New circumstellar structure in the T Tauri system

Abstract

Aims. The immediate vicinity of T Tauri was observed with the new high-contrast imaging instrument SPHERE at the VLT to resolve remaining mysteries of the system, such as the putative small edge-on disk around T Tauri Sa and the assignment of the complex outflow patterns to the individual stars. Methods. We used SPHERE IRDIS narrow-band classical imaging in Paβ, Brγ, and the ν = 1−0 S(1) line of H 2 , as well as in the nearby continua to obtain high spatial resolution and high-contrast images over the near-infrared spectral range. Line maps were created by subtracting the nearby continuum. We also reanalyzed coronagraphic data taken with SPHERE's integral field spectrograph in J-and H-band with the goal of obtaining a precise extinction estimate to T Tauri Sb, and of verifying the recently reported claim of another stellar or substellar object in the system. Results. A previously unknown coiling structure is observed southwest of the stars in reflected light, which points to the vicinity of T Tauri N. We map the circumbinary emission from T Tauri S in J-and H-band scattered light for the first time, showing a morphology that differs significantly from that observed in K-band. Molecular Hydrogen emission is found southwest of the stars, near the coiling structure. We also detect the H 2 emitting region T Tauri NW. The motion of T Tauri NW with respect to T Tauri N and S between previous images and our 2014 data provides strong evidence that the southeast-northwest outflow triggering T Tauri NW is likely to be associated with T Tauri S. We also present accurate relative photometry of the stars, which confirms that T Tauri Sa is brightening again. Our analysis rules out the presence of the recently proposed companion to T Tauri N with high confidence.

High-contrast Polarimetry Observation of the T Tau Circumstellar Environment

“…The position of the N2 structure appears to match the position of the R2 structure reported by Kasper et al (2016), but in our H-band image it looks much shorter (about 0 1) than the R2 in the J-band image of Kasper et al (2016) (about 0 25). The N3 structure is about 0 4 from T Tau Sa and has a length of about 0 4.…”

“…In our PI image, the N1 structure is associated with T Tau S, and extends to about 0 5 southeast from T Tau Sa. Its position is near the R1 structure reported by Kasper et al (2016), the 1 and 2 structure reported by Gustafsson et al (2010), and the C4 structure reported by Herbst et al (2007), suggesting that they are related.…”

“…For clarification, they are labeled N1-N5 and "coil" in Figure 1(b). To help understand what these structures are, we made detailed comparisons with previous observations, including the multi-band (J, H, K, and several hydrogen emission lines) observations in 2014 and 2015 using VLT/ SPHERE-IRDIS, IRDIFS (Kasper et al 2016), the H 2 v= 1−0S(1) emission line observations performed in 2004 using VLT/SINFONI (Gustafsson et al 2010), and the H 2 v= 1−0S(1) emission line observations using VLT/NACO with a Fabry-Perot interferometer (Herbst et al 2007). The comparisons were done by carefully overlapping these images on our image, and matching the positions of the stars (for T Tau S, we use the barycenter as a reference) and scales to see the differences in the structures.…”

“…In addition, Gustafsson et al (2010) suggested the presence of another southwest outflow coming from T Tau Sb based on near-infrared hydrogen emission observations. Kasper et al (2016) also detected a coil-like structure extending to the southwest of the T Tau system in their multi-band near-infrared high-contrast imaging study. This structure can be attributed to a precessing outflow, but it is still unknown whether this originates from T Tau N or S. Identification of these outflow features will help determine the evolution of the stars in the multiple system.…”

Binary outflows from young stars: interaction of co-orbital jet and wind

“…On the other hand, T Tau S is established as a binary, Sa/Sb, with a suggested circumbinary disc and up to three distinct outflows (Duchêne et al 2005;Kasper et al 2016;Yang et al 2018). This prompts the question of how these outflows may interact on the scale of their development between 10 AU and 100 AU.…”