We present a near-infrared image of the Herbig Ae star AB Aur obtained with the Coronagraphic Imager with Adaptive Optics mounted on the Subaru Telescope. The image shows a circumstellar emission extending out to a radius of AU, with a double spiral structure detected at AU. The surface brightness r p 580 r p 200-450 decreases as , steeper than the radial profile of the optical emission possibly affected by the scattered Ϫ3.01.0ע r light from the envelope surrounding AB Aur. This result, together with the size of the infrared emission similar to that of the 13 CO ( ) disk, suggests that the spiral structure is indeed associated with the circumstellar J p 1-0 disk but is not part of the extended envelope. We identified four major spiral arms, which are trailing if the brighter southeastern part of the disk is the near side. The weak gravitational instability, maintained for millions of years by continuous mass supply from the envelope, might explain the presence of the spiral structure at the relatively late phase of the pre-main-sequence period.
We present the detection of a young brown dwarf companion DH Tau B associated with the classical T Tauri star DH Tau. Near-infrared coronagraphic observations with CIAO on the Subaru Telescope have revealed DH Tau B with H = \~15 mag located at 2.3" (330 AU) away from the primary DH Tau A. Comparing its position with a Hubble Space Telescope archive image, we confirmed that DH Tau A and B share the common proper motion, suggesting that they are physically associated with each other. The near-infrared color of DH Tau B is consistent with those of young stellar objects. The near-infrared spectra of DH Tau B show deep water absorption bands, a strong K I absorption line, and a moderate Na I absorption line. We derived its effective temperature and surface gravity of Teff = 2700 -- 2800 K and log g = 4.0--4.5, respectively, by comparing the observed spectra with synthesized spectra of low-mass objects. The location of DH Tau B on the HR diagram gives its mass of 30 -- 50 M_Jupiter.Comment: 10 pages, 14 figures, 1 table, accepted for publication in Ap
We present new results of [Fe II] λ1.644 µm spectroscopy toward the jets from HL Tau and RW Aur carried out with the Subaru Telescope combined with the adaptive optics system. We observed the regions within 2 ′′ -3 ′′ from the stars with the sub-arcsecond resolutions of 0.′′ 5 and 0. ′′ 2 for HL Tau and RW Aur, respectively. In addition to the strong, high velocity emission extended along each jet, we detected a blueshifted low velocity emission feature seen as a wing or shoulder of the high velocity emission at each stellar position. Detailed analysis shows that the low velocity emission of HL Tau is peaked at 0. ′′ 077 ± 0. ′′ 04 away from the stellar position, or 15 AU of actual distance from the star. We did not confirm such displacement for RW Aur in its position velocity diagram (PVD). The PVDs of HL Tau and RW Aur show a characteristic similar to those of the cold disk wind and X-wind models in that the [Fe II] line width is broad
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