3 Otherrefereedarticles . . . 19

7 Academicdegreesbetween1995and2001 21

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In order to guarantee the developmentof astronomical

research and teaching at theUniversityof Helsinki, we

aimforhighqualityresearchinthoseeldsofAstronomy

that are pursued by thefour researchgroups currently

workingattheObservatory. Accordingtoitsstrategyfor

2001-2003theUniversityofHelsinkiputsspecialempha-

sis onresearch and researchertraining. These are very

muchthesamegoalswhichtheObservatoryemphasizes.

Thechosenstrategicmeansare:

Participationinlargeastronomyandspaceresearch

projects: Ourincreasing spaceresearch activity is

an investment to the future of Astronomy. Our

spaceresearchinstrumentdevelopmentguarantees

us future observing time with several satellites.

High quality research requires access to the best

existinginstruments. Themembershipin interna-

tionalorganizationsoersthisadvantage.TheOb-

servatoryisactivelyinvolvedinseveralESA(Euro-

peanSpaceAgency)projects,suchasISO,INTE-

GRAL,SMART-1andPlanck. Wearealsolooking

forwardto thenewresourcesoeredbytheimmi-

nentmembershipofFinlandintheESO(European

SouthernObservatory). Amongourongoingjoint

researchprojectsare,e.g. theuseofSwedish-ESO

Submillimetre Telescope (SEST) and the Nordic

OpticalTelescope(NOT).Ouractiveparticipation

in the aforementioned, and several new interna-

tionalprojects(e.g. XEUS-andRoemer-satellites)

securesthecontinuityofhighqualityastronomical

research.

Increasing theresearch volumewith externalfund-

ing: Modern astronomicalresearch is team work,

whereoneoftenencounterstheterm\criticalmass"

used in dening an eective research group. The

Observatory encourages all eorts by the perma-

nentstato acquireexternalfunding fortheirre-

searchgroups. Themostimportantfundingsources

are the Academy of Finland, the National Tech-

nologyAgencyTEKES,theEuropeanUnion,and

privatefoundations.

EÆcient Ph.D. teaching: Ph.D. is the \basic de-

gree"foraresearcherinAstronomy. Weaimfora

moreeÆcientPh.D.studentsupervisioninsidethe

researchgroups,which will leadto faster gradua-

tion. We continue active participation in the na-

tional\GraduateSchoolforAstronomyandSpace

Physics". In spring 2001, we initiateda program

whereapersonal \teachertutor" isappointed for

everyundergraduatestudentstudying Astronomy

ashis/hermainsubject. Inshort,wedoourbestto

encourageclose connectionsbetweenthe students

andtheresearchgroups.

PublicOutreach: Astronomyenjoystheinterestof

the general public, and it is also a highly pop-

ular minor subject at the University of Helsinki.

Weaimatincreasingoureectivenessinreporting

aboutastronomicalresearch,e.g. inthepress,tele-

visionand www. Wealsohaveacloseconnection

to the Finnish Amateur Astronomer Association

URSA.

The popularity of basic courses in Astronomy has

been constantly growing. Continuous development of

these basic courses also strengthens the motivation of

students majoring in Astronomy. Another major goal

forthesebasiccoursesistoteachthemodernworldpic-

tureofnaturalsciencetothestudentsfrom allfaculties

oftheUniversityofHelsinki. Thedirectconnectionbe-

tweenAstronomycoursesandtheresearchperformedat

the Observatory will be strengthened. As an example

oftheeectivenessofthisstrategy,theresearchprojects

performedbythestudentsduringanundergraduatelevel

course hasalready been published twice in an interna-

tionalrefereedjournal.

Thefundingandthevolumeofourresearchbetween

1995and2001isillustratedbelow. Thechosenstrategy

seemstopredictasuccessfulfuture fortheObservatory

oftheUniversityofHelsinki.

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and star formation

Projectnumber 81525002

Researchagreements AcademyofFinland

Typeofresearch Basicresearch

Directorofresearch Prof.Mattila,Kalevi

Telephone 09-19122947

Fax 09-19122952

E-mail Kalevi.Mattila@Helsinki.Fi

ResearchstawithaPh.D. KaleviMattila,Prof

JormaHarju,Docent

MikaJuvela,Docent

KimmoLehtinen,Ph.D.

MarkRawlings,Ph.D.

Viktor,Toth,Ph.D.

PetriVaisanen,Ph.D.

Ph.D.student(s) PaiviHarjunpaa,Phil.Lic.

PeterJohansson,M.Sc.

JereKahanpaa,M.Sc.

SamuKontinen,M.Sc.

AskoPalviainen,M.Sc.

M.Sc.student(s) CajusPomren

Associatedresearchsta LauriHaikala,Docent(atESO)

Technicalsta MikkoToriseva,Lic.Tech.

2.1 Research activities

Theactivities ofthe researchgroupare directed to the

followingelds: 1) the evolutionof dust and molecular

gasininterstellarclouds;2)theformationofprotostars

in dense molecular cloud cores; 3) star formation his-

toryanddustemissionathighredshifts;and4)radiative

transferandmagnetohydrodynamic(MHD)modellingof

interstellarclouds.

The rst topic involves the study of grain popula-

tions and theirphysical properties and distributions in

molecularclouds,andtheircorrelationwiththephysical

propertiesand chemicalcompositionof thegas compo-

nent. Theaimistounderstandtheinterrelationbetween

interstellargasanddust,theenergybalanceininterstel-

larcloudsandespeciallyincoldcores,andtherelation-

ship of gas and dust properties to the star-formation

activity. These studies are conducted via observations

of far-infrared and (sub)millimetre continuum emission

fromdust, andmolecularlineemissionfromgas.

Thesecondtopiccontainsprotostellaraccretiondisks

and the violent ejection of `surplus' material through

jets, which drive shocks and outows in the surround-

ing gas. The parameters of shocks associated with ac-

cretion/outowarestudied withtheaidofthermaland

maserline emission. The nature and theoriginof pro-

tostellar jetsarestudied with theaidofinterferometric

radiocontinuumimaging.

The study of the star formation in the early Uni-

verseconcentratesonthefar-infrared andoptical/near-

infraredbackgroundradiation,andinfrared-brightgalax-

ies. Both topics are related to the dust content of the

forming and very young galaxies, and depend on the

physical processes taking place in them. The group is

developingmethods of component separation to disen-

tangletheextragalacticbackgroundfromGalacticcirrus

TheMonte Carloradiativetransfercodesdeveloped

in the group are essential tools for our research. The

codesare used formodelling ofradio spectral linesand

infraredemissionfromGalacticandextragalacticmolec-

ularclouds. Theircombinationwithrealisticcloudmod-

els from MHD calculations makesit possible to derive

thephysicalcharacteristicsofasourcefromitsemission

properties and to calculate the coolingby thedierent

molecularspeciesin theclouds.

Theresultsemerging fromtheresearchofthegroup

will allow detailed testing of the current theories con-

cerninginterstellar cloud evolution and chemistry, and

star formationin the MilkyWay and in other galaxies

attheirearlieststages.

The group is following amulti-wavelength observa-

tionalapproachwheretop-classspaceborneandground-

basedinfrared,(sub)millimetre,andradiotelescopesare

beingutilized. Duringthepastseveralyearsthetwoob-

servationalfacilitiesmostimportant forthegrouphave

been ESA's InfraredSpace Observatory(ISO) and the

Swedish-ESOSubmillimetreTelescope(SEST)atESO/-

La Silla. The launch of the Odin satellite in February

2001openedupanimportantnewresearchopportunity

forthegroup. Recently,Finland hasstartedtheoÆcial

negotiationsofESOmembership. Thegrouphasalready

succesfullyperformedits rstESO/VLTobserving pro-

gramme, and the ESO facilities will be of growing im-

portanceforthegroup. BasedonitsISOexperience,the

group is participating in the relevant Planck Surveyor

scienceprojects.

2.2 Progress

ISO:

Thegroupcontinuestheanalysisoftheextensivesetof

ISOdata which resultedfrom thesuccesfulGuaranteed

andOpenTime projectsofthe group. Themain tasks

ofscienticworkduring 2001havebeenthefollowing:

Far infrared emission by cold dust and study of its

physicalpropertiesinnearbymolecularclouds. Wehave

completedthe100/200mstudyofthedarkcloudLynds

183showingthepresenceofverycolddust,T

dust 12K

(Juvela etal. 2002). Wealsocomparedandcorrelated

the molecular gas and the cold dust properties in this

cloud. In2001progresswasmadewithsimilaranalysisof

severalfurther nearbymolecular clouds, star formation

regions, and globules: ChamaeleonI, L 1642, R Cr A,

L 1780, the Draco Molecular Cloud. For most of the

clouds we havealso performed molecular line mapping

of CO isotopomerswith SEST. We shall compare and

correlatethedustandmoleculargaspropertiesin these

clouds.

Detection and physical properties of newly formed

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regions. In the course of an extensive mapping pro-

grammeme of the Chamaeleon I molecular cloud com-

plex at 80, 100, 150 and 200m we have studied the

youngstellarobjectsassociatedwiththereectionneb-

ulaCederblad110(Lehtinenetal.2001). Thespectral

energy distribution and bolometric temperature of the

1.3mm continuum source Cha-MMS1 was derived and

itwasproventobeaClass0object(thatisaprotostar

which has not yet accumulated its nal stellar mass).

We have recently veried the presence of two gravita-

tionallyboundpre-protostellarsourcesatthecoreofthe

dark cloudLynds 183(Lehtinen, Mattila, Juvela et

al. 2002, submitted), and detected twopreviously un-

knownpointlikefar-IRsourcesintheirvicinity. Thelat-

teraregoodcandidatesfor(pre)-protostellarsources

Wearestudyingthedensitystructureanddustprop-

erties of two morphologically similar, almost spherical

globuleslocatedintheChamaeleonII/IIIcomplex. One

of them showsno signs of star formation(Thumbprint

Nebula), while the other one has an embedded IRAS

pointsourcewithin(DC303.8-14.2). TheISOPHOT100/

200m maps and a7.7m stripscan for DC303.8-14.2

have beenanalysed. The SED of the embedded IRAS

sourceindicatesatemperatureof20Kandaluminos-

ity of 1L

. The source is between the evolutionary

Classes0and I.(Lehtinen, Mattilaand Lemke2002,

tobesubmitted). As afollow-upprojectweapplied for

observing time at the near-infrared ISAAC instrument

atESO's8.2-meterVeryLargeTelescopeforthispairof

globules. Thiswassuccessful: forthersttimeaFinnish

PIgroupwasgrantedobserving time(20 hours)at the

VLT.

Mid-infrared spectrophotometryof the Unidentied

Infrared Bands (6 - 12 um) in the diuse emission of

the Galactic Plane, and in several individual Galactic

objects from diuse to molecular clouds and reection

nebulae.The diuse emission of the inner Galaxy be-

tween 5.8 and 11.6 m has been observed by us using

the ISO low-resolution spectrometer PHOT-S, comple-

mentedbylterphotometryatlongerwavelengths. The

49 selected positions are representativeof the galactic

radiation awayfrom bright discrete sources. Theanal-

ysis of this data set has been completed (Kahanpaa,

Mattila, Lehtinen et al. 2002, to be submitted). In

anotherpartoftheprojectweareanalysinganextensive

ISOPHOTdatasetofadiusecloudintheChamaeleon

complex(Rawlings, Mattila et al.) Inthis projectit

isessentialthatwecombinethemid-IRUIRband data

withmid-andfar-IRISOPHOTphotometrydataalong

thesamelinesofsightinordertostudytheconnections

betweenthePAHsandtheotherdustpopulations. The

data-analysisincluding thecalibrationwith help of the

COBE/DIRBEdatabase hasbeencompleted.

scale,itisnecessarytoobservegalaxiesatinfraredwave-

lengths. Thisisprimarilybecausemuchoftheradiation

from forming galaxies is absorbed in the UV and opti-

cal and re-emitted in the FIR. As part of the ELAIS

(\European Large Area ISO Survey") and POE (EU

Network\ProbingtheOriginoftheExtragalacticback-

groundradiation")collaborations,wehavemadealarge

near-IRsurveyofeldsobservedwithISO(Vaisanenet

al. 2000, ApJ 540, 593). The eld surveyed contains

hundreds of mid- and far-IR sources detected by ISO,

includingbrightIR-galaxiesandpossiblygalaxiesin the

process of formation. Wehave classiedgalaxies using

theirnear-to-mid-IRcoloursaswellasstudiedtheirstar-

forming properties using the ISOCAM 6.7/15 m ux

ratio(Vaisanen et al. 2002). TheELAIS surveyis

showntomostlyincludelate-typestar-forminggalaxies,

andtopickoutseveralAGN.TheELAISmid-IRgalaxy

countswerealsoutilizedinastudytopredicttheconfu-

sionlimitfordeepgalaxysurveystobeperformedwith

SIRTF(Vaisanen,Tollestrup,Fazio2001)

Combiningthemid-andfar-IRISO/ELAISdata,our

NIR-survey, and optical follow-up by other ELAIS col-

laborators, we have studied the extremely red objects

(ERO) and star-formationinducedbyinteractions. We

havealreadyobservedadeepsub-sampleofISO/ELAIS

sourceswiththeIRTFonMaunaKea. Anon-goingmor-

phological analysis of these K-band data clearly shows

thatalargepartoftheMIR-selectedobjectsareinteract-

ingormerginggalaxies( Johansson,Vaisanen 2002,

in preparation). The ISO data include objects which

have very red (R K 5 6) colours. The overall

surfacedensityofEROsin oureld andtheMIR coun-

terpartshelpustodeterminetheproportionsofevolved

high redshift ellipticals,dusty starbursts, and obscured

activegalacticnucleiin theEROsample.

Vaisanen has defended his PhD Thesis based on

extensive use of ISO/ELAIS data on 20.06.2001. The

Faculty Opponent was Prof. Malcolm Longair, Head

ofthe Cavendish Laboratory, Universityof Cambridge.

Vaisanen'sthesisandthepaperVaisanen etal.2002

markthenalscienticresultofour4-yearinvolvement

intheEU-TMRELAIS-Network.

AMonte Carlocodehasbeendevelopedforpredict-

ing the optical and infrared continuum emission from

galaxies.Theprogrammeusesthree-dimensionalmodels

forthe galaxies andtakes theinhomogeneous dust dis-

tributionand stellar populationgradientsfully into ac-

count. Theprogrammehasalreadybeenusedto model

ISOFIRobservationsofthegalaxyNGC253(Radovich,

Kahanpaaet al. 2001)

Methods fortheseparationof theFarInfraredCos-

micBackgroundradiationfromtheforegroundskycom-

ponentshavebeen furtherdevelopedand applied toan

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Workshop was organisedin Helsinki on April 5-6 2001

withparticipantsfromtheco-operatinginstitutesMPIA/

HeidelbergandKonkolyObservatory/Budapest.Wehave

participated instudies oftheinfrared backgroundradi-

ation uctuations(Kiss et al. 2001) anddust emission

in clustersofgalaxies(Stickelet al. 2001).

SEST,ATCA and other radio telescopes:

Wehavecarried outseveral researchprojectswhich, in

additiontotheirownscienticvalue,havealsoservedas

preparatory studiesfortheOdin satelliteorascomple-

mentary/followupstudiesforourISOprojects:

Extensivemappings of nearby molecular clouds in dif-

ferent CO lines have been used to study the dynami-

calandchemicalevolutionofpre-stellarandprotostellar

coresandtheirrelationtonewly-bornstars. Along-term

projecton ChamaeleonIII hasbeen completed (Gahm,

Lehtinen,Harjuetal. 2002),andaprojectonthehigh

latitude cloudLynds1642 is close to completion (Rus-

seil, Juvela, Lehtinen, Mattila, in preparation). A

compact cloud core Barnard 217 in Taurus has been

studied both by means of ammonia spectral lines and

ISOPHOT Serendipity Survey FIR dust emission data

(Hotzeletal. 2001). AstudyoftheCOabundanceand

its depletion in the Barnard 68 globulehas been com-

pleted (Hotzelet al. 2002, in press). Harjunpaa has

analysed her SEST CO observations of globules in a

studywhichaimsatdeterminingtheCO/H

2

indierent

interstellarcloudenvironments.

AthermaldustemissionmapoftheRCoronaeAus-

traliscloudwasobservedwithSEST/SIMBAat1.2mm

by Kontinen during his stay as SEST assistant (cf.

Nyman,... Kontinen et al., 2001). Several pre-stellar

clumps as well as some individual young stars can be

identied in thedust emission map. Selected positions

of the cloud have been observed in the NH

3

(1;1) and

(2;2) transitions with the 64-m Parkesradio telescope

(Harju et al.) and in several other molecular lines at

SEST.ThewholeareahasbeencoveredbyISO200m

and100mmapping.

We have recently imaged two star forming regions,

oneintheCoronaAustraliscloud,andtheotherin the

ChamaeleonIcloudintheradiocontinuumat3.6,6and

21cmwiththeAustralianCompactArray(ATCA).The

purposeoftheseobservationsistotosearchfornewpro-

tostellar candidatesand identify theradio counterparts

of IR sources. A particulartask is to study thenature

ofthedoublesourceCrA/IRS7andtheassociatedradio

lobes. (Harju et al. 2001).The fainter IRS 7B shows

what appears to be a clumpy double-jet morphology.

TheextendedlobesassociatedwithIRS7Barenotvisible

at3cm. Theupperlimitfortheirspectralindexis 0:7.

Thissuggeststhattheemissionissynchrotronradiation,

whichwould beveryunusualforaprotostellarjet. The

viouslydiscoveredgalactic synchrotron jetsources. We

have recently obtained new high quality images of the

centralsourceandtheassociatedlobesusingtheATCA

atthewavelengths3.6,6and21cm, choosingthebase-

linesandfrequenciesinsuchawaythattheuv-coverages

aresimilaratthetwoshortestwavelengths. Theanalysis

oftheradioimagesofthetworegionshasbeencompleted

andthecorrelationwiththeexistingdata(intheinfared

andhardX-rays)isunder way

Computationalastrophysics:

AneÆcientMonteCarlocodehasbeendevelopedbyJu-

vela for the treatment of radiation transfer in clumpy

molecular clouds and it has now been made publicly

available.Inconjunctionwiththree-dimensionalmagne-

tohydrodynamic(MHD)simulationstheradiativetrans-

fer modelling is used to study thestructure and physi-

calparametersof largemolecular clouds(Juvelaet al.

2001; Padoan, Juvela et al. 2001, 2002). Studies of

thecoolingeÆciencyofinhomogeneouscloudshavebeen

startedand forthe rsttime MHD simulationsare be-

ing used to provide a realistic description of the cloud

structure(Juvelaetal. 2001). Radiativetransfercalcu-

lationsarebeingroutinelyusedtoassisttheinterpreta-

tionofmolecularlineobservationswithSESTandother

radiotelescopes(Juvelaetal. 2002,Hotzeletal. 2002,

Tothet al. 2002,Russeiletal. 2002).Radiativetrans-

fer calculations havebeen used to assist studies of the

statisticalpropertiesof interstellarclouds(e.g. Padoan

etal. 2002, inpreparation).

Odin:

Asaculminationofmorethan10yearsofeorts,includ-

ing our participation over the whole period, Odin was

successfullylaunchedonFebruary20th2001. Ourgroup

participated in the organisation of a joint aeronomy-

astronomypressconferenceforFinland. SeveralTV/ra-

diointerviewsweregiven. The commissioningphaseof

the Odin astronomical observing programme included

testing/checking of the pointing and calibration proce-

duresaswellasfrequencytuning. Thisphasetooksome-

what longer than intended. The rst high-priority as-

tronomical observations were started in October 2001.

These included targets from our "Odin Dark Clouds"

programme(LeadScientistsHarjuandFalgarone). The

analysis of the rawdata, which we candownload from

the central Odin data storage in Stockholm, has been

startedat theendof2001,aidedbyanOdin astronom-

icaldataanalysis workshop which wasorganisedinDe-

cemberin Onsala. Important preparatorywork for our

Odin programmeme has been done using the Swedish-

ESOSubmillimetre Telescope(SEST) at ESOLa Silla,

especially using the newly established SEST Imaging

BolometerArray(SIMBA).OurgroupmemberandYo-

ungOdinAssociateKontinenhasservedasSEST-As-

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Finland researchgrant.

Planck Surveyor:

HelsinkiObservatoryparticipatesinthePlanckSurveyor

project. Preparatoryworkandscienticstudiesarecar-

riedouttoensureeÆcientuseofPlanckdataforstudies

of astronomicalforeground objects ranging from exter-

nal galaxies tolocal interstellarmedium and regions of

star formation. The researchersparticipating in scien-

tic Planck projects are K. Mattila, J. Harju, M.

Juvela, K. Lehtinen, M. Rawlings, P. Vaisanen,

andJ. Kahanpaa.

ThescienticBaselineCoreProgrammemeofPlanck

wascreatedduring2001. AftertheESAcallforpropos-

alsin April2001,researchproposalswerewrittenunder

theleadership ofcoordinatorsselectedearlierthat year

at the rst Planck General Meeting. The science pro-

gramme was accepted by the Planck Science Team in

July2001. EachproposalhasaScienceWorkingGroup

leadby twocoordinators. Three of the acceptedscien-

ticproposalsarecoordinatedbyresearchersatHelsinki

UniversityObservatory:"Thelocalinterstellarmedium"

(Juvela), "Cold Cores" (Mattila) and "Low z dusty

galaxies"(Mattila). IntotalHelsinkiObservatorypar-

ticipatesintheworkofeightscienticworkgroups. The

topics of these work groupsreect thecurrentresearch

of interstellarmedium carried out at the Observatory:

Planckdata will be used for studies of diuse gas and

dust, molecular cloudsand star-formation in theMilky

Wayandothergalaxies.

Part of the work in the Planck consortiumis orga-

nized throughseparateTechnicalWork Groups. Juve-

la is a coordinator of the group"Simulation of diuse

interstellar emission" which provides templates of the

diuse foregroundsources to beused in theseparation

of emissioncomponentsfrom Planckobservations. The

workis in progressand template maps are being made

available to researchers within the Planck community.

Templatesalreadyexistforsynchrotronemission(polar-

izedemissionandtotalintensity),thermaldustemission

and free-free radiation. As a special case, the impor-

tanceofzodiacallightisbeingevaluatedusingthelatest

theoretical and laboratory results for the emissivity of

dustgrainsatsub-mmwavelengths. Juvelaisstudying

possibilitiestoprovidetemplatesfortheanomalousmi-

crowaveemission, which may becaused by verysmall,

rapidlyspinningdustgrains.

Juvela attended the kick-o meeting of technical

workgroupsoncomponentseparationinPadovainSep-

tember 2001. Together with P. Paatero (Helsinki Uni-

versityPhysicsDepartment)Juvelahasstudiedmethods

to separate dierent emission components from Planck

observations. Preliminary resultswere presentedat the

PlanckImageProcessingWorkshopinPisainJuly2001.

Person-monthsofwork: 113

Externalnancing:

AcademyofFinland: 1450000FIM

GraduateSchoolforAstronomyandSpacePhy-

sics: 180000FIM

Wihuri Foundation50000FIM

VaisalaFoundation42000FIM

2.4 Tests of learning

Vaisanen, Petri

Infraredpropertiesofgalaxiesandconstraints

of galaxy evolution; PhD dissertation 2001; De-

partmentofAstronomy,UniversityofHelsinki

Johansson,Peter

Infraredanddynamicalstudies ofinteracting

galaxies; M.Sc. thesis; 2001; Department of As-

tronomy,UniversityofHelsinki

2.5 Visits abroad

Harju, Jorma

KungligaTekniskaHogskolan,AlfvenLabora-

torium,Sweden,18.-20.6.2001,3days

Chalmers Tekniska Hogskolan, Onsala Rym-

dobservatorium,Sweden,14.-16.12.2001,3days

Juvela,Mika

ESA/ESTEC, "The Scientic programme of

PlanckSurveyor"meeting,Noordwijk,TheNether-

lands,30.1.-2.2.2001,4days

VILSPA,Spain,5.-9.2.2001,5days

C.N.R.ResearchArea,Italy,4.-6.7.2001,3days

AstronomicalObservatoryofPadua,Italy,26.-

27.9.2001,2days

Konkoly Observatory, Hungary, 4.-5.10.2001,

2days

PlanckLFIConsortiumMeeting,Eibsee,Ger-

many,16.-18.10.2001,3days

Kahanpaa, Jere

CESR-CNRS,Toulouse,France,11.-13.6.2001,

3days

(8)

EuropeanSpaceAgency(ESA-Vilspa),Spain,

5.2.-9.2.2001,5days

KungligaTekniskaHogskolan,AlfvenLabora-

torium,Sweden,17.-19.6.2001,3days

many,17.-18.10.2001,2days

Mattila,Kalevi

OdinScienceTeammeeting,Stockholm(Solna),

Sweden,9.1.2001,1day

ESA/ESTEC, "The Scientic programme of

PlanckSurveyor"meeting,Noordwijk,TheNether-

lands,30.1.-2.2.2001,4days

Copenhagenobservatory,ESA'sGAIAproject

Workshop,Denmark,21.-22.3.2001,2days

OdinScienceTeammeeting,Kiruna,Sweden,

23.-24.4.2001,2days

EuropeanSouthernObservatory,Observing

ProgrammemesCommitteemeeting,Germany,29.-

30.5.2001,2days

KonkolyObservatory,ISOPHOT-EBLWork-

shop,Budapest,Hungary,4.-7.10.2001,4days

many,17.-18.10.2001,2days

ChalmersTekniskaHogskola,OdinScienceTeam

meeting,Goteborg,Sweden,25.10.2001,1day

EuropeanSouthernObservatory,ObservingPro-

grammemesCommittee meeting, Germany , 27.-

28.11.2001,2days

Rawlings, MarkG.

LaPalmaObservatory,CanaryIslands,Spain,

26.7.-3.8.2001,9days

2.6 Visiting academics

Hotzel,Stephan,Dr.rer.nat.,MPIAstronomie,

Germany,August-September2001,45days

Lemke,Dietrich,Prof.,MPIAstronomie,Ger-

many,4.-8.4.2001,5days

del Burgo, Carlos, Ph.D., MPI Astronomie,

Germany,5.-8.4.2001,4days

Abraham,Peter,Ph.D.,MPIAstronomie,Ger-

many,5.-8.4.2001,4days

Balasz, Laszlo, Prof., Konkoly Observatory,

Hungary,5.-8.4.2001,4days

Kiss,Csaba,MSc.,KonkolyObservatory,Hun-

gary,5.-8.4.2001,4days

Sweden,23.7.2001,1day

Longair, Malcolm, Prof., Cavendish Labora-

tory,GreatBritain,19.-20.6.2001,2days

2.7 Papers read at scientic confer-

ences, symposia, meetings etc.

Harju, Jorma

"Radiocontinuumemissionfromprotostars",

colloquium lecture, Oulu University, Department

ofphysicalsciences14.11.2001,Oulu,Finland

Juvela,Mika

"ComparisonofISOPHOT,DIRBEandIRAS

FIRmapsinregionsoffaintcirrusemission",Cal-

ibration Legacy of the ISO mission, 5.-9.2.2001,

VILSPA, Spain

"Cirruscolours",EBLWorkshop,5.-6.4.2001,

Helsinki,Finland

"ComparisonofISOandDIRBEcalibration",

EBLWorkshop,5.-6.4.2001,Helsinki,Finland

"Separation of ZL, Cirrus and EBL", EBL

Workshop,5.-6.4.2001,Helsinki,Finland

"Component separation with multilinear en-

gine", PlanckImageProcessingWorkshop,4.-6.7.

2001,Pisa,C.N.R.ResearchArea, Italy

"SeparationoftheZL,CirrusandEBL:asta-

tusreport",3rdInternalExtragalacticBackground

Meeting, 4.-5.10.2001, Budapest, Konkoly Obser-

vatory,Hungary

"PlanckrelatedresearchoftheInterstellarMat-

terandStarFormation",Antaresseminar,1.11.2001,

Helsinki,Finland

Kahanpaa, Jere

"ISOObservationsoftheunidentiedinfrared

bandsinthediuseISM",XXXVAnnualMeeting

oftheFinnish PhysicalSociety,22.-24.3.2001,Jy-

vaskyla,Finland,poster

"PolyaromatichydrocarbonsinthediuseISM",

InfraredandSubmillimeterSpaceAstronomy,11.6.

2001,Toulouse,France

Lehtinen, KimmoK.

"ComparisonofFIRISOPHOTmapsofbright

molecularcloudswithIRASandCOBE/DIRBE",

The Calibration Legacyof the ISO Mission, 5.2.-

9.2.2001, European Space Agency (ESA-Vilspa),

Spain

(9)

\Prospects of diuse sky brightnessphotom-

etrywith GAIA", invited talk at theGAIA Pho-

tometryWorkshop,Copenhagen21-22.3.2001

"ISO and Odin related research of theInter-

stellarMatterandStarFormation",Antaressem-

inar,1.11.2001,Helsinki,Finland

2.8 Membershipinscienticandschol-

arly societies

Harju, Jorma

Finnish National Committee of URSI, 2000-

2002

Lehtinen,KimmoK.

FinnishAstronomicalSocietyry,chairman2000-

2001

Mattila,Kalevi

FinnishAcademyofScienceandLetters,mem-

ber1982-

FinnishNationalCommitteeofAstronomy(IAU),

1973-

FinnishCOSPAR-Committe,1988-

FinnishNationalCommitteeofURSI, 1972-

2.9 Additional information

Juvela, Mika

CoordinatoroftheTechnicalWorkGroups2.8

"Simulation of the diuse interstellar emission",

7.3 \Simulation of diuse emission and analysis

tools", and oftheScienticWorkingGroup"The

LocalInterstellarMedium"inPlancksatellitecon-

sortium

PlanckLFIAssociate(ESA)

Kontinen,Samu

SEST-AssistantatLaSilla,Chile1.4. {31.12.2001

Mattila,Kalevi

EuropeanSouthernObservatory,expertadvi-

sorinObservingProgrammesCommittee

Odin ScienceTeammember

ISO/ISOPHOTConsortium,Co-Investigator

PlanckLFIAssociate(ESA)

Finnish Graduate School of Astronomy and

SpacePhysics,Boardmember

\Dustynearbygalaxies"and\Colscores"inPlanck

satelliteconsortium

Rawlings,Mark G.

Actedasscienticrefereeforproposalsto the

U.K.panelfortheallocationoftelescopetime(P.-

A.T.T.). Grantedobservingtimeforproposalsfor

telescopetime.

Course assistant in the Summer School \In-

strumentation forSpace Physicsand Astronomy"

oftheFinnishGraduateSchoolofAstronomyand

SpacePhysics,atUniversityofTurku,Department

ofPhysics28.5.-1.6.2001

Johansson,Peter

Participant of 'COSMO-01: Particle Physics

andtheEarlyUniverse',Rovaniemi,Finland,29.8-

5.9.2001

(10)

NationalTechnologyAgency

(Pigmentproject,1999-2001)

Typeofresearch Basicresearch,share:70%

Appliedresearch,share:20%

Developmentwork,share:10%

Directorofresearch Prof.Lumme,Kari

Telephone 19122910

Fax 19122952

E-mail Kari.Lumme@Helsinki.Fi

ResearchstawithaPh.D. KariLumme,Prof

LarsLamberg,Ph.D.

Ph.D.student(s) KimGreen,M.Sc.

M.Sc.student(s) RiikkaKangaslampi

AnttiPenttila

SeppoPietarinen

JaniTyynela

Theplanetarygroup(PRG)attheUniversityofHelsinki

Observatoryhascontinueditsbasicresearchintheeld

of light scattering and radiativetransfer. Results have

beenappliedto cosmic dustin order tounderstand the

physical properties of those small particles. The same

methodshavealsobeenappliedtosomeindustrialprod-

uctslikepigmentsinpapercoatings.

3.2 Progress

ThePRGattheUniversityofHelsinkiObservatoryhas

concentratedonsomekeytheoreticalproblemsrelevant

tomodernsolarsystemstudies. Theseactivitiesinclude

the analysis and modelling of dust and aerosol parti-

clesbothonthesurfaces ofatmospherelesssolarsystem

bodies,inMartianatmosphereandintheinterplanetary

space and cometary comae. Interestingly enough light

scattering studies haverecentlyfound applications also

in thepigment,paperandpaintindustries. Thereason

for this is that in these areas light scattering plays an

essentialrole. Thisresearchhasbeensupportedbothby

theNational Technology Agency (TEKES)and various

industrialcompanies.

Lummeisparticipating at aCo.Ilevelbothin the

MarsExpress/HRSC-experimentandin theMicrograv-

ity project (ICAPS) on board the International Space

Station (ISS). The PRCis taking the responsibility to

analyzeandmodelthepropertiesofthesmalldustpar-

ticlesintheMartianatmosphere. IntheICAPS-project

thegroupisresponsiblefordevelopingandtestingvari-

ouslightscatteringandradioactivetransfercodes.

ThePRChassystematicallystudied andfurtherde-

veloped demanding codes to compute light scattering

bynonsphericalparticles. Developed byourowngroup

wehaveformulatedaso-calledIntEq(integralequation)

codewhichiscapabletocomputelightscatteringbyany

irregular solid oraggregatedparticle. Theparticle can

alsobeoptically amisotropicorinhomogeneous.

lightscatteringbyarotationallysymmetricsolidparticle

oranaggregatecomposedofspheres. Thesecodeshave

been improvedand somefundamental errorshavebeen

corrected.

The PRC hasalso actively been studying how par-

ticlesize and shapestatisticcanbededuced fromtheir

projections,mainlyobtainedfromtheTEM-images. We

havealso been able to develop quite new a l gorithms

how irregular solids canbe closely-packedwithout any

overlapping. These are important both in the eld of

cosmicduststudiesandseveralindustrial applications.

Wearecurrentlytryingtounderstandthelargedata

set of cometary polarization by applying our extensive

pooloflightscatteringcodes. Itseemsquitereasonable

that in near future we will knowmuch moreabout the

cometarydust.

The PRC consists of ve reseachers and students

partly paid by the funds from the Academy and the

National Technology Agency. The group leader Kari

Lummehasin the last few years given severalinvited

talks in international meetings. Nine refereed papers

havebeenpublished inthelastthreeyears.

3.3 Money and resources

2001: Man-monthsofwork: 35

Basicresources: 1300000FIM.

3.4 Visits abroad

Lumme,Kari

ObservatoiredeParis,France,9.-12.4.2001,4

days

ESA/ESTEC,TheNetherlands,12,-15.6.2001,

4days

ICAPS/ISS,Germany,3.-5.10. 2001,3days

4th Japan-Finland Joint symposium 'Optics

inEngineering',Japan,23.-28.10.2001,6days

DivisionforPlanetarySciences, AAS,United

States,24.11.-2.12.2001,9days

Lumme,Kari

"Modellingofmultiwavelengthpolarizationdata

of Hale-Boppand high Pmax comets",Workshop

oncometarypolarization,9.-12.4.2001,Paris,France

"Deducing particleshapesin thePROGRA2

experiment",ICAPS/ISSprojectmeeting'APhase

(11)

Netherlands

"InterpretingPROGRA2polarizationmeasure-

ments", ICAP/ISS, 3.-5.10.2001, Munchen, Ger-

many

"Light scattering studies of paper and some

pigments",4thJapan-FinlandJointsymposiumon

OpticsandEngineering,23.-28.10.2001,Osaka,Ja-

pan

"Polarization of cosmic dust in various envi-

ronments", DPS 2001, 24.11.-2.12.2001,New Or-

leans,UnitedStates

Lumme,Kari

Assessmentofcandidatesforprofessorshipat

GoddardInstituteforSpace Sciences(GISS)

(12)

NationalTechnologyAgency

Typeofresearch Basicresearch,share:50%

Developmentwork,share:50%

Directorofresearch DocentVilhu,Osmi

Telephone 19122801

Fax 19122952

E-mail Osmi.Vilhu@Helsinki.Fi

ResearchstawithaPh.D. OsmiVilhu,Docent

JuhaniHuovelin,Docent

JarkkoLaukkanen,Ph.D.

Ph.D.student(s) LauriAlha,M.Sc.

SamiMaisala,M.Sc.

PanuMuhli,M.Sc.

ArtoSalminen,lic.tech.

JuhoSchultz,M.Sc.

MikkoVaananen.M.Sc.

M.Sc.student(s) EeroEsko

PetterNikula

IrisSoranta

Associatedresearchsta PasiHakala,Docent

DianaHannikainen,Ph.D.

JukkaNevalainen,Ph.D.

JuriPoutanen,professor

The project is doingfundamental sciencewith existing

equipment, nalising FM-hardware (INTEGRAL and

SMART-1 missions), preparing1st year observing pro-

grammesforthese anddevelopingnewinstrumentation

forfuturespacemissions.

4.2 Progress

The project has studied a wide range of astrophysical

topics: Solarsystembodiesandlightscattering,thesun

and active stars, X-ray binaries and microquasars and

ActiveGalacticNuclei(AGN).

Theoretical scattering models have been advanced

substantially(tobeappliedfor AMIEmeasurementsof

the lunar surface). The coronal FeXXI 1354 line was

analysed in AB Dor using Hubble data, and thermal

sombreromodelsweredevelopedandappliedtothemi-

croquasar GRS 1915+105. The 10 new sources found

by BeppoSAX in the eld of an X-ray transient were

analysed,andgeneticalgorithmsweredevelopedtomap

gasstreams inclose binaries. Themultifrequency spec-

tra (includingCOMPTON)andVLBIpropertiesof3C

279wereanalysedinunprecedenteddetailandcompared

with models for gamma-ray production in relativistic

jets.

4.2.1 Missionsunderdevelopment

FlightModeldetectors forthetwounits of JEM-X(X-

raymonitor)ofINTEGRALhavebeendeliveredtoESA

andsuccessfullyintegratedtowaitforthelaunchinOc-

tober2002. Theprojectmembersarepreparingseveral

eldsofthecoreprogramme(guaranteedtime)andpar-

ticipate(asPIorCo-I)in7AO-1programmes.

for SMART-1 is underway and the delivery will take

placeduring 2002. XSM willoerlongtime seriesover

twoyears of X-rayaring, and methods to analyse the

dataareunder development. TheScience Validationof

the AMIEcamera of SMART-1 wasperformedin Fin-

land.

The design of the CDH computers (Command and

Data handling) of the Danish ROEMER satellite has

beennished,andiswaitingforthenancialdecisionto

buildtheFMcomputersaswell. Ifsuccessful,theproject

will have2months observing time (during 2years)for

themainMONStelescope,toobservestellaroscillations

withhighphotometricaccuracy,andtocoordinateactive

starobservationswiththeeldmonitor.

4.2.2 Missionsunder planning

Development of X-ray calorimeter for XEUS has been

madeinparallelattheUniversityofJyvaskyla,Metorex

International, and VTT. The work at Jyvaskyla and

MetorexhasconcentratedonTESdetectordesign,while

the work at VTT aims at readout (SQUID-) electron-

icsdesign. Progressin bothareashas beenachievedas

planned. ANTARESfunding has beenin akey role in

this work, since funding from other resources (mainly

ESATRP and GSTP contracts) has been signicantly

delayed.

TheIR-lter developmentwork at theUniversityof

Joensuu,aimingatinstrumentthermalltersforXEUS,

hasalsoprogressedasplanned. Newprocessingmethod

forlter gridhas been applied with success, leadingto

bettertransmissionproperties.

Growth methods of TlBr crystals have been devel-

opedforthehardX-raydetectorofXEUS.During2002

anewtravellingmoltenzoneset-upforpuricationand

crystalgrowthwill be applied and characterizedby X-

raypowderdiraction,IRandUV-VISspectroscopy.

DesignofaGEMdetectorwithdouble foilandtwo-

dimensionalreadoutboardhasbeenstartedandcharac-

terizationofsinglefoilGEMscontinued. Thedataacqui-

sitionsystembasedonutilizationofaHELIX128chan-

nelpreamplierchipandVMEADCsequencermodules

hasbeenconstructedandtested. Thecomplexgasanal-

ysissystemhasbeenreassembledandtestedin thenew

laboratory at Kumpula campus. The results obtained

withtheinstrumentwerepresentedin theInternational

Workshop on Aging Phenomena in Gaseous Detectors

(DESY, Hamburg Oct 2-5, 2001). The project has a

Co-Iin theINSPIREproposalforNASA/ MIDEXpro-

gramme(Nov. 2001),includingaGEMX-raypolarime-

ter. Mass Inst of Tech (MIT) has ordered two GEM

detectors(agasowcounterandasealedone)fromour

industrial collaborator METOREX (with NASA fund-

ing).

(13)

Externalnancing:

AcademyofFinland: 1500000FIM

NationalTechnologyAgency: 8500000FIM

4.4 Visits abroad

Vilhu, Osmi

ESA,France,18.-20.4.2001,3days

DSRI, Denmark,21.-22.5.2001,2days

ISDC,Switzerland,16.-17.8.2001,2days

UniversityofArhus,Denmark,15.-16.11.2001,

2days

Huovelin,Juhani

DSRI/Copenhagen,JEM-XSDASTmeeting,

Denmark,10.1.2001,1day

RAL/D-CIXS/XSMinterfacemeeting,Great

Britain,16.-17.5.2001,2days

ESTEC,SMART-I/D-CIXS/XSMCriticalDe-

signReviewmeeting,TheNetherlands,21.-23.5.2001,

3days

SMART-1STOWTmeeting,Darmstadt,Ger-

many,25.-26.6.2001,2days

SDAST/JEM-X meeting, Copenhagen, Den-

mark,9.10.2001,1day

ESTEC, SMART-1/MCDR meeting, Noord-

wijk,TheNetherlands,21.-22.11.2001,2days

Maisala,Sami

DSRI,JEM-X/SDASTmeeting,Copenhagen,

Denmark,9.-10.1.2001,2days

ISCD,JEM-X/SDASTmeeting,Geneve/Versoix,

Switzerland,14.-17.3.2001,3days

ISCD,JEM-X/SDASTmeeting,Geneve/Versoix,

9.-11.4.2001,3days

DSRI,JEM-X/SDASTmeeting,Copenhagen,

Denmark,7.-8.6.2001,2days

JEM-X/SDAST meeting, Copenhagen, Den-

mark,9.-10.10.2001,2days

JEM-X/SDAST meeting, Copenhagen, Den-

mark,12.12.2001,1day

Muhli,Panu

Moletai Astronomical Observatory, Institute

of Theoretical Physicsand Astronomy, Lithuania

30.3.-2.4.2001,4days

Vilhu, Osmi

"SIXASiliconX-rayArray",ESA/SXGeval-

uationmeeting,18.-20.4.2001,Paris,France,

"LowMassX-rayBinaries",Jem-X/INTEGRAL

coreprogrammemeeting,21-22.5.2001,Copenhagen,

Denmark

"Bright LMXB s", Integral LMXB subeld

meeting,16.8.2001,Versoix,Switzerland

"StatusinFinland",ROEMERPI-teammeet-

ing,15.-16.11.2001,Arhus, Denmark

Huovelin, Juhani

"InstrumentdevelopmentforXEUSandSMART-

1",ANTARESseminar,1.11.2001,Kaapelitehdas,

Helsinki,Finland,

arly societies

Huovelin, Juhani

Suomen Fyysikkoseura, Astro- ja avaruusfy-

siikanjaosto,2001-,Finland,chairman

4.7 ActingasOpponentandpre-exam-

inations of doctoral dissertations

Vilhu, Osmi

S.M.Harun-or-Rashid:"CosmologicalParam-

etersandBlackHoles",UniversityofHelsinki,19.10.

2001,pre-examination

Vilhu, Osmi

InternationalAstronomicalUnionDiv. XISpace

Astronomy and High Energy Astrophysics Orga-

nizingCommittee

Leader of the consortium 'High Energy As-

trophysics and Space Astronomy (HESA)' of the

ANTARESspaceresearchprogrammeoftheAcademy

ofFinlandandTEKES

MemberoftheRoemer-satellitePI-team

Co-InvestigatorofJem-X/INTEGRALandXSM/

SMART-1satelliteprojects

(14)

Finnish Graduate School in Astronomy and

SpacePhysics,Summer School: "Instrumentation

forSpacePhysicsandAstronomy"programmecom-

mittee,2001,Finland

Principal investigatorofthe SMART-1/XSM

project.

Co-investigatoroftheINTEGRAL/JEM-Xpro-

ject.

ChairmanofthesteeringboardinTEKESin-

strument projectsINTEGRAL/JEM-X, SMART-

1/XSM, instrument development for XEUS, and

IRltersforXEUS.

Muhli,Panu

MemberoftheScienticOrganisingCommit-

tee of the2002 Nordic-Baltic Research School on

"Astrophysicsof Interacting Stars", tobe heldat

theMoletaiAstronomicalObservatory,Lithuania,

August2002.

(15)

Typeofresearch Basicresearch

Directorofresearch DocentMuinonen,Karri

Telephone 19122941

Fax 19122952

E-mail Karri.Muinonen@Helsinki.Fi

ResearchstawithaPh.D. KarriMuinonen,Docent

LauriJetsu,Docent

MikkoKaasalainen,Docent

JukkaPiironen,Docent

Phdstudent(s) ThomasHackman,M.Sc.

MikaKokko,M.Sc.

JenniVirtanen,M.Sc.

JohannaTorppa,M.Sc.

TeemuLaakso,DI

SannaKaasalainen,M.Sc.

M.Sc.student(s) JoonasLyytinen

JyriNaranen

OlaviLindroos

Associatedresearchsta TimoNousiainen,Ph.Lic.

ThescienticinterestsofSPAcan bedividedintothree

main partially overlapping categories of (i) astronomi-

cal observations, (ii) fundamental physics, and (iii) in-

verse problems. Astronomical observations are carried

outusing modern telescopes(e.g., NordicOptical Tele-

scope,VeryLargeTelescope)inasteroidphotometry,po-

larimetry,andastrometry,andthephotometryandspec-

troscopyoflate-typestars. SPAisplayingacrucialrole

in the Science Validation and Calibration of the fore-

comingSMART-1/AMIEobservationsof theMoon(vi-

sual wavelengths). In addition, SPA is taking part in

SMART-1/D-CIXSexperiment with animportantcon-

tributiontounderstandingthemonochromaticX-rayscat-

tering by the lunar surface. In 2001, SPA has taken

a task-leading role in asteroidorbit determination and

predictionfor theESAastrometric cornerstonemission

GAIA.Infundamentalphysics,boththeoreticalandex-

perimental advances arebeingmade. As totheory, the

SPA research is focussed on scattering and absorption

oflightbysinglesmallparticlesand byparticulateme-

dia, and the celestial mechanics of the few-body prob-

lem,whereasexperimentsarebeingcarriedouttomea-

surealbedosofsinglesmallparticlesandbackscattering

characteristics of particulate media (scattering labora-

tory at the Observatory). SPA is participating in the

ICAPS experiment (Interactionsin Cosmic and Atmo-

sphericParticleSystems)aboardtheInternationalSpace

Station(ISS).TheSPAinverseproblemscanbedivided

into mathematical methods and astronomical applica-

tions. Astotheformer,SPAisdevelopingtechniquesfor

statisticaldetermination ofasteroidorbits,forthecom-

putation of collision probability of near-Earth objects,

for lightcurveinversion of physical properties of aster-

oids(e.g., rotationand shape,microscopicsurfaceprop-

erties),andfortime-seriesanalyses. Astothelatter,the

applicationsinclude,e.g.,theimpacthazardfromnear-

imagingduringtheSMART-1mission,time-seriesanaly-

sisapplications,stellarmagneticactivity,andindustrial

applications.

5.2 Progress

Inwhat follows,SPA publicationsin theyear 2001are

brieyreviewed. Theyearwasparticularlygroundbreak-

ing in inverse light scattering problems concerning as-

teroidsaswell assmallparticles. A signicantadvance

wasmadeinthecomputationofEarth-asteroidcollision

probabilities. Thereweresubstantialadvancesinstudies

of Gaussian randomparticles and their light-scattering

characteristics.

SaarinenandMuinonen(2001)publishedaGaus-

sian (or lognormal) wood-bre model along with ray

tracing computations, and succeeded in estimating the

statisticalparametersusingangularlight-scatteringmea-

surementsat DLR-Stuttgart. Volten et al. (2001)pub-

lishedextensivemeasurementsofscatteringmatrices(at

theFreeUniversityofAmsterdam)foratmosphericaero-

solparticlesand,asapioneeringachievement,provideda

successfulinterpretationof themeasurementsusingray

optics treatment for Gaussian random particles. The

worksbySaarinen andMuinonen,ononehand,and

Voltenet al. ontheother,areexamplesofinverselight

scattering problems, where particle physical properties

arederivedfromlaboratorymeasurementsoftheirscat-

teringcharacteristics. Theseworkssuggestabrightfu-

tureforinversescatteringproblems.

Gaussian random particles oer a challenging geo-

metricalinverseproblem asthemselves: givenasample

of particle shapes, how can one estimate the statisti-

cal shapeparameters? Thecornerstone work by Lam-

berget al. (2001)oersamaximumlikelihood estima-

torfortheinverseproblem,sofartherstandtheonly

existing solution to the problem. This study was car-

riedoutincollaborationwiththePlanetaryAstronomy

-groupledbyProf. K.Lumme.

Nousiainenet al. (2001)appliedsecond-orderper-

turbationseries to the computation of radar backscat-

teringcharacteristicsof nonsphericalice particles mod-

eled as Gaussian random spheres. Muinonen et al.

(2001b) carried out extensive simulations for the clas-

sical shadowingeect in light scattering by clusters of

opaquesphericalparticles. Theyestablished, unequivo-

cally,thegradual strengtheningofthe shadowingeect

foragrowingnumberofconstituentsphericalparticles.

Zubkoet al. (2001)studied compositeparticle scatter-

ingand,inparticular,approximatingcompositeparticles

withsystemsofsphericalsub-particles.

M. Kaasalainen and Torppa (2001) formulated

eÆcient methods for determining the shapes of irreg-

(16)

ular bodies from their lightcurves; in M. Kaasalai-

nenet al. (2001a,b)the rotationalstateand scattering

properties were added to the inversion procedure, and

the results showed complete agreement with the exist-

ing space-probe images and radar-based models of as-

teroids. M. Kaasalainen (2001)further showed that

the dynamical parameters of an object in a complex

rotational state can also be deduced from photometric

data. M. Kaasalainen and Laakso (2001)developed

aneworbitintegrationschemeforsolarsystemdynam-

icsthatisespeciallysuitableforincludingnonconserva-

tive forces. L. Lamberg and M. Kaasalainen (2001)

presented a robust numerical algorithm for solving the

so-calledMinkowskiproblem.

Muinonenetal. (2001a)publishedrigorousnumer-

icaltechniquesforthecomputationofthecollisionprob-

abilitybetweenasteroidsandplanetary bodies. Incon-

tradistinction to earlier techniques by others, the new

oneaccountsforthefullsix-dimensionalnonlinearprob-

abilitydensityoftheasteroidorbitalelements. Thetech-

niquereliesontheso-calledstatisticalrangingmethodof

asteroidorbitdetermination(Virtanenetal.,inpress).

S.Kaasalainenetal. (2001)carriedoutacompara-

tive,partlysemiempiricalstudyoftheoppositioneects

for atmosphereless solar system bodies. Using a sta-

tistical, inversion-theoretical technique, they were able

to estimate the number and character of photometric

data necessary for well-dened opposition eects. The

method has been futher dev elopedand applied to e.g.

asteroiddata.

We have constructed a device for zero phase mea-

surements of terrestrial materials, which is being used

in bothlaboratoryand eldmeasurements. Thedevice

consistsofalightsource(laserorwhite),linearpolariz-

ersforbothincidentand emergentlight beam,and the

beamsplittertoreachthesmallestphaseangles. Thede-

vice hasbeenused this far fore.g. powders, sand, and

meteoriterocks.

Hackman, Jetsu and Tuominen (2001) presented

Doppler imagingsurface temperature maps for theFK

Comae -typestar HD199178. Theimages showaper-

sistent high latitude spot and indications of antisolar

dierential rotation. Piironen, S. Kaasalainen, and

Virtanenparticipated,besidecarryingoutasteroidob-

servations, to the photometric program of FK Comae

(Korhonenetal.,2001). TheprojectispartofthePhD

studiesbyHeidiKorhonenfromDepartmentofPhysical

sciences, University of Oulu. Observations were made

withthe60-cmKVA-telescopeatLaPalmain 1999.

SPAparticipatedintheASTROVIRTELproject,in

whichcontextcrucialfollow-upandprecoveryastromet-

ric observations were obtained for the transneptunian

object 2001 KX76. That object turned out to be the

largestof allasteroidslistedupto date. Pleasesee the

ESOandESAPressReleases.

Sincethebeginningofitsactivitiesin1998,SPAhas

published altogether (7+1)+(10+6)+(9+8)+(17+1) =

(43+16) = 59 articles in either refereed scientic jour-

nalsorrefereedscienticcompilationworks/proceedings

(in addition, as of January 2002, with 0+0 published,

6+8inpressand6+0submitted). SPAappearstoreach

thesteadystateofpublishing16-17refereedpaperseach

year.

Keywords: absorption,scattering,multiplescatter-

ing, coherent backscattering, small particles, reection,

regolith, asteroids, comets, planetary satellites, plane-

tary rings, interplanetary dust, atmospheric particles,

celestialmechanics, statistical orbit determination, im-

pacthazard,collisionprobability,numericalintegrators,

Hamiltonian dynamics, time series analysis, solar-type

stars, cool stars, variable stars, stellar activity, stellar

magnetism,stellarspots,stellardierentialrotation,stel-

larDopplerimaging

5.3 Money and resources

Specialresources: 140000FIM.

Externalnancing:

Academy of Finland, 'Light Scattering by

GaussianRandomMedia': 457700FIM

AcademyofFinland,'Coherentmultipleback-

scatteringbyinhomogeneousmedia': 46300FIM

AcademyofFinland,'PlanetarySciencePro-

gram': 70900FIM

Academy of Finland, 'Inner-coma interac-

tion of cometary dust, gas, and electromagnetic

radiation': 15500FIM

AcademyofFinland,AcademyResearchFel-

lowpost: 302000FIM

MinistryofEducation,'GraduateSchoolfor

AstronomyandSpacePhysics': 190000FIM

INTAS,'InterpretingbasisforESASMART-

1/AMIEobservationsoftheMoonwithexperience

fromClementineandLunarProspectordataanal-

ysis, laboratoryand theoreticalmodellingof light

scatteringindustysurfaces': 10000EUR

1

http://www.hq.eso.org/ outreach/press-rel/pr-2001/phot-27-

01.html

2

http://sci.esa.int/hubble/news/newsrelease.cfm?oid=28146

(17)

Saarinen,Kari

Saarinen, Kari; NearInfra-RedMeasurement

BasedControlSystemforThermo-MechanicalRe-

ners; Ph. D. thesis; 2001; Department ofMath-

ematicalInformationtechnology,UniversityofJy-

vaskyla

5.5 Visits abroad

Muinonen,Karri

Smart-1/Amiesciencemeeting,France,3.-4.5.

2001,2days

Asteroids2001meeting,Palermo,Italy10. 6.

-16. 6. and OsservatorioAstronomicodi Torino,

16. 6. -20. 6.,together11days

Osservatoriodi Torino,Italy,27.7.2001-31.12.

2001,158days

JapanSpaceguardAssociation,Japan,22.10.-

28.10.2001,7days

AstronomicalInstituteoftheSlovakAcademy

of Sciences, Slovak Republic, 15.11.-19.11.2001, 5

days

AMIE Science Meeting, Helsinki, and AMIE

FlightModelScienceValidation,Tampere, 12.12.-

20.12.2001,8days

Piironen,Jukka

Uppsala observatory, Sweden, 31.1.-5.2.2001,

6days

Asteroids 2001 meeting,Palermo, Italy, 9.6.-

16.6.2001,8days

OsservatorioAstronomicodiTorino,Italy,29.7.-

7.8.2001,10days

DLR/Stuttgart,GermanyjaOsservatorioAs-

tronomicodi Torino,Italy,30.7.-7.8.2001,12days

Future Lunar Exploration and Workshop on

LunarScience,Germany,15.-19.9.2001,5days

Hackman, Thomas

NordicOpticalTelescope,Spain,3.-12.6.2001,

10days

Universityof Colorado, United States, 30.7.-

3.8.2001,5days

Kaasalainen,Mikko

OsservatorioAstronomicodiPalermoetc.,Italy,

9.-16.6.2001,8days

Paris,France,9.-12.10.2001,4days

States,26.-30.11.2001,5days

Kaasalainen, Sanna

EuropeanGeophysicalSocietyXXVIGeneral

Assembly,France,25.-30.3.2001,7days

NordicOpticalTelescope,Spain,17.-24.11.2001,

8days

States,26.11.-3.12.2001,8days

Virtanen,Jenni

Asteroids 2001 meeting Santa Flavia, Italy,

10.-15.6.2001,6days

Celmec III meeting,Monte Porzio,Italy,16.-

22.6.2001,7days

NOTObservatory,LaPalma,CanaryIslands,

Spain,21.-23.11.2001,2days

5.6 Visiting academics

VladislavSidorenko,Ph.D.,Russia,7.5.-18.5.2001,

12days

GonzaloTancredi,Ph.D.,Uruguay,10.5.-19.5.2001,

10days

Yurij Shkuratov, Ph.D., Ukraine, 21.5.-17.6.2001,

27days

OlgaMyloslavskaya,Ph.D.,Ukraine,21.5.-17.6.2001,

27days

DmytroStankevych,Ph.D.,Ukraine,21.5.-8.6.2001,

18days

DmytroStankevych,Ph.D.,Ukraine,13.12.-18.12.

2001,6days

AndrejOvcharenko,Ph.D.,Ukraine,21.5.-8.6.2001,

18days

Jean-LucJosset, Ph.D., SMART-1/AMIE Princi-

palInvestigator,Switzerland, 13.12.-16.12.2001,3

days

Stephane Beauvivre, Ph.D., Switzerland, 13.12.-

19.12.2001,6days

Patrick Pinet, Ph.D., AMIE-CoI, France, 13.12.-

15.12.2001,2days

AntonellaBarucci,Ph.D.,AMIE-CoI,France,13.12.-

15.12.2001,

(18)

16.12.2001,3days

Claes-InvarLagerkvist,Docent,AstronomiskaOb-

servatoriet,Sweden,11-12.10.2001,2days

Josef Durech, PhD, Charles University, Prague,

CzechRepublic,3.12.-8.12.2001,6days

Muinonen,Karri

"CollisionprobabilitycomputationusingBay-

esianprobabilities",InternationalWorkshoponCol-

laborationandCoordination AmongNEOObser-

vers and Orbital Computers, 23.-26.11.2001, Ku-

rashiki,Okayama,Japan

"Acceleration of non-spherical dust particles

inacometaryKnudsenlayer",EGSXXVIGeneral

Assembly,Nice,France

"Asteroid photometry and polarimetry: re-

viewand future prospects",Asteroids 2001: from

Piazzitothe3rdMillenium,Palermo,Italy,poster

"Invarianceandvalidityofstatisticalorbitde-

termination methods", Asteroids 2001: from Pi-

azzito the3rdMillenium,11.-16.6.2001,Palermo,

Italy,poster

"Interpreting asteroid photometry and pola-

rimetryusingasinglemultiple-scatteringmodel",

Asteroids2001: from Piazzitothe3rdMillenium,

11.-16.6.2001,Palermo,Italy

"Laboratorystudies for the opposition eect

andnegativepolarizationofsimulatedasteroidre-

goliths", Asteroids 2001: from Piazzi to the 3rd

Millenium,11.-16.6.2001,Palermo,Italy

"Applicationsofstatisticalranging",DPS2001,

26.-30.11.2001,NewOrleans,United States

"Coherentbackscatteringbysingleinhomoge-

neousparticleslargecomparedtothewavelength",

NATOAdvanced ResearchWorkshop onthe Op-

ticsofCosmicDust,16.-19.11.2001,Bratislava,Slo-

vakRepublic

Piironen,Jukka

"Spin rates of asteroids", Asteroids 2001, 6-

10.6.2001,Palermo,Italy,poster

"Comparativestudyofasteroidoppositionpho-

tometry and polarimetry", Asteroids 2001: from

Piazzitothe3rdMillenium,Palermo,Italy,poster

"Laboratory photometry and polarimetry of

regolith-typeparticulatesamples",Asteroids2001:

poster

"Statistics ofasteroidsrotationperiods",As-

teroids 2001: from Piazzi to the 3rd Millenium,

11.-16.6.2001,Palermo,Italy,poster

Kaasalainen, Mikko

"Asteroidmodelsfromdisk-integratedphoto-

metry",Ceres2001-workshop,9.-12.10.2001,Paris,

France

"Asteroidmodelsfromphotometricdata",In-

verse Days 2001 (Finnish Inverse Problems Soci-

ety),12.-14.12.2001,Helsinki,Finland

"Modelsofselectedmain-beltandnear-Earth

asteroids",DPS2001,26.-30.11.2001,NewOrleans,

UnitedStates

"Modernmethodsofasteroidlightcurveinver-

sion: results and discussion", Asteroids 2001, 9.-

16.6.2001,SantaFlavia,Sisilia, Italy,poster

"Integratorpackageforstatisticalorbitdeter-

mination",Asteroids2001: fromPiazzi tothe3rd

Millenium,11.-16.2001,Palermo,Italy,poster

Hackman, Thomas

"SurfaceimagingofHD199178:Highlatitude

spot and dierential rotation ", 12th Cambridge

Workshop onCoolStars,Stellar Systemsandthe

Sun,30.7.-3.8. 2001,UniversityofColorado,Boul-

der,UnitedStates,poster

Kaasalainen, Sanna

"Laboratorystudiesontheoppositioneectof

regolith-type materials", XXXV Annual Meeting

vaskyla,Finland

"Oppositioneectofregolith-typematerials",

EuropeanGeophysical SocietyXXVI GeneralAs-

sembly,25.-30.3.2001,Nice,France

"Laboratory photometry and polarimetry of

regolith-typeparticulatesamples",Asteroids2001,

11.-16.6.2001,Palermo,Italy,poster

"Coherent Backscattering from regolithsam-

ples", DPS 2001, 26.11.-3.12.2001, New Orleans,

UnitedStates,poster

"Oppositioneectofregolith-typematerials",

EGSXXVIGeneralAssembly,PS5. Opensession

on lunar exploration: Lunar Odyssey 2001, Nice,

France, poster

"Laboratorystudiesoftheoppositioneectof

regolith-type materials", XXXV Annual Meeting

vaskyla,Finland

(19)

particulate samples", DPS 2001, 26.-30.11.2001,

NewOrleans,United States,poster

Virtanen,Jenni

"Optimizedstatistical ranging ofasteroidor-

bits", CELMEC'III - Third Meeting on Celestial

Mechanics,16.-22.6.2001,Rome,Italy

"Integratorpackageforstatisticalorbitalrang-

ing", CELMEC'III - Third Meeting on Celestial

Mechanics,Rome,Italy,poster

"Optimizedorbitalrangingfortrans-Neptunian

andnear-Earthobjects",Asteroids2001: fromPi-

azzito the3rdMillenium,10.-15.6.2001,Palermo,

Italy

"Orbits for Trans-Neptunian Objects Using

StatisticalRanging",DPS2001,26.-30.11.2001,New

Orleans,UnitedStates,poster

arly societies

Muinonen,Karri

Finnish Physical Society, Division for Astro

andSpace Physics,2001,Finland

TheSpaceguardFoundation,2001,Italy,board

member

International Astronomical Union, Commis-

sion15OrganizingCommittee,2001

InternationalAstronomicalUnion,WorkingGroup

forNear-EarthObjects,MemberofOrganizingCom-

mittee,2001

forNear-EarthObjects,MemberofTechnicalRe-

viewCommittee,2001

forCometsandDistantObjects,2001

Jetsu,Lauri

FinnishNationalCommitteeofAstronomy10.9.-

31.12,2001,Finland,boardmemberandsecretary

Departmentofastronomy,UniversityofHelsinki,

1.1.-31.12. 2001,Finland,chairmanoftheboard

Piironen,Jukka

TelescopioNazionaleGalilei,TimeAllocation

Committee,Italy,expertmember

Hackman, Thomas

TahtitieteellinenyhdistysUrsary.,14.11.2000

-31.12.2001,Finland,boardmember

inations of doctoral dissertations

Muinonen,Karri

Wang Huining: "Microwaveemission models

ofsnow", Helsinki Universityof Technology,27.4.

2001,Finland,actingasopponent

Pasi Nurmi: "Long-term simulations of the

dynamicevolutionofcometsandmeteoroids",Uni-

versityofTurku,June2001,Finland,pre-examina-

tion

Muinonen,Karri

Piazzi2001, Palermo,Italy, 2000June11-15;

memberoforganizingcommittee

AsteroidsIIIbook,SpaceScienceSeries;mem-

beroforganizingcommittee

WorkshoponCollaborationandCoordination

among NEO Observers and Orbital Computers,

Kurashiki,Okayama,Japan,2001Oct. 23-26;mem-

beroforganizingcommittee

(20)

6.1 Scientic monographs

Harju, Jorma; Juvela, Mika; Kontinen, Sa-

mu;Heikkila,Arto;Wiik,Kaj: Johdatusradioas-

tronomiaan. Report1/2001,Observatory,Univer-

sityofHelsinki.

Huovelin, Juhani: Tahtien rakenne ja kehitys.

Report2/2001,Observatory,UniversityofHelsinki.

Vaisanen, Petri: Infrared properties of galax-

ies and constraints of galaxy evolution. Report

3/2001,Observatory,UniversityofHelsinki.

6.2 Articles in refereed journals

1. BerdyuginA.;TeerikorpiP.;HaikalaLauri;Han-

skiM.;KnudeJ.;MarkkanenTapio: Interstellar

polarizationathighgalacticlatitudesfromdistant

stars. IV. A catalog of polarization data for the

NorthGalacticPoleArea. Astron. Astrophys. 372

(2001): 276-280.

2. Green, Kim; Lumme, Kari: Comparison of

radiative transfer Monte Carlo and volume inte-

gral equation methods of studying the clustering

of small scatterers. Appl. Opt. 40: 22 (2001):

3711-3717.

3. Hackman, Thomas; Jetsu, Lauri; Tuominen,

I.: Surface imagingof HD199178(V1794 Cygni):

high latitude spots and dierentialrotation. As-

tron. Astrophys. 374(2001): 171-181.

4. Homer,L.;Charles,P.A.;Hakala, Pasi;Muhli,

Panu; Shih,I.-C.; Smale, A. P.; Ramsay, G.: On

themulti-periodicitiesintheX-raydipperXB1916-

053. MonthlyNot. R.A.S.322(2001): 827-842.

5. Hotzel, S.; Harju, Jorma; Lemke, D.; Matti-

la,Kalevi;Walmsley,C.M.: Densegasandcold

dust in the dark core B217. Astron. Astrophys.

372(2001):302-316.

6. Juvela, Mika;PadoanP.;Nordlund,

A.: Cooling

Ratesof MolecularClouds Basedon MHD Simu-

lationsandnon-LTERadiativeTransfer. Astroph.

J.563(2001): 853-866.

7. Kaasalainen, Mikko; Laakso, Teemu: Near-

integrability as a numerical tool in solar system

dynamics. Astron. Astroph. 368(2001): 706-711

8. Kaasalainen,Mikko(2001): Interpretationof

lightcurvesofprecessingasteroids. Astron. Astro-

phys. 376(2001): 302-309.

so, Teemu: Shapes and scattering properties of

largeirregularbodiesfrom photometricdata. Op-

ticsExpress8(2001): 296.

10. Kaasalainen,Mikko;Torppa,Johanna: Opti-

mizationmethodsforasteroidlightcurveinversion.

I.Shapedetermination. Icarus153(2001): 24.

11. Kaasalainen,Mikko;Torppa,Johanna;Mui-

nonen, Karri: Optimization methods for aster-

oid lightcurve inversion. II.The complete inverse

problem. Icarus153(2001): 37.

12. Kaasalainen, Sanna; Muinonen, Karri; Pii-

ronen,Jukka: Comparativestudy onopposition

eectoficysolarsystemobjects. JournalofQuan-

titativeSpectroscopy&RadiativeTransfer70(2001):

529-543.

13. Kiss,Cs.;

Abraham,P.;Klaas,U.;Juvela,Mika;

Lemke,D.: Skyconfusionnoiseinthefar-infrared:

Cirrus, galaxies andthe cosmic far-infraredback-

ground. Astronon. Astrophys. 379(2001): 1161-

1169.

14. Korhonen, H.; Berdyugina, S. V.; Tuominen, I.;

Andersen, M. I.; Piironen, Jukka; Strassmeier,

K. G.; Grankin, K. N.; Kaasalainen, Sanna;

Karttunen, H.; Mel'nikov, S. Yu.; Shevchenko,V.

S.;Trisoglio, M.;Virtanen, Jenni: StudyofFK

ComaeBerenicesIII.Photometryfortheyears1993-

2001. Astron. Astroph. 374(2001): 1049-1055

15. Lamberg, Lars;Kaasalainen, Mikko: Numer-

icalsolutionof theMinkowskiproblem. J.Comp.

Appl. Math. 137(2001): 213.

16. Lamberg, Lars;Muinonen, Karri;Ylonen,J.;

Lumme, Kari: Spectral estimation of Gaussian

randomcircles andspheres. Journalof Computa-

tional andApplied Mathematics 136(2001): 109-

121.

17. Lehtinen,KimmoK.;Haikala, Lauri;Matti-

la, Kalevi;Lemke,D.: Afarinfraredviewoflow

mass star formationin theCederblad 110nebula

of Chamaeleon I. Astron. Astroph. 367 (2001):

311-320

18. Morgan,D. H.; ParkerQ. A.; Russeil, D.: New

Wolf-Rayetcentralstarsofplanetarynebulaeiden-

tiedontheAAO/UKSTH[alpha]Survey. Monthly

NoticesoftheR.A.S. 322(2001): 877-884.

19. Muinonen, Karri; Virtanen, Jenni; Bowell,

E.: Collisionprobability forEarth-crossingaster-

oidsusingorbitalranging. CelestialMechanicsand

DynamicalAstronomy81(2001)93-101.