Transcript E N 1”=140 AU

Tomonori
1
Hioki ([email protected]),
Yoichi
1
Itoh ,
Yumiko
1
Oasa ,
Misato
2
Fukagawa ,
SDPS
3
Team
（1: Kobe University, 2: Nagoya University, 3: NAOJ)
☆Abstract☆
We obtained a high spatial resolution (FWHM ~ 0.1”) near-infrared image of XZ Tau, a 0.3” separated binary system, using Subaru/CIAO. A jetlike structure (Jet1 of Fig 5) was detected at northeast side of the binary. It is possibly driven from the secondary. Previous HST observations of
the binary showed a shock (bubble structure of Fig 3) created by another jet (Jet2 of Fig 5) from the primary.
1. Introduction
4. Result
1.1 Motivation
4.1 Jet from the secondary
・Many T Tauri stars (~1 Myr) have protoplanetary disks
and bipolar jets.
Jet
・The observations have focused mainly on single T Tauri
stars.
Fig5 presents that the jet (Jet1) drive from
the secondary in the direction of P.A.~54 deg.
Disk
Brightness ∝ r -4
・ More than half of T Tauri stars are binaries. (Ghez et al)
Fig1 Circumstellar
A limited number of studies have so far examined the disks disk and jet of HH30
and the jets around binary systems.
(HST/WFPC2;
(e.g., UY Aur; Hioki et al. 2007)
Burrows et al. 1996）
1.2 CIAO－Coronagraphic Imager with Adaptive Optics
Limiting
magnitude
●：Northeast
○：Southwest
Fig6 Brightness of the northeast (●) and
southwest (○) jets from the secondary
・Mask has ~2% transmission for the central star.
Fig5 Coronagraphic image of XZ Tau
<Northeast side>
・A pupil Lyot stop reduce the diffracted light.
①Extending to ~ 300 AU from the secondary
②Surface brightness ∝ r ^-4 (r : distance from the secondary)
If the structure is scattering from the central binary, its brightness ∝ r^-3.
⇒CIAO is effective for the detection of protoplanetary disks
and jets around the stellar vicinity.
Fig2 Coronagraph structure
1.3 XZ Tau (Classical T Tauri Binary)
・Location: Taurus star forming region (L1551; d~140 pc, Elias 1978）
・Separation: ~0”.3 (=40 AU; Haas et al. 1990)
・Mass: 0.4 Msun (Primary), 0.3 Msun (Secondary) （Hartigan & Kenyon 2003）
1.4 Previous Study of XZ Tau
①Detection of a bipolar jet （Mundt et al. 1988, 1990）
⇒Blue-shifted (northeast side)
& red-shifted (southwest side)
Therefore,
[1] the more it is distant from the stars, the optically thinner
or
[2] it emits not only by scattering but also by emission lines (such as [Fe II]).
<Southwest side>
Outstanding structure is not seen.
⇒The jet is probably obscured by a circumbinary disk (if any) in the plane
perpendicular to the jet.
4.2 H-band Magnitude, Separation, Position Angle
②HST/WFPC2 Observations
（Fig 3; Krist et al. 1997, 1999, Coffey et al. 2004）
⇒A bubble of emission nebulosity was detected to
north (P.A. ~20 deg) of the binary system.
Its structure is the following:
・The bubble extending with time
・[S II], Hα, and [O I] emission lines
・The bubble = Shock created by collision between
circumstellar material and jet from the primary??
・Accretion from the circumstellar disk around the
primary is very active（White & Ghez 2001).
・The primary is an EXor, which periodically undergo
outbursts （Coffey et al. 2004）.
Fig3 XZ Tau image
taken by HST/WFPC2
（R-band; Krist et al.
1999）
Blue: Secondary (～0.6 mag up)
Red： Primary （～1.3 mag down)
Blue：Separation ~0.3” (=42 AU)
Red： Angular velocity ~1.2 deg/yr
These variations may originate from:
⇒Orbital period ~300 yrs
Total mass ~0.8 M sun
・variable accretion rate to the stars
・ rotation of the secondary with hot
spots on its surface.
(assuming its orbit is circular)
The variation of the primary possibly
contributes to its outburst.
On the other hand, it is thought that the secondary is equable
compared with the primary.
5. Discussion
⇒Does the secondary drive the jet? or not??
5.1 Jet? or Reflection Nebulae?
2．Observations
Date: 2005 Nov 9, 2007 Dec 16
Mask size
[arcsec]
Ex time
[sec]
FWHM
[arcsec]
Instrument: Subaru/ CIAO
XZ Tau
0.6
720
0.1
FOV: 22” by 22”
PSF-ref
0.6
228
0.1
It is possibility that the jet-like structure is scattering from the central binary.
⇒We also carried out the [Fe II] observations in 2007 Dec.
5.2 Result of [Fe II] image
Wavelength: H-band (1.6 um), [Fe II]
N
PSF-reference stars were obtained before and after XZ Tau observations.
3．Reduction (IRAF)
E
北
東
①Dark subtraction
②Flat-fielding by twilight flat
③Hot and bad pixel removal
④Sky subtraction
Primary
●
Was a weak [Fe II] emission detected??
If it is real, the jet-like structure corresponds to
the jet from the secondary.
Because forbidden lines are indicative of the jet
from young stellar objects.
●
1”=140 AU
1” = 140 AU
⑤Shift each frame to adjust the position of the stars Fig4 Raw image of XZ
Tau
⑥Rotation of PSF-reference stars to adjust the position angle of the spider
⑦Combining XZ Tau frames subtracted their PSFs
Secondary
But…
This image is the result of simplified reduction.
More detailed reduction is needed!!
Fig7 [Fe II] coronagraphic image of
the XZ Tau binary (ex time: 1280 s)