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Nagayoshi Ohashi, ASIAA Kyoto Univ. 09.11.2009 Observations of Circumstellar Disks around YSOs.

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Presentation on theme: "Nagayoshi Ohashi, ASIAA Kyoto Univ. 09.11.2009 Observations of Circumstellar Disks around YSOs."— Presentation transcript:

1 Nagayoshi Ohashi, ASIAA Kyoto Univ Observations of Circumstellar Disks around YSOs

2 Outline of Talk Brief introduction of the SMA Project Star formation and disk formation/evolution Overview Disks around PMSs; HD Disks around protostars; B335 Brief introduction of the SMA Project Star formation and disk formation/evolution Overview Disks around PMSs; HD Disks around protostars; B335 LAB, France

3 SMA Project Joint project of the SAO and ASIAA. ASIAA joined the project in SMA consists of eight 6-m telescopes operating at submm wavelengths (1mm to 350 m) at the top of Mauna Kea. ASIAA has delivered two telescopes with receiver systems. Currently 230, 345, and 690 GHz bands are under regular operation. The SMA was dedicated in November The SMA is the fore-runner to ALMA. Joint project of the SAO and ASIAA. ASIAA joined the project in SMA consists of eight 6-m telescopes operating at submm wavelengths (1mm to 350 m) at the top of Mauna Kea. ASIAA has delivered two telescopes with receiver systems. Currently 230, 345, and 690 GHz bands are under regular operation. The SMA was dedicated in November The SMA is the fore-runner to ALMA. Kyoto Univ

4 Science using SMA Star formation Star formation Jet/outflow Jet/outflow Circumstellar disks Circumstellar disks Magnetic field Magnetic field Extragalactic Extragalactic Nearby galaxies/AGN Nearby galaxies/AGN High-z galaxies High-z galaxies Evolved stars Evolved stars Astrochemistry Astrochemistry Solar system Solar system Star formation Star formation Jet/outflow Jet/outflow Circumstellar disks Circumstellar disks Magnetic field Magnetic field Extragalactic Extragalactic Nearby galaxies/AGN Nearby galaxies/AGN High-z galaxies High-z galaxies Evolved stars Evolved stars Astrochemistry Astrochemistry Solar system Solar system LAB, France Syfert/AGN Outflow Magnetic field Solar system

5 Star and Planet Formation: Overview LAB, France Dense molecular cloud A low-mass star (protostar) is formed in a dense molecular cloud core through its gravitational collapse. The dense cloud becomes flatted (along the associated magnetic field). The associated magnetic field is also dragged inward. A circumstellar disk is also formed around a YSO. A molecular outflow takes place at some point. Infall is terminated and a dense core is dispersed. The central star becomes optically visible (T Tauri star). Planets are formed in the circumstellar disk? A low-mass star (protostar) is formed in a dense molecular cloud core through its gravitational collapse. The dense cloud becomes flatted (along the associated magnetic field). The associated magnetic field is also dragged inward. A circumstellar disk is also formed around a YSO. A molecular outflow takes place at some point. Infall is terminated and a dense core is dispersed. The central star becomes optically visible (T Tauri star). Planets are formed in the circumstellar disk? Takakuwa et al Lada et al. 2003, Alves et al Optically invisible! Girart et al. 2006

6 Research on Protostellar Disks and Protoplanetary Disks Formation of protostellar/protoplanetary disks; early phase (class 0 or even younger protostars) Evolution of PSD/PPD; intermediate phase (class I and II) Dissipation of PPD/Planet formation; late phase (class II and III) Disks around massive stars and brown dwarfs. Formation of protostellar/protoplanetary disks; early phase (class 0 or even younger protostars) Evolution of PSD/PPD; intermediate phase (class I and II) Dissipation of PPD/Planet formation; late phase (class II and III) Disks around massive stars and brown dwarfs. LAB, France

7 HH211 SiO 8–7 at 0.2 (60 AU) resolution Lee et al. ApJ in press A possible velocity gradient across the innermost pair of knots ~0.5 km /s at ~10 AU A possible velocity gradient across the innermost pair of knots ~0.5 km /s at ~10 AU 7LAB, France

8 8 NGC1333/IRAS4A 345 GHz Total Intensity and Linear Polarization (B field) Dust Polarization & Magnetic Field Girart et al Crutcher (2006), Science, 313, 771

9 Protoplanetary Disk: the site of planet formation Protoplanetary disks (PPDs) are most probable sites for planet formation. Important to understand their physical conditions. Common characteristics or more variety? More than 150 extra-solar planets have been discovered. More systems with hot Jupiters and high eccentricity. How were these extra-solar planets formed? Protoplanetary disks (PPDs) are most probable sites for planet formation. Important to understand their physical conditions. Common characteristics or more variety? More than 150 extra-solar planets have been discovered. More systems with hot Jupiters and high eccentricity. How were these extra-solar planets formed? 9LAB, France

10 MM High Resolution Images of PPDs Geometry: compact, disklike structures Kinematics: Kepler motions Geometry: compact, disklike structures Kinematics: Kepler motions LAB, France mm cont 0.6 x 0.7 (~80 AU x 100 AU) GM Aur (Dutrey et al. 1998)

11 Protoplanetary disks with spiral arms Fukagawa et al AB 1.6 micron HD 1.6 micron Fukagawa et al LAB, France

12 HD Herbig Ae star (F6 IIIe; M * ~ 2Mo) Subaru observations revealed that the disk has a spiral arm (Fukagawa et al. 2006) Subaru observations at MIR revealed a hole in the disk (Fujiwara et al. 2006). ASTE observations suggested existence of a gas disk. There was no mm interferometric observations due to its low declination. Herbig Ae star (F6 IIIe; M * ~ 2Mo) Subaru observations revealed that the disk has a spiral arm (Fukagawa et al. 2006) Subaru observations at MIR revealed a hole in the disk (Fujiwara et al. 2006). ASTE observations suggested existence of a gas disk. There was no mm interferometric observations due to its low declination. 12LAB, France

13 HD142527: Subaru Infrared Images 1.6 m CIAO image (Fukagawa et al. 06) 24.5 m COMICS image (Fujiwara et al. 06) 13LAB, France

14 SMA Observations of HD CO 3-2 and 340 GHz continuum simultaneous observations One track with the compact configuration One track with the extended configuration 1.2 x 0.6 for dust continuum 2.1 x 1.1 for 12 CO 3-2 Ohashi & Momose (09, submitted) 12 CO 3-2 and 340 GHz continuum simultaneous observations One track with the compact configuration One track with the extended configuration 1.2 x 0.6 for dust continuum 2.1 x 1.1 for 12 CO 3-2 Ohashi & Momose (09, submitted) SMA is a joint project between the SAO and the ASIAA. 14LAB, France

15 SMA Results: 340 GHz Continuum 340 GHz continuum distribution resembles to the 1.6 m scattered emission. An arc-like structure enclosing the central star two peaks; one at the NE and the other at the NW. Peak positions are shifted to the N as compared to those seen at 1.6 m. No clear emission on the southern side. Total flux density ~1.2 Jy 340 GHz continuum distribution resembles to the 1.6 m scattered emission. An arc-like structure enclosing the central star two peaks; one at the NE and the other at the NW. Peak positions are shifted to the N as compared to those seen at 1.6 m. No clear emission on the southern side. Total flux density ~1.2 Jy HD LAB, France

16 SMA Result 12 CO CO also shows a central hole, with peak emissions coincident with the infrared features. 16LAB, France

17 SMA Results: Spiral arms in gas? LAB, France

18 12 CO 3-2 Mean Velocity Clear velocity gradient from NW to SE, which is probably due to rotation. Roughly consistent with Kepler rotation around a 2Mo star. Disk axis is from NE to SW? Additional velocity gradient suggestive of non-circular motion. Any relationship with gas possibly associated with the spiral arm? Clear velocity gradient from NW to SE, which is probably due to rotation. Roughly consistent with Kepler rotation around a 2Mo star. Disk axis is from NE to SW? Additional velocity gradient suggestive of non-circular motion. Any relationship with gas possibly associated with the spiral arm? 18LAB, France

19 12 CO 3-2 Channel Maps 19LAB, France

20 Submm vs Infrared LAB, France

21 Is 12 CO 3-2 emission optically thin? 12 CO shows similar structures to the dust emission. Low brightness temperature (8.5 K). 12 CO shows similar structures to the dust emission. Low brightness temperature (8.5 K). LAB, France Chiang & Goldreich CO 3-2 emission may be optically thin.

22 HD142527: Disk Mass 345 GHz total flux ~ 1.2 Jy, corresponding to 4.1E-2 M o Gas/dust mass ratio 100; T dust = 50K 12 CO 3-2 integrated flux ~ 15 Jy km/s, corresponding 6.6E-6 M o. [H 2 ]/[ 12 CO] = 10 4 ; Tex = 50 K The disk mass derived from 12 CO 3-2 is factor of smaller that that derived from 345 GHz dust. CO depletion factor ~10000? H 2 dissipation factor ~10000? Combination of CO depletion and gas dissipation? 345 GHz total flux ~ 1.2 Jy, corresponding to 4.1E-2 M o Gas/dust mass ratio 100; T dust = 50K 12 CO 3-2 integrated flux ~ 15 Jy km/s, corresponding 6.6E-6 M o. [H 2 ]/[ 12 CO] = 10 4 ; Tex = 50 K The disk mass derived from 12 CO 3-2 is factor of smaller that that derived from 345 GHz dust. CO depletion factor ~10000? H 2 dissipation factor ~10000? Combination of CO depletion and gas dissipation? 22LAB, France

23 Unknown factors to estimate mass Dust temperature and CO excitation temperature Even if we assume Td=Tex=100 K, the mass difference is still more than three orders of magnitude. -index (mass opacity) Even if we assume a smaller -index, the mass derived from dust becomes just a factor of 2 smaller. CO depletion factor, f(co) Around TTSs, f(CO) has been estimated to be upto ~200. Since Td would be higher around Herbig Ae stars, f(CO) would be less than 200. Dust temperature and CO excitation temperature Even if we assume Td=Tex=100 K, the mass difference is still more than three orders of magnitude. -index (mass opacity) Even if we assume a smaller -index, the mass derived from dust becomes just a factor of 2 smaller. CO depletion factor, f(co) Around TTSs, f(CO) has been estimated to be upto ~200. Since Td would be higher around Herbig Ae stars, f(CO) would be less than 200. Even if we take into account of these unknown factors, it still seems to be difficult to explain the mass difference of 4 orders of magnitude. 23LAB, France

24 Gas dispersal in disk by photoevaporation Takeuchi et al. (05; see also Alexander & Armitage 07) studied disk clearing processes. using a model taking into account combined effects of viscous evolution, photoevaporation, differential radial motion of dust grains and gas. Around an Herbig Ae/Be star with more ionizing photon, a gas-poor dust ring will be formed in 10 6 yr. Takeuchi et al. (05; see also Alexander & Armitage 07) studied disk clearing processes. using a model taking into account combined effects of viscous evolution, photoevaporation, differential radial motion of dust grains and gas. Around an Herbig Ae/Be star with more ionizing photon, a gas-poor dust ring will be formed in 10 6 yr. 24LAB, France

25 Takeuchi et al A gap is created at ~17 AU (r g ) by photoevapolation Inside the gap Both gas and dust accrete onto star due to viscosity. Outside the gap Gas is gradually evaporated from the inner edge, and the inner edge gets larger. Dust accumulates at the inner edge. A gap is created at ~17 AU (r g ) by photoevapolation Inside the gap Both gas and dust accrete onto star due to viscosity. Outside the gap Gas is gradually evaporated from the inner edge, and the inner edge gets larger. Dust accumulates at the inner edge. 25LAB, France

26 Protostellar Disks around Protostars Kyoto Univ

27 L1551 IRS5: Infalling Envelope Kyoto Univ C 18 O (1-0) with NMA (Momose et al. 1998) A1A1 A2A2 B1B1 B2B2 Mass ~0.08 M Radius ~ 1200 AU Freely infalling and slowly rotating Freely infalling and slowly rotating with angular momentum conserved P-V diagrams 0.1 Mo

28 L1551 IRS5: Formation of a protostellar disk Kyoto Univ SMA CS7-6 mean velocity SMA CS 7-6 Total Intensity NMA C 18 O 1-0 Takakauwa, Ohashi

29 Specific Angular Momenta around YSOs Kyoto Univ Ohashi et al new data (Yen, Takakuwa, Ohashi 2009) Specific angular momentum seems to be constant within a radius of ~6000 AU.

30 B335 (IRAS ) Class 0 Protostar Lbol ~ 1.5 Lo, Tdust ~ 30 K Associated with a well developed outflow (e.g., Hirano et al. 88, 92) Infall signatures were observed (Zhou et al. 93; Choi et al. 95; Saito et al. 99). Class 0 Protostar Lbol ~ 1.5 Lo, Tdust ~ 30 K Associated with a well developed outflow (e.g., Hirano et al. 88, 92) Infall signatures were observed (Zhou et al. 93; Choi et al. 95; Saito et al. 99). Kyoto Univ

31 SMA Observations of B CO, 13 CO, C 18 O 2-1 and 230 GHz continuum simultaneous observations One track with the compact configuration 3.9 x 3.3 for dust continuum 3.7 x 3.2 for C 18 O 2-1 (Yen, Takakuwa, Ohashi 09, submitted) 12 CO, 13 CO, C 18 O 2-1 and 230 GHz continuum simultaneous observations One track with the compact configuration 3.9 x 3.3 for dust continuum 3.7 x 3.2 for C 18 O 2-1 (Yen, Takakuwa, Ohashi 09, submitted) SMA is a joint project between the SAO and the ASIAA. 31LAB, France

32 B335: 1.3 mm continuum Size ~ 740 AU x 350 AU Mass ~ Mo Size ~ 740 AU x 350 AU Mass ~ Mo Kyoto Univ

33 B335: C 18 O 2-1 Size ~ 1500 AU Partially affected by the outflow. Mass ~ 5.2 x Mo C 18 O depletion (f d ~10) Size ~ 1500 AU Partially affected by the outflow. Mass ~ 5.2 x Mo C 18 O depletion (f d ~10) Kyoto Univ

34 B335: C 18 O 2-1 kinematics Kyoto Univ V infall ~ AU, Mstar ~ Mo, Mass infall rate ~ x Mo/yr

35 B335: C 18 O 2-1 Kinematics (II) Kyoto Univ No detectable velocity gradient along the N-S direction; V rot < AU

36 Specific Angular Momentum in B x km/s AU 5.4 x km/s 1000 AU (Saito et al.99) 7 x km/s 370 AU (SMA results) 4.6 x km/s AU 5.4 x km/s 1000 AU (Saito et al.99) 7 x km/s 370 AU (SMA results) Kyoto Univ The specific angular momentum is not conserved outside R ~ 370 AU. If the specific angular momentum is conserved within R ~370 AU, Rd ~ 6 AU

37 With ALMA? Observations with spatially high dynamic range ( AU scale) Kepler disk formation; age estimation based on the disk size? Observations with high sensitivity and resolution Pick up the earliest phase of the disk formation. Signature of the planet formation/disk dissipation. Observations with a large sample. Observations with spatially high dynamic range ( AU scale) Kepler disk formation; age estimation based on the disk size? Observations with high sensitivity and resolution Pick up the earliest phase of the disk formation. Signature of the planet formation/disk dissipation. Observations with a large sample. Kyoto Univ


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