Disk Evolution Research Articles

Formation of pebbles in (gravito-)viscous protoplanetary disks with various turbulent strengths

Aims. Dust plays a crucial role in the evolution of protoplanetary disks. We study the dynamics and growth of initially submicron dust particles in self-gravitating young protoplanetary disks with various strengths of turbulent viscosity. We aim to understand the physical conditions that determine the formation and spatial distribution of pebbles when both disk self-gravity and turbulent viscosity are at work. Methods. We performed thin-disk hydrodynamics simulations of self-gravitating protoplanetary disks over an initial time period of 0.5 Myr using the FEOSAD code. Turbulent viscosity was parameterized in terms of the spatially and temporally constant α parameter, while the effects of gravitational instability on dust growth were accounted for by calculating the effective parameter αGI. We considered the evolution of the dust component, including the momentum exchange with gas, dust self-gravity, and a simplified model of dust growth. Results. We find that the level of turbulent viscosity strongly affects the spatial distribution and total mass of pebbles in the disk. The α = 10−2 model is viscosity-dominated, pebbles are completely absent, and the dust-to-gas mass ratio deviates from the reference 1:100 value by no more than 30% throughout the extent of the disk. On the contrary, the α = 10−3 model and, especially, the α = 10−4 model are dominated by gravitational instability. The effective parameter α + αGI is now a strongly varying function of radial distance. As a consequence, a bottleneck effect develops in the innermost disk regions, which makes gas and dust accumulate in a ring-like structure. Pebbles are abundant in these models, although their total mass and spatial extent is sensitive to the dust fragmentation velocity and to the strength of gravitoturbulence. The use of the standard dust-to-gas mass conversion is not suitable for estimating the mass of pebbles. Conclusions. Our numerical experiments demonstrate that pebbles can already be abundant in protoplanetary disks at the initial stages of disk evolution. Dust growth models that consider disk self-gravity and ice mantles may be important for studying planet formation via pebble accretion.

Three-dimensional evolution of radiative circumbinary discs: The size and shape of the inner cavity

In this study we present the results of 3D hydrodynamical simulations of circumbinary discs that orbit around analogues of the Kepler-16 and Kepler-34 systems, including the effect of stellar heating and radiative cooling on the thermal disc structure. We find that, compared to their 2D counterparts, the structures of the cavities in 3D circumbinary disc models appear to reach a quasi-stationary state more rapidly, and in a subset of our runs the evidence for this is unambiguous. Furthermore, the sizes and eccentricities of the inner cavity are smaller in 3D compared to 2D. We attribute this difference to enhanced spiral wave dissipation in disc regions above the midplane, where the cooling time is of the order of the dynamical timescale, resulting in smaller inner cavity sizes in 3D disc models. Our results suggest that migrating planets should park closer to the central binary in 3D models of circumbinary discs, and point to the importance of including the 3D structure when simulating circumbinary discs and planets.

MEGADES: MEGARA galaxy disc evolution survey

The main interest of the science team for the exploitation of the MEGARA instrument at the 10.4 m Gran Telescopio Canarias (GTC) is devoted to the study of nearby galaxies. The focus lies on researching the history of star formation, and the chemical and kinematical properties of disc systems. We refer to this project as MEGADES: the MEGARA galaxy disc evolution survey. The initial goal of MEGADES is to provide a detailed study of the inner regions of nearby disc galaxies in terms of their spectrophotometric and chemical evolution, and to provide a dynamical characterisation by distinguishing the contribution of in situ and ex situ processes to the history of star formation and effective chemical enrichment of these regions. In addition, the dynamical analysis of these inner regions naturally includes the identification and characterisation of galactic winds that might be present in these regions. At a later stage, we will extend this study farther out in galactocentric distance. The first stage of this project encompasses the analysis of the central regions of 43 nearby galaxies observed with the MEGARA integral field unit for ~114 h, including both guaranteed time and open time observations. In this paper we provide a set of all the processed data products available to the community and early results from the analysis of these data regarding stellar continuum and ionised and neutral gas features.

NEOWISE Variability of the New Gaia Herbig Ae/Be and Classical Be Stars—Variability Sample and Statistical Analysis

Light variability is an essential attribute of young stellar objects (YSOs) at the pre-main-sequence (PMS) stage, which can be treated as an indicator to trace star formation. We present a statistical study on the infrared NEOWISE variability of new and large-sized PMS stars as well as Herbig Ae/Be (HAeBe) and classical Be (CBe) stars identified from Gaia Data Release 2. A total of 3792 (including 714 HAeBe), 417, and 473 NEOWISE variable sources were detected from the catalog of 8470 PMS (including 1361 HAeBe), 693 CBe, and 1309 uncertain (possibly belonging to either HAeBe or CBe) stars, respectively. We found that 80% of the PMS variables are dominated by irregular infrared variability, whereas variables in the CBe and uncertain categories exhibit comparable contributions from secular (linear, curved, and periodic) and stochastic (burst, drop, and irregular) variables. This, in combination with infrared W1–W2 colors, W4 luminosities, and the spectral energy distribution slope at near- and mid-infrared wavelengths, suggests different evolutionary stages of the PMS (including HAeBe), uncertain, and CBe stars, from less to more evolved. A statistical analysis of variable source properties (e.g., period and fractional amplitude) further reveals a potential sequence possibly associated with disk evolution for different types of light curves (from linear, to curved, periodic, stochastic, and nonvariable stars). Possible mechanisms for the variable sources are suggested to be related to either extinction via circumstellar matter, or contribution of multiple systems surrounding the YSOs, as opposed to variable accretion (e.g., episodic accretion or accretion burst).

A mixed stirring mechanism for debris discs with giant and dwarf planetary perturbations

ABSTRACT Debris discs consist of belts of bodies ranging in size from dust grains to planetesimals; these belts are visible markers of planetary systems around other stars that can reveal the influence of extrasolar planets through their shape and structure. Two key stirring mechanisms – self-stirring by planetesimals and secular perturbation by an external giant planet – have been identified to explain the dynamics of planetesimal belts; their relative importance has been studied independently, but are yet to be considered in combination. In this work, we perform a suite of 286 N-body simulations exploring the evolution of debris discs over 1 Gyr, combining the gravitational perturbations of both dwarf planets embedded in the discs, and an interior giant planet. Our systems were somewhat modelled after the architecture of the outer Solar system: a Solar mass star, a single massive giant planet at 30 au (MGP = 10 to 316 M⊕), and a debris disc formed by 100 massive dwarf planets and 1000 massless particles (MDD = 3.16 to 31.6 M⊕). We present the evolution of both the disc and the giant planet after 1 Gyr. The time evolution of the average eccentricity and inclination of the disc is strongly dependent on the giant planet mass as well as on the remaining disc mass. We also found that efficient stirring is achieved even with small disc masses. In general, we find that a mixed mechanism is more efficient in the stirring of cold debris discs than either mechanism acting in isolation.

Observational and Energetic Properties of Astrophysical and Galactic Black Holes

The work reviews the investigation of electromagnetic, optical, and energetic properties of astrophysical and galactic black holes and surrounding matter. The astrophysical applications of the theoretical models of black hole environment to the description of various observed phenomena, such as cosmic rays of the ultra-high-energy, black hole shadow, gravitational lensing, quasinormal modes, jets showing relativistic effects such as the Doppler beaming, thermal radiation from the accretion discs, quasiperiodic oscillations are discussed. It has been demonstrated that the observational data strongly depends on the structure and evolution of the accretion disk surrounding the central black hole. It has been shown that the simulated images of supermassive black holes obtained are in agreement with the observational images obtained by event horizon telescope collaboration. High energetic activity from supermassive black holes due to the magnetic Penrose process discussed in the work is in agreement with the highly energetic cosmic rays observed. The astronomical observation of black holes provides rich fundamental physics laboratories for experimental tests and verification of various models of black hole accretion and different theories of gravity in the regime of strong gravity.

The impact of spurious collisional heating on the morphological evolution of simulated galactic discs

ABSTRACT We use a suite of idealized N-body simulations to study the impact of spurious heating of star particles by dark matter (DM) particles on the kinematics and morphology of simulated galactic discs. We find that spurious collisional heating leads to a systematic increase of the azimuthal velocity dispersion (σϕ) of stellar particles and a corresponding decrease in their mean azimuthal velocities ($\overline{v}_\phi$). The rate of heating is dictated primarily by the number of DM halo particles (or equivalently, by the DM particle mass at fixed halo mass) and by radial gradients in the local DM density along the disc; it is largely insensitive to the stellar particle mass. Galaxies within haloes resolved with fewer than ≈106 DM particles are particularly susceptible to spurious morphological evolution, irrespective of the total halo mass (with even more particles required to prevent heating of the galactic centre). Collisional heating transforms galactic discs from flattened structures into rounder spheroidal systems, causing them to lose rotational support in the process. It also affects the locations of galaxies in standard scaling relations that link their various properties: at fixed stellar mass, it increases the sizes of galaxies, and reduces their mean stellar rotation velocities and specific angular momenta. Our results urge caution when extrapolating simulated galaxy scaling relations to low masses where spurious collisional effects can bias their normalization, slope, and scatter.

A unified chronology of dust formation in the early solar system

The chronology of dust formation in the early solar system remains controversial. Chondrules are the most abundant high-temperature objects formed during the evolution of the circumsolar disk. Considering chondrule formation, absolute lead‑lead (PbPb) ages and aluminum‑magnesium (26Al26Mg) ages relative to calcium‑aluminum-rich inclusions (CAIs) provide inconsistent chronologies, with PbPb ages showing early and protracted chondrule formation episodes whereas 26Al26Mg ages suggest that chondrule production was delayed by >1.5 Ma. Here, we develop a new method to precisely determine in situ26Al26Mg ages of spinel-bearing chondrules, which are not affected by secondary asteroidal processes. Our data demonstrate that 26Al26Mg chondrule formation ages are actually 1 Ma older than previously thought and extend over the entire lifetime of the disk. This shift in chondrule formation ages relative to CAIs, however, is not sufficient to reconcile the PbPb and 26Al26Mg chronologies of chondrule and achondrite formation. Thus, either chondrules' PbPb ages and volcanic achondrites' 26Al26Mg ages are incorrect or the age of CAIs should be reevaluated at 4,568.7 Ma to ensure consistency between chronometers. We favor the second hypothesis, given that (i) the canonical age of CAIs was determined using only 4 specimens and (ii) older ages of 4,568.2 Ma have also been measured. We show that the adoption of 4,568.7 Ma as the new canonical age of CAIs and the use of our new spinel-derived 26Al26Mg ages enable reconciling the PbPb and 26Al26Mg ages of chondrules and achondrites. This new chronology implies the existence of a 0.7–1 Ma gap between the formation of refractory inclusions and chondrules, and supports the homogeneous distribution of 26Al in the circumsolar disk.

The influence of metallicity on a combined stellar and disk evolution

Context. Determining the effects of an accretion disk is crucial to understanding the evolution of young stars. During the combined evolution, stellar and disk parameters influence one another, which motivated us to develop a combined stellar and disk model. This makes a combined numerical model, with the disk evolving alongside the star, the next logical step in the progress of studying early stellar evolution. Aims. We aim to understand the effects of metallicity on the accretion disk and the stellar spin evolution during the T Tauri phase. Methods. We combined the numerical treatment of a hydrodynamic disk with stellar evolution, including a stellar spin model and allowing a self-consistent calculation of the back-reactions between the individual components. Results. We present the self-consistent theoretical evolution of T Tauri stars coupled to a stellar disk. We find that disks in low-metallicity environments are heated differently and have shorter lifetimes compared to their solar-metallicity counterparts. Differences in stellar radii, the contraction rate of the stellar radius, and the shorter disk lifetimes result in low-metallicity stars rotating more rapidly. Conclusions. We present an additional explanation for the observed short disk lifetimes in low-metallicity clusters. A combination of our model with those of previous studies (e.g., a metallicity-based photo-evaporation) could help us understand disk evolution and dispersal at different metallicities. Furthermore, our stellar spin evolution model includes several important effects that had previously been ignored (e.g., the stellar magnetic field strength and a realistic calculation of the disk lifetime). We encourage others to include our results as initial or input parameters in further spin evolution models that cover the stellar evolution toward and during the main sequence.

VERTICO V: The environmentally driven evolution of the inner cold gas discs of Virgo cluster galaxies

Abstract The quenching of cluster satellite galaxies is inextricably linked to the suppression of their cold interstellar medium (ISM) by environmental mechanisms. While the removal of neutral atomic hydrogen (H i) at large radii is well studied, how the environment impacts the remaining gas in the centres of galaxies, which are dominated by molecular gas, is less clear. Using new observations from the Virgo Environment traced in CO survey (VERTICO) and archival H i data, we study the H i and molecular gas within the optical discs of Virgo cluster galaxies on 1.2-kpc scales with spatially resolved scaling relations between stellar ( $\Sigma_{\star}$ ), H i ( $\Sigma_{\text{H}\,{\small\text{I}}}$ ), and molecular gas ( $\Sigma_{\text{mol}}$ ) surface densities. Adopting H i deficiency as a measure of environmental impact, we find evidence that, in addition to removing the H i at large radii, the cluster processes also lower the average $\Sigma_{\text{H}\,{\small\text{I}}}$ of the remaining gas even in the central $1.2\,$ kpc. The impact on molecular gas is comparatively weaker than on the H i, and we show that the lower $\Sigma_{\text{mol}}$ gas is removed first. In the most H i-deficient galaxies, however, we find evidence that environmental processes reduce the typical $\Sigma_{\text{mol}}$ of the remaining gas by nearly a factor of 3. We find no evidence for environment-driven elevation of $\Sigma_{\text{H}\,{\small\text{I}}}$ or $\Sigma_{\text{mol}}$ in H i-deficient galaxies. Using the ratio of $\Sigma_{\text{mol}}$ -to- $\Sigma_{\text{H}\,{\small\text{I}}}$ in individual regions, we show that changes in the ISM physical conditions, estimated using the total gas surface density and midplane hydrostatic pressure, cannot explain the observed reduction in molecular gas content. Instead, we suggest that direct stripping of the molecular gas is required to explain our results.

Inviscid protostellar disc ring formation and high-density ring edges due to the ejection and subsequent infall of material onto a protostellar disc

Abstract Discs of gas and dust are ubiquitous around protostars. Hypothetical viscous interactions within the disc are thought to cause the gas and dust to accrete onto the star. Turbulence within the disc is theorised to be the source of this disc viscosity. However, observed protostellar disc turbulence often appears to be small and not always conducive to disc accretion. In addition, theories for disc and planet evolution have difficulty in explaining the observed disc rings/gaps which form much earlier than expected. Protostellar accretion discs are observed to contain significant quantities of dust and pebbles. Observations also show that some of this material is ejected from near the protostar, where it travels to the outer regions of the disc. Such solid infalling material has a relatively small amount of angular momentum compared to the material in the disc. This infalling material lowers the angular momentum of the disc and should drive a radial flow towards the protostar. We show that the local radial accretion speed of the disc is proportional to the mass rate of infalling material onto the disc. Higher rates of infall onto the disc implies higher radial accretion disc speeds. As such, regions with high rates of infall of gas, dust, and pebbles onto the disc will produce gaps on relatively short timescales in the disc, while regions associated with relative low rates of infalling material will produce disc rings. As such, the inner edge of a disc gap will tend to have a higher surface density, which may enhance the probability of planet formation. In addition, the outer edge of a disc gap will act as a dust trap and may also become a site for planet formation. For the early Solar System, such a process may have collected O $^{16}$ -poor forsterite dust from the inner regions of the protosolar disc and O $^{16}$ -rich CAIs and AOAs from the inner edge regions of the protosolar disc, thereby constructing a region favourable to the formation of pre-chondritic planetesimals.

The link between infall location, early disc size, and the fraction of self-gravitationally fragmenting discs

Context. Many protoplanetary discs are self-gravitating early in their lives. If they fragment under their own gravity, they form bound gaseous clumps that can evolve to become giant planets. Today, the fraction of discs that undergo fragmentation, and therefore also the frequency of conditions that may lead to giant planet formation via gravitational instability, is still unknown. Aims. We study the formation and evolution of a large number of star-disc systems, focusing on the early sizes of the discs and their likelihood to fragment. We investigate how the fraction of discs that fragments depends on the disc-size distribution at early times. Methods. We performed a population synthesis of discs from formation to dispersal. Whilst varying the infall radius, we study the relationship between early disc size and fragmentation. Furthermore, we investigate how stellar accretion heating affects the fragmentation fraction. Results. We find that discs fragment only if they become sufficiently large early in their lives. This size depends sensitively on where mass is added to the discs during the collapse of their parent molecular cloud core. Infall locations derived from pure hydrodynamic and non-ideal magnetised collapse simulations lead to large and small discs, respectively, and 22 and 0% fragmentation fractions, respectively, in populations representative of the initial mass function; however, the resulting synthetic disc size distribution is larger and smaller, respectively, than the observed Class 0 disc size distribution. By choosing intermediate infall locations, leading to a synthetic disc size distribution that is in agreement with the observed one, we find a fragmentation fraction of between 0.1 and 11%, depending on the efficiency of stellar accretion heating of the discs. Conclusions. We conclude that the frequency of fragmentation is strongly affected by the early formation process of the disc and its interaction with the star. The early disc size is mainly determined by the infall location during the collapse of the molecular cloud core and controls the population-wide frequency of fragmentation. Stellar accretion heating also plays an important role in fragmentation and must be studied further. Our work is an observationally informed step towards a prediction of the frequency of giant planet formation by gravitational instability. Upcoming observations and theoretical studies will further our understanding of the formation and early evolution of discs in the near future. This will eventually allow us to understand how infall, disc morphology, giant planet formation via gravitational instability, and the observed extrasolar planet population are linked.

Measuring the Dust Masses of Protoplanetary Disks in Lupus with ALMA: Evidence That Disks Can Be Optically Thick at 3 mm

Accurate disk mass measurements are necessary to constrain disk evolution and the timescale of planet formation, but such measurements are difficult to make and are very dependent on assumptions. Here, we look at the assumption that the disk is optically thin at radio wavelengths and the effect of this assumption on measurements of disk dust mass. We model the optical to radio spectral energy distributions of 41 protoplanetary disks located in the young (∼1–3 Myr old) Lupus star-forming region, including 0.89 1.33 and 3 mm flux densities when available. We measure disk dust masses that are ∼1.5–6 times higher than when using the commonly adopted disk dust mass equation under the assumption of optically thin emission in the (sub)millimeter range. The cause of this discrepancy is that most disks are optically thick at millimeter wavelengths, even up to 3 mm, demonstrating that observations at longer wavelengths are needed to trace the fully optically thin emission of disks.

Hyperion: the origin of the stars. A far UV space telescope for high-resolution spectroscopy over wide fields

We present Hyperion, a mission concept recently proposed to the December 2021 NASA Medium Explorer announcement of opportunity. Hyperion explores the formation and destruction of molecular clouds and planet-forming disks in nearby star-forming regions of the Milky Way. It does this using long-slit high-resolution spectroscopy of emission from fluorescing molecular hydrogen, which is a powerful far-ultraviolet (FUV) diagnostic. Molecular hydrogen (H2) is the most abundant molecule in the universe and a key ingredient for star and planet formation but is typically not observed directly because its symmetric atomic structure and lack of a dipole moment mean there are no spectral lines at visible wavelengths and few in the infrared. Hyperion uses molecular hydrogen’s wealth of FUV emission lines to achieve three science objectives: (1) determining how star formation is related to molecular hydrogen formation and destruction at the boundaries of molecular clouds, (2) determining how quickly and by what process massive star feedback disperses molecular clouds, and (3) determining the mechanism driving the evolution of planet-forming disks around young solar-analog stars. Hyperion conducts this science using a straightforward, highly efficient, single-channel instrument design. Hyperion’s instrument consists of a 48-cm primary mirror with an f/5 focal ratio. The spectrometer has two modes, both covering 138.5- to 161.5-nm bandpasses. A low resolution mode has a spectral resolution of R ≥ 10,000 with a slit length of 65 arcmin, whereas the high-resolution mode has a spectral resolution of R ≥ 50,000 over a slit length of 5 armin. Hyperion occupies a 2-week-long high-earth lunar resonance TESS-like orbit and conducts 2 weeks of planned observations per orbit, with time for downlinks and calibrations. Hyperion was reviewed as category I, which is the highest rating possible but was not selected.

X-shooter survey of young intermediate-mass stars – I. Stellar characterization and disc evolution

ABSTRACT Intermediate-mass stars (IMSs) represent the link between low-mass and high-mass stars, and cover a key mass range for giant planet formation. In this paper, we present a spectroscopic survey of 241 young IMS candidates with IR-excess, the most complete unbiased sample to date within 300 pc. We combined VLT/X-Shooter spectra with BVR photometric observations and Gaia DR3 distances to estimate fundamental stellar parameters such as Teff, mass, radius, age, and luminosity. We further selected those stars within the intermediate-mass range 1.5 ≤ M⋆/M⊙ ≤ 3.5, and discarded old contaminants. We used 2MASS and WISE photometry to study the IR-excesses of the sample, finding 92 previously unidentified stars with IR-excess. We classified this sample into ‘protoplanetary’, ‘hybrid candidates’, and ‘debris’ discs based on their observed fractional excess at 12 $\mu$m, finding a new population of 17 hybrid disc candidates. We studied inner disc dispersal time-scales for $\lambda < 10 \,\mu$m and found very different trends for IMSs and low-mass stars (LMSs). IMSs show excesses dropping fast during the first 6 Myr independently of the wavelength, while LMSs show consistently lower fractions of excess at the shortest wavelengths, and increasingly higher fractions for longer wavelengths with slower dispersal rates. In conclusion, this study demonstrates empirically that IMSs dissipate their inner discs very differently than LMSs, providing a possible explanation for the lack of short period planets around IMSs.

Isolating the extreme debris disc signature – explorations of eccentric extreme debris discs formed by giant impacts

ABSTRACT In this work, we used N-body simulations and a radiative transfer package to model the evolution of eccentric debris discs produced by giant impacts between planetary embryos. This included how the morphology and infrared emission of these discs varied with embryo eccentricity and collision true anomaly. We found that eccentric discs inherit the eccentric properties of the centre of mass orbit of the two colliding embryos. However, the orientation of the collision with the respect to this orbit plays a key role in determining how closely the disc material resembles the centre of mass orbit. Additionally, we found that increased eccentricity acted to suppress the formation of certain short-term variations in the disc emission depending on the collision position. These short-term variations have been associated with an observational phenomenon called extreme debris discs. Short-term variability has been suggested as a potential signature for giant impacts.

Evolution of protoplanetary discs with magnetically driven disc winds (Corrigendum)

Evolution of protoplanetary discs with magnetically driven disc winds (<i>Corrigendum</i>)

The evolution of circumstellar discs in the galactic centre: an application to the G-clouds

ABSTRACT The Galactic Centre is known to have undergone a recent star formation episode a few Myr ago, which likely produced many T Tauri stars hosting circumstellar discs. It has been suggested that these discs may be the compact and dusty ionized sources identified as ‘G-clouds’. Given the Galactic Centre’s hostile environment, we study the possible evolutionary pathways these discs experience. We compute new external photoevaporation models applicable to discs in the Galactic Centre that account for the subsonic launching of the wind and absorption of UV photons by dust. Using evolutionary disc calculations, we find that photoevaporation’s rapid truncation of the disc causes them to accrete onto the central star rapidly. Ultimately, an accreting circumstellar disc has a lifetime ≲ 1 Myr, which would fail to live long enough to explain the G-clouds. However, we identify a new evolutionary pathway for circumstellar discs in the Galactic Centre. Removal of disc material by photoevaporation prevents the young star from spinning down due to magnetic braking, ultimately causing the rapidly spinning young star to torque the disc into a ‘decretion disc’ state which prevents accretion. At the same time, any planetary companion in the disc will trap dust outside its orbit, shutting down photoevaporation. The disc can survive for up to ∼10 Myr in this state. Encounters with other stars are likely to remove the planet on Myr time-scales, causing photoevaporation to restart, giving rise to a G-cloud signature. A giant planet fraction of $\sim 10{{\ \rm per\ cent}}$ can explain the number of observed G-clouds.

Creating the Radius Gap without Mass Loss

The observed exoplanet population features a gap in the radius distribution that separates the smaller super-Earths (≲1.7 Earth radii) from the larger sub-Neptunes (∼1.7–4 Earth radii). While mass-loss theories can explain many of the observed features of this radius valley, it is difficult to reconcile them with the potentially rising population of terrestrials beyond orbital periods of ∼30 days. We investigate the ability of gas accretion during the gas-poor phase of disk evolution to reproduce both the location of the observed radius gap and the existence of long-period terrestrial planets. Updating the analytic scaling relations of gas accretion rate accounting for the shrinking of the bound radius by hydrodynamic effects and deriving a more realistic disk temperature profile, we find that the late-stage gas accretion alone is able to carve out the observed radius gap, with slopes R gap ∝ P −0.096 and for top-heavy; and R gap ∝ P −0.089 and for bottom-heavy core mass distributions, in good agreement with observations. The general morphology of the primordial radius gap is stable against a range of disk gas density and disk accretion rate with the latter affecting mostly the population of large planets (≳3–4 R ⊕). The peaks and valleys in the radius distribution were likely set in place primordially while post-formation mass loss further tunes the exoplanetary population. We provide potential observational tests that may be possible with TESS, PLATO, and Roman Space Telescope.

Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Scattered light detection of a possible disk wind in RY Tau

Context. Disk winds are an important mechanism for accretion and disk evolution around young stars. The accreting intermediate-mass T-Tauri star RY Tau has an active jet and a previously known disk wind. Archival optical and new near-infrared observations of the RY Tau system show two horn-like components stretching out as a cone from RY Tau. Scattered light from the disk around RY Tau is visible in the near-infrared, but not seen at optical wavelengths. In the near-infrared, dark wedges separate the horns from the disk, indicating that we may see the scattered light from a disk wind. Aims. We aim to test the hypothesis that a dusty disk wind could be responsible for the optical effect in which the disk around RY Tau is hidden in the I band, but visible in the H band. This could be the first detection of a dusty disk wind in scattered light. We also want to constrain the grain size and dust mass in the wind and the wind-launching region. Methods. We used archived Atacama-Large-Millimetre-Array (ALMA) and Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) I band observations combined with newly acquired SPHERE H band observations and available literature to build a simple geometric model of the RY Tau disk and disk wind. We used Monte Carlo radiative transfer modelling MCMax3D to create comparable synthetic observations that test the effect of a dusty wind on the optical effect in the observations. We constrained the grain size and dust mass needed in the disk wind to reproduce the effect from the observations. Results. A model geometrically reminiscent of a dusty disk wind with small micron to sub-micron-sized grains elevated above the disk can reproduce the optical effect seen in the observations. The mass in the obscuring component of the wind has been constrained to 1 × 10−9 M⊙ ≤ M ≤ 5 × 10−8 M⊙, which corresponds to a mass-loss rate in the wind of about ~1 × 10−8 M⊙ yr−1. Conclusions. A simple model of a disk wind with micron to sub-micron-sized grains elevated above the disk is able to prevent stellar radiation to scatter in the disk at optical wavelengths while allowing photons to reach the disk in the near-infrared. Estimates of mass-loss rate correspond to previously presented theoretical models and points towards the idea that a magneto-hydrodynamic-type wind is the more likely scenario.