Scattered Light Models of Protostellar Envelopes: Multiple Outflow Cavities and Misaligned Circumstellar Disks

Context. Near-IR polarimetric images of protoplanetary disks enable us to characterize substructures that might be due to the interaction with (forming) planets. The available census is strongly biased toward massive disks around old stars, however. Aims. The DARTTS program aims at alleviating this bias by imaging a large number of T Tauri stars with diverse properties. Methods. DARTTS-S employs VLT/SPHERE to image the polarized scattered light from disks. In parallel, DARTTS-A provides ALMA images of the same targets for a comparison of different dust components. In this work, we present new SPHERE images of 21 circumstellar disks, which is the largest sample released to date. We also recalculated some relevant stellar and disk properties following Gaia DR2. Results. The targets of this work are significantly younger than those published thus far with polarimetric near-IR (NIR) imaging. Scattered light is unambiguously resolved in 11 targets, and some polarized unresolved signal is detected in 3 additional sources. Some disk substructures are detected. However, the paucity of spirals and shadows from this sample reinforces the trend according to which these NIR features are associated with Herbig stars, either because they are older or more massive. Furthermore, disk rings that are apparent in ALMA observations of some targets do not appear to have corresponding detections with SPHERE. Inner cavities larger than ~15 au are also absent from our images, even though they are expected from the spectral energy distribution. On the other hand, 3 objects show extended filaments at larger scale that are indicative of strong interaction with the surrounding medium. All but one of the undetected disks are best explained by their limited size (≲20 au), and the high occurrence of stellar companions in these sources suggests an important role in limiting the disk size. One undetected disk is massive and very large at millimeter wavelengths, implying that it is self-shadowed in the NIR. Conclusions. This work paves the way toward a more complete and less biased sample of scattered-light observations, which is required to interpret how disk features evolve throughout the disk lifetime.

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HST Imaging of New Edge-on Circumstellar Disks in Nearby Star-forming Regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313008004 ◽

2013 ◽

Vol 8 (S299) ◽

pp. 99-103

Author(s):

K.R. Stapelfeldt ◽

G. Duchêne ◽

M. Perrin ◽

S. Wolff ◽

J.E. Krist ◽

...

Keyword(s):

Structural Parameters ◽

Scattered Light ◽

Spectral Energy Distribution ◽

Circumstellar Disks ◽

Central Star ◽

Young Stellar Objects ◽

Spectral Energy ◽

Ancillary Data ◽

Nearby Star ◽

Space Telescope

AbstractEdge-on, optically thick circumstellar disks have been previously imaged at subarcsecond resolution around about a dozen nearby young stellar objects. In these systems the central star is occulted from direct view, bright star image artifacts are absent, and the disk reflected light is clearly seen. Comparison of Hubble Space Telescope (HST) edge-on disk images with scattered light models has allowed key disk structural parameters and dust grain properties to be determined. Edge-on disks have been systematically undercounted to date: while 10% of young stars should statistically be occulted by their disk, the observed frequency is much less. Thus there is a significant potential for discovering and imaging new examples. Spitzer Space Telescope legacy science programs have provided the first good spectral energy distribution (SED) measurements for the previously known edge-on disks. These can be used as templates to identify new candidates in far-infrared survey datasets.We report on the results of our HST program to image twenty-one edge-on disk candidates mostly selected from their SEDs. Eleven are well-resolved with radii ranging from 30-400 AU, nine for the first time and six showing highly collimated jets. Outstanding individual sources include a large and symmetric new template object, a highly flattened disk not accreting onto its central star, and an asymmetric disk with a misaligned jet which likely traces tidal perturbations in a binary system. Follow-up work to obtain ancillary data and perform scattered light modeling of the most symmetric disks is now being pursued. The results of this program will guide a new round of searches for these rare but important snapshots of protoplanetary disk evolution.

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Why circumstellar disks are so faint in scattered light: the case of HD 100546

Astronomy and Astrophysics ◽

10.1051/0004-6361/201219522 ◽

2013 ◽

Vol 549 ◽

pp. A112 ◽

Cited By ~ 50

Author(s):

G. D. Mulders ◽

M. Min ◽

C. Dominik ◽

J. H. Debes ◽

G. Schneider

Keyword(s):

Scattered Light ◽

Circumstellar Disks

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Ongoing flyby in the young multiple system UX Tauri

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038356 ◽

2020 ◽

Vol 639 ◽

pp. L1 ◽

Cited By ~ 5

Author(s):

F. Ménard ◽

N. Cuello ◽

C. Ginski ◽

G. van der Plas ◽

M. Villenave ◽

...

Keyword(s):

Coming Out ◽

Scattered Light ◽

Circumstellar Disks ◽

Major Axis ◽

Position Angle ◽

Rotating Disks ◽

Hydrodynamical Models ◽

Co Emission

We present observations of the young multiple system UX Tauri to look for circumstellar disks and for signs of dynamical interactions. We obtained SPHERE/IRDIS deep differential polarization images in the J and H bands. We also used ALMA archival CO data. Large extended spirals are well detected in scattered light coming out of the disk of UX Tau A. The southern spiral forms a bridge between UX Tau A and C. These spirals, including the bridge connecting the two stars, all have a CO (3–2) counterpart seen by ALMA. The disk of UX Tau C is detected in scattered light. It is much smaller than the disk of UX Tau A and has a major axis along a different position angle, suggesting a misalignment. We performed PHANTOM SPH hydrodynamical models to interpret the data. The scattered light spirals, CO emission spirals and velocity patterns of the rotating disks, and the compactness of the disk of UX Tau C all point to a scenario in which UX Tau A has been perturbed very recently (∼1000 years) by the close passage of UX Tau C.

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Observational Possibility of the “Snow Line” on the Surface of Circumstellar Disks with the Scattered Light

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/60.3.557 ◽

2008 ◽

Vol 60 (3) ◽

pp. 557-563 ◽

Cited By ~ 18

Author(s):

Akio K. Inoue ◽

Mitsuhiko Honda ◽

Taishi Nakamoto ◽

Akinori Oka

Keyword(s):

Scattered Light ◽

Circumstellar Disks ◽

Snow Line

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GG Tauri A: dark shadows on the ringworld

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935966 ◽

2019 ◽

Vol 628 ◽

pp. A88 ◽

Cited By ~ 5

Author(s):

R. Brauer ◽

E. Pantin ◽

E. Di Folco ◽

E. Habart ◽

A. Dutrey ◽

...

Keyword(s):

Radiative Transfer ◽

Near Infrared ◽

Binary Star ◽

Scattered Light ◽

Circumstellar Disks ◽

Infrared Emission ◽

Close Binary ◽

Spectral Energy ◽

Multiple Star ◽

The Individual

Context. With its high complexity, large size, and close distance, the ringworld around GG Tau A is an appealing case to study the formation and evolution of protoplanetary disks around multiple star systems. However, investigations with radiative transfer models usually neglect the influence of the circumstellar dust around the individual stars. Aims. We investigate how circumstellar disks around the stars of GG Tau A influence the emission that is scattered at the circumbinary disk and if constraints on these circumstellar disks can be derived. Methods. We performed radiative transfer simulations with the POLArized RadIation Simulator (POLARIS) to obtain spectral energy distributions and emission maps in the H-Band (near-infrared). Subsequently, we compared them with observations to achieve our aims. Results. We studied the ratio of polarized intensity at different locations in the circumbinary disk. We conclude that the observed scattered-light near-infrared emission is best reproduced if the circumbinary disk lies in the shadow of at least two coplanar circumstellar disks surrounding the central stars. This implies that the inner wall of the circumbinary disk is strongly obscured around the midplane, while the observed emission is actually dominated by the upper-most disk layers. In addition, the inclined dark lane (“gap”) on the western side of the circumbinary disk, which has been a stable, nonrotating, feature for approximately 20 yr, can only be explained by the self-shadowing of a misaligned circumstellar disk surrounding one of the two components of the secondary close-binary star GG Tau Ab.

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A Simple Spectropolarimetric Temperature Diagnostic for Circumstellar Disks

International Astronomical Union Colloquium ◽

10.1017/s025292110005661x ◽

2000 ◽

Vol 175 ◽

pp. 603-606 ◽

Cited By ~ 2

Author(s):

Karen S. Bjorkman ◽

Jon E. Bjorkman ◽

Kenneth Wood

Keyword(s):

Scattered Light ◽

Circumstellar Disks ◽

Spectral Lines ◽

Polarization Spectrum ◽

Be Stars ◽

Light Spectrum ◽

Temperature Estimate ◽

Disk Material ◽

Be Star ◽

Temperature Diagnostic

AbstractWe describe a technique for estimating average temperatures of Be star disks from analysis of ultraviolet spectropolarimetry. The technique utilizes the fact that the spectrum of the scattered starlight is sensitive to the circumstellar opacity, and hence temperature, since the signature of the disk material is imprinted on the scattered light spectrum. Analysis of the polarization spectrum thus allows us to disentangle the relative contributions of the star and disk, and thereby obtain an estimate of the average disk opacity as a function of wavelength. Using an LTE line-blanketed model (containing about 106 spectral lines) for the opacity, we determine a theoretical opacity as a function of temperature. By comparing this to the opacity deduced from the spectropolarimetry, we can estimate the average disk temperature. For classical Be stars, the relative strengths of the Fe II and Fe III multiplets at around 2400Å and 1900Å, respectively, are a sensitive temperature diagnostic, so that the temperature estimate can be made within ±1000K. We demonstrate our technique with analysis of UV spectropolarimetry (from WUPPE) of the classical Be star ζ Tau, for which we infer an isothermal disk temperature of14000K.

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Influence of the scattering particle shape on the SiO2 silicate feature

Acta Astrophysica Taurica ◽

10.31059/aat.vol2.iss1.pp26-29 ◽

2021 ◽

Vol 2 (1) ◽

pp. 26-29

Author(s):

Dmitry Petrov ◽

Elena Zhuzhulina ◽

Alexander Savushkin

Keyword(s):

Particle Size ◽

Light Intensity ◽

Particle Shape ◽

Scattered Light ◽

Circumstellar Disks ◽

Dust Particles ◽

Oblate Spheroids ◽

Scattering Factor ◽

Silicate Feature ◽

Ideal Sphere

Silicate dust particles are part of many astronomical objects such as comets and circumstellar disks. In a spectrum, silicates exhibit a number of characteristic silicate emission features. To study these features, Mie’s theory is usually used. This theory assumes that the scattering object is an ideal sphere. In this work, we investigated the contribution of non-spherical quartz particles (SiO2) to these features. We studied the influence of the deviation from sphericity on the 10-micron silicate feature of quartz. It is shown that the deviation from sphericity has a significant effect on both the scattered light intensity and the scattering factor Qsca, and this effect increases with increasing scattering particle size. The main peculiarities of the 10-micron silicate feature have been studied for both prolate and oblate spheroids.

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The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

International Astronomical Union Colloquium ◽

10.1017/s0252921100014780 ◽

1997 ◽

Vol 161 ◽

pp. 267-282 ◽

Cited By ~ 1

Author(s):

Thierry Montmerle

Keyword(s):

Main Sequence ◽

Solar Nebula ◽

Circumstellar Disks ◽

T Tauri Stars ◽

Necessary Condition ◽

Sequence Evolution ◽

T Tauri ◽

Solar Type ◽

Optical Domain ◽

The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

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