Most stars form in a cluster environment. These stars are initially surrounded by discs from which potentially planetary systems form. Of all cluster environments starburst clusters are probably the most hostile for planetary systems in our Galaxy. The intense stellar radiation and extreme density favour rapid destruction of circumstellar discs via photoevaporation and stellar encounters. Evolving a virialized model of the Arches cluster in the Galactic tidal field we investigate the effect of stellar encounters on circumstellar discs in a prototypical starburst cluster. Despite its proximity to the deep gravitational potential of the Galactic centre only a moderate fraction of members escapes to form an extended pair of tidal tails. Our simulations show that encounters destroy one third of the circumstellar discs in the cluster core within the first 2.5 Myr of evolution, preferentially affecting the least and most massive stars. A small fraction of these events causes rapid ejection and the formation of a weaker second pair of tidal tails that is overpopulated by disc-poor stars. Two predictions arise from our study: (i) If not destroyed by photoevaporation protoplanetary discs of massive late B- and early O-type stars represent the most likely hosts of planet formation in starburst clusters. (ii) Multi-epoch K- and L-band photometry of the Arches cluster would provide the kinematically selected membership sample required to detect the additional pair of disc-poor tidal tails.
To date, 204 individual molecular species, comprised of 16 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. These molecules range in size from two atoms to seventy, and have been detected across the electromagnetic spectrum from cm-wavelengths to the ultraviolet. This census presents a summary of the first detection of each molecular species, including the observational facility, wavelength range, transitions, and enabling laboratory spectroscopic work, as well as listing tentative and disputed detections. Tables of molecules det…
We investigate the effects of magnetic field configurations on the ionization rate by cosmic rays in protoplanetary disks. First, we consider cosmic-ray propagation from the interstellar medium (ISM) to the protoplanetary disks and showed that the cosmic-ray density around the disk should be 2 times lower than the ISM value. Then, we compute the attenuation of cosmic rays in protoplanetary disks. The magnetic fields in the disk are stretched to the azimuthal directions, and cosmic rays need to detour while propagating to the midplane. Our results show that the detouring effectively enhances th…
The formation of asteroids, comets and planets occurs in the interior of protoplanetary disks during the early phase of star formation. Consequently, the chemical composition of the disk might shape the properties of the emerging planetary system. In this context, it is crucial to understand whether and what organic molecules are synthesized in the disk. In this Letter, we report the first detection of formic acid (HCOOH) towards the TW Hydrae protoplanetary disk. The observations of the trans-HCOOH 6$_{(1,6)-5(1,5)}$ transition were carried out at 129~GHz with ALMA. We measured a disk-average…
We use two-dimensional Fourier transformation to measure the pitch angle ($φ$) of the dominant spiral Fourier mode of well-defined spiral arms in 13 protoplanetary disks, making use of near-infrared scattered-light images of AB Aur, SAO 206462, MWC 758, V1247 Ori, HD 142527, DZ Cha, LkH$α$ 330, and HD 100453, and ALMA millimeter continuum images of Elias 2-27, IM Lup, AS 205, and HT Lup. We find that the measured pitch angle correlates strongly with disk mass ($M_{D}$), such that more massive protoplanetary disks have smaller pitch angles, following $|φ| = -(7.8\pm1.7)\log(M_{D}/M_{\odot})+(2.…
The investigation of polarized light of protoplanetary disks is key for constraining the dust properties, disk morphology and embedded magnetic fields. However, different polarization mechanisms and the diversity of dust grain shapes and compositions lead to ambiguities in the polarization pattern. The so-called "self-scattering" of thermal, re-emitted radiation in the infrared and mm/submm is discussed as a major polarization mechanism. If the net flux of the radiation field is in radial direction, it is commonly assumed that the polarization pattern produced by scattering in a protoplanetary…
Measurements of the gas mass are necessary to determine the planet formation potential of protoplanetary disks. Observations of rare CO isotopologues are typically used to determine disk gas masses; however, if the line emission is optically thick this will result in an underestimated disk mass. With ALMA we have detected the rarest stable CO isotopologue, 13C17O, in a protoplanetary disk for the first time. We compare our observations with the existing detections of 12CO, 13CO, C18O and C17O in the HD163296 disk. Radiative transfer modelling using a previously benchmarked model, and assuming …
It has recently been established that the evolution of protoplanetary disks is primarily driven by magnetized disk winds, requiring large-scale magnetic flux threading the disks. The size of such disks is expected to shrink in time, as opposed to the conventional scenario of viscous expansion. We present the first global 2D non-ideal magnetohydrodynamic (MHD) simulations of protoplanetary disks that are truncated in the outer radius, aiming to understand the interaction of the disk with the interstellar environment, as well as global evolution of the disk and magnetic flux. We find that as the…
Ionization-recombination balance in dense interstellar and circumstellar environments is a key factor for a variety of important physical processes, such as chemical reactions, dust charging and coagulation, coupling of the gas with magnetic field and development of instabilities in protoplanetary disks. We determine a critical gas density above which the recombination of electrons and ions on the grain surface dominates over the gas-phase recombination. For this regime, we present a self-consistent analytical model which allows us to exactly calculate abundances of charged species in dusty ga…
We assess the ionising effect of low energy protostellar cosmic rays in protoplanetary disks around a young solar mass star for a wide range of disk parameters. We assume a source of low energy cosmic rays located close to the young star which travel diffusively through the protoplanetary disk. We use observationally inferred values from nearby star-forming regions for the total disk mass and the radial density profile. We investigate the influence of varying the disk mass within the observed scatter for a solar mass star. We find that for a large range of disk masses and density profiles that…
The volatile contents of protoplanetary disks both set the potential for planetary chemistry and provide valuable probes of defining disk system characteristics such as stellar mass, gas mass, ionization, and temperature structure. Current disk molecular inventories are fragmented, however, giving an incomplete picture: unbiased spectral line surveys are needed to assess the volatile content. We present here an overview of such a survey of the protoplanetary disks around the Herbig Ae star MWC 480 and the T Tauri star LkCa 15 in ALMA Band 7, spanning $\sim$36 GHz from 275--317 GHz and represen…
Recent observations show that the CO gas abundance, relative to H$_2$, in many 1-10 Myr old protoplanetary disks may be heavily depleted, by a factor of 10-100 compared to the canonical interstellar medium value of 10$^{-4}$. When and how this depletion happens can significantly affect compositions of planetesimals and atmospheres of giant planets. It is therefore important to constrain if the depletion occurs already at the earliest protostellar disk stage. Here we present spatially resolved observations of C$^{18}$O, C$^{17}$O, and $^{13}$C$^{18}$O $J$=2-1 lines in three protostellar disks. …
