Survey for Dust Continuum Emissions toward Circumstellar Disks (I - PowerPoint PPT Presentation

Survey for Dust Continuum Emissions toward Circumstellar Disks (I will focus on nearby T Tauri stars) Munetake MOMOSE (Ibaraki)

Detection No Detection Strategy Observations of Dust Disks in Star Forming Regions (d ~ 150 pc) � ~ 1" � -index measurement in 0.01" Snapshot at Band 4 ( � =130/145GHz) � = 230 - 875 GHz for derivation of T(r) in the ′′ ( 10 − 2 M ⊙ ) 0 . 1 > inner regions ′′ ( Detection Survey at 10 − 3 M ⊙ ) or 0 . 3 > ∆ T 5 K ∼ � =345GHz ∆ T 90 mK ∼ Exposure Time 30min. each ∼ Exposure Time 40 min. each ∼ Detection Limit 0 . 11 mJy ∼ Targets 30 × freq ∼ Targets 30 − 50 ∼ 10 − 5 M ⊙ ∼ Exposure Time 3 min. each ∼ Targets 100 − 200 ∼ 0.1" imaging at higher 0.01" Deep imaging at freq ( � =345 or 675GHz) � =345 or 675GHz ′′ ( 10 − 3 M ⊙ ) 0 . 1 > ∆ T 500 mK ∼ ∆ T 20 mK ∼ Deep Detection Survey Exposure Time 9 hrs each ∼ Exposure Time 120 min. each ∼ at � =345 or 675GHz Targets 5 − 10? ∼ Targets 30 − 50 ∼ Detection Limit 0 . 011 mJy ∼ 10 − 6 M ⊙ ∼ � ~ 0.1" � ~ 0.01" Exposure Time 5 hrs each ∼ Targets 10 − 20 ∼

ALMA ʼ s Goals Understanding the formation of planetary systems “general scenario” (unified theory) ? when/how a planet is formed ? core-accretion vs. gravitational instability rocky planet / gaseous planet / icy planet how common the planet formation is ? YSO Disks = Initial condition for planet formation inner regions (< 10 2 AU) will critically be important survey will be essential (details are in a later slide)

Previous Trial (e.g., Kitamura et al. 2002 with the NMA) 13 Single T Tauri stars Strong continuum emission at 1.3mm 1-2” (140-280AU) resolution imaging at λ = 2mm (Image + SED) ← Model Fitting Systematic Derivation of Disk Parameters such as Σ (r), T(r), β

1.5σ interval, contour starting at ±1.5σ Images : ~ 1” resolution

Radial Expansion Evolution of Accretion Disks ? embedded Evolution protostars

Limitation of NMA survey Inadequate angular resolution & sensitivity Derivation of Disk Parameters: Model dependent

Observations with the ALMA “Direct” Derivation of Disk Structure Brightness distribution at multi- λ s → Σ (surface density), T (Temperature), β (emissivity) directly at each position Comparison with Cont. at mid/far-IR and Line → Vertical Structure Higher Sensitivity → Detection of less massive disks Very-high resolution (~ 1AU) observations Better than (current) Optical/nIR telescopes ?

Why we shall need “survey” ? Statistics to discuss ... disk evolution (how to proceed planet formation ?) diversity (related to diversity in planetary systems) “Highlights” = relatively short timescale ... dust growth / formation of planetesimals (e.g., Miyake & Nakagawa 1993, Wada et al. 2007, 2008) disk clearing by proto-planets photo-evaporation / gas dispersion (e.g.,Takeuchi et al. 2005; Ohashi & Momose submitted)

Dust Disk Mass evolution Wyatt et al. 2003 �

Dust Disk Mass evolution Gap ？ Wyatt et al. 2003 �

Why we shall need “survey” ? Statistics to discuss ... disk evolution (how to proceed planet formation ?) diversity (related to diversity in planetary systems) “Highlights” = relatively short timescale ... dust growth / formation of planetesimals (e.g., Miyake & Nakagawa 1993, Wada et al. 2007, 2008) disk clearing by proto-planets photo-evaporation / gas dispersion (e.g.,Takeuchi et al. 2005; Ohashi & Momose submitted)

Initial Mass Distribution vs. Resultant Planetary Systems ※ based on “Core-accretion” Scenario Gas Planets (Ida & Kokubo Solar System type 2002) --------------------- 1: Cores (= Protoplanets) can Earth-like planets only grow above Mcrit 2: Core accretion timescale < gas disk lifetime Distance from the star (AU)

Why we shall need “survey” ? Statistics to discuss ... disk evolution (how to proceed planet formation ?) diversity (related to diversity in planetary systems) “Highlights” = relatively short timescale ... dust growth / formation of planetesimals (e.g., Miyake & Nakagawa 1993, Wada et al. 2007, 2008) disk clearing by proto-planets photo-evaporation / gas dispersion (e.g.,Takeuchi et al. 2005; Ohashi & Momose submitted)

Dust Growth Wada et al. (2008) Dust Emissivity: β : 2 -> 1 as dust grows where ν β

Gap by Protoplanet

Why we shall need “survey” ? Statistics to discuss ... disk evolution (how to proceed planet formation ?) diversity (related to diversity in planetary systems) “Highlights” = relatively short timescale ... dust growth / formation of planetesimals (e.g., Miyake & Nakagawa 1993, Wada et al. 2007, 2008) disk clearing by proto-planets photo-evaporation / gas dispersion (e.g.,Takeuchi et al. 2005; Ohashi & Momose submitted)

内部構造： 1-D Simple Model to examine survey strategy • Axisymmetric, Physical parameters as a function of r – Boundaries : r in , r out – Temperature: T ( r ) ∝ r − q . ∗ Source Function: S ν ( r ) = B ν ( T ( r )) – Surface Density: Σ ( r ) ∝ r − p . – Dust Emissivity: κ ν ( r ) ∝ ν β ( r ) ∗ Vertical Optical Depth: τ ν ( r ) = κ ν ( r ) Σ ( r ) • Observer’s Parameters: – Distance: d – Inclination; i

Beckwith et al. (1990)

Vertical Structure ? Almost all the Submm - mm Continuum will come from interior part because of its lower opacity ... → “1-D” approx. is OK Chiang & Goldreich (1997) see also Dullemond et al. (2001)

Detection No Detection Strategy Observations of Dust Disks in Star Forming Regions (d ~ 150 pc) � ~ 1" � -index measurement in 0.01" Snapshot at Band 4 ( � =130/145GHz) � = 230 - 875 GHz for derivation of T(r) in the ′′ ( 10 − 2 M ⊙ ) 0 . 1 > inner regions ′′ ( Detection Survey at 10 − 3 M ⊙ ) or 0 . 3 > ∆ T 5 K ∼ � =345GHz ∆ T 90 mK ∼ Exposure Time 30min. each ∼ Exposure Time 40 min. each ∼ Detection Limit 0 . 11 mJy ∼ Targets 30 × freq ∼ Targets 30 − 50 ∼ 10 − 5 M ⊙ ∼ Exposure Time 3 min. each ∼ Targets 100 − 200 ∼ 0.1" imaging at higher 0.01" Deep imaging at freq ( � =345 or 675GHz) � =345 or 675GHz ′′ ( 10 − 3 M ⊙ ) 0 . 1 > ∆ T 500 mK ∼ ∆ T 20 mK ∼ Deep Detection Survey Exposure Time 9 hrs each ∼ Exposure Time 120 min. each ∼ at � =345 or 675GHz Targets 5 − 10? ∼ Targets 30 − 50 ∼ Detection Limit 0 . 011 mJy ∼ 10 − 6 M ⊙ ∼ � ~ 0.1" � ~ 0.01" Exposure Time 5 hrs each ∼ Targets 10 − 20 ∼

が小さいほうが有利。 円盤質量 とし， すべての場合，点源で検出として，ある時間での達成感度を として， を で近似的に予想される 円盤質量 が小さいほうが有利。 とし， すべての場合，点源で検出として，ある時間での達成感度を を で近似的に予想される として， Best Frequency Bands for Detection Survey 10 Mean Temperature β =1 case (Mass-weighted) Relative Mass Sensitivity (1 at 110GHz) � r out 2 π r Σ ( r ) T ( r ) dr r in ¯ T ≡ M d ※ proportional to � for the sample in Kitamura et al. ∆ F ν ※ 23 K for the sample κ ν B ν ( ¯ T ) in Kitamura et al. (2002) –––– T = 20 K –––– = 50 K = 80 K –––– ν = 345 or 675 GHz ? 1 100 1000 Frequency [GHz]

Point-Source Detection Assuming ¯ T = 20 K and β = 1 ... • ν = 345 GHz � 2 � t integ � − 1 / 2 � d ∆ M disk = 10 − 5 M � (3) . 150 pc 157 sec • ν = 675 GHz � 2 � t integ � − 1 / 2 � d ∆ M disk = 10 − 5 M � (4) . 150 pc 64 sec c.f. M Jupiter = 10 − 3 M � , M Earth = 3 × 10 − 6 M � .

Detection No Detection Strategy Observations of Dust Disks in Star Forming Regions (d ~ 150 pc) � ~ 1" � -index measurement in 0.01" Snapshot at Band 4 ( � =130/145GHz) � = 230 - 875 GHz for derivation of T(r) in the ′′ ( 10 − 2 M ⊙ ) 0 . 1 > inner regions ′′ ( Detection Survey at 10 − 3 M ⊙ ) or 0 . 3 > ∆ T 5 K ∼ � =345GHz ∆ T 90 mK ∼ Exposure Time 30min. each ∼ Exposure Time 40 min. each ∼ Detection Limit 0 . 11 mJy ∼ Targets 30 × freq ∼ Targets 30 − 50 ∼ 10 − 5 M ⊙ ∼ Exposure Time 3 min. each ∼ Targets 100 − 200 ∼ 0.1" imaging at higher 0.01" Deep imaging at freq ( � =345 or 675GHz) � =345 or 675GHz ′′ ( 10 − 3 M ⊙ ) 0 . 1 > ∆ T 500 mK ∼ ∆ T 20 mK ∼ Deep Detection Survey Exposure Time 9 hrs each ∼ Exposure Time 120 min. each ∼ at � =345 or 675GHz Targets 5 − 10? ∼ Targets 30 − 50 ∼ Detection Limit 0 . 011 mJy ∼ 10 − 6 M ⊙ ∼ � ~ 0.1" � ~ 0.01" Exposure Time 5 hrs each ∼ Targets 10 − 20 ∼