Gas temperature structure across transition disk cavities

Leemker, M.; Booth, Alice S.; Dishoeck, E. F. van; Pérez-Sánchez, A. F.; Szulágyi, J.; Bosman, Arthur D.; Bruderer, S.; Facchini, Stefano; Hogerheijde, M. R.; Paneque-Carreño, Teresa; Sturm, J. A.

doi:10.1051/0004-6361/202243229

Cited by 23 publications

(38 citation statements)

References 141 publications

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“…The presence of material along the horseshoe orbit from the ALMA data presented here would prefer the lower-planet-mass scenario. As a higher-mass planet would more effectively prevent gas flowing through the cavity, this low-mass scenario is also more consistent with the presence of substantial amounts of molecular gas in the inner LkCa 15 disk (Leemker et al 2022). Nevertheless, this B42 planet may not be sufficient to fully account for both the wide inner cavity and the B101 ring further out, where additional planets and/or other mechanisms might act in concert to shape the LkCa 15 disk.…”

Section: Discussionmentioning

confidence: 53%

ALMA Detection of Dust Trapping around Lagrangian Points in the LkCa 15 Disk

Long

Andrews

Zhang

et al. 2022

ApJL

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We present deep high-resolution (∼50 mas, 8 au) Atacama Large Millimeter/submillimeter Array (ALMA) 0.88 and 1.3 mm continuum observations of the LkCa 15 disk. The emission morphology shows an inner cavity and three dust rings at both wavelengths, but with slightly narrower rings at the longer wavelength. Along a faint ring at 42 au, we identify two excess emission features at ∼10σ significance at both wavelengths: one as an unresolved clump and the other as an extended arc, separated by roughly 120° in azimuth. The clump is unlikely to be a circumplanetary disk (CPD) as the emission peak shifts between the two wavelengths even after accounting for orbital motion. Instead, the morphology of the 42 au ring strongly resembles the characteristic horseshoe orbit produced in planet–disk interaction models, where the clump and the arc trace dust accumulation around Lagrangian points L 4 and L 5, respectively. The shape of the 42 au ring, dust trapping in the outer adjacent ring, and the coincidence of the horseshoe ring location with a gap in near-IR scattered light, are all consistent with the scenario of planet sculpting, with the planet likely having a mass between those of Neptune and Saturn. We do not detect pointlike emission associated with a CPD around the putative planet location (0.″27 in projected separation from the central star at a position angle of ∼60°), with upper limits of 70 and 33 μJy at 0.88 and 1.3 mm, respectively, corresponding to dust mass upper limits of 0.02–0.03 M ⊕.

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Section: Discussionmentioning

confidence: 53%

ALMA Detection of Dust Trapping around Lagrangian Points in the LkCa 15 Disk

Long

Andrews

Zhang

et al. 2022

ApJL

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“…This was done by following the maxima of emission along the upper layer in channels where it is possible to identify the far and near sides of the upper layer (for a detailed sketch see Figures 2 and 3 of Pinte et al 2018). This method was used for the extraction of the C 18 O and 13 CO vertical emitting layer in Elias 2-27 (Paneque-Carreño et al 2021) and in various works, for other sources and/or CO isotopologs (e.g., Law et al 2021a;Rich et al 2021;Leemker et al 2022).…”

Section: Height Of Cn Emissionmentioning

confidence: 99%

Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

Paneque-Carreño

Miotello

Dishoeck

et al. 2022

A&A

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Context. Cyanide (CN) emission is expected to originate in the upper layers of protoplanetary disks, tracing UV-irradiated regions. This hypothesis, however, has been observationally tested only in a handful of disks. Elias 2-27 is a young star that hosts an extended, bright, and inclined disk of dust and gas. The inclination and extreme flaring of the disk make Elias 2-27 an ideal target to study the vertical distribution of molecules, particularly CN. Aims. Our aim is to directly trace the emission of CN in the disk around Elias 2-27 and compare it to previously published CO isotopolog data of the system. The two tracers can be combined and used to constrain the physical and chemical properties of the disk. Through this analysis we can test model predictions of CN emission and compare observations of CN in other objects to the massive, highly flared, asymmetric, and likely gravitationally unstable protoplanetary disk around Elias 2-27. Methods. We analyzed CN N = 3 − 2 emission in two different transitions J = 7/2 − 5/2 and J = 5/2 − 3/2, for which we detect two hyperfine group transitions. The vertical location of CN emission was traced directly from the channel maps, following geometrical methods that had been previously used to analyze the CO emission of Elias 2-27. Simple analytical models were used to parameterize the vertical profile of each molecule and study the extent of each tracer. From the radial intensity profiles we computed radial profiles of column density and optical depth. Results. We show that the vertical location of CN and CO isotopologs in Elias 2-27 is layered and consistent with predictions from thermochemical models. A north-south asymmetry in the radial extent of the CN emission is detected, which is likely due to shadowing on the north side of the disk. Combining the information from the peak brightness temperature and vertical structure radial profiles, we find that the CN emission is mostly optically thin and constrained vertically to a thin slab at z/r ∼0.5. A column density of 10 14 cm −2 is measured in the inner disk, which for the north side decreases to 10 12 cm −2 and for the south side to 10 13 cm −2 in the outer regions. Conclusions. In Elias 2-27, CN traces a vertically elevated region above the midplane, very similar to that traced by 12 CO. The inferred CN column densities, low optical depth (τ ≤1), and location near the disk surface are consistent with thermo-chemical disk models in which CN formation is initiated by the reaction of N with UV-pumped H 2 . The observed north-south asymmetry may be caused by either ongoing infall or by a warped inner disk. This study highlights the importance of tracing the vertical location of various molecules to constrain the disk physical conditions.

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“…By masking the channels after visual inspection, we reach locations of lower SNR and avoid contamination from the lower surface, obtaining a more accurate description of the vertical profile. Our implementation has been tested and illustrated in previous works (Paneque-Carreño et al 2021;Leemker et al 2022) and in this analysis we also compare it to the results of Law et al (2021b) using DISKSURF (See Appendix B). Our results are consistent for bright tracers such as 12 CO and 13 CO, particularly in the inner region (<200 au), however, through our methodology we are able to trace a larger inventory of molecules to further radii.…”

Section: Vertical Profile Extractionmentioning

confidence: 99%

“…where R c is the characteristic radius and γ the surface density exponent. The vertical structure of the disk follows a Gaussian distribution, which we have modified from the typical DALI prescription (see for example Leemker et al 2022) to match the prescription of Zhang et al (2021). The scale height angle (h) is set at each radius following,…”

Section: Appendix C3: Dali Models Setupmentioning

confidence: 99%

“…Of the handful of moderately inclined systems with direct extraction of their vertical surfaces, the vast majority have been analyzed using only CO isotopologue emission (Pinte et al 2018a;Paneque-Carreño et al 2021;Rich et al 2021;Law et al 2021b;Leemker et al 2022;Law et al 2022). The exceptions are AS 209, HD163296 and MWC 480 where the vertical location of HCN and C 2 H emission was constrained in the inner ∼150 au (Law et al 2021b).…”

Section: Introductionmentioning

confidence: 99%

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Directly tracing the vertical stratification of molecules in protoplanetary disks

Paneque-Carreño¹,

Miotello²,

Dishoeck³

et al. 2022

Preprint

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Context. The specific location from where molecules emit in a protoplanetary disk depends on the system properties. Therefore, directly constraining the emitting regions radially, azimuthally and vertically is key towards studying the environment of planet formation. Due to the difficulties and lack of high resolution observations, most of the current observational constraints for the vertical distribution of molecular emission rely on indirect methods. Aims. We aim to directly trace the vertical location of the emitting surface of multiple molecular tracers in protoplanetary disks. Our sample of disks includes Elias 2-27, WaOph 6 and the sources targeted by the MAPS ALMA Large Program. The set of molecules studied include CO isotopologues in various transitions, HCN, CN, H 2 CO, HCO + , C 2 H and c-C 3 H 2 . Methods. The vertical emitting region is determined directly from the channel maps using the geometrical method described in Pinte et al. (2018a). This method has been used in previous studies, however we implement an accurate masking of the channel emission in order to recover the vertical location of the emission surface even at large radial distances from the star and for low-SNR lines. Parametric models are used to describe the emission surfaces and characterize any structure within the vertical profile.Results. The vertical location of the emitting layer is obtained for 10 different molecules and transitions in HD 163296. In the rest of the sample it is possible to vertically locate between 4-7 lines. Brightness temperature profiles are obtained for the entire sample and for all CO isotopologues. IM Lup, HD163296 and MWC 480 12 CO and 13 CO show vertical modulations, which are characterized and found to be coincident with dust gaps and kinematical perturbations. We also present estimates of the gas pressure scale height in the disks from the MAPS sample. Compared to physical-chemical models we find good agreement with the vertical location of CO isotopologues. In HD 163296 CN and HCN trace a similar intermediate layer, which is expected from physical chemical models. For the other disks, we find that UV flux tracers and the vertical profiles of HCN and C 2 H are lower than predicted in theoretical models. HCN and H 2 CO show a highly structured vertical profile, possibly indicative of different formation pathways in the case of H 2 CO. Conclusions. It is possible to trace the vertical locations of multiple molecular species that trace a wide variety of physical and chemical disk properties. The distribution of CO isotopologues is in agreement with theoretical predictions and the emission is found at a wide range of vertical heights z/r = 0.5-0.05. The vertical location of CO may be inversely related to the stellar mass. Other molecular lines are mostly found at z/r ≤0.15. The vertical layering of molecules is in agreement with theoretical predictions in some systems, but not in all, therefore dedicated chemical-physical models are needed to further study and understand the diversity of the emission surf...

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Gas temperature structure across transition disk cavities

Cited by 23 publications

References 141 publications

ALMA Detection of Dust Trapping around Lagrangian Points in the LkCa 15 Disk

ALMA Detection of Dust Trapping around Lagrangian Points in the LkCa 15 Disk

Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

Directly tracing the vertical stratification of molecules in protoplanetary disks

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