HerbigHerbig Ae/BeAe/Be starsstars RensRens WatersWaters George Herbig 1920-2013 SRONSRON UniversityUniversity ofof AmsterdamAmsterdam

Herbig Ae/Be stars OverviewOverview

• A bit of history • Herbig Ae/Be stars and their disks • Disk geometry • Dust diagnostics • Gas diagnostics • Links to planetary systems • Conclusions

Herbig Ae/Be stars HerbigHerbig Ae/BeAe/Be starsstars

• First introduced as a group by George Herbig in 1960 • A or B type stars with IR excess, Hα emission, reflection nebulosity • In star forming regions • Surrounded by what we now know are proto-planetary/accretion disks, envelopes

• Later: criterion “association with reflection nebulosity” was relaxed

• See also e.g. Bastian et al. (1983), Lamers et al. (1998) Confusion with post main sequence stars remains an issue

Herbig Ae/Be stars Herbig Ae/Be stars Herbig Ae/Be stars SamplesSamples ofof HerbigHerbig Ae/BeAe/Be starsstars

• Original list of Herbig (1960) (26 objects, candidates) • Herbig & Rao (1972) (T Tau and Herbig Ae/Be stars) • Finkenzeller & Mundt (1984) (57 stars including candidate HAEBE stars) • The et al catalogue (1994) (287 objects, including candidate HAEBE stars)

• Cross-referencing IRAS point source catalogue and optical star catalogues: e.g. Weintraub (1990), Oudmaijer et al. (1992), Malfait et al. (1998)

Searches for intermediate mass young stars in massive star forming regions (e.g. Hanson, Blum, Bik, Kaper)

Herbig Ae/Be stars Central star characterization

Strom et al. 1972

See also Cohen & Kuhi 1979

Acke & Waelkens 2004

Strom et al. 1972

Chemical composition Rotation speed Magnetic fields binarity

Herbig Ae/Be stars FinkenzellerFinkenzeller && MundtMundt 19841984

Outflows IR excess due to dust

Herbig Ae/Be stars SpectralSpectral energyenergy distributionsdistributions

Hillenbrand et al. 1992

Herbig Ae/Be stars MassMass accretionaccretion ratesrates

Skinner et al. (1993) from radio continuum

Muzerolle et al (2004)

Typical accretion rates 10-8 -7 to 10 Mo/yr

Herbig Ae/Be stars OutflowsOutflows andand accretion,accretion, HerbigHerbig HaroHaro objects,objects, jetsjets

rAB Aur

Praderie et al. 1986 Grady et al.2000 HD100546

Herbig stars show phenomena that are similar to T Tau stars

Grady et al. (1996) Herbig Ae/Be stars First international meeting on herbig Ae/Be stars Amsterdam, 1993

Herbig Ae/Be stars TremendousTremendous progressprogress inin thethe pastpast 2020 years!years!

HST KECK

ISO VLT(I)

Spitzer Subaru

Herschel ALMA

Herbig Ae/Be stars SpectralSpectral evolutionevolution duringduring starstar andand planetplanet formation:formation: picturepicture forfor allall intermediateintermediate massmass PMSPMS stars?stars?

Van Boekel and refs therein (2004)

Eur osci enc e20 06 EvolutionaryEvolutionary tracks:tracks: pre-main-sequencepre-main-sequence phasephase

Palla & Stahler 1990, 1993 Birth line for Herbig Ae/Be stars

8 M0 Upper mass limit for PMS phase Faster evolution of intermediate mass PMS stars

Herbig Ae/Be stars IsolatedIsolated HerbigHerbig Ae/BeAe/Be stars:stars: relativelyrelatively oldold disksdisks

~1-4 Myr intermediate mass stars in clusters

isolated

Van den Ancker et al. 1997 Fedele et al. Bik, Maaskant

Herbig Ae/Be stars ProgenitorsProgenitors ofof HerbigHerbig Ae/BeAe/Be starsstars

• Herbig Ae stars: Intermediate mass T Tau stars • Herbig Be stars: Massive, embedded YSOs

Calvet et al. (2004) -8 Mass accretion rates ~3 10 Mo/yr

Herbig Ae/Be stars IsolationIsolation versusversus clustercluster environmentenvironment

Triggered star formation

Disk evaporation timescale

Impact on planet formation

Odell & Wong 1996

Herbig Ae/Be stars Disks,Disks, disksdisks disks!disks!

• How does planet formation proceed? • How does it depend on stellar mass, environment? • Which disks produce which planetary system architectures? • What is the stellar upper mass limit for planet Henning & Semenov formation to proceed?

Herbig stars are truly intermediate between massive YSOs and low mass T Tau stars

Herbig Ae/Be stars DiskDisk models:models: ChiangChiang andand GoldreichGoldreich

Chiang & Goldreich (1997) Hydrostatic equilibrium disk models

Herbig Ae/Be stars • “Puffed-up” inner rim, casting shadow • Flaring versus self- shadowed disks: Natta et al; grain growth Dullemond, • Planet formation: formation of inner Dominik, holes and disk Natta gaps

Herbig Ae/Be stars StateState ofof thethe artart diskdisk modelsmodels

Prodimo (Woitke, Kamp, Thi) Gas and dust treated separately Chemical network

Herbig Ae/Be stars DiskDisk geometry:geometry: signpostsignpost ofof planetplanet formationformation

Flaring versus Spiral density Disk Dust flat waves gaps/holes traps

HD104237 Group 2

AB Aurigae Group 1 HD100546 HD142527 IRS 48 Meeus et al. Grady et al. Honda et al; Van der 2001 Verhoeff et al. Marel et al.

Herbig Ae/Be stars FromFrom flaringflaring toto self-shadowedself-shadowed disksdisks

Dust settles and grows, Dullemond & Dominik removal of small grains from disk surface; gas disk Do disks remains flaring evolve from flaring to self- shadowed Nakagawa et al. 1986 disks?

Herbig Ae/Be stars Gas-richGas-rich diskdisk withwith dustdust settledsettled toto mid-planemid-plane

Verhoeff et al (2009) Herbig Ae/Be stars FlaringFlaring outerouter diskdisk inin HD97048HD97048

mid-IR imaging, Lagage et al. 2006 (Science) Direct measure of outer disk flaring angle Agrees with hydrostatic equilibrium models

Herbig Ae/Be stars However…However… ““FlaringFlaring disksdisks”” areare transitionaltransitional disks!disks!

Khalafinejad, Maaskant et al. (in preparation)

Herbig Ae/Be stars InnerInner diskdisk structurestructure

Near-IR interferometry: optically thin inner cavities, dust sublimation at ~1500 K

Monnier et al.

Herbig Ae/Be stars InnerInner diskdisk structurestructure

• Natta et al (2001), Dullemond et al. (2001): disk wall directiy irradiated • Isella & Natta (2005): rounded off inner wall; Kama et al: optically thin inner region Kama et al. • Problem: hydrostatic equilibrium disks do not produce enough near-IR flux • Solutions: • optically thin halo (Vinkovic et al. 2006) • Extended disk atmosphere (Thi et al) • Magnetically supported region in disk atmosphere (turner et al. Turner et al. 2013)

Herbig Ae/Be stars DustDust asas aa tracertracer ofof planetplanet formationformation amorphous • Grain size: • Dust settling & growth: flaring to self- shadowed… • spatial distribution as a function of grain size (dust traps) • Grain composition: crystalline • Thermal processing: thermal annealing of amorphous silicates, carbon combustion • Gas phase condensation of crystalline silicates in inner regions • Formation of new solids, e.g. FeS

• Origin of crystalline silicates: • Thermal annealing near the star • Radial mixing to outer disk regions • Local processing: shocks caused by planet formation / gap formation

Herbig Ae/Be stars ISOISO openedopened aa newnew viewview onon HAeBeHAeBe disksdisks

e.g. Bouwman et al. 2003 Meeus et al. 2001 Acke & van den Ancker 2004 Herbig Ae/Be stars VLTI/MIDIVLTI/MIDI :: crystalscrystals formform nearnear thethe youngyoung starstar

• Annealing,Annealing, formationformation ofof forsteriteforsterite andand enstatiteenstatite • ChemicalChemical equilibriumequilibrium reactionsreactions E F E F Van Boekel et al. 2004

Herbig Ae/Be stars SpitzerSpitzer spectra:spectra: dustdust mineralogymineralogy

More enstatite in the inner disk More forsterite in the outer disk Traces formation history

Juhasz et al.

Herbig Ae/Be stars HerbigHerbig Ae/BeAe/Be starstar HD100546HD100546

[OI] Bouwman

Water Ice

[CII]

forsterite

(see also McClure et al. (2012) GQ Lupi disk spectrum) DustDust trapstraps inin herbigherbig Ae/BeAe/Be disksdisks

Ohashi et al. (2007) Van der Marel et al. (2013) Vortex-shaped dust trap caused by companion

Herbig Ae/Be stars DustDust trapstraps inin HerbigHerbig Ae/BeAe/Be disks:disks: HD142527HD142527

Mid-infrared imaging Sub-mm imaging (ALMA) Warm grains Cold gas/dust Verhoeff et al. (2010) Fukagawa et al. (2013) Gravitationally unstable outer disk?

Herbig Ae/Be stars GasGas diagnoticsdiagnotics

• Outflows • Jets • Accretion • Disk structure • Disk kinematics • Chemistry

Many papers, ISO A. Carmona (2009) spectroscopy, Spitzer, Herschel, Keck, VLT, ALMA,…

Herbig Ae/Be stars CO ro-vibrational line GasGas inin upperupper diskdisk layerslayers [OI] 6300 A

Brittain et al.: CO ro- vibrational emission Van der Plas et al T (gas) > 1000K

Herbig Ae/Be stars HerschelHerschel observationsobservations ofof coolcool gasgas inin disks;disks; example:example: GasGas LinesLines inin HD100546HD100546

CO, OH, H2O lines detected. CO rotation diagrams: T = 300, 800 K N(CO) 1016 – 1017 cm–2 B. Sturm et al. (2010)

See also Meeus et al. (2012)

CO modeling: gas temperature in disk atmosphere larger than dust temperatures (Bruderer 2012) ColdCold gasgas tracedtraced inin COCO andand HCO+HCO+

Casassus et al. 2013

Herbig Ae/Be stars Near-IR Far-IR

T Tauri [OI], CO, OH, H O CO, OH, 2

< 1.5 M☼ H2O,HCN,C2

H2

[OI], CO, OH HAeBe I (flared) CH+, H O CO 2 OH

> 1.5 M☼

HAeBe II (flat) [OI], OH, H2O CO OH

D. Fedele EvidenceEvidence forfor planetsplanets orbitingorbiting intermediateintermediate massmass starsstars

Image: NASA

Herbig Ae/Be stars Exo-planetsExo-planets orbitingorbiting intermediateintermediate massmass starsstars

Exoplanet database

Herbig Ae/Be stars ZeerZeer jongejonge planeetplaneet inin stofschijfstofschijf

Young planet in Beta Pic disk!

Lagrange et al. (2008) Herbig Ae/Be stars massivemassive planetsplanets surroundingsurrounding youngyoung intermediateintermediate massmass starsstars

HR 8799 Beta Pic Marois et al 2008 Science Lagrange et al.

Herbig Ae/Be stars Proto-planetProto-planet inin HD100546?HD100546?

Quanz et al. 2013

Herbig Ae/Be stars Questions/issuesQuestions/issues

• How does disk evolution proceed? • How does disk evolution/planet formation change as a function of stellar luminosity? • Do all intermediate mass stars from planetary systems? • What is the importance of environment on intermediate mass star & planet formation? • How do disks evolve chemically? • Can we link planetary system architecture to disk structure?

Herbig Ae/Be stars The end

Herbig Ae/Be stars Backup slides

Herbig Ae/Be stars ConnectionConnection withwith solarsolar systemsystem

• SolidSolid bodiesbodies andand dustdust inin solarsolar systemsystem tracetrace formationformation historyhistory • RockyRocky planets:planets: memorymemory ofof naturenature buildingbuilding blocksblocks erasederased • Asteroids:Asteroids: highhigh temperaturetemperature condensation,condensation, processingprocessing inin innerinner solarsolar systemsystem • Comets:Comets: primitive,primitive, representingrepresenting pristinepristine materials?materials? • KuiperKuiper belt:belt: icyicy bodiesbodies formedformed inin outerouter regionsregions solarsolar systemsystem • ZodiacalZodiacal dust:dust: collisionscollisions betweenbetween asteroids,asteroids, debrisdebris fromfrom cometscomets

Herbig Ae/Be stars …… andand eveneven youngeryounger objectsobjects

Ellerbroek et al.

IRAS08576n292 central star: temperature corresponds to mid-A spectral type

Herbig Ae/Be stars DiskDisk structurestructure

• MCMax (Min et al, 2009) modeling of SEDs (Maaskant et al, in prep) • Inner hole  Lower inner Dotted: Herbig SED rim temperature, excess Dashed-dotted: best fit starts at longer wavelength • Lower disk scale height. • Future evolution of SEDs • Inner rim temperature becomes hotter as Teff of central star increases  Herbig like SED • Transition disk; disk is disappearing (disk fraction declines strongly with age, I06084-0611, Maaskant et al, 2011 Hernandez et al, 2008) HerbigHerbig Ae/Ae/BeBe precursors?precursors?

• Masses similar to those of Herbig stars (1-5 Msun).

• Excess emission starts only at 3 micron

• They will evolve to A and B stars (HAeBe?) •I060840611 (Maaskant et al, 2011) • Different disk structure? •RCW 34 (Bik et al, 2010) • Dissolving disks? [OI][OI] ExcitationExcitation

Line ratios consistent with PDR models with densities 5 –3 of about 10 cm and G0 = 103 to 107 Because of possible contamination of [CII] by diffuse emission,

densities and G0 are lower limits. IcesIces andand HydrosilicatesHydrosilicates inin HD142527HD142527

ISO Data

Herschel/PACS Bouwman, Henning, et al. In prep.

Large disk gap

H2O Ice Bands

(Malfait et al 1999) Amazingly strong water ice bands! FlaringFlaring versusversus flatflat (self-shadowed)(self-shadowed) disksdisks

• RedRed IRIR spectrumspectrum • BlueBlue IRIR spectrumspectrum • (strong)(strong) [OI][OI] 63006300 AA • Weak/absentWeak/absent [OI][OI] • StrongStrong PAHPAH em.em. • Weak/absentWeak/absent PAHsPAHs • SpatiallySpatially resolvedresolved PAHPAH • Weak/absentWeak/absent COCO • COCO fund.fund. 4.64.6 micronmicron fund.fund. • ScatteredScattered lightlight • NoNo scatteredscattered lightlight • OftenOften nono silicatessilicates • SilicatesSilicates detecteddetected • SteeperSteeper mmmm • FlatFlat mmmm continuumcontinuum continuumcontinuum Herbig Ae/Be stars Gas-richGas-rich diskdisk withwith dustdust settledsettled toto mid-planemid-plane

Verhoeff et al (2009) Herbig Ae/Be stars EvidenceEvidence forfor diskdisk shadow:shadow: thethe outerouter diskdisk knowsknows aboutabout thethe innerinner diskdisk

red

Grain growth e p o l s

blue sh ad ow Inner rim height increases

Acke et al. (2009) Herbig Ae/Be stars Exo-planetsExo-planets orbitingorbiting intermediateintermediate massmass starsstars

Herbig Ae/Be stars DiskDisk gaps:gaps: planets!planets!

Lack of hot dust • PlanetsPlanets clearclear orbitorbit • dustdust removedremoved • Lack of emission Lack of emission star inin partpart ofof IRIR spectrumspectrum dust

Herbig Ae/Be stars IntermediateIntermediate massmass pre-pre- main-sequencemain-sequence starsstars inin embeddedembedded clustersclusters • Classification as G and K stars (Teff: 5000 - 6000 K) • Surface gravity: lower than that of dwarfs, PMS stars, still contracting. • 50 % sources: IR-excess detected with Spitzer • Ages between 1 and 4 Myrs.

RCW34, Bik et al, 2010 HDHD 100546:100546: aa youngyoung starstar withwith crystallinecrystalline silicatessilicates

Grady et al, HST imaging

Malfait et al. ISO spectroscopy

Herbig Ae/Be stars HD100546:HD100546: DetailedDetailed ModelsModels

• WithWith 2-D2-D radiativeradiative transfertransfer • MuldersMulders etet al.al. (2011);(2011); Bouwman,Bouwman, Min,Min, MuldersMulders etet al.al. (in(in prep)prep) • ForsteriteForsterite isis nearnear thethe innerinner wallwall ofof outerouter diskdisk • 13-2013-20 AU,AU, belowbelow diskdisk surfacesurface • CrystallineCrystalline massmass fractionfraction 40-60%40-60% • LessLess thanthan 0.5%0.5% IronIron contentcontent • NoNo parentparent bodybody processing,processing, resemblesresembles IDPsIDPs andand cometscomets • PreliminaryPreliminary waterwater iceice modeling:modeling: • ~1%~1% waterwater iceice • SnowSnow lineline atat 2020 AUAU DivisionDivision intointo twotwo groups:groups: flaringflaring versusversus flatflat disksdisks

HD104237

Group 2

Meeus et al. 2001

AB Aurigae

Group 1

Herbig Ae/Be stars SEDsSEDs ofof herbigherbig BeBe stars:stars: nono flaringflaring disks?disks?

Verhoeff et al. 2010

Outer disk evaporation (Gorti & Hollenbach) Dust settling timescale versus disk evaporation timescale What is the stellar upper mass limit for planet formation?

Herbig Ae/Be stars HSTHST imagingimaging ofof scatteredscattered lightlight fromfrom disks:disks: flaringflaring andand self-shadowedself-shadowed

Grady et al. 2005

Herbig Ae/Be stars