4
Nuage moléculaire
10 pc ― 4°
Effondrement Fragmentation
1 pc ― 20’ 0.1 pc ― 2’ (Taurus)
1000 AU ― 7’’ 300 AU ― 2’’ 30 AU ― 0.2’’
Accretion disk and bipolar ejection
Molecular clouds Collapse Fragmentation
Debris disk and protoplanets Planetary system
105 / 106 yrs old
[Bou
vier
& M
albe
t 200
1]
TTauristars(TTS): ‐Solarmassobjects(~M☉) ‐SpectraltypesG‐M
HH30 - HST
Jet
Disk
• OpEcallythickdisks• ObscuraEonthecentralstaraccordingtogeometry• DetailedverEcalstructureofthedisk,physicsofgrainformaEon• Jetsandnebularstructure(accreEon,shocks)
HH30 seen almost edge-on by the HST (optical + NIR)
HAEBE=PMSstarsofintermediatemass(1.5–10M) Spectraltypes:BtoF8
Surroundedbyaprotoplanetarydiskofgasanddust(complexenvironment)
LikeTTauristars,alargefracEonofHAEBEliesinmulEplesystems(68±11%–Bainesetal.2006).
BUTcontrarytothelessmassiveTTauristars,formaEonscenarioisveryuncertain.
⇒HAEBEareataninterfacebetweentworegimesofstarforma6on
Accre6onviatheaccreEoncolumns(TTau)ortheinnerdisk⇒Veiling,IRexcess
ConnecEonsstar/innerdisk,innerdisk/dustdisk? Morphologyoftheinnerrimofthedustdisk?
ProcessusofdissipaEonandevoluEonofthedisk? Lawoftemperature,velocity,densityinthedisk?
Ejec6onviaawind(star,disk,…)andjets Launchingpointandmorphologyofjets?
MechanismsthatfavorjetcollimaEon?
Mass‐lossratewrtmass‐accreEonrate?
Forma6onoftheHydrogenemissionlines⇒ConnecEonbetweenaccreEonandejecEon
Lineformingregions?
Mechanismsthatcouldexplainthetemporalvariability?
6
Near‐infrared(spectro‐)interferometrydirectlyprobestheemissionwithintheinnermost astronomical unit (AU), where key quanEEes for the star‐disk‐protoplanet(s) interacEons are set. The regions probed by this technique aremuchmorecomplexthanexpected.
3DMHDsimula6onsofaccreEon(drivenbymagneto‐rota3onalinstability)ontoarotaEngmagneEzedstarwithaElteddipolemagneEcfieldproducecomplexmaps.
Allthesecomplicatedinner
diskstructuresarestrongly
6mevariableonaEmescale
ofweekstoyears…
[Romanova et al. 2012]
8
Simultaneousspectroscopyandphotometrystudies[Bouvier et al. 1999, 2003, 2007]
[Ménard et al. 2003]
Light curve shows periodical (~ 8.2 days) eclipses of the photosphere that occur without much color variation.
The linear polarization increases as the system fades.
Periodical occultation of the photosphere by an optically thick, magnetically-warped inner disk region
Periodicaleclipses
(innerdiskwarp)
P=8.22d
Balmerlines
(accre6onfunnel)
Veiling
(accre6onshock)
Diskwarp,accre6oncolumn,accre6onshock:allspa6allyassociated
Inclinedmagnetosphere
[Bouvier et al. 2007]
[Donati et al. 2010]
Spectro‐polarimetricstudies:
2‐3kGdipolarmagneEcfield,Eltedat~20degontotherotaEonaxis
HeI
Themagne6cpoleislocatedataboutthesameazimuthasthediskwarpthatproducestheeclipse Bothacold(magneEc)spotandahot(accreEon)
spotarefoundclosetothemagneEcpole
Shortterm(weeks)variabilitysupportstheideaof“magnetosphericaccre6oncycles”onaEmescaleofafewrotaEonperiodsinaccreEngTTauristars.
MagneEcconfiguraEonsofthestar‐diskinteracEoncanalsovaryonamuchlongerEmescale(~afewyears).
AATau’seclipses
0.6mas
• StarsorbitinagapopenedbyEdalinteracEonsinsideacircumbinarydisk.
• Youngshortperiodbinaries(P<afew10days,sep~afew0.1AU)cannotsupportlargecircumstellardisks.⇒Theyaresurroundedbyacircumbinarydisk.
• EvidenceofenhancedemissionlineacEvityclosetoperiastronpassages(DQTau(Basrietal.1997),UZTauE(Martynetal.2005)⇒ non‐axisymmetricaccre6onperturbedbytheorbitalinteracEonwiththeinnerdisk
Howdoesaccre6onproceedfromthecircumbinarydiskontothe
componentsofthesystem?
Howdothecomponentsevolveifpreferen6alaccre6on? 12
[de Val-Borro et al. 2011]
Stronginteresttoaccesstoimagingcapabili6esoftheseobjects
inthevisible(+IR)ranges
09/11/2012 Conférence XX - Mon Nom et mon prénom - lieu YY 14
16
0
10
20
30
40
50
60
70
4,5 5,5 6,5 7,5 8,5 9,5 10,5 11,5 12,5 13,5 14,5 15,5 16,5 17,5 18,5 19,5 20,5
Obj
ect n
umbe
rs
Magnitude
Pre-Main sequence stars in Taurus-Auriga
K
R
From Kenyon et al. 2008
KinemaEcsstudiesareofstrongimportancefor:
Windandjets:◦ SeveralspectralchannelsinHα
AccreEonflows:◦ Smallradialvelocityofthefunnelflowclosetotheinnerrimofthedisk
◦ Freefallvelocity(~300km/s)closetothestar
Spectralresolu6onofseveralthousandsandupto20000
09/11/2012 Conférence XX - Mon Nom et mon prénom - lieu YY 17
[Whe
lan
& Ga
rcia
20
08]