The 2014 Alma Long Baseline Campaign: First Results From High Angular Resolution Observations Toward the Hl Tau Region

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0″. 075 (10 AU) to 0″. 025 (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analog HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46 .72 0 .05 ± • •) and position angle (138 .02 0 .07).

A Multi-ringed, Modestly Inclined Protoplanetary Disk around AA Tau

“…In contrast to HL Tau and TW Hya (ALMA Partnership et al 2015;Andrews et al 2016), however, which host power-law dust disks with numerous narrow gaps, the dust in AA Tau is distributed in rings with broad gaps (Figure 1, panel (c)), more similar to HD 163296 and HD 169142 (Isella et al 2016;Fedele et al 2017). If the dust gaps in AA Tau result from a planet-disk interaction, as suggested for HD 163296 and HD 169142, multiple massive planets might be involved (Pinilla et al 2012;Picogna & Kley 2015), although Gonzalez et al (2015) have Figure 1, panel (a).…”

“…Recent observations, however, have revealed more complex disk dust structures. Multiple dust rings have been imaged in the disks around HL Tau, TW Hya, HD 163296, and HD 169142 (ALMA Partnership et al 2015;Andrews et al 2016;Isella et al 2016;Fedele et al 2017), and visibility modeling has suggested one other candidate system, DM Tau (Zhang et al 2016). These rings, and the gaps between them, may trace planet formation at its earliest stages (e.g., Flock et al 2015;Ruge et al 2016), although other explanations have also been proposed (e.g., Zhang et al 2015a;Okuzumi et al 2016).…”

A SEARCH FOR SUBMILLIMETER H2O MASERS IN ACTIVE GALAXIES: THE DETECTION OF 321 GHz H2O MASER EMISSION IN NGC 4945

“…Since the masers detected in this program are unresolved, their spatial structures have yet to be explored for studying the circumnuclear regions of their host galaxy. ALMA has progressively achieved longer baselines and has attained a maximum angular resolution of ∼30 mas (corresponding to 1.5 pc at a distance of 10 Mpc) in Band 7 (e.g., ALMA Partnership et al 2015aPartnership et al , 2015b. Future observations will be able to resolve the circumnuclear gas of AGNs on scales that are becoming comparable to very long baseline interferometry observations at 22 GHz.…”

The Circumstellar Disk HD 169142: Gas, Dust, and Planets Acting in Concert?*

“…These spiral arms have large opening angles, and their origin is still not fully understood. The presence of one or more rings and gaps in disks seems to be quite a common feature; they are found in both young (e.g., HL Tau; ALMA Partnership et al 2015;Carrasco-González et al 2016) and rather old systems (e.g., TW Hya; Rapson et al 2015;Andrews et al 2016;Tsukagoshi et al 2016;van Boekel et al 2017) and around stars of very different spectral types (e.g., de Boer et al 2016;Ginski et al 2016;van der Plas et al 2017). Various mechanisms have been proposed in the literature that can be assigned to three main categories: structures caused by fluid dynamics, dust evolution effects, and planet-disk perturbations.…”