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

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

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

Formation of Keplerian disks around protostars: A conventional picture Dynamical Infall region V infall > V rotation Keplerian rotation region V infall << V rotation 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) NMA Obs c. f. Terebey et al. 1984; Basu 1998

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

Inner regions of the infalling envelope around L1551 IRS5 SMA CS7-6 mean velocity SMA CS 7-6 Total Intensity NMA C 18 O 1-0 Takakauwa, Ohashi

Infall  Rotation NMA C 18 O (1-0) (Momose et al. 1998) SMA CS7-6 mean velocity Takakauwa, Ohashi SMA CS 7-6 Infalling motions are dominant on large scales, while rotating motions are dominant on small scales

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

L1527 IRS (IRAS ) Class0/I protostar L bol ~ 1.9 L solar, T bol ~ 56 K Wide opening outflow (Tamura et al. 1996) Infalling envelope of 1000 AU scale (Ohashi et al. 1997) Inclination~85° Spitzer IRAC Tobin et al. (2008)

NMA C 18 O 1-0 Infalling Envelope Elongated envelope perpendicular to the outflow (Ohashi et al 1997). –2000 AU in radius –Dynamical infall –V infall ~ 0.3 km/s –V rotation ~0.05 km/s –dM/dt ~ 1x10 -6 Mo/yr

CARMA 13 CO 2-1: Keplerian Disk? NMA C 18 O 1-0 CARMA 13 CO 2-1 Tobin et al Nature V rot  R -1 V rot  R -0.5 How to distinguish R -1 and R -0.5 dependences?

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

C 18 O 2-1 with SMA (Yen et al. 2013) Position (arcsec) Vekicity (km s –1 )

SMA C 18 O 2-1 Rotation Curve Yen et al Radius (AU) Velocity (km s –1 )

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 CO, C 18 O 2-1, SO , 220 GHz continuum etc  ~ 0.96” x 0.73” (PA ~ 11 deg)  V ~ 0.17 km/s L1527 IRS, TMC1A (Aso’s talk), L1489 IRS c. f. Sakai et al. have observed L1527 IRS in C 3 H 2, SO, etc. with ALMA cycle 0 as well (submitted)

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

Rotation Curve N S Rotation Radius (AU) Rotation Velocity (km s –1 ) R b ~ 54 ± 0.44 AU p in ~ –0.41 ± 0.24 P out ~ ± 0.13 M * ~0.33 Mo

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