Alma Hints at the Presence of Two Companions in the Disk Around Hd 100546

Abstract

HD 100546 is a well-studied Herbig Be star-disk system that likely hosts a close-in companion with compelling observational evidence for an embedded protoplanet at 68 AU. We present ALMA observations of the HD 100546 disk which resolve the gas and dust structure at (sub)mm wavelengths. The CO emission (at 345.795 GHz) originates from an extensive molecular disk (390±20 AU in radius)whereas the continuum emission is more compact (230±20 AU in radius) suggesting radial drift of the mm-sized grains. The CO emission is similar in extent to scattered light images indicating well-mixed gas and µm-sized grains in the disk atmosphere. Assuming azimuthal symmetry, a single-component power-law model cannot reproduce the continuum visibilities. The visibilities and images are better reproduced by a double-component model: a compact ring with a width of 21 AU centered at 26 AU and an outer ring with a width of 75±3 AU centered at 190±3 AU. The influence of a companion and protoplanet on the dust evolution is investigated. The companion at 10 AU facilitates the accumulation of mm-sized grains within a compact ring, ≈ 20-30 AU, by ≈ 10 Myr. The injection of a protoplanet at 1 Myr hastens the ring formation (≈ 1.2 Myr) and also triggers the development of an outer ring (≈ 100-200 AU). These observations provide additional evidence for the presence of a close-in companion and hint at dynamical clearing by a protoplanet in the outer disk.

Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA

“…3. This hints at the presence of a dust gap in the outer part of the disk between 110 and 130 AU, or an additional outer ring of dust, as seen in recent ALMA data of HD 100546 (Walsh et al 2014).…”

“…Perez et al (2015) have modeled the J = 2-1 CO isotopologs and determined the gas mass remaining inside the cavity of that disk. Other transition disks that have been observed in ALMA Cycle 0 are HD 100546 (Walsh et al 2014), TW Hya (Rosenfeld et al 2014), Sz 91 (Canovas et al 2015), and MWC 758 (not yet published), but since their dust holes remain unresolved in the current data, they are not considered in this study.…”

Observations and modelling of CO and [C i] in protoplanetary disks

“…Components of arcsecond-scale multiples are separated with a plus sign. C13 Casassus et al (2013); d1 Pontoppidan et al (2011); d2 Lombardi et al (2008); d3 Knude & Hog (1998) Torres et al (2012); d9 Andersson et al (2002); d10 Torres et al (2008); d11 Wichmann et al (1998); d12 Mamajek (2008); i1 Cox et al (2013); i2 Salyk et al (2014); i3 Koerner & Sargent (1995); i4 Simon et al (2000); i5 Espaillat et al (2007); i6 Hussain et al (2009); i7 Guilloteau et al (2011); i8 Guilloteau et al (1999); i9 Walsh et al (2014); i10 Malfait et al (1998); i11 Matter et al (2014); i12 Weinberger et al (1999); i13 Canovas et al (2013) Meeus et al (2012) which is a re-evaluation of the data reported by Panić et al (2010). For HD 100453, HD 169142, HD 36112 and HD 50138, the 2-1 limits are similar.…”

“…5). All the detected disks have inner holes -HD 97048, HD 100546 and HD 169142 (hole radii 34, 13, and 23 au, respectively, Maaskant et al 2013;Panić et al 2014;Walsh et al 2014). However, the line is not detected towards HD 139614 (5.6 au Matter et al 2014), which has a dust mass and spectral type very similar to HD 169142 (≈1×10 −4 M and A8/A5 Dent et al 2005;Panić et al 2008;Maaskant et al 2013).…”

Direct Detection of Precursors of Gas Giants Formed by Gravitational Instability With the Atacama Large Millimeter/Submillimeter Array

“…Recent observations of putative young protoplanets in HD100546 provide a striking example of how different the distributions of dust and gas can be (Pineda et al 2014;Walsh et al 2014). In particular, in GI-unstable disk dust would tend to concentrate in spiral arms due to ensuing negative pressure gradients toward the overdensity peaks (Rice et al 2004), and would do even more so after dense clumps have formed .…”