Cosmic dust VIII

0.37 MB·

by  Hiroshi Kimura

Editorial
osmic ust
C D VIII
Fordustyouareandtodustyouwillreturn
scientiststacklingcosmicdustproblemsinawiderangeofdis-
ciplinestomeeteachotherandintensivelydiscusstheirrecent
Genesis3:19
results and developments in this field. This meeting started in
2006asasessioncalled“CosmicDust”ofthe3rdAOGS(Asia-
OceaniaGeosciencesSociety)annualmeetinginSingapore,but
71. Interdisciplinaryresearchoncosmicdust detached itself from the AOGS since 2012. We have success-
1
fullykeptorganizing thisseriesofCosmicDust meetingsina
0
These days, once taking a look at cosmic environments in
2 relaxingatmospherewithanexcellentchoiceofspeakersuntil
various spectral ranges, one can catch a glimpse of the dusty todayowingtoourextraordinaryenthusiasmsaboutthedevel-
n
worldindiverseshapesofappearance. Apartfromitselegancy
a opmentofcosmicdustresearch.TheCosmicDustmeetingfea-
Jandbeautyintheappearance,cosmicdusthasagreatinfluence turesthecoziness,endingupwithgrandiosecontributionsbya
on a variety of physical processes and complex chemical evo-
5 greatnumberoftopscientistsfromallaroundtheworld,which
lution in different epochs and sites of the Universe. In widely madethemeetingastrikingsuccess.

A]acceptedscenariosofthecosmossuchastheevolutionofstars The 8th meeting on Cosmic Dust (hereafter Cosmic Dust
and the formation of planetary systems, dust as well as gas is
VIII) was held at the Tokyo Skytree Town Campus of Chiba
Gthedrivingforce. Eventhoughitisfrustratingtofindthatcos-
Institute of Technology, Japan, from August 17 to 21, 2015.
.mic dust obscures vision in the Universe, it is fascinating to
h ThisspecialissueinPlanetaryandSpaceScience(PSS)ispri-
pstudy the dust as the building blocks of planets and life. Our marily intendedfor the paperspresented at Cosmic Dust VIII.
-planetEarth,forexample,issimplymadebytheaccumulation
Nevertheless,wearepleasedthatthisspecialissuealsocontains
o
of dust grains initially condensed in the disk around our new-
r papers beyond the presentations at the meeting such as Hooks
tbornSunabout4.6billionyearsago. Ontheonehand,silicates
s etal.(2016),Kolokolovaetal.(2016),Marboeufetal.(2016),
aand metals, major constituents of cosmic dust, were the most Mattsson(2016),andPodolaketal.(2016). Thefullscientific
[importantandpredominantcontributorstothedevelopmentof program of Cosmic Dust VIII is available at the Cosmic Dust
1 Earth’scrust,mantle,andcore. Ontheotherhand,organic-rich website(https://www.cps-jp.org/˜dust/Program VIII.html)with
vcarbonaceous material, another major constituent of the dust, links to the abstracts of all presentations. Needless to say, in-
1mayhaveplayedavitalroleintheoriginandevolutionoflife vited talks, contributed talks and posters1, as well as on-site
3ontheearlyEarth. Thesurfaceofdustgrainsprovidesafavor- discussions were dedicated to many different aspects of cos-
4
ablesiteonwhichgaseousspeciescanfreezeoutandeventually
1 micdust. InSection2, therefore, weintendtoprovideacriti-
reactbetweeneachotherresultinginarichzoooforganiccom-
0 caloverviewofthemajorscientificissuesthatwereaddressed
1.pounds. Owing to the overwhelming chemical and structural in Cosmic Dust VIII, so that the reader could grasp the most
multiplicityofsuchorganicmaterials,cosmicdustmaybethe
0 recent hot topics of cosmic dust research. The main social
7maindisseminatoroflifeacrosstheUniverse. events of the meeting were a half-day excursion to the Edo-
1 When grazing up at a night sky, we may find it filled with
TokyoOpenAirArchitecturalMuseuminKoganeiParkanda
:a wide variety of unique and interesting dusty phenomena at
v banquetheldatatraditionalJapanesekaisekirestaurant,named
istars, nebulae, clouds, and planetary systems. However, no “Kappou Sansyu-ya”, established in 1889. Fig. 1 is a group
X
matter how long we look into such a phenomenon, it is only
shot of the participants in a Japanese-style tatami-floored hall
ra blink of an eye on a timescale of the entire life of cosmic
a of the restaurant taken immediately after the banquet. With-
dust. Tounderstandthewholelifecycleofthedust,weneedto
unravel the deep mystery of dust coming out of evolved stars,
traveling between different phases of the interstellar medium, 1Xieetal.(2016)andTazakietal.(2015)receivedtheBestPosterAward
dyingoutatprotostars,revivingaroundyoungstars,andfinally ofCosmicDustVIII,onthebasisofjudgementsmadebytheinvitedspeak-
seeding into planetary systems. Solving this mystery is a se- ers,VarshaP.Kulkarni(UniversityofSouthCarolina,USA),GianfrancoVi-
dali (Syracuse University, USA), Christophe Pinte (CNRS/INSU, France),
rious challenge whereof scientists from all over the world are
GrantKennedy(UniversityofCambridge,UK),CharlesM.Telesco(Univer-
working continuously and sharing a common interest. This is sityofFlorida,USA),HaraldKru¨ger(Max-Planck-Institutfu¨rSonnensystem-
the ultimate goal, for which observers, theorists, and experi- forschung, Germany), MartinHilchenbach(Max-Planck-Institutfu¨rSonnen-
mentalistshavetoworkhandinhandwitheachotherandneed systemforschung,Germany),MarcoFulle(INAFTrieste,Italy),MarkS.Bent-
ley(Institutfu¨rWeltraumforschungGraz,Austria),AndrewWestphal(Univer-
tocombinetheiractivitiesandstudiesfortheoptimalsuccess.
sityofCaliforniaatBerkeley,USA),andHongbinDing(DalianUniversityof
TheannualCosmicDustmeetingprovidesanidealplatformfor Technology,China).
1
Figure1:AgrouppictureofparticipantstoCosmicDustVIII;(Innoparticularlyorder)M.Fulle,M.Hilchenbach,H.Hirashita,R.Botet,F.Galliano,P.Woitke,J.
Murthy,H.Kru¨ger,M.Podolak,C.Pinte,D.Lazzati,G.Kennedy,M.S.Bentley,J.Li,H.Senshu,T.Ootsubo,H.Ding,K.Bekki,T.Nozawa,C.Helling,T.Hirai,
V.Sterken,G.Vidali,T.Kondo,H.Kobayashi,T.Kokusho,A.M.Nakamura,J.Pyo,V.P.Kulkarni,M.Hammonds,C.T.Tibbs,S.Hamano,R.Tazaki,Y.Xie,J.Y.
Seok,B.Mills,M.Kiuchi,Z.Wahhaj,G.Rouille´,T.Shimonishi,X.Yang,X.Chen,T.Onaka,A.Li,K.Wada,H.Kimura,L.Kolokolova,M.Buragohain,Shalima
P.,B.Jiang,S.Wang,L.Zhou,andH.Chihara.
outashadowofdoubt,theLocalOrganizingCommittee(LOC) crystalline silicates in distant galaxies would formed by con-
ledbyKojiWada(PERC/Chitech,Japan)didanexcellentjobin densation of gas and did not undergo amorphization, then the
organizingthemeetingalongtherationalebehindit.Thisedito- silicates tend to be magnesium-rich, iron-poor crystals (Mol-
rialwillendwithourremarksonCosmicDustVIIIinSection3, ster and Kemper, 2005). In contrast, laboratory experiments
alongwithourperspectivesonthedevelopmentofcosmicdust onannealingofamorphoussilicateswithembeddedmetalhave
research. shown that the annealing transforms the silicates into moder-
ately iron-rich olivine and pyroxene (Brownlee et al., 2005).
Accordingly, we expect that moderately iron-rich crystalline
2. ThecontentsofCosmicDustVIII
silicates detected in distant galaxies arose from annealing of
2.1. Galaxies amorphoussilicates,ratherthancondensationofgas.
Thecharacterizationofdustindistantgalaxiesisofvitalim-
portanceforabetterunderstandingofgalaxyevolutionandthe
cosmicexpansionrateatearlierepochs.VarshaP.Kulkarnipre- Other papers covered the following topics: a study on dust
sented observational evidence that the composition of dust in propertiesathighredshiftsfromamodelingofdustextinction
distantgalaxiesmaybesystematicallydifferentfromthatinour in gamma-ray bursts by Tayyaba Zafar (Zafar, 2016); simpli-
Galaxy and nearby galaxies (Kulkarni et al., 2016). The most fication of dust size distribution for a modeling of dust en-
notable difference is the predominance of crystalline silicates richments in galaxies by Hiroyuki Hirashita (Hirashita et al.,
insomedistantgalaxies,becauseamorphoussilicatesaredom- 2016);computersimulationsofgalaxyformationandevolution
inantinnearbygalaxies. Thehighcrystallinitymightbeasso- withdustphysicsbyKenjiBekki;detailedanalysesofAKARI,
ciatedwithlowcosmic-rayfluxesbecauseexposuretocosmic 2MASS, and WISE data on spectral energy distributions of
rays transforms a crystalline phase into an amorphous phase early-typegalaxiesbyTakumaKokusho;amodelingofsilicate
(e.g.,Kra¨tschmerandHuffman,1979;Ja¨geretal.,2003). The dustgrainsinthecircumnucleartorusofactivegalacticnuclei
observedspectralfeaturesofcrystallinesilicateswerebestfit- by Yanxia Xie (Xie et al., 2016); a modeling of intergalactic
tedwithlaboratoryprofilesofmoderatelyiron-richcrystalline extinctionbasedonthedepletionofdust-formingelementsby
silicates(Alleretal.,2012,2014). Weshouldpointoutthatif BradleyMills.
2
2.2. Evolvedstars,supernovae,andstar-formingregions 1989). Christophe Pinte indicated that a classical theory of
Owingtothethird-largestabundanceinthelocaluniverseaf- planetesimalformationhasshortcomingsinthemechanismof
terhydrogenandhelium,oxygenplaysanimportantroleinthe collisional grain growth, which has not yet been resolved by
chemistry of gas and dust. Dust particles incorporate oxygen observations (Pinte, 2015). Meter-sized dust aggregates col-
in a variety of forms such as ices, silicates, and organic-rich lide so fast that they cannot stick to grow further, but they
carbonaceousmaterial, dependingontheirenvironments(e.g., suffer from fragmentation, the so-called fragmentation barrier
Whittet, 2010). Gianfranco Vidali reported laboratory exper- (e.g., Dullemond, 2013). However, Wada et al. (2009) have
iments on the chemical reactions of oxygen at grain surfaces shown that dust aggregates consisting of submicrometer-sized
carriedoutinhisgroupaswellastheoreticalsimulationsonthe grainscangobeyondthefragmentationbarrier,iftheyarecom-
reactionsinphoto-dissociationregionsandstar-formingregions posed of ices. Subsequently, the reassessment of surface en-
(Vidali,2015). Allrecentexperimentalstudiesindicatethatthe ergyforamorphoussilicarevealedthatthestickinessofsilicate
binding energy of oxygen is approximately double the value dust aggregates has been underestimated by one to two orders
previously adopted in astrochemical models (Ward and Price, of magnitude (Kimura et al., 2015a). Furthermore, the stick-
2011; Kimber et al., 2014; He et al., 2014, 2015; Minissale et ing efficiency of dust aggregates can be greatly enhanced, if
al., 2016). A higher binding energy of O atoms leads to an submicrometer-sizedmineralgrainsareencasedinorganicre-
increase in the residence time of O atoms on grain surfaces fractorymaterials(Flynnetal.,2013;Kimuraetal.,2015a).In-
and enhances the abundance of H O ice (see He et al., 2015). deed, thechondriticporoussubsetofinterplanetarydustparti-
2
Veryrecently,Wangetal.(2015)andPoteetetal.(2015)have cles,whichismostlikelyofcometaryorigin,isanaggregateof
postulated a population of very large, micrometer-sized H O submicrometer-sizedgrainswhoseouterlayersarecoveredby
2
ice grains in the diffuse interstellar medium to account for the organic-richcarbonaceousmaterials(Kelleretal.,2000;Flynn
observed mid-infrared extinction as a major repository for O etal.,2013). Therefore,thepresenceoforganicrefractoryma-
atomsdepletedfromthegasphase.However,micrometer-sized terialsmaybeanimportantaidtoovercomethefragmentation
H O ice grains are not exactly a requisite for the mid-infrared barrierandthusplaysavitalroleintheformationofplanetesi-
2
extinction,becausemicrometer-sizedamorphouscarbongrains malsinprotoplanetarydisks.
couldalsohelptoreproducetheobservedmid-infraredextinc- Otherpaperscoveredthefollowingtopics:numericalevalua-
tion(Wangetal.,2014). Furthermore,sizedegradationoflarge tionofejectamassproducedbycollisionsofsinglegrainsonto
grains by photodesorption, shattering, and sputtering would dustaggregatesbyKojiWada;numericalsimulationsonlarge-
continuously replenish small grains, but small H O ice grains scale radial transport and mixing of centimeter-sized grains in
2
areabsentinthediffuseinterstellarmedium(cf.Whittetetal., a marginally gravitationally unstable disk by Morris Podolak;
1988). TheprocessingofH Oicebyexposuretoultravioletra- adevelopmentofaholisticmodelingapproachtodustandgas
2
diationandcosmicraysalsoresultsintheformationoforganic in protoplanetary disks by Peter Woitke; a development of a
refractorymaterialaswellaspolycyclicaromatichydrocarbons modelfordustformationinatmospheresofplanetaryobjectsby
(PAHs)(Greenbergetal.,2000). Therefore,organicrefractory ChristianeHelling;anapplicationoftheRayleigh-Gans-Debye
materialcouldbethemaincarrierofOatomsinthedustphase, theory to computations of phase function for fractal dust ag-
althoughspectroscopicobservationshavenotprovidedconclu- gregates by Ryo Tazaki (Tazaki et al., 2015); numerical simu-
siveevidence(Jenkins,2009;Whittet,2010).Consequently,the lations of polarimetric disk images in the mid-infrared wave-
newdeterminationofoxygenbindingenergyalonehasnotyet lengthsbyHanZhang.
givenasolutiontotheproblemofthe“missing”oxygenatoms,
whichhasbeenamatterofdebateforseveraldecades. 2.4. Debrisdisks
Other papers covered the following topics: a numerical Debrisdiskshavebeendetectedandimagedaroundanum-
modelofdustnucleationandgrowthinyoungsupernovarem- ber of main-sequence stars since the discoveries of the disks
nants by Davide Lazzati; a nucleation and growth model of aroundVegabyAumannetal.(1984)andβPictorisbySmith
small carbon grains based on the ab-initio density functional andTerrile(1984). Earlystudiesondebrisdiskshavebeenlim-
theorybyChristopherMauney(MauneyandLazzati,2016); a itedtotheouterpartofthedisks, sinceonlythepopulationof
modelingofthereddeninglawobservedforTypeIasupernovae colddustoriginatingfromtheexo-Kuiperbeltswasspatiallyre-
by Takaya Nozawa (Nozawa, 2016); a modeling of the color solved. Recent infrared interferometric observations of debris
excesses toward the Type Ia supernova SN 2014J in the star- diskshaveprovidedanopportunitytoexploretheinnerpartof
burst galaxy M82 by Jun Li; a revision of the infrared extinc- the disks, namely, the exo-zodiacal light from warm dust, or
tionlawbasedontheAPOGEEspectroscopicsurveybyBiwei even the innermost part of the disk, the exo-F-corona of hot
Jiang; a model constraint on the abundance of small spinning dust. Near-infraredobservationsofdebrisdisksaroundnearby
grainsindensecoresbasedonPlanckcentimeterobservations main-sequencestarshaverevealednoclearcorrelationbetween
byChristopherT.Tibbs. excessemissionfromhotdustgrainsandthepresenceofcold
dustpopulations(Erteletal.,2014). Becausealltheproposed
2.3. Protoplanetarydisks mechanisms for supplying the great population of hot dust in
The collisional growth of dust particles in protoplanetary thevicinityofstarsarebynomeansconclusive,GrantKennedy
disks is currently considered a plausible scenario for the for- statedthatthepresenceofthehotdustpopulationisatotalmys-
mation of planetesimals and planets (Weidenschilling et al., tery(Kennedy,2015). Itmightbeworthwhiletorecognizethat
3
near-infrared excess emission observed in the solar F-corona Otherpaperscoveredthefollowingtopics: thephysicaland
isasimilarenigmaticphenomenon. Theexcessemissionofthe chemical properties of dust in the coma of 67P/C-G based on
solarF-coronahasbeendetectedaround4R fromtheSununtil Rosetta/COSIMA’s in-situ measurements by Martin Hilchen-
(cid:12)
1983intheHandJbandsanduntil1973intheKandLbands, bach(Hornungetal.,2016);thedynamicalpropertiesofdustin
butitsoriginisstillanopenquestion(KimuraandMann,1998). the coma of 67P/C-G based on Rosetta/GIADA’s in-situ mea-
Herewe cannothelpbut wonderwhetherthehot dustpopula- surements by Marco Fulle; a report on the latest results from
tionscouldbereplenishedbythesuper-catastrophicdisruption the Rosetta/MIDAS experiment by Mark S. Bentley; an ex-
ofsub-kilometertokilometersizedplanetesimalsinthevicinity perimental study on the fragmentation, penetration, and con-
ofthestar(cf.Granviketal.,2016).Ifthemechanismtosupply solidation of small bodies impacting on an asteroid by Akiko
the population of hot dust in debris disks would be identified, M. Nakamura; low-velocity impact experiments onto granu-
then it might give a clue about the origin of the near-infrared lar materials under reduced gravity conditions by Masato Ki-
excessemissioninthesolarF-corona,andviceversa. uchi; a laboratory study on the infrared spectra of aggregate
Other papers covered the following topics: early results of particles at a synchrotron facility by Akemi Tamanai; three-
the mid-IR multi-mode facility camera CanariCam for deter- dimensional molecular dynamics simulations of polydisperse
miningdustpropertiesinyoungcircumstellardisksbyCharles charged dust particles in a gravitational field by Robert Botet;
M. Telesco; a modeling of dust and PAHs in the debris disk far-infrared AKARI observations of asteroidal dust bands in
around HD 34700 based on the spectral energy distribution the zodiacal light by Takafumki Ootsubo; an improvement on
of the disk by Ji Yeon Seok; an improvement on the signal the COBE/DIRBE model of zodiacal emission based on the
to noise ratio in the direct imaging of the HD 32297 debris AKARI mid-infrared all-sky maps by Toru Kondo; the char-
diskbyZahedWahhaj;numericalsimulationonthecoagulation acterizationofregolithdustparticlesusingthewavelengthde-
and fragmentation of planetesimals in debris disks by Hiroshi pendenceoftheoppositioneffectofairlessbodiesbyLudmilla
Kobayashi. Kolokolova; an analysis of the COBE/DIRBE, AKARI, and
MIRIS data for the zodiacal light toward the ecliptic poles by
JeonghyunPyo; thedeterminationofthealiphatic-to-aromatic
2.5. SolarSystem
carbon abundance ratio for Solar System objects from their
After a decade-long journey to the Jupiter-family comet near-infraredspectrabyLiZhou;anumericalstudyonthecon-
67P/Churyumov-Gerasimenko (67P/C-G), Rosetta is now in tributionofhigh-energyphotoelectronstodustlevitationabove
themidstofin-situmeasurementswithvariousinstrumentson- thesurfaceofairlessbodiesbyHirokiSenshu.
board the Rosetta orbiter and the Philae lander (Taylor et al.,
2015). HaraldKru¨gerwasthefirstspeakerinaseriesofthein- 2.6. Interstellarmedium
vitedtalksdedicatedtosuccessfulresultsofthemeasurements The Local Interstellar Cloud (LIC) is a partially ionized in-
acquiredbyRosetta’sdustinstruments(Kru¨geretal.,2015).He terstellar cloud that moves toward the galactic anticenter and
introduced the Dust Impact Monitor (DIM) and the Cometary currently surrounds the Sun (Bertin et al., 1993). The chem-
Acoustic Sounding Surface Experiment (CASSE), which are ical composition of interstellar grains could be inferred from
parts of the Surface Electric Sounding and Acoustic Monitor- the argument of missing atoms, which is a classical method
ingExperiment(SESAME)onboardPhilae,andtheCometary based on the depletions, namely, the underabundances of ele-
SamplingandComposition(COSAC)experiment,withparticu- ments in the gas phase with respect to the cosmic abundances
laremphasisontheDIM.TheDIMmeasurementswerenotsuc- (e.g.,Spitzer,1978;Whittet,2003).Aclearcorrelationbetween
cessfulbeforetheseparationfromtheorbiterandafterlanding silicon and magnesium in the LIC and no correlation between
on the nucleus due to unfavorable positions of the instrument. siliconandironindicatethatinterstellargrainsaremainlycom-
However,duringtheshortperiodofPhilae’sdescenttothenu- posed of magnesium-rich silicates and iron-bearing alloys, as
cleus,theDIMdetectedoneandonlymillimeter-sizeddustpar- wellasorganicrefractorymaterials(Kimura,2015). Inthepast
ticleatanaltitudeof2.4kmfromthesurface. Laboratorycal- twodecades, spacemissionshaveprovidedustheopportunity
ibration experiments show that the measured signal amplitude ofstudyingthecompositionsofLICgrainsthatpenetratedeep
and long contact duration are consistent with an impact of a intotheSolarSystem. AndrewWestphalreportedontheanal-
porous particle with a density ρ = 250kgm−3. We are aware ysesofsevenparticlesthatwerecapturedbytheStardustInter-
that millimeter-sized primordial dust aggregates have a much stellarDustCollector,returnedtoEarth,andidentifiedtobeof
smallerdensityofρ∼0.1kgm−3inprotoplanetarydisksbased LIC origin (Westphal et al., 2014; Westphal, 2015). A typical
onamodelofparticlegrowthbycoagulation(Weidenschilling pictureoftheinterstellardustcandidatesismagnesium-richsil-
et al., 1989). Although 67P/C-G’s millimeter-sized particles icategrainswithiron-richphaseswithoutcarbonaceousmateri-
may have a broad range of densities, the DIM’s measurement als. Thisisconsistentwiththemineralogicalcharacteristicsof
alreadyprovidesstrongevidencethatmillimeter-sizedparticles interstellargrainsderivedfromanalysesoftheirchemicalcom-
could have a density of ρ (cid:29) 0.1kgm−3. Therefore, we may positions measured in situ by Cassini near the Saturnian orbit
concludethatdustparticlesincometshaveexperiencedintense (Altobelli et al., 2016). However, the organic refractory com-
compactionatsomestagesuchasacertainperiodoftheforma- ponent of interstellar dust has likely been dissipated en route
tionofcometnucleiortheformationofadustmantleontheir totheSolarSystemasthegas-to-dustmassratioandthecom-
surfaces. position of pick-up ions have preserved a trace of missing or-
4
ganicmatter(Kimuraetal.,2015b). Itisworthmentioningthat model, but does not necessarily mean that the former is more
porous interstellar grains with mass m = 3–4×10−15kg were realistic than the latter. The popularity of the DL model most
identifiedbyStardust,whilenon-porousinterstellargrainswith probablyresultsfromitseasinessofuse,sincethesizedistribu-
m<5×10−16kgweredetectedbyCassini. Inaddition,acom- tionisdescribedasamathematicallysimplepower-lawandthe
parisonoftheUlyssesin-situdataoninterstellargrainsandnu- dielectricfunctionsofgrainmaterialsaregivenintabularform
mericalsimulationsoftheirdynamicsintheSolarSystemsug- (cf. Draine, 1985). The DL model has remained in an area of
geststhatthegrainswithm>2×10−16kgareporous(Sterken consensusonthecompositionofinterstellardustwhereamor-
etal.,2015). Toachieveaconsensusonthisissue,smallinter- phous silicate and graphite are seemingly responsible for the
stellar grains of m ≤ 2×10−16kg must be compact particles, 9.7µmand18µmabsorptionfeatures,andthe217.5nmextinc-
whilelargeinterstellargrainsofm>2×10−16kgmaybefluffy tion feature, respectively. However, the DL model may be in-
aggregatesconsistingofthesmallcompactparticles. compatiblewiththelatestfindingsofgrainmaterialsandsizes
Other papers covered the following topics: a review on the inthelocalinterstellarmedium,mostofwhichhavebeenpre-
diffuse interstellar bands by Hongbin Ding; a report on the sentedinaseriesofCosmicDustmeetings: Thesizedistribu-
sublimation of organic material in interstellar dust en route to tion of interstellar grains is skewed toward heavier masses by
the Solar System by Hiroshi Kimura; a dynamical modeling morethanoneorderofmagnitudeandhasashallowerpower-
of interstellar dust streaming into the Solar System by Veerle law index than expected from the DL model (Kimura et al.,
Sterken; numerical simulation on the mid-infrared extinction 2003; Sterken et al., 2015); There is no evidence for the pres-
curvewithmicrometer-sizedgraphiteinterstellargrainsbyShu enceofcarbonaceousmaterialsininterstellargrainsmeasured
Wang; a Monte Carlo modeling of UV radiation scattered at byCassiniandStardust,althoughgraphitegrains,ifexistasin
interstellar dust based on the GALEX data by Jayant Murthy; theDLmodel,shouldhavebeenidentifiedbyCassini(Kimura
condensationexperimentsofsilicateandcarbongrainsatcryo- etal.,2015b;Westphal,2015);Interstellargrainsextractedfrom
genic temperatures by Gae¨l Rouille´; a modeling of dust prop- theaerogelcollectorofStardustcontainforsteriticolivine,con-
erties in the Magellanic clouds based on Herschel and Spitzer trarytoamorphoussilicateexpectedfromtheDLmodel(West-
observations by Fre´de´ric Galliano; infrared spectroscopic ob- phal,2015;Westphaletal.,2014). Veryrecently,Wrightetal.
servations of ice absorption bands in the Large Magellanic (2016)havefoundevidenceforcrystallinesilicatesintheinter-
Cloud by Takashi Shimonishi; a summary of AKARI’s near- stellarmediumfromtheirinfraredspectralobservationstoward
infraredspectroscopicdataforinterstellaricesbyTakashiOn- theGalacticCenter,incontrasttotheDLmodel. Furthermore,
aka; a correlational study between far ultraviolet and mid in- it turned out that interstellar grains are compositionally ho-
frared intensities in the Large Magellanic Cloud by Shalima mogeneous and seem to contain magnesium-rich silicates and
Puthiyaveettil (Saikia et al., 2016); a numerical study on the metalliciron,dissimilarfromMg Fe SiO intheDLmodel
1.1 0.9 4
contributionofgraphenetotheinterstellarextinctioncurveand (Altobellietal.,2016). Theserecentdiscoveriesofinterstellar
infrared emission spectra by Xiuhui Chen; a demonstration grain properties would give an impact on existing models for
of the AKARI far-infrared all-sky atlas by Yasuo Doi; near- interstellardustandwillshednewlightonunificationbetween
infrared high resolution spectral observations of diffuse inter- differentmodelsbyconsensusintherelevantscientificcommu-
stellar bands by Satoshi Hamano; data analyses of AKARI nity.
and ISO spectra from PAHs by Mark Hammonds; numerical Ourunderstandingofthephysicalprocessesintheinterstel-
simulation on infrared emission features of PAHs with vari- lar medium and in circumstellar environments is to some ex-
ousaliphaticsubstituentsbyXuejuanYang;atheoreticalstudy tentbasedondustgrainmodelsunderdifferentconditions. The
on infrared spectral emission features of deuterated PAHs by knowledgeoftheseprocesseshelpsustocorrectlyinterpretthe
MridusmitaBuragohain(Buragohainetal.,2016). spectra of astronomical objects and to deduce their composi-
tionsandstructuresfromthecorrectinterpretations. However,
there are still many gaps in our understanding of the physical
3. Perspectivesforthedevelopmentofcosmicdustresearch
processesoccurringoncosmicdustthathavetobefilledbefore
Wesometimesfindthatitisverydifficult,ifnotimpossible, wecanfinallystatethatdustgrainmodelsarecompletelyreal-
to reach a consensus among experts even on a single issue of istic. Fortunately, we are living in an era of new and exciting
cosmic dust research. Such a difficulty is clearly exemplified observationalinstrumentsandtechniquessuchasthespaceob-
byawidevarietyofmodelsthathavebeenproposedforinter- servatoriesPlanckandHerschel,theStratosphericObservatory
stellardustoverrecentdecades. InCosmicDustVI,AntJones forInfraredAstronomy(SOFIA),andtheAtacamaLargeMil-
introducedhisnewinterstellardustmodel(hereafterAJ)thatre- limeter Array (ALMA) that will reach unprecedented spatial
producesthemajorityofobservationsandfulfillsobservational resolutionsandsensitivities. Astronomicalobservationsofdust
constraints (see Jones et al., 2013). However, almost all the and molecular gas emission in circumstellar shells, molecular
papers on interstellar dust presented two years later in Cosmic clouds, protoplanetary disks, and other dusty regions with the
Dust VIII still rely on the classical model of Draine and Lee HerschelSpaceTelescopeopennewperspectivesontheevolu-
(1984) (hereafter DL), in which interstellar dust is composed tion of matter in the Universe. Consequently, many discover-
ofeitheramorphoussilicate(Mg Fe SiO )orgraphiteasre- iesarestilltobeexpectedfromacombinationofastronomical
1.1 0.9 4
finementtotheso-calledMRNmodelafterMathisetal.(1977). observations, theoretical modelings, and laboratory studies in
This indicates that the DL model is more popular than the AJ thenextfuture. WecannothelpbutanticipatethatthisCosmic
5
Dust meeting series will act as a catalyst for new findings out Ertel,S.,Absil,O.,Defre`re,D.,LeBouquin,J.-B.,Augereau,J.-C.,Marion,
ofacomprehensivestudyontheevolutionofcosmicdust. L.,Blind,N.,Bonsor,A.,Bryden,G.,Lebreton,J.,Milli,J.,2014.Anear-
infraredinterferometricsurveyofdebris-diskstars.IV.Anunbiasedsample
ThereaderiscordiallyinvitedtotakepartintheCosmicDust
of92southernstarsobservedinHbandwithVLTI/PIONIER.Astron.As-
meeting series and to join us for the development of cosmic trophys.570,A128.doi:10.1051/0004-6361/201424438
dustresearch2. The9thmeetingonCosmicDust(CosmicDust Flynn, G.J., Wirick, S., Keller, L.P., 2013.Organicgraincoatingsinprimi-
IX)willbeheldatTohukuUniversity,Sendai,JapanonAugust tiveinterplanetarydustparticles:implicationsforgrainstickingintheSolar
Nebula.EarthPlanetsSp.65,1159–1166.doi:10.5047/eps.2013.05.007
15–19, 2016. More information on the Cosmic Dust meeting
Granvik, M., Morbidelli, A., Jedicke, R., Bolin, B., Bottke, W.F., Beshore,
seriesisavailableattheCosmicDustwebsite(https://www.cps- E.,Vokrouhlicky´,D.,Delbo`,M.,Michel,P.,2016.Super-catastrophicdis-
jp.org/˜dust). ruption of asteroids at small perihelion distances. Nature 530, 303–306.
doi:10.1038/nature16934
Greenberg,J.M.,Gillette,J.S.,Mun˜ozCaro,G.M.,Mahajan,T.B.,Zare,R.N.,
Acknowledgements Li,A.,Schutte,W.A.,deGroot,M.,Mendoza-Go´mez,C.,2000.Ultravi-
oletphotoprocessingofinterstellardustmantlesasasourceofpolycyclic
aromatichydrocarbonsandotherconjugatedmolecules.Astrophys.J.531,
WeexpressoursinceregratitudetoKojiWada(LOCChair),
L71–L73.doi:10.1086/312526
Hiroki Senshu, Hiroki Chihara, Hiroshi Kobayashi, Takaya He,J.,Jing,D.,Vidali,G.,2014.Atomicoxygendiffusiononanddesorption
Nozawa,TakashiShimonishi,TakayukiHirai,RyoTazaki,and fromamorphoussilicatesurfaces.Phys.Chem.Chem.Phys.16,3493–3500.
AkioInouefortheircheerfuldedicationtotheorganizationof doi:10.1039/c3cp54328e
Cosmic Dust VIII as a member of the LOC. We thank all the He, J., Shi, J., Hopkins, T., Vidali, G., Kaufman, M.J., 2015. A new de-
termination of the binding energy of atomic oxygen on dust grain sur-
authorsandthereviewersaswellastheeditorialboardofPSS faces: experimentalresultsandsimulations.Astrophys.J.801, 120(7pp).
andElsevierforputtingtheireffortsintothisspecialissue. We doi:10.1088/0004-637X/801/2/120
Hirashita,H.,Nozawa,T.,Asano,R.S.,Lee,T.,2016.Revisitingthelifetime
areindebtedtoOsakaSangyoUniversity,JSPS(JapanSociety
estimateoflargepresolargrainsintheinterstellarmedium.Planet.Sp.Sci.
for the Promotion of Science), National Astronomical Obser-
inthisissue.
vatoryofJapan(NAOJ),andChibaInstituteofTechnologyfor Hooks,J.M.,etal.,2016.Optimizeddustvelocitygridsystemaidingthecom-
their various supports to the organization of the meeting. We positionalmappingofJoviansatellites.Planet.Sp.Sci.inthisissue.
Hornung, K., Merouane, S., Hilchenbach, M., Langevin, Y., Mellado, E.M.,
wouldalsoliketoacknowledgethegrantofResearchAssembly
Della Corte, V. Kissel, J., Engrand, C., Schulz, R., Ryno, J., Silen, J.,
supportedbytheResearchCoordinationCommitteeofNAOJ,
theCOSIMAteam, 2016.Afirstassessmentofthestrengthofcometary
NationalInstitutesofNaturalSciences. particlescollectedin-situbytheCOSIMAinstrumentonboardROSETTA.
Planet.Sp.Sci.inthisissue.
Ja¨ger,C.,Fabian,D.,Schrempel,F.,Dorschner,J.,Henning,T.,Wesch,W.,
References 2003.Structuralprocessingofenstatitebyionbombardment.Astron.Astro-
phys.401,57–65.doi:10.1051/0004-6361:20030002
Jenkins,E.B.,2009.Aunifiedrepresentationofgas-phaseelementdepletions
Aller, M.C., Kulkarni, V.P., York, D.G., Vladilo, G., Welty, D.E., Som, D.,
2012.Interstellarsilicatedustinthez = 0.89absorbertowardPKS1830- intheinterstellarmedium.Astrophys.J.700,1299–1348.doi:10.1088/0004-
637X/700/2/1299
211: crystalline silicates at high redshift? Astrophys. J. 748, 19(35pp).
doi:10.1088/0004-637X/748/1/19 Jones,A.P.,Fanciullo,L.,Ko¨hler,M.,Verstraete,L.,Guillet,V.,Bocchio,M.,
Ysard, N., 2013. The evolution of amorphous hydrocarbons in the ISM:
Aller, M.C., Kulkarni, V.P., York, D.G., Welty, D.E., Vladilo, G., Liger, N.,
2014. Interstellar silicate dust in the z = 0.685 absorber toward TXS dust modelling from a new vantage point. Astron. Astrophys. 558, A62.
0218+357.Astrophys.J.785,36(16pp).doi:10.1088/0004-637X/785/1/36 doi:10.1051/0004-6361/201321686
Altobelli,N.,Postberg,F.,Fiege,K.,Trieloff,M.,Kimura,H.,Sterken,V.J., Keller,L.P.,Messenger,S.,Bradley,J.P.,2000.Analysisofadeuterium-rich
interplanetarydustparticle(IDP)andimplicationsforpresolarmaterialin
Hsu,H.-W.,Hillier,J.,Khawaya,N.,Moragas-Klostermeyer,G.,Blum,J.,
IDPs.J.Geophys.Res.105,10397–10402.doi:10.1029/1999JA900395
Burton,M.,Srama,R.,Kempf,S.,Gruen,E.,2016,Fluxandcomposition
Kennedy, G., 2015. Debris Disks: Seeing Dust, Thinking of Asteroids,
ofinterstellardustatSaturnfromCassini’sCosmicDustAnalyzer.Science,
352,312–318.doi:10.1126/science.aac6397 Comets, and Planets. Presented at Cosmic Dust VIII. (cid:104)https://www.cps-
jp.org/˜dust/ProgramVIIIfiles/dust8-2-4-1.pdf(cid:105)
Aumann,H.H.,Gillett,F.C.,Beichman,C.A.,deJong,T.,Houck,J.R.,Low,
Kimber, H.J., Ennis, C.P., Price, S.D., 2014. Single and double addition of
F.J.,Neugebauer,G.,Walker,R.G.,Wesselius,P.R.,1984.Discoveryofa
shellaroundAlphaLyrae.Astrophys.J.278,L23–L27.doi:10.1086/184214 oxygenatomstopropyneonsurfacesatlowtemperatures.FaradayDiscuss.
168,167–184.doi:10.1039/C3FD00130J
Bertin,P.,Lallement,R.,Ferlet,R.,Vidal-Madjar,A.,1993.Detectionofthe
Kimura, H., 2015.InterstellardustintheLocalCloudsurroundingtheSun.
localinterstellarcloudfromhigh-resolutionspectroscopyofnearbystars:
Mon.Not.R.Astron.Soc.449,2250–2258.doi:10.1093/mnras/stv427
Inferencesontheheliosphericinterface.J.Geophys.Res.98,15193–15197.
doi:10.1029/93JA01179 Kimura,H.,Mann,I.,1998.BrightnessofthesolarF-corona.EarthPlanetsSp.
50,493–499.doi:10.1186/BF03352140
Brownlee,D.E.,Joswiak,D.J.,Bradley,J.P.,Matrajt,G.,Wooden,D.H.,2005.
Kimura,H.,Mann,I.,Jessberger,E.K.,2003.Composition,structure,andsize
CookedGEMS–Insightintothehotoriginofcrystallinesilicatesincircum-
distributionofdustintheLocalInterstellarCloud.Astrophys.J.583,314–
stellardisksandthecoldoriginGEMS.LunarPlanet.Sci.XXXVI,2391.
321.doi:10.1086/345102
Buragohain,M.,Pathak,A.,Sarre,P.,Onaka,T.,Sakon,I.,2016.Mid-infrared
Kimura, H., Wada, K., Senshu, H., Kobayashi, H., 2015a. Cohesion of
vibrationalstudyofdeuterium-containingPAHvariants.Planet.Sp.Sci.in
amorphous silica spheres: toward a better understanding of the coagu-
thisissue.
lation growth of silicate dust aggregates. Astrophys. J. 812, 67(12pp).
Draine,B.T.,1985.Tabulatedopticalpropertiesofgraphiteandsilicategrains.
Astrophys.J.Suppl.Ser.57,587–594.doi:10.1086/191016 doi:10.1088/0004-637X/812/1/67
Kimura,H.,Postberg,F.,Altobelli,N.,Trieloff,M.,2015b.MissingOrganic
Draine,B.T.,Lee,H.M.,1984.Opticalpropertiesofinterstellargraphiteand
silicategrains.Astrophys.J.285,89–108.doi:10.1086/162480 MaterialsFromInterstellarDustInsidetheSolarSystem.PresentedatCos-
micDustVIII.(cid:104)https://www.cps-jp.org/˜dust/ProgramVIIIfiles/dust8-5-1-
Dullemond,C.P.,2013.Formationof(exo-)planets.Astron.Nachr.334,589–
594.doi:10.1002/asna.201311899 2.pdf(cid:105)
Kolokolova, L., Nagdimunov, L., A’Hearn, M., King, A., Wolff, M., 2016.
StudyingthenucleusofComet9P/Tempel1usingthestructureoftheDeep
Impactejectacloudattheearlystagesofitsdevelopment.Planet.Sp.Sci.in
2Contact:[email protected]
6
thisissue. Weidenschilling,S.,Donn,B.,Meakin,P.,1989.Thephysicsofplanetesimal
Kra¨tschmer,W.,Huffman,D.R.,1979.Infraredextinctionofheavyionirradi- formation.In: Weaver, H., Danly, L., Fall, S.(Eds.), TheFormationand
atedandamorphousolivine,withapplicationstointerstellardust.Astrophys. Evolution of Planetary Systems. Cambridge Univ. Press, Cambridge, pp.
Sp.Sci.61,195–203.doi:10.1007/BF00645803 131–150.
Kru¨ger, H., Seidensticker, K.J., Fischer, H.-H., Albin, T., Apathy, I., Westphal, A.J., Stroud, R.M., Bechtel, H.A., Brenker, F.E., Butterworth,
Arnold, W., Flandes, A., Hirn, A., Kobayashi, M., Loose, A., Pe´ter, A.L., Flynn, G.J., et al., 2014. Evidence for interstellar origin of seven
A., Podolak, M., 2015. Dust Impact Monitor (SESAME-DIM) measure- dustparticlescollectedbytheStardustspacecraft.Science345,786–791.
ments at comet 67P/Churyumov-Gerasimenko. Astron. Astrophys. 583, doi:10.1126/science.1252496
A15.doi:10.1051/0004-6361/201526400 Westphal,A.J.,2015.LaboratoryAnalysesofSevenParticlesofLikelyInter-
Kulkarni, V.P., Aller, M.C., York, D.G., Welty, D.E., Vladilo, G., Som, D., stellarOriginReturnedbytheStardustSpacecraft.PresentedatCosmicDust
2016.Probingtheinterstellardustingalaxiesover>10Gyrofcosmichis- VIII.(cid:104)https://www.cps-jp.org/˜dust/ProgramVIIIfiles/dust8-5-1-1.pdf(cid:105)
tory.Planet.Sp.Sci.inthisissue. Whittet,D.C.B.,2003.DustintheGalacticEnvironment,2nded.Instituteof
Marboeuf,U.,Bonsor,A.,Augereau,J.-C.,2016.Extrasolarcomets:theorigin Physics,Bristol.Section2.4.
ofdustinexozodiacaldisks?Planet.Sp.Sci.inthisissue. Whittet,D.C.B.,2010.Oxygendepletionintheinterstellarmedium: implica-
Mathis,J.S.,Rumpl,W.,Nordsieck,K.H.,1977.Thesizedistributionofinter- tionsforgrainmodelsandthedistributionofelementaloxygen.Astrophys.
stellargrains.Astrophys.J.217,425–433.doi:10.1086/155591 J.710,1009–1016.doi:10.1088/0004-637X/710/2/1009
Mattsson,L.,2016.Modellingdustprocessingandtheevolutionofgrainsizes Whittet, D.C.B., Bode, M.F., Longmore, A.J., Adamson, A.J., McFadzean,
intheISMusingthemethodofmoments.Planet.Sp.Sci.inthisissue. A.D.,Aitken,D.K.,Roche,P.F.,1988.Infraredspectroscopyofdustinthe
Mauney, C.M., Lazzati, D., 2016.Formationandpropertiesofastrophysical Taurusdarkclouds: iceandsilicates.Mon.Not.R.Astron.Soc.233,321–
carbonaceousdust.Planet.Sp.Sci.inthisissue. 336.doi:10.1093/mnras/233.2.321
Minissale,M.,Congiu,E.,Dulieu,F.,2016.Directmeasurementofdesorption Wright,C.M.,DoDuy,T.,Lawson,W.,2016.Absorptionat11µminthein-
anddiffusionenergiesofOandNatomsphysisorbedonamorphoussur- terstellarmediumandembeddedsources:evidenceforcrystallinesilicates.
faces.Astron.Astrophys.585,A146.doi:10.1051/0004-6361/201526702 Mon.Not.R.Astron.Soc.457,1593–1625.doi:10.1093/mnras/stw041
Molster,F.,Kemper,C.,2005.Crystallinesilicates.Sp.Sci.Rev.119,3–28. Xie, Y., Nikutta, R., Hao, L. Li, A., 2016. A tale of three galaxies:
doi:10.1007/s11214-005-8066-x a “CLUMPY” view of the spectroscopically anomalous galaxies IRAS
Nozawa,T.,2016.Propertiesofinterstellardustresponsibleforextinctionlaws F10398+1455,IRASF21013-0739andSDSSJ0808+3948.Planet.Sp.Sci.
withunusuallylowtotal-to-selectiveextinctionratiosofRV =1–2.Planet. inthisissue.
Sp.Sci.inthisissue. Zafar, T., 2016.GRBafterglows: dustextinctionpropertiesfromthelowto
Pinte, C., 2015. Dust Evolution in Protoplanetary Disks. Presented at Cos- highredshiftuniverse.Planet.Sp.Sci.inthisissue.
micDustVIII.(cid:104)https://www.cps-jp.org/˜dust/ProgramVIIIfiles/dust8-2-2-
1.pdf(cid:105)
HiroshiKimura
Podolak,M.,Flandes,A.,DellaCorte,V.,Kru¨ger,H.,2016.Asimplemodel
for understanding the DIM dust measurement at comet 67P/Churyumov- GraduateSchoolofScience,KobeUniversity,c/oCPS(Center
Gerasimenko.Planet.Sp.Sci.inthisissue. forPlanetaryScience),Chuo-kuMinatojimaMinamimachi
Poteet, C.A., Whittet, D.C.B., Draine, B.T., 2015. The composition of in-
7-1-48,Kobe650-0047,Japan
terstellar grains toward ζ Ophiuchi: constraining the elemental budget
near the diffuse-dense cloud transition. Astrophys. J. 801, 110(12pp).
doi:10.1088/0004-637X/801/2/110 LudmillaKolokolova
Saikia,G.,Shalima,P.,Gogoi,R.,Pathak,A.,2016.Comparisonofdiffusein-
PlanetaryDataSystemGroup,DepartmentofAstronomy,
fraredandfar-ultravioletemissionintheLargeMagellanicCloud:thedata.
Planet.Sp.Sci.inthisissue. UniversityofMaryland,CollegePark,MD20742,USA
Smith,B.A.,Terrile,R.J.,1984.AcircumstellardiskaroundβPictoris.Science
226,1421–1424.doi:10.1126/science.226.4681.1421
AigenLi
Spitzer,L.,1978.PhysicalProcessesintheInterstellarMedium.Wiley-VCH,
Weinheim.Section1.41. DepartmentofPhysicsandAstronomy,Universityof
Sterken,V.J.,Strub,P.,Kru¨ger,H.,vonSteiger,R.,Frisch,P.,2015.Sixteen Missouri,314PhysicsBuilding,Columbia,MO65211,USA
years of Ulysses interstellar dust measurements in the Solar System. III.
Simulationsanddataunveilnewinsightsintolocalinterstellardust.Astro-
phys.J.812,141(24pp).doi:10.1088/0004-637X/812/2/141 HidehiroKaneda
Taylor,M.G.G.T.,Alexander,C.,Altobelli,N.,Fulle,M.,Fulchignoni,M.,Grn, GraduateSchoolofScience,NagoyaUniversity,Furo-cho,
E.,Weissman,P.,2015.Rosettabeginsitscomettale.Science347,387–387.
Chikusa-ku,Nagoya464-8602,Japan
doi:10.1126/science.aaa4542
Tazaki, R., Okuzumi, S., Kataoka, A., Tanaka, H., Nomura, H., 2015.Opti-
calPropertiesofFractalDustAggregates.PresentedatCosmicDustVIII. CorneliaJa¨ger
(cid:104)https://www.cps-jp.org/˜dust/ProgramVIIIfiles/dust8-P06.pdf(cid:105)
MaxPlanckInstituteforAstronomy,Heidelberg,Laboratory
Vidali, G., He, J., Hopkins, T., Shi, J., Kaufman, M., 2015. Measure-
ment of Binding of Oxygen on Dust Grains (Amorphous Silicates and AstrophysicsandClusterphysicsGroupattheInstituteofSolid
Amorphous Water Ice): Consequences for Oxygen Chemistry in the StatePhysics,FriedrichSchillerUniversityJena,
Interstellar Medium. Presented at Cosmic Dust VIII. (cid:104)https://www.cps- Helmholtzweg3,07743Jena,Germany
jp.org/˜dust/ProgramVIIIfiles/dust8-2-1-1.pdf(cid:105)
Wada, K., Tanaka, H., Suyama, T., Kimura, H., Yamamoto, T., 2009.Colli-
sionalgrowthconditionsfordustaggregates.Astrophys.J.702,1490–1501. Jean-CharlesAugereau
doi:10.1088/0004-637X/702/2/1490 Universite´ GrenobleAlpes,IPAG,F-38000Grenoble,France
Wang,S.,Li,A.,Jiang,B.W.,2014.Modelingtheinfraredinterstellarextinc-
tion.Planet.SpaceSc.100,32–39.doi:10.1016/j.pss.2014.03.018 CNRS,IPAG,F-38000Grenoble,France
Wang,S.,Li,A.,Jiang,B.W.,2015.Theinterstellaroxygencrisis,orwhere
havealltheoxygenatomsgone? Mon.Not.R.Astron.Soc.454,569–575.
doi:10.1093/mnras/stv1900
Ward, M.D., Price, S.D., 2011. Thermal reactions of oxygen atoms with
alkenesatlowtemperaturesoninterstellardust.Astrophys.J.741,121(9pp).
doi:10.1088/0004-637X/741/2/121
7