We have observed 99 mid-infrared-bright, massive young stellar objects and compact H ii regions drawn from the Red MSX source survey in the J = 3−2 transition of 12CO and 13CO, using the James Clerk ...Maxwell Telescope. 89 targets are within 6 kpc of the Sun, covering a representative range of luminosities and core masses. These constitute a relatively unbiased sample of bipolar molecular outflows associated with massive star formation. Of these, 59, 17 and 13 sources (66, 19 and 15 per cent) are found to have outflows, show some evidence of outflow, and have no evidence of outflow, respectively. The time-dependent parameters of the high-velocity molecular flows are calculated using a spatially variable dynamic time-scale. The canonical correlations between the outflow parameters and source luminosity are recovered and shown to scale with those of low-mass sources. For coeval star formation, we find the scaling is consistent with all the protostars in an embedded cluster providing the outflow force, with massive stars up to ∼30 M⊙ generating outflows. Taken at face value, the results support the model of a scaled-up version of the accretion-related outflow-generation mechanism associated with discs and jets in low-mass objects with time-averaged accretion rates of ∼10−3 M⊙ yr−1 on to the cores. However, we also suggest an alternative model, in which the molecular outflow dynamics are dominated by the entrained mass and are unrelated to the details of the acceleration mechanism. We find no evidence that outflows contribute significantly to the turbulent kinetic energy of the surrounding dense cores.
Abstract
We observed the W51 high-mass star-forming complex with the Atacama Large Millimeter/submillimeter Array’s longest-baseline configurations, achieving an angular resolution of ∼20 mas, ...corresponding to a linear resolution of ∼100 au at
D
W51
= 5.4 kpc. The observed region contains three high-mass protostars in which the dust continuum emission at 1.3 mm is optically thick up to a radius ≲1000 au and has brightness temperatures ≳200 K. The high luminosity (≳10
4
L
⊙
) in the absence of free–free emission suggests the presence of massive stars (
M
≳ 20
M
⊙
) at the earliest stages of their formation. Our continuum images reveal remarkably complex and filamentary structures arising from compact cores. Molecular emission shows no clear signs of rotation or infall on scales from 150 to 2000 au; we do not detect disks. The central sources drive young (
t
dyn
∼ 100 yr), fast (
v
∼ 100 km s
−1
), powerful (
M
⊙
yr
−1
), collimated outflows. These outflows provide indirect evidence of accretion disks on scales
r
≲ 100–500 au (depending on the object). The active outflows are connected to fossil flows that have different orientations on larger spatial scales, implying that the orientations of these small disks change over time. These results together support a variant of an accretion model for high-mass star formation in which massive protostars do not form a large, stable Keplerian disk during their early stages but instead accrete material from multiple massive flows with different angular momentum vectors. This scenario therefore contrasts with the simplified classic paradigm of a stable disk+jet system, which is the standard model for low-mass star formation, and provides experimental confirmation of a multidirectional and unsteady accretion model for massive star formation.
Context.
Star formation (SF) is a multi-scale process in which the mode of fragmentation of the collapsing clump on scales of 0.1–1 pc determines the mass reservoir and affects the accretion process ...of the individual protostars on scales of 10–100 au.
Aims.
We want to investigate the nearby (located at 1.63 ± 0.05 kpc) high-mass star-forming region IRAS 21078+5211 at linear scales from ~1 pc down to ~10 au.
Methods.
We combine the data of two recent programs: the NOrthern Extended Millimeter Array large project CORE and the Protostellar Outflows at the EarliesT Stages (POETS) survey. The former provides images of the 1 mm dust continuum and molecular line emissions with a linear resolution of ≈600 au covering a field of view up to ≈0.5 pc. The latter targets the ionized gas and 22 GHz water masers, mapping linear scales from a few 10
3
au down to a few astronomical units.
Results.
In IRAS 21078+5211, a highly fragmented cluster (size ~0.1 pc) of molecular cores is observed, located at the density peak of an elongated (size ~1 pc) molecular cloud. A small (≈1 km s
−1
per 0.1 pc) LSR velocity (
V
LSR
) gradient is detected across the major axis of the molecular cloud. Assuming we are observing a mass flow from the harboring cloud to the cluster, we derive a mass infall rate of ≈10
−4
M
⊙
yr
−1
. The most massive cores (labeled 1, 2, and 3) are found at the center of the cluster, and these are the only ones that present a signature of protostellar activity in terms of emission from high-excitation molecular lines or a molecular outflow. The masses of the young stellar objects (YSOs) inside these three cores are estimated in the range 1–6
M
⊙
. We reveal an extended (size ~0.1 pc), bipolar collimated molecular outflow emerging from core 1. We believe this is powered by the compact (size ≲1000 au) radio jet discovered in the POETS survey, ejected by a YSO embedded in core 1 (named YSO-1), since the molecular outflow and the radio jet are almost parallel and have a comparable momentum rate. By means of high-excitation lines, we find a large (≈14 km s
−1
over 500 au)
V
LSR
gradient at the position of YSO-1, oriented approximately perpendicular to the radio jet. Assuming this is an edge-on, rotating disk and fitting a Keplerian rotation pattern, we determine the YSO-1 mass to be 5.6 ± 2.0
M
⊙
. The water masers observed in the POETS survey emerge within 100–300 au from YSO-1 and are unique tracers of the jet kinematics. Their three-dimensional (3D) velocity pattern reveals that the gas flows along, and rotates about, the jet axis. We show that the 3D maser velocities are fully consistent with the magneto-centrifugal disk-wind models predicting a cylindrical rotating jet. Under this hypothesis, we determine the jet radius to be ≈ 16 au and the corresponding launching radius and terminal velocity to be ≈ 2.2 au and ≈ 200 km s
−1
, respectively.
Conclusions.
Complementing high-angular resolution, centimeter and millimeter interferometric observations in thermal tracers with Very Long Baseline Interferometry of molecular masers, is invaluable in studying high-mass SF. The combination of these twodatasets allows us to connect the events that we see at large scales, as clump fragmentation and mass flows, with the physical processes identified at small scales, specifically, accretion and ejection in disk-jet systems.
Context.
Water is a key volatile that provides insight into the initial stages of planet formation. The low water abundances inferred from water observations toward low-mass protostellar objects may ...point to a rapid locking of water as ice by large dust grains during star and planet formation. However, little is known about the water vapor abundance in newly formed planet-forming disks.
Aims.
We aim to determine the water abundance in embedded Keplerian disks through spatially-resolved observations of H
2
18
O lines to understand the evolution of water during star and planet formation.
Methods.
We present H
2
18
O line observations with ALMA and NOEMA millimeter interferometers toward five young stellar objects. NOEMA observed the 3
1,3
–
2
2,0
line (
E
up
∕
k
B
= 203.7 K) while ALMA targeted the 4
1,4
–
3
2,1
line (
E
up
∕
k
B
= 322.0 K). Water column densities were derived considering optically thin and thermalized emission. Our observations were sensitive to the emission from the known Keplerian disks around three out of the five Class I objects in the sample.
Results.
No H
2
18
O emission is detected toward any of our five Class I disks. We report upper limits to the integrated line intensities. The inferred water column densities in Class I disks are
N
H
2
18
O
< 10
15
cm
−2
on 100 au scales, which include both the disk and envelope. The upper limits imply a disk-averaged water abundance of ≲10
−6
with respect to H
2
for Class I objects. After taking the physical structure of the disk into account, the upper limit to the water abundance averaged over the inner warm disk with
T
> 100 K is between ~10
−7
and 10
−5
.
Conclusions.
Water vapor is not abundant in warm protostellar envelopes around Class I protostars. Upper limits to the water vapor column densities in Class I disks are at least two orders of magnitude lower than values found in Class 0 disk-like structures.
Abstract
Background
Problems with mobility, functioning and social participation make living independently difficult for frail older adults. To continue living independently, therapy adherence is a ...prerequisite. The causes for non-adherence among older adults are multiple and complex, which is why insight into older adults’ perspectives regarding their functioning is an essential factor to increase therapy adherence.
This study investigates the perspectives of older adults on their functioning, social participation and health, and the factors influencing these elements.
Methods
We conducted a qualitative study on the older adult’s perceived functioning, social participation and health. Fourteen home-dwelling older adults suffering from chronic health issues were purposively selected.
Semi-structured interviews were conducted with open-ended questions.
Data were analysed following the Basic Logical Model of Abduction and Creswell’s coding method.
Results
Assistive devices, the older adult’s dwelling and living environment, professional and informal support, and medication are perceived as important determinants for retaining functioning and social participation.
Attitude, social influence and personal effectiveness were found to influence whether a person performs or participates in an activity. A person’s attitude is related to the significance the activity has to that person, the activity’s importance, personal wellbeing, the person’s values, and their desire for autonomy. Peers and children have a social influence on the level of activity of the older person. Traditions, in particular religious activities, along with personal effectiveness are motivating factors determining whether a person performs or participates in an activity. Personal effectiveness is linked to the person’s belief in their personal competencies and to the relationship between effort and result.
Finally, it appears that the type of coping strategy the older adult adopts, has an influence on their behavior. The participating older adults often used remarkable problem-focused strategies, which had a positive effect on their level of autonomy.
Conclusions
Older adults have identified barriers and facilitators that influence their level of functioning and social participation. These findings help to create a framework for maintaining and increasing therapy adherence, which may be helpful in facilitating occupational therapists and other healthcare professionals to detect determinants of therapy adherence.
As part of our effort to search for circumstellar disks around high-mass stellar objects, we observed the well-known core G31.41 +0.31 with ALMA at 1.4 mm with an angular resolution of ~0.′′22 (~1700 ...au). The dust continuum emission has been resolved into two cores namely Main and NE. The Main core, which has the stronger emission and is the more chemically rich, has a diameter of ~5300 au, and is associated with two free-free continuum sources. The Main core looks featureless and homogeneous in dust continuum emission and does not present any hint of fragmentation. Each transition of CH3CN and CH3OCHO, both ground and vibrationally excited, as well as those of CH3CN isotopologues, shows a clear velocity gradient along the NE–SW direction, with velocity linearly increasing with distance from the center, consistent with solid-body rotation. However, when comparing the velocity field of transitions with different upper level energies, the rotation velocity increases with increasing energy of the transition, which suggests that the rotation speeds up toward the center. Spectral lines towardtoward the dust continuum peak show an inverse P-Cygni profile that supports the existence of infall in the core. The infall velocity increases with the energy of the transition suggesting that the infall is accelerating toward the center of the core, consistent with gravitational collapse. Despite the monolithic appearance of the Main core, the presence of red-shifted absorption, the existence of two embedded free-free sources at the center, and the rotational spin-up are consistent with an unstable core undergoing fragmentation with infall and differential rotation due to conservation of angular momentum. Therefore, the most likely explanation for the monolithic morphology is that the large opacity of the dust emission prevents the detection of any inhomogeneity in the core.
The large majority of protoplanetary disks have very compact continuum emission (≲15 AU) at millimeter wavelengths. However, high angular resolution observations that resolve these small disks are ...still lacking, due to their intrinsically fainter emission compared with large bright disks. In this Letter we present 1.3 mm ALMA data of the faint disk (∼10 mJy) orbiting the TTauri star CX Tau at a resolution of ∼40 mas, ∼5 AU in diameter. The millimeter dust disk is compact, with a 68% enclosing flux radius of 14 AU, and the intensity profile exhibits a sharp drop between 10 and 20 AU, and a shallow tail between 20 and 40 AU. No clear signatures of substructure in the dust continuum are observed, down to the same sensitivity level of the DSHARP large program. However, the angular resolution does not allow us to detect substructures on the scale of the disk aspect ratio in the inner regions. The radial intensity profile closely resembles the inner regions of more extended disks imaged at the same resolution in DSHARP, but with no rings present in the outer disk. No inner cavity is detected, even though the disk has been classified as a transition disk from the spectral energy distribution in the near-infrared. The emission of 12CO is much more extended, with a 68% enclosing flux radius of 75 AU. The large difference of the millimeter dust and gas extents (> 5) strongly points to radial drift, and closely matches the predictions of theoretical models.
Objectives
The objective is to assess the effectiveness of occupational therapy to improve performance in daily living activities in community‐dwelling physically frail older people.
Design
We ...conducted a systematic review and meta‐analysis. We included randomized controlled trials reporting on occupational therapy as intervention, or as part of a multidisciplinary approach. This systematic review was carried out in accordance with the Cochrane methods of systematic reviews of interventions.
Measurements
Meta‐analyses were performed to pool results across studies using the standardized mean difference. The primary outcome measures were mobility, functioning in daily living activities, and social participation. Secondary outcome measures were fear of falling, cognition, disability, and number of falling persons.
Results
Nine studies met the inclusion criteria. Overall, the studies were of reasonable quality with low risk of bias. There was a significant increase in all primary outcomes. The pooled result for functioning in daily living activities was a standardized mean difference of −0.30 (95% CI −0.50 to −0.11; P = .002), for social participation −0.44 (95% CI −0.69, −0.19; P = .0007) and for mobility −0.45 (95% CI −0.78 to −0.12; P = .007). All secondary outcomes showed positive trends, with fear of falling being significant. No adverse effects of occupational therapy were found.
Conclusion
There is strong evidence that occupational therapy improves functioning in community‐dwelling physically frail older people.
Context. The hierarchical process of star formation has so far mostly been studied on scales from thousands of au to parsecs, but the smaller sub-1000 au scales of high-mass star formation are still ...largely unexplored in the submillimeter regime. Aims. We aim to resolve the dust and gas emission at the highest spatial resolution to study the physical properties of the densest structures during high-mass star formation. Methods. We observed the high-mass hot core region G351.77-0.54 with the Atacama Large Millimeter Array with baselines extending out to more than 16 km. This allowed us to dissect the region at sub-50 au spatial scales. Results. At a spatial resolution of 18/40 au (depending on the distance), we identify twelve sub-structures within the inner few thousand au of the region. The brightness temperatures are high, reaching values greater 1000 K, signposting high optical depth toward the peak positions. Core separations vary between sub-100 au to several 100 and 1000 au. The core separations and approximate masses are largely consistent with thermal Jeans fragmentation of a dense gas core. Due to the high continuum optical depth, most spectral lines are seen in absorption. However, a few exceptional emission lines are found that most likely stem from transitions with excitation conditions above 1000 K. Toward the main continuum source, these emission lines exhibit a velocity gradient across scales of 100–200 au aligned with the molecular outflow and perpendicular to the previously inferred disk orientation. While we cannot exclude that these observational features stem from an inner hot accretion disk, the alignment with the outflow rather suggests that it stems from the inner jet and outflow region. The highest-velocity features are found toward the peak position, and no Hubble-like velocity structure can be identified. Therefore, these data are consistent with steady-state turbulent entrainment of the hot molecular gas via Kelvin–Helmholtz instabilities at the interface between the jet and the outflow. Conclusions. Resolving this high-mass star-forming region at sub-50 au scales indicates that the hierarchical fragmentation process in the framework of thermal Jeans fragmentation can continue down to the smallest accessible spatial scales. Velocity gradients on these small scales have to be treated cautiously and do not necessarily stem from disks, but may be better explained with outflow emission. Studying these small scales is very powerful, but covering all spatial scales and deriving a global picture from large to small scales are the next steps to investigate.
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