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The TW Hya Rosetta Stone Project. III. Resolving the Gaseous Thermal Profile of the DiskCalahan, Jenny K.Bergin, EdwinZhang, KeTeague, RichardCleeves, IlsedoreBergner, JenniferBlake, Geoffrey A.Cazzoletti, PaoloGuzmán, VivianaHogerheijde, Michiel R.Huang, JaneKama, MihkelLoomis, RyanÖberg, KarinQi, Charlievan Dishoeck, Ewine F.Terwisscha van Scheltinga, JeroenWalsh, CatherineWilner, DavidDOI: info:10.3847/1538-4357/abd255v. 9088
Calahan, Jenny K., Bergin, Edwin, Zhang, Ke, Teague, Richard, Cleeves, Ilsedore, Bergner, Jennifer, Blake, Geoffrey A., Cazzoletti, Paolo, Guzmán, Viviana, Hogerheijde, Michiel R., Huang, Jane, Kama, Mihkel, Loomis, Ryan, Öberg, Karin, Qi, Charlie, van Dishoeck, Ewine F., Terwisscha van Scheltinga, Jeroen, Walsh, Catherine, and Wilner, David. 2021. "The TW Hya Rosetta Stone Project. III. Resolving the Gaseous Thermal Profile of the Disk." The Astrophysical Journal 908:8. https://doi.org/10.3847/1538-4357/abd255
ID: 159280
Type: article
Authors: Calahan, Jenny K.; Bergin, Edwin; Zhang, Ke; Teague, Richard; Cleeves, Ilsedore; Bergner, Jennifer; Blake, Geoffrey A.; Cazzoletti, Paolo; Guzmán, Viviana; Hogerheijde, Michiel R.; Huang, Jane; Kama, Mihkel; Loomis, Ryan; Öberg, Karin; Qi, Charlie; van Dishoeck, Ewine F.; Terwisscha van Scheltinga, Jeroen; Walsh, Catherine; Wilner, David
Abstract: The thermal structure of protoplanetary disks is a fundamental characteristic of the system that has wide-reaching effects on disk evolution and planet formation. In this study, we constrain the 2D thermal structure of the protoplanetary disk TW Hya structure utilizing images of seven CO lines. This includes new ALMA observations of 12CO J = 2-1 and C18O J = 2-1 as well as archival ALMA observations of 12CO J = 3-2, 13CO J = 3-2 and 6-5, and C18O J = 3-2 and 6-5. Additionally, we reproduce a Herschel observation of the HD J = 1-0 line flux and the spectral energy distribution and utilize a recent quantification of CO radial depletion in TW Hya. These observations were modeled using the thermochemical code RAC2D, and our best-fit model reproduces all spatially resolved CO surface brightness profiles. The resulting thermal profile finds a disk mass of 0.025 M and a thin upper layer of gas depleted of small dust with a thickness of ∼1.2% of the corresponding radius. Using our final thermal structure, we find that CO alone is not a viable mass tracer, as its abundance is degenerate with the total H2 surface density. Different mass models can readily match the spatially resolved CO line profiles with disparate abundance assumptions. Mass determination requires additional knowledge, and, in this work, HD provides the additional constraint to derive the gas mass and support the inference of CO depletion in the TW Hya disk. Our final thermal structure confirms the use of HD as a powerful probe of protoplanetary disk mass. Additionally, the method laid out in this paper is an employable strategy for extraction of disk temperatures and masses in the future.
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). V. Sample, overview, and demography of disk molecular emissionGarufi, A.Podio, L.Codella, C.Fedele, D.Bianchi, E.Favre, C.Bacciotti, F.Ceccarelli, C.Mercimek, S.Rygl, K.Teague, RichardTesti, L.DOI: info:10.1051/0004-6361/202039483v. 645A145
Garufi, A., Podio, L., Codella, C., Fedele, D., Bianchi, E., Favre, C., Bacciotti, F., Ceccarelli, C., Mercimek, S., Rygl, K., Teague, Richard, and Testi, L. 2021. "ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). V. Sample, overview, and demography of disk molecular emission." Astronomy and Astrophysics 645:A145. https://doi.org/10.1051/0004-6361/202039483
ID: 159565
Type: article
Authors: Garufi, A.; Podio, L.; Codella, C.; Fedele, D.; Bianchi, E.; Favre, C.; Bacciotti, F.; Ceccarelli, C.; Mercimek, S.; Rygl, K.; Teague, Richard; Testi, L.
Abstract: We present an overview of the ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT), a campaign devoted to the characterization of the molecular emission from partly embedded young stars. The project is aimed at attaining a better understanding of the gaseous products delivered to planets by means of high-resolution maps of the assorted lines probing disks at the time of planet formation (≲1 Myr). Nine different molecules are surveyed through our observations of six Class I/flat-spectrum sources. As part of a series of articles analyzing specific targets and molecules, in this work we describe the sample and provide a general overview of the results, focusing specifically on the spatial distribution, column densities, and abundance ratios of H2CO, CS, and CN. In these embedded sources, the 12CO emission is dominated by envelope and outflow emission while the CS and, especially, the H2CO are good tracers of the gaseous disk structure. The spatial distribution and brightness of the o-H2CO 31,2-21,1 and CS 5-4 lines are very similar to each other and across all targets. The CN 2-1 line emission is fainter and distributed over radii larger than the dust continuum. The H2CO and CS emission is always dimmed in the inner ~50 au. While the suppression by the dusty disk and absorption by the line-of-sight material significantly contributes to this inner depression, an actual decrease in the column density is plausible in most cases, making the observed ring-like morphology realistic. We also found that the gaseous disk extent, when traced by H2CO (150-390 au), is always 60% larger than the dust disk. This systematic discrepancy may, in principle, be explained by the different optical depth of continuum and line emission without invoking any dust radial drift. Finally, the o-H2CS 71,6-61,5 and CH3OH 50,5-40,4 line emission are detected in two disks and one disk, respectively, while the HDO is never detected. The H2CO column densities are 12-50 times larger than those inferred for Class II sources while they are in line with those of other Class 0/I. The CS column densities are lower than those of H2CO, which is an opposite trend with regard to Class II objects. We also inferred abundance ratios between the various molecular species finding, among others, a H2CS/H2CO ratio that is systematically lower than unity (0.4-0.7 in HL Tau, 0.1 - 0.2 in IRAS 04302+2247, and CO ratio that is systematically lower than unity (0.4-0.7 in HL Tau, 0.1 - 0.2 in IRAS 04302+2247, and 3OH/H2CO ratio (<0.7 in HL Tau and 0.5-0.7 in IRAS 04302+2247) that is lower than the only available estimate in a protoplanetary disks (1.3 in TW Hya) and between one and two orders of magnitude lower than those of the hot corinos around Class 0 protostars. These results are a first step toward the characterization of the disk's chemical evolution, which ought to be complemented by subsequent observations of less exceptional disks and customized thermo-chemical modeling.
ALMA CN Zeeman Observations of AS 209: Limits on Magnetic Field Strength and Magnetically Driven Accretion RateHarrison, Rachel E.Looney, Leslie W.Stephens, Ian W.Li, Zhi-YunTeague, RichardCrutcher, Richard M.Yang, HaifengCox, Erin G.Fernández-López, ManuelShinnaga, HirokoDOI: info:10.3847/1538-4357/abd94ev. 908141
Harrison, Rachel E., Looney, Leslie W., Stephens, Ian W., Li, Zhi-Yun, Teague, Richard, Crutcher, Richard M., Yang, Haifeng, Cox, Erin G., Fernández-López, Manuel, and Shinnaga, Hiroko. 2021. "ALMA CN Zeeman Observations of AS 209: Limits on Magnetic Field Strength and Magnetically Driven Accretion Rate." The Astrophysical Journal 908:141. https://doi.org/10.3847/1538-4357/abd94e
ID: 159621
Type: article
Authors: Harrison, Rachel E.; Looney, Leslie W.; Stephens, Ian W.; Li, Zhi-Yun; Teague, Richard; Crutcher, Richard M.; Yang, Haifeng; Cox, Erin G.; Fernández-López, Manuel; Shinnaga, Hiroko
Abstract: While magnetic fields likely play an important role in driving the evolution of protoplanetary disks through angular momentum transport, observational evidence of magnetic fields has only been found in a small number of disks. Although dust continuum linear polarization has been detected in an increasing number of disks, its pattern is more consistent with that from dust scattering than from magnetically aligned grains in the vast majority of cases. Continuum linear polarization from dust grains aligned to a magnetic field can reveal information about the magnetic field's direction, but not its strength. On the other hand, observations of circular polarization in molecular lines produced by Zeeman splitting offer a direct measure of the line-of-sight magnetic field strength in disks. We present upper limits on the net toroidal and vertical magnetic field strengths in the protoplanetary disk AS 209 derived from Zeeman splitting observations of the CN 2-1 line. The 3σ upper limit on the net line-of-sight magnetic field strength in AS 209 is 5.0 mG on the redshifted side of the disk and 4.2 mG on the blueshifted side of the disk. Given the disk's inclination angle, we set a 3σ upper limit on the net toroidal magnetic field strength of 8.7 and 7.3 mG for the red and blue sides of the disk, respectively, and 6.2 and 5.2 mG on the net vertical magnetic field on the red and blue sides of the disk. If magnetic disk winds are a significant mechanism of angular momentum transport in the disk, magnetic fields of a strength close to the upper limits would be sufficient to drive accretion at the rate previously inferred for regions near the protostar.
Dynamical Masses and Stellar Evolutionary Model Predictions of M StarsPegues, JamilaCzekala, IanAndrews, Sean M.Öberg, Karin I.Herczeg, Gregory J.Bergner, Jennifer B.Ilsedore Cleeves, L.Guzmán, Viviana V.Huang, JaneLong, FengTeague, RichardWilner, David J.DOI: info:10.3847/1538-4357/abd4ebv. 90842
Pegues, Jamila, Czekala, Ian, Andrews, Sean M., Öberg, Karin I., Herczeg, Gregory J., Bergner, Jennifer B., Ilsedore Cleeves, L., Guzmán, Viviana V., Huang, Jane, Long, Feng, Teague, Richard, and Wilner, David J. 2021. "Dynamical Masses and Stellar Evolutionary Model Predictions of M Stars." The Astrophysical Journal 908:42. https://doi.org/10.3847/1538-4357/abd4eb
ID: 159623
Type: article
Authors: Pegues, Jamila; Czekala, Ian; Andrews, Sean M.; Öberg, Karin I.; Herczeg, Gregory J.; Bergner, Jennifer B.; Ilsedore Cleeves, L.; Guzmán, Viviana V.; Huang, Jane; Long, Feng; Teague, Richard; Wilner, David J.
Abstract: In this era of Gaia and ALMA, dynamical stellar mass measurements, derived from spatially and spectrally resolved observations of the Keplerian rotation of circumstellar disks, provide benchmarks that are independent of observations of stellar characteristics and their uncertainties. These benchmarks can then be used to validate and improve stellar evolutionary models, the latter of which can lead to both imprecise and inaccurate mass predictions for pre-main-sequence, low-mass (≤0.5 M) stars. We present the dynamical stellar masses derived from disks around three M stars (FP Tau, J0432+1827, and J1100-7619) using ALMA observations of 12CO (J = 2-1) and 13CO (J = 2-1) emission. These are the first dynamical stellar mass measurements for J0432+1827 and J1100-7619 (0.192 ± 0.005 M and 0.461 ± 0.057 M, respectively) and the most precise measurement for FP Tau (0.395 ± 0.012 M). Fiducial stellar evolutionary model tracks, which do not include any treatment of magnetic activity, agree with the dynamical stellar mass measurement of J0432+1827 but underpredict the mass by ∼60% for FP Tau and by ∼80% for J1100-7619. Possible explanations for the underpredictions include inaccurate assumptions of stellar effective temperature, undetected binarity for J1100-7619, and that fiducial stellar evolutionary models are not complex enough to represent these stars. In the former case, the stellar effective temperatures would need to be increased by amounts ranging from ∼40 to ∼340 K to reconcile the fiducial stellar evolutionary model predictions with the dynamically measured masses. In the latter case, we show that the dynamical masses can be reproduced using results from stellar evolutionary models with starspots, which incorporate fractional starspot coverage to represent the manifestation of magnetic activity. Folding in low-mass M stars from the literature and assuming that the stellar effective temperatures are imprecise but accurate, we find tentative evidence of a relationship between fractional starspot coverage and observed effective temperature for these young, cool stars.
A highly non-Keplerian protoplanetary disc Spiral structure in the gas disc of CQ TauWoelfer, L.Facchini, S.Kurtovic, N. T.Teague, Richardvan Dishoeck, E. F.Benisty, M.Ercolano, B.Lodato, G.Miotello, A.Rosotti, G.Testi, L.Gabellini, M. G. UbeiraDOI: info:10.1051/0004-6361/202039469v. 648
Woelfer, L., Facchini, S., Kurtovic, N. T., Teague, Richard, van Dishoeck, E. F., Benisty, M., Ercolano, B., Lodato, G., Miotello, A., Rosotti, G., Testi, L., and Gabellini, M. G. Ubeira. 2021. "A highly non-Keplerian protoplanetary disc Spiral structure in the gas disc of CQ Tau." Astronomy & Astrophysics 648:https://doi.org/10.1051/0004-6361/202039469
ID: 159538
Type: article
Authors: Woelfer, L.; Facchini, S.; Kurtovic, N. T.; Teague, Richard; van Dishoeck, E. F.; Benisty, M.; Ercolano, B.; Lodato, G.; Miotello, A.; Rosotti, G.; Testi, L.; Gabellini, M. G. Ubeira
Abstract: Context. In recent years high-angular-resolution observations have revealed that circumstellar discs appear in a variety of shapes with diverse substructures being ubiquitous. This has given rise to the question of whether these substructures are triggered by planet-disc interactions. Besides direct imaging, one of the most promising methods to distinguish between different disc-shaping mechanisms is to study the kinematics of the gas disc. In particular, the deviations of the rotation profile from Keplerian velocity can be used to probe perturbations in the gas pressure profile that may be caused by embedded (proto-) planets. Aims. In this paper we aim to analyse the gas brightness temperature and kinematics of the transitional disc around the intermediate-mass star CQ Tau in order to resolve and characterise substructure in the gas caused by possible perturbers. Methods. For our analysis we used spatially resolved ALMA observations of the three CO isotopologues (CO)-C-12, (CO)-C-13, and (CO)-O-18 (J = 2-1) from the disc around CQ Tau. We further extracted robust line centroids for each channel map and fitted a number of Keplerian disc models to the velocity field. Results. The gas kinematics of the CQ Tau disc present non-Keplerian features, showing bent and twisted iso-velocity curves in (CO)-C-12 and (CO)-C-13. Significant spiral structures are detected between similar to 10 and 180 au in both the brightness temperature and the rotation velocity of (CO)-C-12 after subtraction of an azimuthally symmetric model, which may be tracing planet-disc interactions with an embedded planet or low-mass companion. We identify three spirals, two in the brightness temperature and one in the velocity residuals, spanning a large azimuth and radial extent. The brightness temperature spirals are morphologically connected to spirals observed in near-infrared scattered light in the same disc, indicating a common origin. Together with the observed large dust and gas cavity, these spiral structures support the hypothesis of a massive embedded companion in the CQ Tau disc.
Chemical Evolution in a Protoplanetary Disk within Planet Carved Gaps and Dust RingsAlarcón, FelipeTeague, Richard D.Zhang, KeBergin, E. A.Barraza-Alfaro, M.DOI: info:10.3847/1538-4357/abc1d6v. 90568
Alarcón, Felipe, Teague, Richard D., Zhang, Ke, Bergin, E. A., and Barraza-Alfaro, M. 2020. "Chemical Evolution in a Protoplanetary Disk within Planet Carved Gaps and Dust Rings." The Astrophysical Journal 905:68. https://doi.org/10.3847/1538-4357/abc1d6
ID: 158631
Type: article
Authors: Alarcón, Felipe; Teague, Richard D.; Zhang, Ke; Bergin, E. A.; Barraza-Alfaro, M.
Abstract: Recent surveys of protoplanetary disks show that substructure in dust thermal continuum emission maps is common in protoplanetary disks. These substructures, most prominently rings and gaps, shape and change the chemical and physical conditions of the disk, along with the dust size distributions. In this work, we use a thermochemical code to focus on the chemical evolution that is occurring within the gas-depleted gap and the dust-rich ring often observed behind it. The compositions of these spatial locations are of great import, as the gas and ice-coated grains will end up being part of the atmospheres of gas giants and/or the seeds of rocky planets. Our models show that the dust temperature at the midplane of the gap increases, enough to produce local sublimation of key volatiles and pushing the molecular layer closer to the midplane, while it decreases in the dust-rich ring, causing a higher volatile deposition onto the dust grain surfaces. Further, the ring itself presents a freeze-out trap for volatiles in local flows powered by forming planets, becoming a site of localized volatile enhancement. Within the gas-depleted gap, the line emission depends on several different parameters, such as the depth of the gap in surface density, the location of the dust substructure, and the abundance of common gas tracers, such as CO. In order to break this uncertainty between abundance and surface density, other methods, such as disk kinematics, become necessary to constrain the disk structure and its chemical evolution.
Annular substructures in the transition disks around LkCa 15 and J1610Facchini, S.Benisty, M.Bae, J.Loomis, R.Perez, L.Ansdell, M.Mayama, S.Pinilla, P.Teague, RichardIsella, A.Mann, A.DOI: info:10.1051/0004-6361/202038027v. 639A121
Facchini, S., Benisty, M., Bae, J., Loomis, R., Perez, L., Ansdell, M., Mayama, S., Pinilla, P., Teague, Richard, Isella, A., and Mann, A. 2020. "Annular substructures in the transition disks around LkCa 15 and J1610." Astronomy and Astrophysics 639:A121. https://doi.org/10.1051/0004-6361/202038027
ID: 157486
Type: article
Authors: Facchini, S.; Benisty, M.; Bae, J.; Loomis, R.; Perez, L.; Ansdell, M.; Mayama, S.; Pinilla, P.; Teague, Richard; Isella, A.; Mann, A.
Abstract: We present high-resolution millimeter continuum ALMA observations of the disks around the T Tauri stars LkCa 15 and 2MASS J16100501-2132318 (hereafter, J1610). These transition disks host dust-depleted inner regions, which have possibly been carved by massive planets, and they are of prime interest to the study of the imprints of planet-disk interactions. While at moderate angular resolution, they appear as a broad ring surrounding a cavity, the continuum emission resolves into multiple rings at a resolution of ~60 × 40 mas (~7.5 au for LkCa 15, ~6 au for J1610) and ~7 μJy beam-1 rms at 1.3 mm. In addition to a broad extended component, LkCa 15 and J1610 host three and two narrow rings, respectively, with two bright rings in LkCa 15 being radially resolved. LkCa 15 possibly hosts another faint ring close to the outer edge of the mm emission. The rings look marginally optically thick, with peak optical depths of ~0.5 (neglecting scattering), in agreement with high angular resolution observations of full disks. We performed hydrodynamical simulations with an embedded, sub-Jovian-mass planet and show that the observed multi-ringed substructure can be qualitatively explained as the outcome of the planet-disk interaction. We note, however, that the choice of the disk cooling timescale alone can significantly impact the resulting gas and dust distributions around the planet, leading to different numbers of rings and gaps and different spacings between them. We propose that the massive outer disk regions of transition disks are favorable places for planetesimals, and possibly second-generation planet formation of objects with a lower mass than the planets carving the inner cavity (typically few MJup), and that the annular substructures observed in LkCa 15 and J1610 may be indicative of planetary core formation within dust-rich pressure traps. Current observations are compatible with other mechanisms contributing to the origin of the observed substructures, in particular with regard to narrow rings generated (or facilitated) at the edge of the CO and N2 snowlines.
The reduced images are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/639/A121
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). I. CO, CS, CN, and H2CO around DG Tau BGarufi, A.Podio, L.Codella, C.Rygl, K.Bacciotti, F.Facchini, S.Fedele, D.Miotello, A.Teague, RichardTesti, L.DOI: info:10.1051/0004-6361/201937247v. 636A65
Garufi, A., Podio, L., Codella, C., Rygl, K., Bacciotti, F., Facchini, S., Fedele, D., Miotello, A., Teague, Richard, and Testi, L. 2020. "ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). I. CO, CS, CN, and H2CO around DG Tau B." Astronomy and Astrophysics 636:A65. https://doi.org/10.1051/0004-6361/201937247
ID: 157116
Type: article
Authors: Garufi, A.; Podio, L.; Codella, C.; Rygl, K.; Bacciotti, F.; Facchini, S.; Fedele, D.; Miotello, A.; Teague, Richard; Testi, L.
Abstract: The chemical composition of planets is determined by the distribution of the various molecular species in the protoplanetary disk at the time of their formation. To date, only a handful of disks have been imaged in multiple spectral lines with high spatial resolution. As part of a small campaign devoted to the chemical characterization of disk-outflow sources in Taurus, we report on new ALMA Band 6 (~1.3 mm) observations with ~0.15'' (20 au) resolution toward the embedded young star DG Tau B. Images of the continuum emission reveals a dust disk with rings and, putatively, a leading spiral arm. The disk, as well as the prominent outflow cavities, are detected in CO, H2CO, CS, and CN; instead, they remain undetected in SO2, HDO, and CH3OH. From the absorption of the back-side outflow, we inferred that the disk emission is optically thick in the inner 50 au. This morphology explains why no line emission is detected from this inner region and poses some limitations toward the calculation of the dust mass and the characterization of the inner gaseous disk. The H2CO and CS emission from the inner 200 au is mostly from the disk, and their morphology is very similar. The CN emission significantly differs from the other two molecules as it is observed only beyond 150 au. This ring-like morphology is consistent with previous observations and the predictions of thermochemical disk models. Finally, we constrained the disk-integrated column density of all molecules. In particular, we found that the CH3OH/H2CO ratio must be smaller than ~2, making the methanol non-detection still consistent with the only such ratio available from the literature (1.27 in TW Hya).
The reduced datacubes are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz- bin/cat/J/A+A/636/A65
Predicting the Kinematic Evidence of Gravitational InstabilityHall, C.Dong, R.Teague, Richard D.Terry, J.Pinte, C.Paneque-Carreño, T.Veronesi, B.Alexander, R. D.Lodato, G.DOI: info:10.3847/1538-4357/abac17v. 904148
Hall, C., Dong, R., Teague, Richard D., Terry, J., Pinte, C., Paneque-Carreño, T., Veronesi, B., Alexander, R. D., and Lodato, G. 2020. "Predicting the Kinematic Evidence of Gravitational Instability." The Astrophysical Journal 904:148. https://doi.org/10.3847/1538-4357/abac17
ID: 158630
Type: article
Authors: Hall, C.; Dong, R.; Teague, Richard D.; Terry, J.; Pinte, C.; Paneque-Carreño, T.; Veronesi, B.; Alexander, R. D.; Lodato, G.
Abstract: Observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) have dramatically improved our understanding of the site of exoplanet formation: protoplanetary disks. However, many basic properties of these disks are not well understood. The most fundamental of these is the total disk mass, which sets the mass budget for planet formation. Disks with sufficiently high masses can excite gravitational instability and drive spiral arms that are detectable with ALMA. Although spirals have been detected in ALMA observations of the dust, their association with gravitational instability, and high disk masses, is far from clear. Here we report a prediction for kinematic evidence of gravitational instability. Using hydrodynamics simulations coupled with radiative transfer calculations, we show that a disk undergoing such instability has clear kinematic signatures in molecular line observations across the entire disk azimuth and radius, which are independent of viewing angle. If these signatures are detected, it will provide the clearest evidence for the occurrence of gravitational instability in planet-forming disks, and provide a crucial way to measure disk masses.
A Multifrequency ALMA Characterization of Substructures in the GM Aur Protoplanetary DiskHuang, JaneAndrews, Sean M.Dullemond, Cornelis P.Öberg, Karin I.Qi, ChunhuaZhu, ZhaohuanBirnstiel, TilmanCarpenter, John M.Isella, AndreaMacías, EnriqueMcClure, Melissa K.Pérez, Laura M.Teague, RichardWilner, David J.Zhang, ShangjiaDOI: info:10.3847/1538-4357/ab711ev. 89148
Huang, Jane, Andrews, Sean M., Dullemond, Cornelis P., Öberg, Karin I., Qi, Chunhua, Zhu, Zhaohuan, Birnstiel, Tilman, Carpenter, John M., Isella, Andrea, Macías, Enrique, McClure, Melissa K., Pérez, Laura M., Teague, Richard, Wilner, David J., and Zhang, Shangjia. 2020. "A Multifrequency ALMA Characterization of Substructures in the GM Aur Protoplanetary Disk." The Astrophysical Journal 891:48. https://doi.org/10.3847/1538-4357/ab711e
ID: 156375
Type: article
Authors: Huang, Jane; Andrews, Sean M.; Dullemond, Cornelis P.; Öberg, Karin I.; Qi, Chunhua; Zhu, Zhaohuan; Birnstiel, Tilman; Carpenter, John M.; Isella, Andrea; Macías, Enrique; McClure, Melissa K.; Pérez, Laura M.; Teague, Richard; Wilner, David J.; Zhang, Shangjia
Abstract: The protoplanetary disk around the T Tauri star GM Aur was one of the first hypothesized to be in the midst of being cleared out by a forming planet. As a result, GM Aur has had an outsized influence on our understanding of disk structure and evolution. We present 1.1 and 2.1 mm ALMA continuum observations of the GM Aur disk at a resolution of ∼50 mas (∼8 au), as well as HCO+ J = 3 - 2 observations at a resolution of ∼100 mas. The dust continuum shows at least three rings atop faint, extended emission. Unresolved emission is detected at the center of the disk cavity at both wavelengths, likely due to a combination of dust and free-free emission. Compared to the 1.1 mm image, the 2.1 mm image shows a more pronounced "shoulder" near R ∼ 40 au, highlighting the utility of longer-wavelength observations for characterizing disk substructures. The spectral index α features strong radial variations, with minima near the emission peaks and maxima near the gaps. While low spectral indices have often been ascribed to grain growth and dust trapping, the optical depth of GM Aur's inner two emission rings renders their dust properties ambiguous. The gaps and outer disk (R > 100 au) are optically thin at both wavelengths. Meanwhile, the HCO+ emission indicates that the gas cavity is more compact than the dust cavity traced by the millimeter continuum, similar to other disks traditionally classified as "transitional."
Hints of a Population of Solar System Analog Planets from ALMALong, Deryl E.Zhang, KeTeague, RichardBergin, Edwin A.DOI: info:10.3847/2041-8213/ab94a8v. 895L46
Long, Deryl E., Zhang, Ke, Teague, Richard, and Bergin, Edwin A. 2020. "Hints of a Population of Solar System Analog Planets from ALMA." The Astrophysical Journal 895:L46. https://doi.org/10.3847/2041-8213/ab94a8
ID: 157485
Type: article
Authors: Long, Deryl E.; Zhang, Ke; Teague, Richard; Bergin, Edwin A.
Abstract: The recent Atacama Large Millimeter/submillimeter Array (ALMA) Disk Substructures at High Angular Resolution Project (DSHARP) survey provided illuminating results on the diversity of substructures in planet-forming disks. These substructures trace pebble-sized grains accumulated at local pressure maxima, possibly due to planet-disk interactions or other planet formation processes. DSHARP sources are heavily biased to large and massive disks that only represent the high (dust flux) tail end of the disk population. Thus it is unclear whether similar substructures and corresponding physical processes also occur in the majority of disks that are fainter and more compact. Here we explore the presence and characteristics of features in a compact disk around GQ Lup A, the effective radius of which is 1.5-10 times smaller than those of DSHARP disks. We present our analysis of ALMA 1.3 mm continuum observations of the GQ Lup system. By fitting visibility profiles of the continuum emission, we find substructures including a gap at ∼10 au. The compact disk around GQ Lup exhibits similar substructures to those in the DSHARP sample, suggesting that mechanisms of trapping pebble-sized grains are at work in small disks as well. Characteristics of the feature at ∼10 au, if due to a hidden planet, are evidence of planet formation at Saturnian distances. Our results hint at a rich world of substructures to be identified within the common population of compact disks, and subsequently a population of solar system analogs within these disks. Such study is critical to understanding the formation mechanisms and planet populations in the majority of protoplanetary disks.
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). III. The interplay between gas and dust in the protoplanetary disk of DG TauPodio, L.Garufi, A.Codella, C.Fedele, D.Rygl, K.Favre, C.Bacciotti, F.Bianchi, E.Ceccarelli, C.Mercimek, S.Teague, Richard D.Testi, L.DOI: info:10.1051/0004-6361/202038600v. 644A119
Podio, L., Garufi, A., Codella, C., Fedele, D., Rygl, K., Favre, C., Bacciotti, F., Bianchi, E., Ceccarelli, C., Mercimek, S., Teague, Richard D., and Testi, L. 2020. "ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). III. The interplay between gas and dust in the protoplanetary disk of DG Tau." Astronomy and Astrophysics 644:A119. https://doi.org/10.1051/0004-6361/202038600
ID: 158629
Type: article
Authors: Podio, L.; Garufi, A.; Codella, C.; Fedele, D.; Rygl, K.; Favre, C.; Bacciotti, F.; Bianchi, E.; Ceccarelli, C.; Mercimek, S.; Teague, Richard D.; Testi, L.
Abstract: Context. Planets form in protoplanetary disks and inherit their chemical composition. It is therefore crucial to understand the molecular content of protoplanetary disks in their gaseous and solid components.
Aims: We aim to characterize the distribution and abundance of molecules in the protoplanetary disk of DG Tau and to compare them with its dust distribution.
Methods: In the context of the ALMA chemical survey of Disk-Outflow sources in the Taurus star forming region (ALMA-DOT) we analyze ALMA observations of the nearby disk-outflow system around the T Tauri star DG Tau in H2CO 31,2-21,1, CS 5-4, and CN 2-1 emission at an unprecedented resolution of ~0''.15, which means ~18 au at a distance of 121 pc.
Results: Both H2CO and CS emission originate from a disk ring located at the edge of the 1.3 mm dust continuum. CS probes a disk region that is slightly further out with respect to H2CO; their peaks in emission are found at ~70 and ~60 au, with an outer edge at ~130 and ~120 au, respectively. CN originates from an outermost and more extended disk/envelope region with a peak at ~80 au and extends out to ~500 au. H2CO is dominated by disk emission, while CS also probes two streams of material possibly accreting onto the disk with a peak in emission at the location where the stream connects to the disk. CN emission is barely detected and both the disk and the envelope could contribute to the emission. Assuming that all the lines are optically thin and emitted by the disk molecular layer in local thermodynamic equilibrium at temperatures of 20-100 K, the ring- and disk-height-averaged column density of H2CO is 2.4-8.6 × 1013 cm-2, that of CS is ~1.7-2.5 × 1013 cm-2, while that of CN is ~1.9-4.7 × 1013 cm-2. Unsharp masking reveals a ring of enhanced dust emission at ~40 au, which is located just outside the CO snowline (~30 au).
Conclusions: Our finding that the CS and H2CO emission is co-spatial in the disk suggests that the two molecules are chemically linked. Both H2CO and CS may be formed in the gas phase from simple radicals and/or desorbed from grains. The observed rings of molecular emission at the edge of the 1.3 mm continuum may be due to dust opacity effects and/or continuum over-subtraction in the inner disk, as well as to increased UV penetration and/or temperature inversion at the edge of the millimeter(mm)-dust which would cause enhanced gas-phase formation and desorption of these molecules. CN emission originates only from outside the dusty disk, and is therefore even more strongly anti-correlated with the continuum, suggesting that this molecule is a good probe of UV irradiation. The H2CO and CS emission originate from outside the ring of enhanced dust emission, which also coincides with a change in the linear polarization orientation at 0.87 mm. This suggests that outside the CO snowline there could be a change in the dust properties that manifests itself as an increase in the intensity (and change of polarization) of the continuum and of the molecular emission.
Spiral arms in the protoplanetary disc HD100453 detected with ALMA: evidence for binary-disc interaction and a vertical temperature gradientRosotti, G. P.Benisty, M.Juhász, A.Teague, RichardClarke, C.Dominik, C.Dullemond, C. P.Klaassen, P. D.Matrà, LucaStolker, T.DOI: info:10.1093/mnras/stz3090v. 4911335–1347
Rosotti, G. P., Benisty, M., Juhász, A., Teague, Richard, Clarke, C., Dominik, C., Dullemond, C. P., Klaassen, P. D., Matrà, Luca, and Stolker, T. 2020. "Spiral arms in the protoplanetary disc HD100453 detected with ALMA: evidence for binary-disc interaction and a vertical temperature gradient." Monthly Notices of the Royal Astronomical Society 491:1335– 1347. https://doi.org/10.1093/mnras/stz3090
ID: 155674
Type: article
Authors: Rosotti, G. P.; Benisty, M.; Juhász, A.; Teague, Richard; Clarke, C.; Dominik, C.; Dullemond, C. P.; Klaassen, P. D.; Matrà, Luca; Stolker, T.
Abstract: Scattered light high-resolution imaging of the protoplanetary disc orbiting HD100453 shows two symmetric spiral arms, possibly launched by an external stellar companion. In this paper, we present new, sensitive high-resolution (∼30 mas) Band 7 ALMA observations of this source. This is the first source where we find counterparts in the sub-mm continuum to both scattered light spirals. The CO J = 3-2 emission line also shows two spiral arms; in this case, they can be traced over a more extended radial range, indicating that the southern spiral arm connects to the companion position. This is clear evidence that the companion is responsible for launching the spirals. The pitch angle of the submillimetre continuum spirals (∼6°) is lower than the one in scattered light (∼16°). We show that hydrodynamical simulations of binary-disc interaction can account for the difference in pitch angle only if one takes into account that the mid-plane is colder than the upper layers of the disc, as expected for the case of externally irradiated discs.
The efficiency of dust trapping in ringed protoplanetary discsRosotti, Giovanni P.Teague, RichardDullemond, CornelisBooth, Richard A.Clarke, Cathie J.DOI: info:10.1093/mnras/staa1170v. 495173–181
Rosotti, Giovanni P., Teague, Richard, Dullemond, Cornelis, Booth, Richard A., and Clarke, Cathie J. 2020. "The efficiency of dust trapping in ringed protoplanetary discs." Monthly Notices of the Royal Astronomical Society 495:173– 181. https://doi.org/10.1093/mnras/staa1170
ID: 157299
Type: article
Authors: Rosotti, Giovanni P.; Teague, Richard; Dullemond, Cornelis; Booth, Richard A.; Clarke, Cathie J.
Abstract: When imaged at high resolution, many protoplanetary discs show gaps and rings in their dust sub-mm continuum emission profile. These structures are widely considered to originate from local maxima in the gas pressure profile. The properties of the underlying gas structures are however unknown. In this paper, we present a method to measure the dust-gas coupling α/St and the width of the gas pressure bumps affecting the dust distribution, applying high-precision techniques to extract the gas rotation curve from emission line data cubes. As a proof of concept, we then apply the method to two discs with prominent substructure, HD 163296 and AS 209. We find that in all cases the gas structures are larger than in the dust, confirming that the rings are pressure traps. Although the grains are sufficiently decoupled from the gas to be radially concentrated, we find that the degree of coupling of the dust is relatively good (α/St ∼ 0.1). We can therefore reject scenarios in which the disc turbulence is very low and the dust has grown significantly. If we further assume that the dust grain sizes are set by turbulent fragmentation, we find high values of the α turbulent parameter (α ∼ 10-2). Alternatively, solutions with smaller turbulence are still compatible with our analysis if another process is limiting grain growth. For HD 163296, recent measurements of the disc mass suggest that this is the case if the grain size is 1 mm. Future constraints on the dust spectral indices will help to discriminate between the two alternatives.
Accretion disks around young stars: the cradles of planet formationSemenov, Dmitry A.Teague, Richard D.DOI: info:10.1051/epn/2020104v. 51No. 129–32
Semenov, Dmitry A. and Teague, Richard D. 2020. "Accretion disks around young stars: the cradles of planet formation." Europhysics News 51 (1):29– 32. https://doi.org/10.1051/epn/2020104
ID: 157324
Type: article
Authors: Semenov, Dmitry A.; Teague, Richard D.
Abstract: Protoplanetary disks around young stars are the birth sites of planetary systems like our own. Disks represent the gaseous dusty matter left after the formation of their central stars. The mass and luminosity of the star, initial disk mass and angular momentum, and gas viscosity govern disk evolution and accretion. Protoplanetary disks are the cosmic nurseries where microscopic dust grains grow into pebbles, planetesimals, and planets.
A three-dimensional view of Gomez's hamburgerTeague, RichardJankovic, Marija R.Haworth, Thomas J.Qi, ChunhuaIlee, John D.DOI: info:10.1093/mnras/staa1167v. 495No. 1451–459
Teague, Richard, Jankovic, Marija R., Haworth, Thomas J., Qi, Chunhua, and Ilee, John D. 2020. "A three-dimensional view of Gomez's hamburger." Monthly Notices of the Royal Astronomical Society 495 (1):451– 459. https://doi.org/10.1093/mnras/staa1167
ID: 155893
Type: article
Authors: Teague, Richard; Jankovic, Marija R.; Haworth, Thomas J.; Qi, Chunhua; Ilee, John D.
Abstract: Unravelling the three-dimensional physical structure, the temperature and density distribution, of protoplanetary discs is an essential step if we are to confront simulations of embedded planets or dynamical instabilities. In this paper, we focus on submillimeter array observations of the edge-on source, Gomez's Hamburger, believed to host an overdensity hypothesized to be a product of gravitational instability in the disc, GoHam b. We demonstrate that, by leveraging the well-characterized rotation of a Keplerian disc to deproject observations of molecular lines in position-position-velocity space into disc-centric coordinates, we are able to map out the emission distribution in the (r, z) plane and (x, vertical bar y vertical bar, z) space. We show that (CO)-C-12 traces an elevated layer of z / r similar to 0.3, while (CO)-C-13 traces deeper in the disc at z / r less than or similar to 0.2. We identify an azimuthal asymmetry in the deprojected (CO)-C-13 emission coincident with GoHam b at a polar angle of approximate to 30 degrees. At the spatial resolution of similar to 1.5 arcsec, GoHam b is spatially unresolved, with an upper limit to its radius of <190 au.
The Excitation Conditions of CN in TW HyaTeague, RichardLoomis, RyanDOI: info:10.3847/1538-4357/aba956v. 899157
Teague, Richard and Loomis, Ryan. 2020. "The Excitation Conditions of CN in TW Hya." The Astrophysical Journal 899:157. https://doi.org/10.3847/1538-4357/aba956
ID: 157484
Type: article
Authors: Teague, Richard; Loomis, Ryan
Abstract: We report observations of the cyanide anion, CN, in the disk around TW Hya covering the N = 1-0, N = 2-1, and N = 3-2 transitions. Using line-stacking techniques, 24 hyperfine transitions are detected out of the 30 within the observed frequency ranges. Exploiting the super-spectral resolution from the line-stacking method reveals the splitting of hyperfine components previously unresolved by laboratory spectroscopy. All transitions display a similar emission morphology, characterized by an azimuthally symmetric ring, peaking at ≍45 au (0"75), and a diffuse outer tail extending out to the disk edge at ≍200 au. Excitation analyses assuming local thermodynamic equilibrium (LTE) yield excitation temperatures in excess of the derived kinetic temperatures based on the local line widths for all fine-structure groups, suggesting assumptions of LTE are invalid. Using the 0D radiative transfer code RADEX, we demonstrate that such non-LTE effects may be present when the local H2 density drops to 107 cm-3 and below. Comparison with models of TW Hya find similar densities at elevated regions in the disk, typically z / r ≳ 0.2, consistent with model predictions where CN is formed via vibrationally excited H2 in the disk atmospheric layers where UV irradiation is less attenuated.
ALMA and VLA Observations of EX Lupi in Its Quiescent StateWhite, Jacob AaronKóspál, Á.Hughes, A. G.Ábrahám, P.Akimkin, V.Banzatti, A.Chen, L.Cruz-Sáenz de Miera, F.Dutrey, A.Flock, M.Guilloteau, S.Hales, A. S.Henning, T.Kadam, K.Semenov, D.Sicilia-Aguilar, A.Teague, Richard D.Vorobyov, E. I.DOI: info:10.3847/1538-4357/abbb94v. 90437
White, Jacob Aaron, Kóspál, Á., Hughes, A. G., Ábrahám, P., Akimkin, V., Banzatti, A., Chen, L., Cruz-Sáenz de Miera, F., Dutrey, A., Flock, M., Guilloteau, S., Hales, A. S., Henning, T., Kadam, K., Semenov, D., Sicilia-Aguilar, A., Teague, Richard D., and Vorobyov, E. I. 2020. "ALMA and VLA Observations of EX Lupi in Its Quiescent State." The Astrophysical Journal 904:37. https://doi.org/10.3847/1538-4357/abbb94
ID: 158632
Type: article
Authors: White, Jacob Aaron; Kóspál, Á.; Hughes, A. G.; Ábrahám, P.; Akimkin, V.; Banzatti, A.; Chen, L.; Cruz-Sáenz de Miera, F.; Dutrey, A.; Flock, M.; Guilloteau, S.; Hales, A. S.; Henning, T.; Kadam, K.; Semenov, D.; Sicilia-Aguilar, A.; Teague, Richard D.; Vorobyov, E. I.
Abstract: Extreme outbursts in young stars may be a common stage of pre-main-sequence stellar evolution. These outbursts, caused by enhanced accretion and accompanied by increased luminosity, can also strongly impact the evolution of the circumstellar environment. We present Atacama Large Millimeter Array (ALMA) and Very Large Array observations of EX Lupi, a prototypical outburst system, at 100, 45, and 15 GHz. We use these data, along with archival ALMA 232 GHz data, to fit radiative transfer models to EX Lupi's circumstellar disk in its quiescent state following the extreme outburst in 2008. The best-fit models show a compact disk with a characteristic dust radius of 45 au and a total mass of 0.01 M?. Our modeling suggests grain growth to sizes of at least 3 mm in the disk, possibly spurred by the recent outburst, and an ice line that has migrated inward to 0.2-0.3 au post-outburst. At 15 GHz, we detected significant emission over the expected thermal disk emission which we attribute primarily to stellar (gyro)synchrotron and free-free disk emission. Altogether, these results highlight what may be a common impact of outbursts on the circumstellar dust.
An Ideal Testbed for Planet-Disk Interaction: Two Giant Protoplanets in Resonance Shaping the PDS 70 Protoplanetary DiskBae, JaehanZhu, ZhaohuanBaruteau, ClémentBenisty, MyriamDullemond, Cornelis P.Facchini, StefanoIsella, AndreaKeppler, MiriamPérez, Laura M.Teague, RichardDOI: info:10.3847/2041-8213/ab46b0v. 884L41
Bae, Jaehan, Zhu, Zhaohuan, Baruteau, Clément, Benisty, Myriam, Dullemond, Cornelis P., Facchini, Stefano, Isella, Andrea, Keppler, Miriam, Pérez, Laura M., and Teague, Richard. 2019. "An Ideal Testbed for Planet-Disk Interaction: Two Giant Protoplanets in Resonance Shaping the PDS 70 Protoplanetary Disk." The Astrophysical Journal 884:L41. https://doi.org/10.3847/2041-8213/ab46b0
ID: 154716
Type: article
Authors: Bae, Jaehan; Zhu, Zhaohuan; Baruteau, Clément; Benisty, Myriam; Dullemond, Cornelis P.; Facchini, Stefano; Isella, Andrea; Keppler, Miriam; Pérez, Laura M.; Teague, Richard
Abstract: While numerical simulations have been playing a key role in the studies of planet-disk interaction, testing numerical results against observations has been limited so far. With the two directly imaged protoplanets embedded in its circumstellar disk, PDS 70 offers an ideal testbed for planet-disk interaction studies. Using two-dimensional hydrodynamic simulations we show that the observed features can be well explained with the two planets in formation, providing strong evidence that previously proposed theories of planet-disk interaction are in action, including resonant migration, particle trapping, size segregation, and filtration. Our simulations suggest that the two planets are likely in 2:1 mean motion resonance and can remain dynamically stable over million-year timescales. The growth of the planets at 10-8-10-7 M Jup yr-1, rates comparable to the estimates from Hα observations, does not destabilize the resonant configuration. Large grains are filtered at the gap edge and only small, (sub-)μm grains can flow to the circumplanetary disks (CPDs) and the inner circumstellar disk. With the submillimeter continuum ring observed outward of the two directly imaged planets, PDS 70 provides the first observational evidence of particle filtration by gap-opening planets. The observed submillimeter continuum emission at the vicinity of the planets can be reproduced when (sub-)μm grains survive over multiple CPD gas viscous timescales and accumulate therein. One such possibility is if (sub-)μm grains grow in size and remain trapped in pressure bumps, similar to what we find happening in circumstellar disks. We discuss potential implications to planet formation in the solar system and mature extrasolar planetary systems.
Spiral Structure in the Gas Disk of TW HyaTeague, RichardBae, JaehanHuang, JaneBergin, Edwin A.DOI: info:10.3847/2041-8213/ab4a83v. 884L56
Teague, Richard, Bae, Jaehan, Huang, Jane, and Bergin, Edwin A. 2019. "Spiral Structure in the Gas Disk of TW Hya." The Astrophysical Journal 884:L56. https://doi.org/10.3847/2041-8213/ab4a83
ID: 154723
Type: article
Authors: Teague, Richard; Bae, Jaehan; Huang, Jane; Bergin, Edwin A.
Abstract: We report the detection of spiral substructure in both the gas velocity and temperature structure of the disk around TW Hya, suggestive of planet-disk interactions with an unseen planet. Perturbations from Keplerian rotation tracing out a spiral pattern are observed in the SE of the disk, while significant azimuthal perturbations in the gas temperature are seen in the outer disk, outside 90 au, extending the full azimuth of the disk. The deviation in velocity is either ∆v ϕ /v kep ̃ 0.1 or ∆v z /v kep ̃ 0.01 depending on whether the perturbation is in the rotational or vertical direction, while radial perturbations can be ruled out. Deviations in the gas temperature are ±4 K about the azimuthally averaged profile, equivalent to deviations of ∆T gas/T gas ̃ 0.05. Assuming all three structures can be described by an Archimedean spiral, measurements of the pitch angles of both velocity and temperature spirals show a radially decreasing trend for all three, ranging from 9° at 70 au, dropping to 3° at 200 au. Such low pitch- angled spirals are not readily explained through the wake of an embedded planet in the location of previously reported at 94 au, but rather require a launching mechanism that results in much more tightly wound spirals. Molecular emission tracing distinct heights in the disk is required to accurately distinguish between spiral launching mechanisms.