Star formation in nearby young clusters! Catarina Alves de Oliveira!

Transcription

1 Star formation in nearby young clusters! Catarina Alves de Oliveira!

2 What determines the mass of a star? Credits: Adapted from Bastian et al & de Marchi et al Introduction

3 Bridging the gap between stars and planets: Brown dwarfs Objects(not(massive(enough(to(sustain(stable(hydrogen(fusion((M( <(0.075(M! ( (75(M Jup ) $ ( TheoreAcal(predicAon(50(years(( ago(by(shiv(s.(kumar:( ( There(exists(a(limiAng(mass(( below(which(a(contracang(star(( cannot(reach(the(mainisequence( (stage. (Kumar(1963( ( WISE Introduction

4 Bridging the gap between stars and planets: Brown dwarfs First(discoveries(in(1995:(( ( ( ( ( ( (((Rebolo,(ZapateroIOsorio(&(MarAn(1995( ( ( ( ( ( (((Nakajima(et(al.(1995( ( ( ( ( ( (((Oppenheimer(et(al.(1995 (( ( This%is%not%a%% brown%dwarf!% Introduction

5 Bridging the gap between stars and planets: Brown dwarfs Fast(growing(field(in(the(last(years:( (( (I(M,(L,(T,(and(Y(spectral(classes( ( (I(coolest(brown(dwarf(known(to(date:(~300(K((~25( o C(!)( ( (I(raAo(of(brown(dwarfs(to(stars(in(the(Galaxy(~(1/5( ( Introduction

6 Brown dwarfs how do they form? Different from solar-type stars Like solar-type stars Disc fragmentation Ejection Photo-Erosion Turbulence Gravity Introduction

7 Advances(in(IR(detectors( impelled(the(development(( of(wideifield(instruments(( shaping(our(view(of(the(( cold(universe.( T. Maschberger Introduction Alves de Oliveira & Casali M. Bate

8 Brown dwarfs in star-forming regions ADVANTAGES _ DETECTABILITY _ MIN. DYNAMICAL EVOLUTION Alves de Oliveira & Casali DISADVANTAGES _ CONTAMINATION _ MODELS M. Bate Introduction

9 Nearby star-forming regions Rho(Oph((120pc,(1Myr)( IC(348((316pc,(2Myr)( Chamaeleon((160pc,(2Myr)( Caltech Introduction

10 How do stars & brown dwarfs form? Initial Mass Function Wide-field IR surveys Complete census of young clusters ( Accretion Discs Multiplicity Kinematics X-rays Where can planets form? CFHT survey Science case

11 CFHT, 3.6m telescope, Mauna Kea WIRCam, near-ir camera (YJHKs) MegaCam, optical camera (z) Survey of nearby clusters with deep exposures over large fields: IC 348 Rho Oph CFHT CFHT survey Observations

12 IC Myr 316 pc 345 members (30 brown dwarfs) WISE Photometry

13 CFHT-photometric survey: 31 substellar candidates IC 348 Photometry

14 Photometry is not enough Need spectroscopy: - to confirm their membership via signature of youth - to derive spectral types, which constrain temperature and mass IC 348 Photometry

15 Spectroscopic follow-up of 24 candidates (84% within completeness limit and Av<4 ) Osiris/GTC 10.4 m, La Palma 10 hours z ~ 20 mag GTC GNIRS/GEMINI 8.1 m, Hawaii 25 hours J ~17 mag Gemini IC 348 Spectroscopy

16 Grid of young templates: M3-M9 (<2Myr): IC 348 / Taurus / Cha I (Briceno et al. 2002, Luhman et al. 2003a,b, Luhman 2004a,b) optical and near-ir spectra (K. Luhman) Numerical spectral fitting to simultaneously derive spectral type and extinction Normalised F! *Spectra provided by K. Luhman id10289.m3 id201.m4 mho7.m525 mho5.m6 kpno5.m75 id405.m m925 kpno4.m !(µm) (H 2 O( ( (H 2 O( ( (H 2 O( ( Na(I( (( ( (H 2 O( (( ( CO( ( ( _( Spectral typing Spectroscopy

17 Grid of L-SpT templates: L0-L5 (10-30Myr): low-gravity field brown dwarfs (moving groups?, Cruz et al. 2009) optical (publicly available) and near-ir (K. Luhman) Luhman et al Normalised F λ MASS J : L0 Taurus (1Myr) 2MASS J : L0 low gravity field (10 30Myr) L0 Taurus: our GEMINI/GNIRS data L0 low-g field: courtesy K. Luhman λ(µm) Spectral typing Spectroscopy

18 Spectroscopic follow-up of 24 candidates (84% within completeness limit and Av<4 ) " Confirmed spectroscopically 16 new members, including 13 brown dwarfs " 5 new members with L0 spectral type (according to models ~ 13M Jup ) " Evidence for disks around two L0 brown dwarfs Log L / L O Dusty (1, 3, 5, 10, 30 Myr) M6 M7 M8 M9 L Log T eff IC 348 Spectroscopy

19 Alves de Oliveira et al. 2012b Log Number = 0.0 ( =1.0) =-0.3 ( =0.7) IC Log Mass (M O ) Substellar mass function IC348: 43 spectroscopic BDs (13 new) Av<4: 35 spectroscopic BDs (9 new)!α = 1.0 ± 0.3 Av<4 + sub-field: 25 spectroscopic BDs (3 new)!α = 0.7 ± 0.4 No%indica2on%for%IMF%varia2ons%(Av<4 + sub-field: Luhman et al our work, 197 spec.)( Log Number m c =0.21, σ=0.52 Γ SP = 1.3 (α SP =2.3) Log Mass (M O ) CDF Data/Chabrier system IMF m [M ] IC 348 IMF

20 Rho Oph 1 Myr 120 pc ~300 members (11 brown dwarfs) Alves de Oliveira & Casali 2008 (Image processing: CASU / Luis Calçada) Photometry

21 CFHT-photometric survey: 110 substellar candidates Rho Oph Photometry

22 Spectroscopic follow-up of 45 candidates (~93% within completeness limit and Av<20) SofI/NTT 3.6 m, La Silla,Chile 6 nights J ~15 mag ESO ISAAC/VLT 8 m, Paranal, Chile 3 nights H ~ 17 mag ESO 12 CFHTWIR-Oph 31 (M5.25) CFHTWIR-Oph 98 (M9.75) CFHTWIR-Oph 37 (M5.75) CFHTWIR-Oph 77 (M9.75) 10 CFHTWIR-Oph 9 (L0) CFHTWIR-Oph 107 (M6.25) Normalised F + Constant 8 6 CFHTWIR-Oph 16 (M6.75) CFHTWIR-Oph 101 (M7) CFHTWIR-Oph 18 (L0) CFHTWIR-Oph 90 (L0) CFHTWIR-Oph 100 (L0) 4 CFHTWIR-Oph 66 (M7.75) CFHTWIR-Oph 103 (L0) 2 CFHTWIR-Oph 78 (M7.75) CFHTWIR-Oph 33 (L4) Rho Oph (µm) Spectroscopy

23 Spectroscopic follow-up of 45 candidates (~93% within completeness limit and Av<20) " Confirmed spectroscopically 27 new members, including 20 brown dwarfs " 4 new L0 members and 1 L4 (according to models ~ 5-9M Jup ) Rho Oph Spectroscopy

24 Alves de Oliveira et al Alves de Oliveira et al. 2012a (A&A) Log Number =-0.3 ( =0.7) =-0.2 ( =0.8) Rho Oph Log Mass (M O ) Substellar mass function Rho Oph: 43 spectroscopic BDs (20 new) Av<15: 33 spectroscopic BDs (18 new)!α = 0.7 ± 0.3 Av<8: 19 spectroscopic BDs (9 new)!α = 0.8 ± 0.4 Peak(of(IMF(and(raAo(BD/stars(are(consistent(with(other(clusters:(no%IMF%varia2on%(251(spec.)( All Av=8 Av=15 Av= All Av=8 Av=15 Av= Av=0 Av=8 Av=15 Av=20 Members: <M6 >M6 uncertain SpT Contaminants: No spectroscopy: Log Number Number H Av=5mag Log Mass (M) 0 B A F GK0 K2 K4 K6 M0 M2 M4 M6 M8 L0 L2 L4 Spectral Type J-H Rho Oph IMF

25 Parker, Maschberger & Alves de Oliveira 2012 (MNRAS) No signature of mass segregation in Rho Oph: - λ MSR (based on minimum spanning tree, Allison et al. 2009a) - m-σ method (based on stellar surface density, Maschberger & Clarke 2011) Indication that mass segregation is not primordial (but dynamical) Rho Oph Mass segregation

26 Parker, Maschberger & Alves de Oliveira 2012 (MNRAS) Rho Oph Mass segregation

27 Alves de Oliveira et al., in prep: Herschel survey of brown dwarf disks in Rho Oph WIRCam Spitzer Herschel WIRCam Spitzer Herschel Spectra 0457 Correct for extinction ( ( Construct SED MCFOST grid of models Find best fit Rho Oph DISC PROPERTIES Disks with Herschel

28 Alves de Oliveira et al., in prep: Herschel survey of brown dwarf disks in Rho Oph - Detect 12 brown dwarf disks ( M6 < SpT < M8.5 ) at 70µm and 100µm (5 at 160µm) PACS%70μm% GY M CFHTWIR-Oph-66 M PACS%100μm% F (Wm 2 ) F (Wm 2 ) (µm) (µm) Rho Oph Disks with Herschel

29 CFHT survey for young T dwarfs: Serpens: 2 photometric candidates (Spezzi, Alves de Oliveira et al. 2012, A&A) IC 348: 1 photometric candidate (Burgess et al. 2009, A&A) Young T dwarfs IC348 and Serpens

30 Chamaeleon 2 Myr pc Cha I: ~300 members Cha II: ~60 members Cha III: no YSOs Ex2nc2on%map% Cham%II% 4(pc( Cham%I% Cham%III%

31 MagneAc( Field( Turbulence Gravity( What determines if a star will form? Chamaeleon

32 Herschel s(view(of(the(largeiscale(structure(in(the(chamaeleon(dark(clouds( SPIRE%250%µm% 4(pc( Chamaeleon

33 Which are the main players in Cha I, II, and III:! Magnetic field, turbulence, gravity, radiative feedback?! Chamaeleon

34 DisPerSe (Sousbie 2011) to trace structure! Tool to characterize filaments Chamaeleon

35 Column density PDF within the simulation by Kritsuk et al. (2011). At t = 0 the distribution is log-normal. At later times, a high density power-law tail develops. From(Hennebelle(&(Falgarone(2012( Chamaeleon

36 Interstellar%maOer%with%Herschel( Bubble(blown(into(the(surrounding(interstellar(mater(and(heated(by(the(star( HD97300% Kóspál(et(al((incl.(Alves(de(Oliveira)(2012,(A&A% A%new%Herschel%view%of%the%young%star% T54:%not%a%transi2onal%disk?% Matrà(et(al((incl.(Alves(de(Oliveira)(2012,(A&A$ ( ( Herschel%survey%of%discs%in%Chamaeleon% Winston(et(al((incl.(Alves(de(Oliveira)(2012,(A&A( Spezzi(et(al((incl.(Alves(de(Oliveira)(2012,(in$prep.$ Ribas(et(al(((incl.(Alves(de(Oliveira)(2012,(in$prep.$ Chamaeleon

37 " CFHT photometric survey of IC348 and Rho Oph uncovered several candidate brown dwarfs, and spectroscopic follow-up confirmed 13 new brown dwarfs in IC 348, and 20 in Rho Oph " Discovery of first L0 dwarfs in IC 348 (~13M Jup ) and Rho Oph (4 L0, 1 L4, 4-9M Jup ) " No evidence for variation of the mass function in both clusters (down to ~13M Jup in IC348, and ~4M Jup in Rho Oph) " New census represents fundamental step for further studying properties of young brown dwarfs, e.g. in Rho Oph: - no indication for mass segregation - on-going Herschel survey detects brown dwarf disks down to 160µm " On-going work: understand star-formation history of the Chamaeleon complex Conclusions

38 Catarina Alves de Oliveira, ESA!!!!!!!!Jérôme Bouvier, IPAG!!Estelle Moraux, IPAG!!Hervé Bouy, CAB!!Gaspard Duchêne, UC Berkeley!!Thomas Maschberger, IPAG!!Richard Parker, ETHZ!!Péter Ábráham, Konkoly Observatory!!Gábor Marton, Konkoly Observatory!!Christophe Pinte, IPAG!!Loredana Spezzi, ESO!!Elaine Winston / Andrew Burgess!! Merín, ESA!!Roland Vavrek, ESA!!Timo Prusti, ESA!!Luca Matrà, ESA!!Ágnes Kóspál, ESA!!Elena Puga, ESA!!Göran Pilbratt, ESA!!Alvaro Ribas, CAB!!Nicola Schneider, LAB!!Philippe André, CEA!!Vera Könyves, CEA!!Doris Arzoumanian, CEA!