scholarly journals High angular resolution study of the super star cluster population in IRAS 17138−1017

2020 ◽  
Vol 639 ◽  
pp. A28
Author(s):  
N. T. Lam ◽  
D. Gratadour ◽  
D. Rouan ◽  
L. Grosset
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Thermal Emission ◽  
Scattered Light ◽  
Dust Emission ◽  
High Angular Resolution ◽  
Evolutionary Track ◽  
Imaging Data ◽  
Host Galaxies ◽  
Super Star Clusters

Aims. Currently, the global characteristics and evolution of super star clusters (SSCs) are not well understood, due to the large distances to their host galaxies. We aim to study the population of SSCs in IRAS 17138-1017, a luminous infrared galaxy (LIRG), in terms of age, extinction, mass, and luminosity distribution. Methods. We analyzed imaging data in the near-infrared from the GeMS/GSAOI instrument on the Gemini telescope and generated simulations with the radiative transfer code MontAGN. The extraction of SSCs from the images and their photometry in J, H, and Ks allowed us to derive color-color and color-magnitude diagrams. Comparison with a theoretical stellar evolutionary track gives a first hint into the extinction towards each SSC, as well as their ages, despite some degeneracy between those two quantities. Spectra given by our radiative transfer code MontAGN, which includes dust emission, also provide insightful predictions and comparisons. Results. We detect with a fair degree of confidence 54 SSCs of mKs between 16 mag and 21 mag with a median instrumental uncertainty of 0.05 mag. When plotted on a color–color diagram and a color–magnitude diagram, it appears that most of the sources are very much extinct with respect to an intrinsic theoretical evolutionary track. Once de-reddened, the colors point unambiguously to two distinct and very recent starburst episodes at 2.8 and 4.5 Myr. While the SSCs in the 4.5 Myr starburst are distributed along the spiral arms, the 2.8 Myr SSCs are concentrated in the central region. The luminosity and mass functions present a classical power-law behavior, although with shallower slopes than generally observed in LIRGs. Comparison with radiative transfer simulations shows that, the dust thermal emission and scattered light are negligible and could not explain the few very red SSCs that could not be de-reddened safely.

scholarly journals Dusty spirals triggered by shadows in transition discs

2019 ◽  
Vol 622 ◽  
pp. A43 ◽  
Author(s):  
N. Cuello ◽  
M. Montesinos ◽  
S. M. Stammler ◽  
F. Louvet ◽  
J. Cuadra
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Thermal Emission ◽  
Dust Emission ◽  
Spiral Waves ◽  
Dust Particles ◽  
Physical Mechanisms ◽  
Gravitational Perturbations ◽  
Hydrodynamical Simulations ◽  
Dust Evolution

Context. Despite the recent discovery of spiral-shaped features in protoplanetary discs in the near-infrared and millimetre wavelengths, there is still an active discussion to understand how they formed. In fact, the spiral waves observed in discs around young stars can be due to different physical mechanisms: planet/companion torques, gravitational perturbations, or illumination effects. Aims. We study the spirals formed in the gaseous phase by two diametrically opposed shadows cast at fixed disc locations. The shadows are created by an inclined non-precessing disc inside the cavity, which is assumed to be optically thick. In particular, we analyse the effect of these spirals on the dynamics of the dust particles and discuss their detectability in transition discs. Methods. We performed gaseous hydrodynamical simulations with shadows, then we computed the dust evolution on top of the gaseous distribution, and finally we produced synthetic ALMA observations of the dust emission based on radiative transfer calculations. Results. Our main finding is that millimetre- to centimetre-sized dust particles are efficiently trapped inside the shadow-triggered spirals. We also observe that particles of various sizes starting at different stellocentric distances are well mixed inside these pressure maxima. This dynamical effect would favour grain growth and affect the resulting composition of planetesimals in the disc. In addition, our radiative transfer calculations show spiral patterns in the disc at 1.6 μm and 1.3 mm. Due to their faint thermal emission (compared to the bright inner regions of the disc) the spirals cannot be detected with ALMA. However, our synthetic observations prove that shadows are observable as dips in the thermal emission.

scholarly journals Flybys in protoplanetary discs – II. Observational signatures

2019 ◽  
Vol 491 (1) ◽  
pp. 504-514 ◽  
Author(s):  
Nicolás Cuello ◽  
Fabien Louvet ◽  
Daniel Mentiplay ◽  
Christophe Pinte ◽  
Daniel J Price ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Scattered Light ◽  
Line Emission ◽  
Star Clusters ◽  
Post Process ◽  
Accretion Rates ◽  
Fu Ori ◽  
Hydrodynamical Simulations ◽  
Multiwavelength Observations

ABSTRACT Tidal encounters in star clusters perturb discs around young protostars. In Cuello et al., we detailed the dynamical signatures of a stellar flyby in both gas and dust. Flybys produce warped discs, spirals with evolving pitch angles, increasing accretion rates, and disc truncation. Here, we present the corresponding observational signatures of these features in optical/near-infrared scattered light and (sub) millimetre continuum and CO line emission. Using representative prograde and retrograde encounters for direct comparison, we post-process hydrodynamical simulations with radiative transfer methods to generate a catalogue of multiwavelength observations. This provides a reference to identify flybys in recent near-infrared and submillimetre observations (e.g. RW Aur, AS 205, HV Tau and DO Tau, FU Ori, V2775 Ori, and Z CMa).

scholarly journals Direct imaging of irregular satellite discs in scattered light

2020 ◽  
Vol 492 (4) ◽  
pp. 5709-5720
Author(s):  
Loic Nassif-Lachapelle ◽  
Daniel Tamayo
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Scattered Light ◽  
Semimajor Axis ◽  
Detection Methods ◽  
Direct Imaging ◽  
Irregular Satellites ◽  
Long Period ◽  
Wide Range ◽  
Collisional Evolution

ABSTRACT Direct imaging surveys have found that long-period super-Jupiters are rare. By contrast, recent modelling of the widespread gaps in protoplanetary discs revealed by Atacama Large Millimetre Array suggests an abundant population of smaller Neptune to Jupiter-mass planets at large separations. The thermal emission from such lower-mass planets is negligible at optical and near-infrared wavelengths, leaving only their weak signals in reflected light. Planets do not scatter enough light at these large orbital distances, but there is a natural way to enhance their reflecting area. Each of the four giant planets in our Solar system hosts swarms of dozens of irregular satellites, gravitationally captured planetesimals that fill their host planets’ spheres of gravitational influence. What we see of them today are the leftovers of an intense collisional evolution. At early times, they would have generated bright circumplanetary debris discs. We investigate the properties and detectability of such irregular satellite discs (ISDs) following models for their collisional evolution from Kennedy & Wyatt (2011). We find that the scattered light signals from such ISDs would peak in the 10–100 au semimajor axis range implied by ALMA, and can render planets detectable over a wide range of parameters with upcoming high-contrast instrumentation. We argue that future instruments with wide fields of view could simultaneously characterize the atmospheres of known close-in planets, and reveal the population of long-period Neptune–Jupiter mass exoplanets inaccessible to other detection methods. This provides a complementary and compelling science case that would elucidate the early lives of planetary systems.

Near-Infrared Photometry of Southern Galactic Wolf-Rayet Stars

1982 ◽  
Vol 99 ◽  
pp. 67-72
Author(s):  
C. Sterken ◽  
C. de Loore
Keyword(s):  
Infrared Radiation ◽  
Interstellar Dust ◽  
Near Infrared ◽  
Thermal Emission ◽  
Dust Emission ◽  
Circumstellar Dust ◽  
Infrared Photometry ◽  
Energy Distributions ◽  
Circumstellar Shell

Allen et al. (1972) observed 40 WR stars in the |1.6µ| and |2.2µ| bands, and found evidence of interstellar dust emission in the WC9 stars Ve 2–45, AS320 and HD 313643. Hackwell et al. (1974) reported 2.3 to 23 µ photometry of 19 WR stars and concluded that the excess infrared radiation from the Wolf-Rayet stars (except for the WC9 stars) could be explained by free-free emission from a hot circumstellar shell. Gehrz and Hackwell (1974) found from 2.3 to 23 µ photometry that three out of four WC stars appear to be embedded in thick circumstellar dust (graphite) shells, and concluded that WC9 stars may form a distinct Wolf-Rayet class. Cohen et al. (1975) derived energy distributions of 23 Wolf-Rayet stars from 3µ-11µ scanner spectrophotometry and infrared photometry, and concluded that WN stars show only free-free emission whereas only WC stars show dust. The excesses in WC9 stars are interpreted as thermal emission by graphite grains.

scholarly journals Observational signatures of eccentric Jupiters inside gas cavities in protoplanetary discs

2021 ◽  
Author(s):  
Clément Baruteau ◽  
Gaylor Wafflard-Fernandez ◽  
Romane Le Gal ◽  
Florian Debras ◽  
Andrés Carmona ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Scattered Light ◽  
Dust Emission ◽  
Three Dimensional ◽  
Continuum Emission ◽  
Integrated Intensity ◽  
Gas Cavity ◽  
Hydrodynamical Simulations ◽  
Small Dust

Abstract Predicting how a young planet shapes the gas and dust emission of its parent disc is key to constraining the presence of unseen planets in protoplanetary disc observations. We investigate the case of a 2 Jupiter mass planet that becomes eccentric after migrating into a low-density gas cavity in its parent disc. Two-dimensional hydrodynamical simulations are performed and post-processed by three-dimensional radiative transfer calculations. In our disc model, the planet eccentricity reaches ∼0.25, which induces strong asymmetries in the gas density inside the cavity. These asymmetries are enhanced by photodissociation and form large-scale asymmetries in 12CO J=3→2 integrated intensity maps. They are shown to be detectable for an angular resolution and a noise level similar to those achieved in ALMA observations. Furthermore, the planet eccentricity renders the gas inside the cavity eccentric, which manifests as a narrowing, stretching and twisting of iso-velocity contours in velocity maps of 12CO J=3→2. The planet eccentricity does not, however, give rise to detectable signatures in 13CO and C18O J=3→2 inside the cavity because of low column densities. Outside the cavity, the gas maintains near-circular orbits, and the vertically extended optically thick CO emission displays a four-lobed pattern in integrated intensity maps for disc inclinations $\gtrsim$ 30○. The lack of large and small dust inside the cavity in our model further implies that synthetic images of the continuum emission in the sub-millimetre, and of polarized scattered light in the near-infrared, do not show significant differences when the planet is eccentric or still circular inside the cavity.

scholarly journals First scattered light detection of a nearly edge-on transition disk around the T Tauri star RY Lupi

2018 ◽  
Vol 614 ◽  
pp. A88 ◽  
Author(s):  
M. Langlois ◽  
A. Pohl ◽  
A.-M. Lagrange ◽  
A.- L. Maire ◽  
D. Mesa ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Planet Formation ◽  
Scattered Light ◽  
Emission Feature ◽  
Point Sources ◽  
Tauri Star ◽  
Dual Band ◽  
High Angular Resolution ◽  
T Tauri

Context. Transition disks are considered sites of ongoing planet formation, and their dust and gas distributions could be signposts of embedded planets. The transition disk around the T Tauri star RY Lup has an inner dust cavity and displays a strong silicate emission feature. Aims. Using high-resolution imaging we study the disk geometry, including non-axisymmetric features, and its surface dust grain, to gain a better understanding of the disk evolutionary process. Moreover, we search for companion candidates, possibly connected to the disk. Methods. We obtained high-contrast and high angular resolution data in the near-infrared with the VLT/SPHERE extreme adaptive optics instrument whose goal is to study the planet formation by detecting and characterizing these planets and their formation environments through direct imaging. We performed polarimetric imaging of the RY Lup disk with IRDIS (at 1.6 μm), and obtained intensity images with the IRDIS dual-band imaging camera simultaneously with the IFS spectro-imager (0.9–1.3 μm). Results. We resolved for the first time the scattered light from the nearly edge-on circumstellar disk around RY Lup, at projected separations in the 100 au range. The shape of the disk and its sharp features are clearly detectable at wavelengths ranging from 0.9 to 1.6 μm. We show that the observed morphology can be interpreted as spiral arms in the disk. This interpretation is supported by in-depth numerical simulations. We also demonstrate that these features can be produced by one planet interacting with the disk. We also detect several point sources which are classified as probable background objects.

scholarly journals Spatial segregation of dust grains in transition disks

2019 ◽  
Vol 624 ◽  
pp. A7 ◽  
Author(s):  
M. Villenave ◽  
M. Benisty ◽  
W. R. F. Dent ◽  
F. Ménard ◽  
A. Garufi ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Scattered Light ◽  
Radiative Transfer Model ◽  
Occurrence Rate ◽  
Transfer Model ◽  
Star Forming ◽  
Spatially Resolved ◽  
Wide Range ◽  
Transition Disks

Context. The mechanisms governing the opening of cavities in transition disks are not fully understood. Several processes have been proposed, but their occurrence rate is still unknown. Aims. We present spatially resolved observations of two transition disks, and aim at constraining their vertical and radial structure using multiwavelength observations that probe different regions of the disks and can help understanding the origin of the cavities. Methods. We have obtained near-infrared scattered light observations with VLT/SPHERE of the transition disks 2MASS J16083070-3828268 (J1608) and RXJ1852.3-3700 (J1852), located in the Lupus and Corona Australis star-forming regions respectively. We complement our datasets with archival ALMA observations, and with unresolved photometric observations covering a wide range of wavelengths. We performed radiative transfer modeling to analyze the morphology of the disks, and then compare the results with a sample of 20 other transition disks observed with both SPHERE and ALMA. Results. We detect scattered light in J1608 and J1852 up to a radius of 0.54′′ and 0.4′′ respectively. The image of J1608 reveals a very inclined disk (i ~ 74°), with two bright lobes and a large cavity. We also marginally detect the scattering surface from the rear-facing side of the disk. J1852 shows an inner ring extending beyond the coronagraphic radius up to 15 au, a gap and a second ring at 42 au. Our radiative transfer model of J1608 indicates that the millimeter-sized grains are less extended vertically and radially than the micron-sized grains, indicating advanced settling and radial drift. We find good agreement with the observations of J1852 with a similar model, but due to the low inclination of the system, the model remains partly degenerate. The analysis of 22 transition disks shows that, in general, the cavities observed in scattered light are smaller than the ones detected at millimeter wavelengths. Conclusions. The analysis of a sample of transition disks indicates that the small grains, well coupled to the gas, can flow inward of the region where millimeter grains are trapped. While 15 out of the 22 cavities in our sample could be explained by a planet of less than 13 Jupiter masses, the others either require the presence of a more massive companion or of several low-mass planets.

scholarly journals Highly structured disk around the planet host PDS 70 revealed by high-angular resolution observations with ALMA

2019 ◽  
Vol 625 ◽  
pp. A118 ◽  
Author(s):  
M. Keppler ◽  
R. Teague ◽  
J. Bae ◽  
M. Benisty ◽  
T. Henning ◽  
...  
Keyword(s):  
Near Infrared ◽  
Angular Resolution ◽  
Dust Emission ◽  
Mass Range ◽  
Position Angle ◽  
Circumstellar Disk ◽  
High Angular Resolution ◽  
Gas Kinematics ◽  
Hydrodynamical Simulations ◽  
Dust Ring

Context. Imaged in the gap of a transition disk and found at a separation of about 195 mas (~22 au) from its host star at a position angle of about 155°, PDS 70 b is the most robustly detected young planet to date. This system is therefore a unique laboratory for characterizing the properties of young planetary systems at the stage of their formation. Aims. We aim to trace direct and indirect imprints of PDS 70 b on the gas and dust emission of the circumstellar disk in order to study the properties of this ~5 Myr young planetary system. Methods. We obtained ALMA band 7 observations of PDS 70 in dust continuum and 12CO (3–2) and combined them with archival data. This resulted in an unprecedented angular resolution of about 70 mas (~8 au). Results. We derive an upper limit on circumplanetary material at the location of PDS 70 b of ~0.01 M⊕ and find a highly structured circumstellar disk in both dust and gas. The outer dust ring peaks at 0.65′′ (74 au) and reveals a possible second unresolved peak at about 0.53′′ (60 au). The integrated intensity of CO also shows evidence of a depletion of emission at ~0.2′′ (23 au) with a width of ~0.1′′ (11 au). The gas kinematics show evidence of a deviation from Keplerian rotation inside ≲0.8′′ (91 au). This implies a pressure gradient that can account for the location of the dust ring well beyond the location of PDS 70 b. Farther in, we detect an inner disk that appears to be connected to the outer disk by a possible bridge feature in the northwest region in both gas and dust. We compare the observations to hydrodynamical simulations that include a planet with different masses that cover the estimated mass range that was previously derived from near-infrared photometry (~5–9 MJup). We find that even a planet with a mass of 10 MJup may not be sufficient to explain the extent of the wide gap, and an additional low-mass companion may be needed to account for the observed disk morphology.

scholarly journals Cluster formation induced by a cloud–cloud collision in [DBS2003]179

2020 ◽  
Author(s):  
Sho Kuwahara ◽  
Kazufumi Torii ◽  
Norikazu Mizuno ◽  
Shinji Fujita ◽  
Mikito Kohno ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cluster Formation ◽  
Dust Emission ◽  
Star Clusters ◽  
High Ratio ◽  
Star Cluster ◽  
High Mass ◽  
Mass Star ◽  
The Galaxy ◽  
Super Star Clusters

Abstract [DBS2003]179 is a super star cluster in the Galaxy discovered in deep near-infrared observations. We carried out CO $J$ = 1–0 and $J$ = 3–2 observations of the region of [DBS2003]179 with NANTEN2, ASTE, and the Mopra 22 m telescope. We identified and mapped two molecular clouds that are likely to be associated with the cluster. This association is supported by the spatial correlation with the corresponding 8$\, \mu$m Spitzer image and by a high ratio of the two transitions of $^{12}$CO($J$ = 3–2 and $J$ = 1–0). The two clouds show complementary distributions in space, and bridging features connect them in velocity. We hypothesize that the two clouds collided with each other 1–2 Myr ago and that the collision compressed the interfacial layer, triggering the formation of the cluster. This offers an additional piece of evidence for a super star cluster formed by a cloud–cloud collision, alongside the four super star clusters Westerlund$\:2$, NGC 3603, RCW 38, and R 136. These findings indicate that the known super star clusters with closely associated dust emission were formed by cloud–cloud collisions, lending support to the important role of cloud–cloud collisions in high-mass star formation.

scholarly journals The Fingerprint of a Galactic Nucleus

2016 ◽  
Vol 11 (S322) ◽  
pp. 257-258
Author(s):  
Francisco Nogueras-Lara ◽  
Rainer Schödel
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Angular Resolution ◽  
Galactic Center ◽  
Fold Increase ◽  
Galactic Centre ◽  
High Angular Resolution ◽  
Imaging Data ◽  
First Results ◽  
Multi Wavelength

AbstractBecause of the unique observational challenges -extreme crowding and extinction- any existing large-scale near-infrared (NIR) imaging data on the Galactic Center (GC) are limited by either one, or a combination, of the following: saturation, lack of sensitivity, too low angular resolution, or lack of multi-wavelength coverage. To overcome this situation, we are currently carrying out a sensitive, 0.2” resolution JHK imaging survey of the Galactic Centre with HAWK-I/VLT. Thanks to holographic imaging, we achieve a similar resolution than with HST/WFC, but can cover also the long NIR, beyond 2 micrometers, which is essential to deal with extinction. Our survey is supported by an ESO Large Programme and will provide photometrically accurate (few percent uncertainty for H < 18 stars), high-angular resolution, NIR data for an area of several 1000 pc2, a more than ten-fold increase compared to the current state of affairs. Here we present an overview and first results.

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