Observational constraints on dust disk sizes in tidally truncated protoplanetary disks in multiple systems in the Taurus region

The impact of stellar multiplicity on the evolution of planet-forming disks is still the subject of debate. Here we present and analyze disk structures around ten multiple stellar systems that were included in an unbiased, high spatial resolution survey performed with ALMA of 32 protoplanetary disks in the Taurus star-forming region. At the unprecedented spatial resolution of ~0.12′′ we detect and spatially resolve the disks around all primary stars, and those around eight secondary and one tertiary star. The dust radii of disks around multiple stellar systems are smaller than those around single stars in the same stellar mass range and in the same region. The disks in multiple stellar systems also show a steeper decay of the millimeter continuum emission at the outer radius than disks around single stars, suggestive of the impact of tidal truncation on the shape of the disks in multiple systems. However, the observed ratio between the dust disk radii and the observed separation of the stars in the multiple systems is consistent with analytic predictions of the effect of tidal truncation only if the eccentricities of the binaries are rather high (typically >0.5) or if the observed dust radii are a factor of two smaller than the gas radii, as is typical for isolated systems. Similar high-resolution studies targeting the gaseous emission from disks in multiple stellar systems are required to resolve this question.

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Gas extent in protoplanetary disks of the Lupus star forming region

10.5194/epsc2020-803 ◽

2020 ◽

Author(s):

Enrique Sanchis

Keyword(s):

Protoplanetary Disks ◽

Stellar Mass ◽

Size Ratio ◽

Gas Content ◽

Continuum Emission ◽

Size Difference ◽

Formation Mechanisms ◽

Star Forming ◽

Dust Disk ◽

Dust Evolution

I will present a demographic study of the gas content in protoplanetary disks of the Lupus star-forming region, based on the previous ALMA surveys of the region. Planets form around stars during their pre-main sequence phase, when still surrounded by a circumstellar disk of dust and gas. Setting observational constraints on the gas and dust properties of protoplanetary disks is crucial in order to understand what are the ongoing physical processes in the disk. These processes shape the planet formation mechanisms, and ultimately tell us about the disk&#8217;s ability to form planets. The advent of ALMA allowed us to characterize dust properties in large populations of disks in several star-forming regions. Nevertheless, demographic studies of the gas content in these disk populations are scarce and generally incomplete, due to the fewer detections, and other difficulties when studying gas content. In this work, we were able to assemble a large and homogeneous sample of disks from the Lupus region, all detected in 12CO and dust continuum. Gas emission profiles and sizes are estimated on 43 disks of the Lupus region. The profiles are inferred from the integrated emission maps of the 12CO transition line in ALMA Band 6. The observed emission is modeled using empirical functions: either the Nuker profile or an elliptical Gaussian for more compact sources. The gas size, defined as a certain fraction (e.g. 68%) of the total flux, is inferred from the modeled emission profiles. These gas properties are then compared to the dust properties of the same objects, estimated from ALMA surveys in Band 7 and using analogous methodology. The relative size of gas and dust is a key diagnostic of dust evolution. Large dust grains are decoupled from gas and drift inwards. Thus, if dust growth is prominent in these disks, the detected dust continuum emission in sub-mm wavelengths are expected to be several times smaller than the gas extent. The results of our extensive sample confirm the larger gas size when compared to the dust size. The gas disk size is on average 2.6 times larger than the dust disk. This size difference can be explained by effective drifting of dust, but also by the optical depth difference between 12CO and dust continuum. Disentangling between these two effects is in general difficult; only large size ratios (typically beyond 4) unequivocally exhibit prominent dust evolution. Only a small fraction (~18%) of the disk population has a size ratio larger than 4. Radial drift is intimately linked to grain growth, both are crucial processes to form the cores of planets. Our results might suggest that dust evolution is less common than previously thought. We also investigated possible trends of the size ratio with stellar and disk properties, e.g. stellar mass, disk mass, integrated CO flux; no clear correlation can be found. Interestingly, the only Brown Dwarf of the sample with characterized gas and dust disk sizes shows a relatively large ratio of 3.8. On the other stellar mass range end, disks around stars with mass > 0.8 Msun have a tentative lower ratio of 2.1. Larger samples in the low mass regime and in the rest of stellar mass ranges are needed in order to discern possible trends between spectral types or other properties of the host stars.

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Less than the sum of its parts: the dust-corrected H α luminosity of star-forming galaxies explored at different spatial resolutions with MaNGA and MUSE

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2557 ◽

2020 ◽

Vol 498 (3) ◽

pp. 4205-4221

Author(s):

N Vale Asari ◽

V Wild ◽

A L de Amorim ◽

A Werle ◽

Y Zheng ◽

...

Keyword(s):

Spatial Resolution ◽

Formation Rate ◽

Flux Ratio ◽

Star Forming ◽

The Galaxy ◽

Nearby Galaxies ◽

Point To Point ◽

Dust Attenuation ◽

The Impact ◽

Lower Limits

ABSTRACT The H α and H β emission-line luminosities measured in a single integrated spectrum are affected in non-trivial ways by point-to-point variations in dust attenuation in a galaxy. This work investigates the impact of this variation when estimating global H α luminosities corrected for the presence of dust by a global Balmer decrement. Analytical arguments show that the dust-corrected H α luminosity is always underestimated when using the global H α/H β flux ratio to correct for dust attenuation. We measure this effect on 156 face-on star-forming galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey. At 1–2 kpc spatial resolution, the effect is small but systematic, with the integrated dust-corrected H α luminosity underestimated by 2–4 per cent (and typically not more than by 10 per cent), and depends on the specific star formation rate of the galaxy. Given the spatial resolution of MaNGA, these are lower limits for the effect. From Multi Unit Spectroscopic Explorer (MUSE) observations of NGC 628 with a resolution of 36 pc, we find the discrepancy between the globally and the point-by-point dust-corrected H α luminosity to be 14 ± 1 per cent, which may still underestimate the true effect. We use toy models and simulations to show that the true difference depends strongly on the spatial variance of the H α/H β flux ratio, and on the slope of the relation between H αluminosity and dust attenuation within a galaxy. Larger samples of higher spatial resolution observations are required to quantify the dependence of this effect as a function of galaxy properties.

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Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833537 ◽

2019 ◽

Vol 621 ◽

pp. A76 ◽

Cited By ~ 35

Author(s):

A. J. Maury ◽

Ph. André ◽

L. Testi ◽

S. Maret ◽

A. Belloche ◽

...

Keyword(s):

Size Distribution ◽

Protoplanetary Disks ◽

Continuum Emission ◽

Formation Mechanisms ◽

Multiple Systems ◽

Protostellar Disks ◽

Disk Size ◽

Small Scales ◽

Prestellar Cores ◽

Protostellar Collapse

Context. Understanding the formation mechanisms of protoplanetary disks and multiple systems and also their pristine properties are key questions for modern astrophysics. The properties of the youngest disks, embedded in rotating infalling protostellar envelopes, have largely remained unconstrained up to now. Aims. We aim to observe the youngest protostars with a spatial resolution that is high enough to resolve and characterize the progenitors of protoplanetary disks. This can only be achieved using submillimeter and millimeter interferometric facilities. In the framework of the IRAM Plateau de Bure Interferometer survey CALYPSO, we have obtained subarcsecond observations of the dust continuum emission at 231 and 94 GHz for a sample of 16 solar-type Class 0 protostars. Methods. In an attempt to identify disk-like structures embedded at small scales in the protostellar envelopes, we modeled the dust continuum emission visibility profiles using Plummer-like envelope models and envelope models that include additional Gaussian disk-like components. Results. Our analysis shows that in the CALYPSO sample, 11 of the 16 Class 0 protostars are better reproduced by models including a disk-like dust continuum component contributing to the flux at small scales, but less than 25% of these candidate protostellar disks are resolved at radii >60 au. Including all available literature constraints on Class 0 disks at subarcsecond scales, we show that our results are representative: most (>72% in a sample of 26 protostars) Class 0 protostellar disks are small and emerge only at radii <60 au. We find a multiplicity fraction of the CALYPSO protostars ≲57% ± 10% at the scales 100–5000 au, which generally agrees with the multiplicity properties of Class I protostars at similar scales. Conclusions. We compare our observational constraints on the disk size distribution in Class 0 protostars to the typical disk properties from protostellar formation models. If Class 0 protostars contain similar rotational energy as is currently estimated for prestellar cores, then hydrodynamical models of protostellar collapse systematically predict a high occurrence of large disks. Our observations suggest that these are rarely observed, however. Because they reduce the centrifugal radius and produce a disk size distribution that peaks at radii <100 au during the main accretion phase, magnetized models of rotating protostellar collapse are favored by our observations.

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Dust Trapping and Coagulation in Protoplanetary Disks

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319002011 ◽

2018 ◽

Vol 14 (S345) ◽

pp. 355-357

Author(s):

Ya-Ping Li

Keyword(s):

Protoplanetary Disks ◽

Large Family ◽

Continuum Emission ◽

Nearby Star ◽

Dust Trapping ◽

Star Forming ◽

Star Forming Regions ◽

Hydrodynamical Simulations ◽

Two Fluid ◽

Key Parameter

AbstractIn this work, we carry out two-fluid (gas+dust) hydrodynamical simulations on a large family of models in order to study the dust coagulation and the dust-gas dynamical processes in protoplanetary disks. Our theoretical effort is guided by the observational results of disks in nearby star forming regions at sub-millimeter and millimeter (mm) wavelengths. By a systematic comparison with the continuum emission at several mm bands from ALMA observations, we find that ringed structures are predicated in the unresolved faint disks for those with mm spectral indexes as low as about 2.0. Our parameter exploration can also be used to constrain the fragmentation velocity, one key parameter of the dust coagulation model, and some other disk parameters.

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High-velocity Wind from IRS 1 in the NGC 2071IR

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315004949 ◽

2014 ◽

Vol 10 (S305) ◽

pp. 301-304

Author(s):

Miguel Angel Trinidad

Keyword(s):

High Velocity ◽

Radio Continuum ◽

Continuum Emission ◽

Central Source ◽

Star Forming ◽

The North ◽

Infrared Sources ◽

The Impact ◽

Water Maser ◽

East West

AbstractWe present the results of 1.3 and 3.6 cm radio continuum emission toward the NGC 2071IR star-forming region, carried out with the VLA in its A configuration. We detect continuum emission toward the infrared sources IRS 1 and IRS 3 at both wavelengths. In particular, IRS 1 breaks up into three continuum peaks (IRS 1E, 1C, and 1W), aligned in the east-west direction, being IRS 1 the central source. The morphology of the condensation IRS 1W is very interesting, which has an elongated structure and shows a significant curvature towards the north. We suggest that this morphology could be explained as the impact of a high-velocity wind or jetlike outflow from IRS 1 on a close companion or other obstruction, which also explains the strong water maser emission observed toward IRS 1W.

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High-mass Star Formation in the Regions IRAS 19217+1651 and 23151+5912

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312006904 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 182-183

Author(s):

V. Migenes ◽

I. T. Rodríguez ◽

M. A. Trinidad

Keyword(s):

Water Vapor ◽

Star Formation ◽

Spatial Resolution ◽

High Sensitivity ◽

High Mass ◽

Continuum Emission ◽

Mass Star ◽

Star Forming ◽

Star Forming Regions

AbstractWe present and discuss VLA-EVLA high-sensitivity and spatial resolution observations of Water Vapor MASERs and continuum emission towards two sources that have been proposed in the literature to be high-mass star forming regions: IRAS 19217+1651 and 23151+5912. Our results indicate the presence of disks which can confirm that these regions are high-mass star forming regions.

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Constraining the radial drift of millimeter-sized grains in the protoplanetary disks in Lupus

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834537 ◽

2020 ◽

Vol 638 ◽

pp. A38 ◽

Cited By ~ 3

Author(s):

L. Trapman ◽

M. Ansdell ◽

M. R. Hogerheijde ◽

S. Facchini ◽

C. F. Manara ◽

...

Keyword(s):

Grain Growth ◽

Optical Depth ◽

Thermal Emission ◽

Signal To Noise Ratio ◽

Protoplanetary Disks ◽

Outer Radius ◽

Size Difference ◽

Star Forming ◽

Dust Evolution ◽

Depth Effects

Context. Recent ALMA surveys of protoplanetary disks have shown that for most disks the extent of the gas emission is greater than the extent of the thermal emission of millimeter-sized dust. Both line optical depth and the combined effect of radially dependent grain growth and radial drift may contribute to this observed effect. To determine whether or not radial drift is common across the disk population, quantitative estimates of the effect of line optical depth are required. Aims. For a sample of ten disks from the Lupus survey we investigate how well dust-based models without radial dust evolution reproduce the observed 12CO outer radius, and determine whether radial dust evolution is required to match the observed gas–dust size difference. Methods. Based on surface density profiles derived from continuum observations we used the thermochemical code DALI to obtain 12CO synthetic emission maps. Gas and dust outer radii of the models were calculated using the same methods as applied to the observations. The gas and dust outer radii (RCO, Rmm) calculated using only line optical depth were compared to observations on a source-by-source basis. Results. For five disks, we find RCO, obs∕Rmm, obs > RCO, mdl∕Rmm, mdl. For these disks we need both dust evolution and optical depth effects to explain the observed gas–dust size difference. For the other five disks, the observed RCO∕Rmm lies within the uncertainties on RCO, mdl∕Rmm, mdl due to noise. For these disks the observed gas–dust size difference can be explained using only line optical depth effects. We also identify six disks not included in our initial sample but part of a survey of the same star-forming region that show significant signal-to-noise ratio (S∕N ≥ 3) 12CO J = 2−1 emission beyond 4 × Rmm. These disks, for which no RCO is available, likely have RCO∕Rmm ≫ 4 and are difficult to explain without substantial dust evolution. Conclusions. Most of the disks in our sample of predominantly bright disks are consistent with radial drift and grain growth. We also find six faint disks where the observed gas–dust size difference hints at considerable radial drift and grain growth, suggesting that these are common features among both bright and faint disks. The effects of radial drift and grain growth can be observed in disks where the dust and gas radii are significantly different, while more detailed models and deeper observations are needed to see this effect in disks with smaller differences.

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Outflows, cores, and magnetic field orientations in W43-MM1 as seen by ALMA

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038024 ◽

2020 ◽

Vol 640 ◽

pp. A111

Author(s):

C. Arce-Tord ◽

F. Louvet ◽

P. C. Cortes ◽

F. Motte ◽

C. L. H. Hull ◽

...

Keyword(s):

Magnetic Field ◽

High Mass ◽

Continuum Emission ◽

High Angular Resolution ◽

Mass Star ◽

Star Forming ◽

The Core ◽

Dense Cores ◽

The Impact ◽

The Magnetic Field

Aims. It has been proposed that the magnetic field, which is pervasive in the interstellar medium, plays an important role in the process of massive star formation. To better understand the impact of the magnetic field at the pre- and protostellar stages, high-angular resolution observations of polarized dust emission toward a large sample of massive dense cores are needed. We aim to reveal any correlation between the magnetic field orientation and the orientation of the cores and outflows in a sample of protostellar dense cores in the W43-MM1 high-mass star-forming region. Methods. We used the Atacama Large Millimeter Array in Band 6 (1.3 mm) in full polarization mode to map the polarized emission from dust grains at a physical scale of ~2700 au. We used these data to measure the orientation of the magnetic field at the core scale. Then, we examined the relative orientations of the core-scale magnetic field, of the protostellar outflows, and of the major axis of the dense cores determined from a 2D Gaussian fit in the continuum emission. Results. We find that the orientation of the dense cores is not random with respect to the magnetic field. Instead, the dense cores are compatible with being oriented 20–50° with respect to the magnetic field. As for the outflows, they could be oriented 50–70° with respect to the magnetic field, or randomly oriented with respect to the magnetic field, which is similar to current results in low-mass star-forming regions. Conclusions. The observed alignment of the position angle of the cores with respect to the magnetic field lines shows that the magnetic field is well coupled with the dense material; however, the 20–50° preferential orientation contradicts the predictions of the magnetically-controlled core-collapse models. The potential correlation of the outflow directions with respect to the magnetic field suggests that, in some cases, the magnetic field is strong enough to control the angular momentum distribution from the core scale down to the inner part of the circumstellar disks where outflows are triggered.

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Fragmentation, rotation, and outflows in the high-mass star-forming region IRAS 23033+5951

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935318 ◽

2019 ◽

Vol 629 ◽

pp. A10 ◽

Cited By ~ 2

Author(s):

F. Bosco ◽

H. Beuther ◽

A. Ahmadi ◽

J. C. Mottram ◽

R. Kuiper ◽

...

Keyword(s):

Gravitational Instability ◽

Signal To Noise Ratio ◽

Spatial Scales ◽

Dust Emission ◽

High Mass ◽

Continuum Emission ◽

Mass Star ◽

Gas Temperature ◽

Multiple Systems ◽

Star Forming

Context. The formation process of high-mass stars (>8 M⊙) is poorly constrained, particularly the effects of clump fragmentation creating multiple systems and the mechanism of mass accretion onto the cores. Aims. We study the fragmentation of dense gas clumps, and trace the circumstellar rotation and outflows by analyzing observations of the high-mass (~500 M⊙) star-forming region IRAS 23033+5951. Methods. Using the Northern Extended Millimeter Array (NOEMA) in three configurations and the IRAM 30 m single-dish telescope at 220 GHz, we probe the gas and dust emission at an angular resolution of ~0.45′′, corresponding to 1900 au. Results. In the millimeter (mm) continuum emission, we identify a protostellar cluster with at least four mm-sources, where three of them show a significantly higher peak intensity well above a signal-to-noise ratio of 100. Hierarchical fragmentation from large to small spatial scales is discussed. Two fragments are embedded in rotating structures and drive molecular outflows, traced by 13CO (2–1) emission. The velocity profiles across two of the cores are similar to Keplerian but are missing the highest-velocity components close to the center of rotation, which is a common phenomena from observations like these, and other rotation scenarios are not excluded entirely. Position–velocity diagrams suggest protostellar masses of ~6 and 19 M⊙. Rotational temperatures from fitting CH3CN (12K− 11K) spectra are used for estimating the gas temperature and thereby also the disk stability against gravitational fragmentation, utilizing Toomre’s Q parameter. Assuming that the candidate disk is in Keplerian rotation about the central stellar object and considering different disk inclination angles, we identify only one candidate disk as being unstable against gravitational instability caused by axisymmetric perturbations. Conclusions. The dominant sources cover different evolutionary stages within the same maternal gas clump. The appearance of rotation and outflows of the cores are similar to those found in low-mass star-forming regions.

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The effect of stellar multiplicity on protoplanetary discs: a near-infrared survey of the Lupus star-forming region

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3674 ◽

2020 ◽

Vol 501 (2) ◽

pp. 2305-2315

Author(s):

Alice Zurlo ◽

Lucas A Cieza ◽

Megan Ansdell ◽

Valentin Christiaens ◽

Sebastián Pérez ◽

...

Keyword(s):

Adaptive Optics ◽

Molecular Cloud ◽

Near Infrared ◽

Main Sequence Stars ◽

Multiple Systems ◽

Star Forming ◽

Very Large Telescope ◽

Pms Stars ◽

First Time ◽

Infrared Survey

ABSTRACT We present results from a near-infrared (NIR) adaptive optics (AO) survey of pre-main-sequence stars in the Lupus molecular cloud with NACO at the Very Large Telescope (VLT) to identify (sub)stellar companions down to ∼20-au separation and investigate the effects of multiplicity on circumstellar disc properties. We observe for the first time in the NIR with AO a total of 47 targets and complement our observations with archival data for another 58 objects previously observed with the same instrument. All 105 targets have millimetre Atacama Large Millimetre/sub-millimetre Array (ALMA) data available, which provide constraints on disc masses and sizes. We identify a total of 13 multiple systems, including 11 doubles and 2 triples. In agreement with previous studies, we find that the most massive (Mdust > 50 M⊕) and largest (Rdust > 70 au) discs are only seen around stars lacking visual companions (with separations of 20–4800 au) and that primaries tend to host more massive discs than secondaries. However, as recently shown in a very similar study of >200 PMS stars in the Ophiuchus molecular cloud, the distributions of disc masses and sizes are similar for single and multiple systems for Mdust < 50 M⊕ and radii Rdust < 70 au. Such discs correspond to ∼80–90 per cent of the sample. This result can be seen in the combined sample of Lupus and Ophiuchus objects, which now includes more than 300 targets with ALMA imaging and NIR AO data, and implies that stellar companions with separations >20 au mostly affect discs in the upper 10${{\ \rm per\ cent}}$ of the disc mass and size distributions.

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