More Like this

1. ALMA Discovery of a Disk around the Planetary-mass Companion SR 12 c

   https://doi.org/10.3847/2041-8213/ac6420  

   Wu, Ya-Lin ; Bowler, Brendan P. ; Sheehan, Patrick D. ; Close, Laird M. ; Eisner, Joshua A. ; Best, William M. ; Ward-Duong, Kimberly ; Zhu, Zhaohuan ; Kraus, Adam L. ( April 2022 , The Astrophysical Journal Letters)

   Abstract We report an Atacama Large Millimeter/submillimeter Array 0.88 mm (Band 7) continuum detection of the accretion disk around SR 12 c, an ∼11 M Jup planetary-mass companion (PMC) orbiting its host binary at 980 au. This is the first submillimeter detection of a circumplanetary disk around a wide PMC. The disk has a flux density of 127 ± 14 μ Jy and is not resolved by the ∼0.″1 beam, so the dust disk radius is likely less than 5 au and can be much smaller if the dust continuum is optically thick. If, however, the dust emission is optically thin, then the SR 12 c disk has a comparable dust mass to the circumplanetary disk around PDS 70 c but is about five times lower than that of the ∼12 M Jup free-floating OTS 44. This suggests that disks around bound and unbound planetary-mass objects can span a wide range of masses. The gas mass estimated with an accretion rate of 10 −11 M ☉ yr −1 implies a gas-to-dust ratio higher than 100. If cloud absorption is not significant, a nondetection of 12 CO(3–2) implies a compact gas disk around SR 12 c. Future sensitive observations may detectmore »more PMC disks at 0.88 mm flux densities of ≲100 μ Jy.« less
2. Annular substructures in the transition disks around LkCa 15 and J1610

   https://doi.org/10.1051/0004-6361/202038027  

   Facchini, S. ; Benisty, M. ; Bae, J. ; Loomis, R. ; Perez, L. ; Ansdell, M. ; Mayama, S. ; Pinilla, P. ; Teague, R. ; Isella, A. ; et al ( July 2020 , Astronomy & Astrophysics)

   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 μ Jy 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 themore »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 M Jup ), 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 N 2 snowlines.« less
3. Detection of Near-infrared Water Ice at the Surface of the (Pre)Transitional Disk of AB Aur: Informing Icy Grain Abundance, Composition, and Size

   https://doi.org/10.3847/1538-3881/ac4d9b  

   Betti, S. K. ; Follette, K. ; Jorquera, S. ; Duchêne, G. ; Mazoyer, J. ; Bonnefoy, M. ; Chauvin, G. ; Pérez, L. M. ; Boccaletti, A. ; Pinte, C. ; et al ( March 2022 , The Astronomical Journal)

   Abstract We present near-infrared Large Binocular Telescope LMIRCam imagery of the disk around the Herbig Ae/Be star AB Aurigae. A comparison of the surface brightness at K s (2.16 μ m), H 2 O narrowband (3.08 μ m), and L ′ (3.7 μ m) allows us to probe the presence of icy grains in this (pre)transitional disk environment. By applying reference differential imaging point-spread function subtraction, we detect the disk at high signal-to-noise ratios in all three bands. We find strong morphological differences between the bands, including asymmetries consistent with the observed spiral arms within 100 au in L ′ . An apparent deficit of scattered light at 3.08 μ m relative to the bracketing wavelengths ( K s and L ′ ) is evocative of ice absorption at the disk surface layer. However, the Δ( K s − H 2 O) color is consistent with grains with little to no ice (0%–5% by mass). The Δ ( H 2 O − L ′ ) color, conversely, suggests grains with a much higher ice mass fraction (∼0.68), and the two colors cannot be reconciled under a single grain population model. Additionally, we find that the extremely red Δ ( Kmore »s − L ′ ) disk color cannot be reproduced under conventional scattered light modeling with any combination of grain parameters or reasonable local extinction values. We hypothesize that the scattering surfaces at the three wavelengths are not colocated, and that the optical depth effects in each wavelength result from probing the grain population at different disk surface depths. The morphological similarity between K s and H 2 O suggests that their scattering surfaces are near one another, lending credence to the Δ( K s − H 2 O) disk color constraint of <5% ice mass fraction for the outermost scattering disk layer.« less
4. ALMA Reveals Extended Cool Gas and Hot Ionized Outflows in a Typical Star-forming Galaxy at Z = 7.13

   https://doi.org/10.3847/1538-4357/ac795b  

   Akins, Hollis B. ; Fujimoto, Seiji ; Finlator, Kristian ; Watson, Darach ; Knudsen, Kirsten K. ; Richard, Johan ; C. Bakx, Tom J. L. ; Hashimoto, Takuya ; Inoue, Akio K. ; Matsuo, Hiroshi ; et al ( July 2022 , The Astrophysical Journal)

   We present spatially resolved morphological properties of [CII] 158μm, [OIII] 88μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy atz= 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius ofr∼ 12 kpc. Using multi-band rest-frame far-infrared continuum data ranging from 52 to 400μm, we find an average dust temperature and emissivity index of$T_{\mathrm{dust}}={41}_{-14}^{+17}$K and$\beta ={1.7}_{-0.7}^{+1.1}$, respectively, across the galaxy. We find slight differences in the dust continuum profiles at different wavelengths, which may indicate that the dust temperature decreases with distance. We map the star formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1M_⊙yr⁻¹with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the localL_[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII], with significant residuals (∼5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggestsmore »a possible origin of the extended [CII] structure from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the highL_[OIII]/L_[CII]ratios recently reported inz> 6 galaxies.

   « less
5. Dust masses of young disks: constraining the initial solid reservoir for planet formation

   https://doi.org/10.1051/0004-6361/202037851  

   Tychoniec, Łukasz ; Manara, Carlo F. ; Rosotti, Giovanni P. ; van Dishoeck, Ewine F. ; Cridland, Alexander J. ; Hsieh, Tien-Hao ; Murillo, Nadia M. ; Segura-Cox, Dominique ; van Terwisga, Sierk E. ; Tobin, John J. ( August 2020 , Astronomy & Astrophysics)

   Context. Recent years have seen building evidence that planet formation starts early, in the first ~0.5 Myr. Studying the dust masses available in young disks enables us to understand the origin of planetary systems given that mature disks are lacking the solid material necessary to reproduce the observed exoplanetary systems, especially the massive ones. Aims. We aim to determine if disks in the embedded stage of star formation contain enough dust to explain the solid content of the most massive exoplanets. Methods. We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 (1.1–1.3 mm) continuum observations of embedded disks in the Perseus star-forming region together with Very Large Array (VLA) Ka -band (9 mm) data to provide a robust estimate of dust disk masses from the flux densities measured in the image plane. Results. We find a strong linear correlation between the ALMA and VLA fluxes, demonstrating that emission at both wavelengths is dominated by dust emission. For a subsample of optically thin sources, we find a median spectral index of 2.5 from which we derive the dust opacity index β = 0.5, suggesting significant dust growth. Comparison with ALMA surveys of Orion shows that the Class I dust disk massmore »distribution between the two regions is similar, but that the Class 0 disks are more massive in Perseus than those in Orion. Using the DIANA opacity model including large grains, with a dust opacity value of κ 9 mm = 0.28 cm 2 g −1 , the median dust masses of the embedded disks in Perseus are 158 M ⊕ for Class 0 and 52 M ⊕ for Class I from the VLA fluxes. The lower limits on the median masses from ALMA fluxes are 47 M ⊕ and 12 M ⊕ for Class 0 and Class I, respectively, obtained using the maximum dust opacity value κ 1.3 mm = 2.3 cm 2 g −1 . The dust masses of young Class 0 and I disks are larger by at least a factor of ten and three, respectively, compared with dust masses inferred for Class II disks in Lupus and other regions. Conclusions. The dust masses of Class 0 and I disks in Perseus derived from the VLA data are high enough to produce the observed exoplanet systems with efficiencies acceptable by planet formation models: the solid content in observed giant exoplanets can be explained if planet formation starts in Class 0 phase with an efficiency of ~15%. A higher efficiency of ~30% is necessary if the planet formation is set to start in Class I disks.« less