GG Tau A: gas properties and dynamics from the cavity to the outer disk
N. T. Phuong, A. Dutrey, P. N. Diep, S. Guilloteau, E. Chapillon, E. Di Folco, Y-W. Tang, V. Pietu, J. Bary, T. Beck, F. Hersant, D. T Hoai, J. M. Hure, P. T. N… 展开作者
N. T. Phuong, A. Dutrey, P. N. Diep, S. Guilloteau, E. Chapillon, E. Di Folco, Y-W. Tang, V. Pietu, J. Bary, T. Beck, F. Hersant, D. T Hoai, J. M. Hure, P. T. Nhung, A. Pierens, P. Tuan-Anh
We used new ALMA $^{13}$CO and C$^{18}$O(3-2) observations obtained at high angular resolution ($\sim$0.2") together with previous CO(3-2) and (6-5) ALMA data and continuum maps at 1.3 and 0.8 mm in order to determine the gas properties (temperature, density, and kinematics) in the cavity and to a lesser extent in the outer disk of GG Tau A, the prototype of a young triple T Tauri star that is surrounded by a massive and extended Keplerian outer disk. By deprojecting, we studied the radial and azimuthal gas distribution and its kinematics. We also applied a new method to improve the deconvolution of the CO data and in particular better quantify the emission from gas inside the cavity. We perform local and nonlocal thermodynamic equilibrium studies in order to determine the excitation conditions and relevant physical parameters inside the ring and in the central cavity. Residual emission after removing a smooth-disk model indicates unresolved structures at our angular resolution, probably in the form of irregular rings or spirals. The outer disk is cold, with a temperature $<20$ K beyond 250 au that drops quickly (r$^{-1}$). The kinematics of the gas inside the cavity reveals infall motions at about 10% of the Keplerian speed. We derive the amount of gas in the cavity, and find that the brightest clumps, which contain about 10% of this mass, have kinetic temperatures 40$-$80 K, CO column densities of a few 10$^{17}$ cm$^{-2}$, and H$_2$ densities around 10$^7$ cm$^{-3}$. Although the gas in the cavity is only a small fraction of the disk mass, the mass accretion rate throughout the cavity is comparable to or higher than the stellar accretion rate. It is accordingly sufficient to sustain the circumstellar disks on a long timescale.
Misalignments between a forming star's rotation axis and its outer disk axis, although not predicted by standard theories of stellar formation, have been observed in several classical T Tauri stars (cTTs). The low-mass cTTs DK Tau is suspected of being among them. It is also an excellent subject to investigate the interaction between stellar magnetic fields and material accreting from the circumstellar disk, as it presents clear signatures of accretion. The goal of this paper is to study DK Tau's average line-of-sight magnetic field (Blos) in both photospheric absorption lines and emission lin…
FS Tau B是为数不多的拥有喷流和反喷流以及光学可见空腔壁的金牛座T星之一。我们利用Subaru/IRCS获得了它的喷流-腔体系统在近红外H和K波段的图像和光谱，并首次在[Fe II] 1.644 μm谱线上探测到了喷流和反喷流。在内部2”内，蓝移喷流更亮，而超过~ 5”，红移反喷流主导[Fe II]发射。最里面的蓝移结在光谱上分辨为~ 110 km/s的大线宽，而最里面的红移结在光谱上分辨不出来。喷流与反喷流的速度比约为1.34，这表明FS Tau B正在驱动一个不对称的喷流，类似于在几颗金牛座T星中发现的喷流。结合文献中的光学观测，我们发现蓝移喷流比红移喷流具有更低的密度和更高的激发。我们认为，亮度和速度的不对称性是双极外流驱动在不同的质量损失率，同时保持平衡的线动量的表现。对FS Tau B系统中不对称性的充分解释有待于详细建模和对与风相关的空腔壁的运动学结构的进一步研究。
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) VII: the layered molecular outflow from HL Tau and its relationship with the ringed disk
Planets form in protoplanetary disks and inherit their chemical composition. It is therefore crucial to understand the disks molecular content. We aim to characterize the distribution and abundance of molecules in the disk of DG Tau. In the context of the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT) we analyse ALMA observations of the disk of DG Tau in H2CO 3(1,2)-2(1,1), CS 5-4, and CN 2-1 at ~0.15", i.e. ~18 au at 121 pc. H2CO and CS originate from a disk ring at the edge of the 1.3mm dust continuum, with CS probing an outer disk region with respect to H2CO (peaking at ~…
We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations for three protoplanetary disks in Taurus at 2.9\,mm and comparisons with previous 1.3\,mm data both at an angular resolution of $\sim0.''1$ (15\,au for the distance of Taurus). In the single-ring disk DS Tau, double-ring disk GO Tau, and multiple-ring disk DL Tau, the same rings are detected at both wavelengths, with radial locations spanning from 50 to 120\,au. To quantify the dust emission morphology, the observed visibilities are modeled with a parametric prescription for the radial intensity profile. The disk o…
On The Secular Evolution of GG Tau A Circumbinary Disc: A Msialigned Disc Scenario
据观测，双星系统GG Tau A有一个环双星盘，其尘埃环比预期的更远，假设它是一个共面盘，相应的半长轴为34 AU。考虑到双星的分离，这个大的空洞可以通过放松共面圆盘的假设来解释，而是用一个偏心双星周围的未对准的环双星圆盘来拟合观测结果，该偏心双星的半长轴较宽，为60 AU，与系统的自行数据拟合一致。我们运行SPH模拟来检查这种可能性，我们确实发现，30度的失准角和0.45的二进制偏心符合天体测量数据和盘腔。然而，这样的配置原则上可能对极性不稳定，而不是对平面对准不稳定。我们调查这种配置的长期演变，并表明它确实是稳定的整个光盘的寿命。
Dust and gas in protoplanetary disks dissipate as central stars evolve. In order to estimate the dust dissipation timescales in the protoplanetary disks, we stacked the WISE 12, 22, and the AKARI 90 $μ$m survey images of known T Tauri stars and derived the average fluxes, well below the survey flux limit in the 90 $μ$m band. We classified 4,783 T Tauri stars into three age groups, which are young ($<$2 Myr), mid-age (2-6 Myr), and old ($>$6 Myr) groups, and stacked the WISE 12 and 22 and the AKARI 90 $μ$m images in each group. The photometry of the stacked image shows the flux decay timescales…
[Abridged] Most disks observed at high angular resolution show substructures. Knowledge about the gas surface density and temperature is essential to understand these. The aim of this work is to constrain the gas temperature and surface density in two transition disks: LkCa15 and HD 169142. We use new ALMA observations of the $^{13}$CO $J=6-5$ transition together with archival $J=2-1$ data of $^{12}$CO, $^{13}$CO and C$^{18}$O to observationally constrain the gas temperature and surface density. Furthermore, we use the thermochemical code DALI to model the temperature and density structure of …
We present high resolution millimeter continuum and CO line observations for the circumbinary disk around V892 Tau to constrain the stellar and disk properties. The total mass of the two near-equal-mass A stars is estimated to be $6.0\pm0.2\,M_{\odot}$ based on our models of the Keplerian-dominated gas disk rotation. The detection of strong ionized gas emission associated with the two stars at 8 mm, when combined with previous astrometric measurements in the near-infrared, provides an updated view of the binary orbit with $a=7.1\pm0.1$ au, $e=0.27\pm0.1$, and $P=7.7\pm0.2$ yr, which is about h…
A large fraction of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question if and how planets in binary systems may form. Protoplanetary disks are the birthplaces of planets, and their characterization is crucial in order to understand the planet formation process. Our aim is to characterize the morphology of the GG Tau A disk, one of the largest and most massive circumbinary disks, and trace evidence for binary-disk interactions. We obtained observations in polarized scattered light of GG Tau A using the SPHE…
We present Atacama Large Millimeter/submillimeter Array (ALMA) gas and dust observations at band 7 (339~GHz: 0.89~mm) of the protoplanetary disk around a very low mass star ZZ~Tau~IRS with a spatial resolution of 0\farcs25. The $^{12}$CO~$J=3\rightarrow2$ position--velocity diagram suggests a dynamical mass of ZZ~Tau~IRS of $\sim$0.1--0.3~$M_{\sun}$. The disk has a total flux density of 273.9 mJy, corresponding to an estimated mass of 24--50~$M_\oplus$ in dust. The dust emission map shows a ring at $r=$ 58~au and an azimuthal asymmetry at $r=$ \jh{45}~au with a position angle of 135\degr. The …
We present a study of the radial distribution of dust species in young brown dwarf disks. Our work is based on a compositional analysis of the 10 and 20 micron silicate emission features for brown dwarfs in the Taurus-Auriga star-forming region. A fundamental finding of our work is that brown dwarfs exhibit stronger signs of dust processing in the cold component of the disk, compared to the higher mass T Tauri stars in Taurus. For nearly all of our targets, we find a flat disk structure, which is consistent with the stronger signs of dust processing observed in these disks. For the case of one…
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a protoplanetary disk around the T Tauri star Sz~84 and analyses of the structures of the inner cavity in the central region of the dust disk. Sz~84's spectral energy distribution (SED) has been known to exhibit negligible infrared excess at $λ\lesssim$10~$μ$m due to the disk's cavity structure. Analyses of the observed visibilities of dust continuum at 1.3~mm and the SED indicate that the size of the cavity in the disk of large (millimeter size) dust grains is 8~au in radius and that in the disk of small (sub-micro…
Molecular line surveys are among the main tools to probe the structure and physical conditions in protoplanetary disks (PPDs), the birthplace of planets. The large radial and vertical temperature as well as density gradients in these PPDs lead to a complex chemical composition, making chemistry an important step to understand the variety of planetary systems. We aimed to study the chemical content of the protoplanetary disk surrounding GG Tau A, a well-known triple T Tauri system. We used NOEMA with the new correlator PolyFix to observe rotational lines at 2.6 to 4 mm from a few dozen molecule…
High-Resolution Near-Infrared Polarimetry of a Circumstellar Disk around UX Tau A
我们目前的H波段偏振图像的UX Tau A采取HiCIAO/AO 188的斯巴鲁望远镜。UX Tau A被归类为前过渡盘天体，其内外盘之间有间隙结构。我们用0.15（21 AU）半径日冕掩模拍摄的图像显示了一个强极化的拱星盘，围绕着UX Tau A，延伸到120 AU，空间分辨率为0.1（14 AU）。它的倾斜度为46 \pm 2度，因为西侧最近。虽然SED建模和亚毫米图像表明在磁盘中存在间隙，外部磁盘的内边缘估计位于25 - 30 AU，但我们在近红外波长的内部工作角（23 AU）的极限处没有发现间隙的证据。我们将观测到的强偏振（高达66%）归因于圆盘中尘埃颗粒的光散射。然而，无论是基于瑞利散射或米氏散射近似的拱星盘的偏振模型与所观察到的盘的偏振度的方位角分布是一致的。相反，与半径为30微米的非球形颗粒的磁盘的几何光学模型是一致的观察到的配置文件。我们认为，尘埃颗粒经历了频繁的碰撞凝聚，并在UX Tau A的拱星盘中生长。
