High-Resolution Optical and Near-Infrared Images of the FS Tauri Circumbinary Disk

Abstract

We present an H-band image of FS Tauri, a 0. ′′ 2-separated classical T Tauri binary system, taken with the Coronagraphic Imager with Adaptive Optics (CIAO) on the Subaru Telescope. This new image, combined with Hubble Space Telescope / Advanced Camera for Surveys (HST /ACS) F606W-band polarimetric images, shows that the binary has complicated circumbinary features, including a circumbinary disk, western and eastern arm-like structures, and two cavities at the northeast and southwest. The circumbinary disk is 630 AU in radius and the southeast side of the disk is bright in the H-band. The brightness ratio (southeast/northwest) is 1.6 ± 0.4. A single Rayleigh-like scattering model indicates that the disk is inclined by 30 • to 40 • and that the southeast side corresponds to the near side along our line of sight. The H-band surface brightness of the southeast side decreases as r −1.9±0.1 from 15.2 mag arcsec −2 to 16.8 mag arcsec −2 . The outer portion of the disk is possibly more flared than its inner portion. The weak centro-symmetric polarization pattern and redder F606W−H color (4.2 ± 0.2 mag) of the southeast side are probably caused by multiple scattering events from the dust grains associated with the binary. The F606W-band image shows the bright northwest side of the disk in contrast with the H-band image. The F606W−H color of the northwest side is between 1.7 mag and 3.0 mag. We consider that Haro 6-5 B (FS Tauri B), 20 ′′ away, produces the neutral scattered light from the northwest side. This idea is supported by the polarization pattern of the northwest side, which is centro-symmetric with respect to Haro 6-5 B. The arms appear to encompass the western and eastern cavities, suggesting that the arms + cavity systems are created by a bipolar outflow from the binary. However, the direction of this outflow is inconsistent with that of outflows inferred from the 1 circumbinary disk model. These differences may arise from misalignment between the circumbinary disk and the circumstellar disks. Another mechanism forming the arms + cavity systems is considered to be the inhomogeneous density distribution of materials in the circumbinary disk.

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

“…FS Tau A is also a close binary system, with separation 0. 24 (Hartigan & Kenyon 2003, equivalent to 34 AU at the distance of Taurus) and surrounded by a circumbinary disk that extends up to 630 AU (Hioki et al 2011). The spatial extension of the emission (Fig.…”

Evolution of linear warps in accretion discs and applications to protoplanetary discs in binaries

“…Additionally, Email: ffoucart@cita.utoronto.edu imaging of circumbinary debris discs show that while the disc plane and the binary orbital plane are aligned for some systems (such as α CrB, β Tri and HD 98800), significant misalignments can occur in others (such as 99 Herculis, with mutual inclination > ∼ 30 • ; see Kennedy et al 2012a,b). Finally, the pre-main sequence binary KH 15D is surrounded by a precessing circumbinary disc inclined with respect to the binary plane by 10 • -20 • (e.g., Winn et al 2004;Chiang & Murray-Clay 2004;Capelo et al 2012), while in the FS Tauri system, circumbinary and circumstellar discs appear to be misaligned (Hioki et al 2011).…”

DR Tauri: Temporal variability of the brightness distribution in the potential planet-forming region

“…Local brightness asymmetries on the scale of several dozens to hundreds of AU have already been observed in the case of various protoplanetary disks, e.g. GM Aur (Schneider et al 2003), FS Tau (Hioki et al 2011), IM Lupi (Pinte et al 2008). However, in contrast to these observations only long-baseline interferometry in the optical/infrared provides the angular resolution so far to trace regions, so close to the central star that the orbital motion on the scale of months to years has to be taken into account in the data analysis.…”