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ALMA Observations of Keplerian Disks around Protostars: the case of L1527

NMA. SMA. NMA. ALMA Observations of Keplerian Disks around Protostars: the case of L1527. Nagayoshi Ohashi (NAOJ). With K. Saigo, Y. Aso, S.-W. Yen, S. Takakuwa, S. Koyamatsu, Y. Aikawa, K. Tomisaka, K. Tomita, M. Machida, M. Saito. ALMA. ?. Summary.

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ALMA Observations of Keplerian Disks around Protostars: the case of L1527

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  1. NMA SMA NMA ALMA Observations of Keplerian Disks around Protostars: the case of L1527 Nagayoshi Ohashi (NAOJ) With K. Saigo, Y. Aso, S.-W. Yen, S. Takakuwa, S. Koyamatsu, Y. Aikawa, K. Tomisaka, K. Tomita, M. Machida, M. Saito ALMA ?

  2. Summary • In order to unambiguously identify Keplerian disks around protostars, it is crucial to distinguish between Kepler rotation (VrotµR-0.5) and rotation conserving angular momentum(VrotµR-1). • ALMA cycle 0 observations of L1527 IRS shows that • Most of C18O 2-1 emission arises from an infalling envelope. • The C18O arising the vicinity of the central star (R < 60 AU) may suggests a Keplerian disk. • SO 65-54 shows rigid-like rotation at lower velocities (DV = -1 — 1 km/s) • The kinematics of the SO emission seems to be not explained with the same kinematics explaining the C18O emission.

  3. Keplerian disks are ubiquitous around PMSs • Keperian disks are formed as by-products of star formation. • It is, however, not well understood when and how disks are formed. • Initial condition of Keprian disks • Dynamical mass of protostars Simon, Dutrey, Guilloteau 2000

  4. Formation of Keplerian disks around protostars: A conventional picture Dynamical Infall region Vinfall> Vrotation NMA Obs Keplerian rotation region Vinfall<< Vrotation Note that B-field could remove angular momentum effectively, preventing disk formation (e.g., Mellon & Li 2008, 2009; Machida et al. 2011, Dapp et al. 2012) c. f. Terebey et al. 1984; Basu 1998

  5. Previous studies to identify (Keplerian) disks around protostars (The list is NOT complete) • Arce and Sargent 2006 • Brinchet al. 2007 • Lommen et al. 2008 • Jorgensen et al. 2009 • Lee et al. 2009, 2010 • Maury et al. 2010 • Tanner and Arce 2011 • Tobin et al. 2011, 2012 It has been difficult to firmly Identify Keplerian disks around protostars. If I miss your papers please kindly let me know!

  6. SMA CS 7-6 Total Intensity NMA C18O 1-0 SMA CS7-6 mean velocity Inner regions of the infalling envelope around L1551 IRS5 Takakauwa, Ohashi + 2004

  7. NMA C18O (1-0) (Momose et al. 1998) SMA CS7-6 mean velocity Infall  Rotation SMA CS 7-6 Infalling motions are dominant on large scales, while rotating motions are dominant on small scales Takakauwa, Ohashi + 2004

  8. Are Kepler motions identified around L1551 IRS5? • Sign of spin-up motion consistent with Kepler motion. • R-1 dependence cannot be ruled out. PV diagram of the SMA CS 7-6 data R-1 and R-0.5 dependences have to be carefully distinguished. Takakuwa et al. 2004

  9. L1527 IRS (IRAS 04368+2557) Spitzer IRAC Tobin et al. (2008) • Class0/I protostar • Lbol ~ 1.9 Lsolar ,Tbol ~ 56 K • Wide opening outflow (Tamura et al. 1996) • Infalling envelope of 1000 AU scale (Ohashi et al. 1997) • Inclination~85°

  10. NMA C18O 1-0 Infalling Envelope • Elongated envelope perpendicular to the outflow (Ohashi et al 1997). • 2000 AU in radius • Dynamical infall • Vinfall ~ 0.3 km/s • Vrotation ~0.05 km/s • dM/dt ~ 1x10-6 Mo/yr

  11. CARMA 13CO 2-1: Keplerian Disk? How to distinguish R-1 and R-0.5 dependences? NMA C18O 1-0 VrotµR-1 CARMA 13CO 2-1 VrotµR-0.5 Tobin et al. 2012 Nature

  12. Rotation Curve with a logarithmic scale(Yen et al. 2013) R > 500 AU: Gaussian fit to the spectrum at a given position R < 500 AU：Gaussian fit to the intensity profile at each channel rotation curve with a logarithmic scale Position (arcsec) Velocity (km s–1)

  13. C18O 2-1 with SMA Vekicity (km s–1) Position (arcsec) (Yen et al. 2013)

  14. SMA C18O 2-1 Rotation Curve Velocity (km s–1) Radius (AU) Yen et al. 2013

  15. ALMA Cycle 0 Observations • In order to investigate kinematics of circumstellar material in detail (particularly rotation), three protostars, including L1527 IRS, have been observed with ALMA cycle 0. • 12CO, C18O 2-1, SO 65-54, 220 GHz continuum etc • Dq ~ 0.96” x 0.73” (PA ~ 11 deg) • DV ~ 0.17 km/s • L1527 IRS, TMC1A (Aso’s talk), L1489 IRS c. f. Sakai et al. have observed L1527 IRS in C3H2, SO, etc. with ALMA cycle 0 as well (submitted)

  16. ALMA can identify a compact rotating component around class 0 protostar! SMA DV = –2.5 km/s DV = 2.5 km/s 140 AU 280 AU

  17. Rotation Curve 5 N Rotation Velocity (km s–1) Rb ~ 54 ± 0.44 AU pin~ –0.41 ± 0.24 Pout ~ -1.16 ± 0.13 M* ~0.33 Mo 1 0.5 50 100 Rotation Radius (AU) S Rotation Radius (AU)

  18. Summary • In order to unambiguously identify Keplerian disks around protostars, it is crucial to distinguish between Kepler rotation (VrotµR-0.5) and rotation conserving angular momentum(VrotµR-1). • ALMA cycle 0 observations of L1527 IRS shows that • Most of C18O 2-1 emission arises from an infalling envelope. • The C18O arising the vicinity of the central star (R < 60 AU) may suggests a Keplerian disk. • SO 65-54 shows rigid-like rotation at lower velocities (DV = -1 — 1 km/s) • The kinematics of the SO emission seems to be not explained with the same kinematics explaining the C18O emission.

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