Perturbers: SPHERE detection limits to planetary-mass companions in protoplanetary disks

Context. Protoplanetary disks contain structures such as gaps, rings, and spirals, which are thought to be produced by the interaction between the disk and embedded protoplanets. However, only a few planet candidates are found orbiting within protoplanetary disks, and most of them are being challenged as having been confused with disk features. Aims. The VLT/MUSE discovery of PDS 70 c demonstrated a powerful way of searching for still-forming protoplanets by targeting accretion signatures with medium-resolution integral field spectroscopy. We aim to discover more proto-planetary candidates with MUSE, with a secondary aim of improving the high-resolution spectral differential imaging (HRSDI) technique by analyzing the instrumental residuals of MUSE. Methods. We analyzed MUSE observations of five young stars with various apparent brightnesses and spectral types. We applied the HRSDI technique to perform high-contrast imaging. The detection limits were estimated using fake planet injections. Results. With a 30 min integration time, MUSE can reach 5σ detection limits in apparent Hα line flux down to 10−14 and 10−15 erg s−1 cm−2 at 0.075′′ and 0.25′′, respectively. In addition to PDS 70 b and c, we did not detect any clear accretion signatures in PDS 70, J1850-3147, and V1094 Sco down to 0.1′′. MUSE avoids the small sample statistics problem by measuring the noise characteristics in the spatial direction at multiple wavelengths. We detected two asymmetric atomic jets in HD 163296 with a very high spatial resolution (down to 8 au) and medium spectral resolution (R ~ 2500). Conclusions. The HRSDI technique when applied to MUSE data allows us to reach the photon noise limit at small separations (i.e., <0.5′′). With the combination of high-contrast imaging and medium spectral resolution, MUSE can achieve fainter detection limits in apparent line flux than SPHERE/ZIMPOL by a factor of ~5. MUSE has some instrumental issues that limit the contrast that appear in cases with strong point sources, which can be either a spatial point source due to high Strehl observations or a spectral point source due to a high line-to-continuum ratio. We modified the HRSDI technique to better handle the instrumental artifacts and improve the detection limits. To avoid the instrumental effects altogether, we suggest faint young stars with relatively low Hα line-to-continuum ratio to be the most suitable targets for MUSE to search for potential protoplanets.

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New mid-infrared imaging constraints on companions and protoplanetary disks around six young stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039261 ◽

2021 ◽

Vol 648 ◽

pp. A92

Author(s):

D. J. M. Petit dit de la Roche ◽

N. Oberg ◽

M. E. van den Ancker ◽

I. Kamp ◽

R. van Boekel ◽

...

Keyword(s):

Spectral Energy Distribution ◽

Protoplanetary Disks ◽

Occurrence Rate ◽

Spectral Energy ◽

Disk Model ◽

Mid Infrared ◽

Geometrical Properties ◽

Planetary Mass ◽

Upper Limits ◽

Ir Emission

Context. Mid-infrared (mid-IR) imaging traces the sub-micron and micron-sized dust grains in protoplanetary disks and it offers constraints on the geometrical properties of the disks and potential companions, particularly if those companions have circumplanetary disks. Aims. We use the VISIR instrument and its upgrade NEAR on the VLT to take new mid-IR images of five (pre-)transition disks and one circumstellar disk with proposed planets and obtain the deepest resolved mid-IR observations to date in order to put new constraints on the sizes of the emitting regions of the disks and the presence of possible companions. Methods. We derotated and stacked the data to find the disk properties. Where available, we compare the data to PRODIMO (Protoplanetary Disk Model) radiation thermo-chemical models to achieve a deeper understanding of the underlying physical processes within the disks. We applied the circularised point spread function subtraction method to find upper limits on the fluxes of possible companions and model companions with circumplanetary disks. Results. We resolved three of the six disks and calculated position angles, inclinations, and (upper limits to) sizes of emission regions in the disks, improving upper limits on two of the unresolved disks. In all cases the majority of the mid-IR emission comes from small inner disks or the hot inner rims of outer disks. We refined the existing PRODIMO HD 100546 model spectral energy distribution (SED) fit in the mid-IR by increasing the PAH abundance relative to the ISM, adopting coronene as the representative PAH, and increasing the outer cavity radius to 22.3 AU. We produced flux estimates for putative planetary-mass companions and circumplanetary disks, ruling out the presence of planetary-mass companions with L > 0.0028 L⊙ for a > 180 AU in the HD 100546 system. Upper limits of 0.5–30 mJy are obtained at 8–12 μm for potential companions in the different disks. We rule out companions with L > 10−2 L⊙ for a > 60 AU in TW Hydra, a > 110 AU in HD 169142, a > 150 AU in HD 163296, and a > 160 AU in HD 36112. Conclusions. The mid-IR emission comes from the central regions and traces the inner areas of the disks, including inner disks and inner rims of outer disks. Planets with mid-IR luminosities corresponding to a runaway accretion phase can be excluded from the HD 100546, HD 169142, TW Hydra, and HD 36112 systems at separations >1′′. We calculated an upper limit to the occurrence rate of wide-orbit massive planets with circumplanetary disks of 6.2% (68% confidence). Future observations with METIS on the ELT will be able to achieve a factor of 10 better sensitivity with a factor of five better spatial resolution. MIRI on JWST will be able to achieve 250 times better sensitivity. Both will possibly detect the known companions to all six targets.

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Shadowing and multiple rings in the protoplanetary disk of HD 139614

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936509 ◽

2020 ◽

Vol 635 ◽

pp. A121 ◽

Cited By ~ 3

Author(s):

G. A. Muro-Arena ◽

M. Benisty ◽

C. Ginski ◽

C. Dominik ◽

S. Facchini ◽

...

Keyword(s):

Radiative Transfer ◽

Scattered Light ◽

Protoplanetary Disks ◽

Position Angle ◽

Protoplanetary Disk ◽

Disk Model ◽

Outer Disk ◽

Planetary Mass ◽

Azimuthal Asymmetries ◽

Multiple Rings

Context. Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an inclined (sub-)stellar companion embedded in the disk. Aims. We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. Methods. We obtained J- and H-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond ~30 au, a broad shadow spans a range of ~240 deg in position angle, in the east. A bright ring at ~16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at ~34 and ~50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. Results. We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones – or a continuously warped region – to cast this broad shadow on the outer disk. A small misalignment of ~4° between adjacent components can reproduce most of the observed shadow features. Conclusions. Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED.

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Hot sphere detection limits for a dual head coincidence imaging system

IEEE Transactions on Nuclear Science ◽

10.1109/23.819302 ◽

1999 ◽

Vol 46 (6) ◽

pp. 2185-2191 ◽

Cited By ~ 16

Author(s):

R.S. Miyaoka ◽

S.G. Kohlmyer ◽

T.K. Lewellen

Keyword(s):

Imaging System ◽

Detection Limits ◽

Sphere Detection ◽

Coincidence Imaging

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Gas Cavities inside Dust Cavities in Disks Inferred from ALMA Observations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315006444 ◽

2015 ◽

Vol 10 (S314) ◽

pp. 139-142

Author(s):

Nienke van der Marel ◽

Ewine F. van Dishoeck ◽

Simon Bruderer ◽

Paola Pinilla ◽

Tim van Kempen ◽

...

Keyword(s):

Protoplanetary Disks ◽

Gas Emission ◽

Chemical Modeling ◽

Gas Density ◽

Spatially Resolved ◽

Outer Disk ◽

Physical Chemical ◽

Planetary Mass ◽

Dust Distribution ◽

Modeling Code

AbstractProtoplanetary disks with cavities in their dust distribution, also named transitional disks, are expected to be in the middle of active evolution and possibly planet formation. In recent years, millimeter-dust rings observed by ALMA have been suggested to have their origin in dust traps, caused by pressure bumps. One of the ways to generate these is by the presence of planets, which lower the gas density along their orbit and create pressure bumps at the edge. We present spatially resolved ALMA Cycle 0 and Cycle 1 observations of CO and CO isotopologues of several famous transitional disks. Gas is found to be present inside the dust cavities, but at a reduced level compared with the gas surface density profile of the outer disk. The dust and gas emission are quantified using the physical-chemical modeling code DALI. In the majority of these disks we find clear evidence for a drop in gas density of at least a factor of 10 inside the cavity, whereas the dust density drops by at least a factor 1000. The CO isotopologue observations reveal that the gas cavities are significantly smaller than the dust cavities. These gas structures suggest clearing by one or more planetary-mass companions.

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Improving Planet Detection with Disk Modeling: Keck/NIRC2 Imaging of the HD 34282 Single-armed Protoplanetary Disk

The Astrophysical Journal ◽

10.3847/2041-8213/ac3e62 ◽

2022 ◽

Vol 924 (1) ◽

pp. L4

Author(s):

Juan Quiroz ◽

Nicole L. Wallack ◽

Bin Ren ◽

Ruobing Dong ◽

Jerry W. Xuan ◽

...

Keyword(s):

Scattered Light ◽

Flux Ratio ◽

Protoplanetary Disks ◽

Detection Limits ◽

Protoplanetary Disk ◽

Young Stars ◽

Giant Planets ◽

Detection Sensitivity ◽

Planet Detection

Abstract Formed in protoplanetary disks around young stars, giant planets can leave observational features such as spirals and gaps in their natal disks through planet–disk interactions. Although such features can indicate the existence of giant planets, protoplanetary disk signals can overwhelm the innate luminosity of planets. Therefore, in order to image planets that are embedded in disks, it is necessary to remove the contamination from the disks to reveal the planets possibly hiding within their natal environments. We observe and directly model the detected disk in the Keck/NIRC2 vortex coronagraph L′-band observations of the single-armed protoplanetary disk around HD 34282. Despite a nondetection of companions for HD 34282, this direct disk modeling improves planet detection sensitivity by up to a factor of 2 in flux ratio and ∼10 M Jupiter in mass. This suggests that performing disk modeling can improve directly imaged planet detection limits in systems with visible scattered light disks, and can help to better constrain the occurrence rates of self-luminous planets in these systems.

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Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013064x ◽

1992 ◽

Vol 50 (2) ◽

pp. 1202-1203

Author(s):

Gianluigi Botton ◽

Gilles L'espérance

Keyword(s):

Statistical Analysis ◽

Spatial Resolution ◽

Personal Computer ◽

Systematic Study ◽

Present Author ◽

Chemical Elements ◽

Detection Limits ◽

Research Groups ◽

Quantitative Performance ◽

Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

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Analysis of completed commercial semiconductors using EPMA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164970 ◽

1996 ◽

Vol 54 ◽

pp. 502-503

Author(s):

R. Packwood ◽

M.W. Phaneuf ◽

V. Weatherall ◽

I. Bassignana

Keyword(s):

Electron Probe Microanalysis ◽

Electron Probe ◽

Semiconductor Industry ◽

Detection Limits ◽

High Technology ◽

Depth Resolution ◽

Analytical Instruments ◽

Wide Range ◽

Numerous Element ◽

Choice Method

The development of specialized analytical instruments such as the SIMS, XPS, ISS etc., all with truly incredible abilities in certain areas, has given rise to the notion that electron probe microanalysis (EPMA) is an old fashioned and rather inadequate technique, and one that is of little or no use in such high technology fields as the semiconductor industry. Whilst it is true that the microprobe does not possess parts-per-billion sensitivity (ppb) or monolayer depth resolution it is also true that many times these extremes of performance are not essential and that a few tens of parts-per-million (ppm) and a few tens of nanometers depth resolution is all that is required. In fact, the microprobe may well be the second choice method for a wide range of analytical problems and even the method of choice for a few.The literature is replete with remarks that suggest the writer is confusing an SEM-EDXS combination with an instrument such as the Cameca SX-50. Even where this confusion does not exist, the literature discusses microprobe detection limits that are seldom stated to be as low as 100 ppm, whereas there are numerous element combinations for which 10-20 ppm is routinely attainable.

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