alma observations of keplerian disks around protostars: the case of l1527
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
ALMA Observations of Keplerian Disks around Protostars:
the case of L1527Nagayoshi 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 (VrotR-0.5) and rotation conserving angular momentum(VrotR-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 (V = -1 —
1 km/s)• The kinematics of the SO emission seems to be not explained
with the same kinematics explaining the C18O 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 Vinfall > Vrotation
Keplerian rotation region Vinfall << Vrotation
Note that B-field could remove angularNote that B-field could remove angularmomentum effectively, preventing diskmomentum effectively, preventing diskformation (e.g., Mellon & Li 2008, 2009;formation (e.g., Mellon & Li 2008, 2009;Machida et al. 2011, Dapp et al. 2012)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. 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
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 C18O 1-0
Takakauwa, Ohashi + 2004
Infall RotationNMA C18O (1-0) (Momose et al. 1998)
SMA CS7-6 mean velocity
Takakauwa, Ohashi + 2004
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 04368+2557)
• 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°
Spitzer IRACTobin et al. (2008)
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
CARMA 13CO 2-1: Keplerian Disk?
NMA C18O 1-0
CARMA 13CO 2-1
Tobin et al. 2012 Nature
VrotR-1
VrotR-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
Posi
tion
(arc
sec)
Velocity (km s–1)
rotation curve with a logarithmic scale
C18O 2-1 with SMA
(Yen et al. 2013)
Position (arcsec)
Veki
city
(km
s–1
)
SMA C18O 2-1 Rotation Curve
Yen et al. 2013Radius (AU)
Velo
city
(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 0.
• 12CO, C18O 2-1, SO 65-54, 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 C3H2, 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 Radius (AU)10050
Rota
tion
Velo
city
(km
s–1
)1
5
0.5
Rb ~ 54 ± 0.44 AUpin~ –0.41 ± 0.24Pout ~ -1.16 ± 0.13M* ~0.33 Mo
Summary• In order to unambiguously identify Keplerian disks around
protostars, it is crucial to distinguish between Kepler rotation (VrotR-0.5) and rotation conserving angular momentum(VrotR-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 (V = -1 —
1 km/s)• The kinematics of the SO emission seems to be not explained
with the same kinematics explaining the C18O emission.