arXiv subjects

N. Kurtovic

Publications and source records attributed to N. Kurtovic.

4 recordsLinked to original sources

arXiv2026

The Circumbinary Disk of HD 34700A: I. CO gas kinematics indicate spirals, infall, and vortex motions

We present the first high-resolution ($\sim$ 0.14") Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 dust continuum and CO molecular line emission observations of the quadruple system HD 34700. In particular, HD 34700AaAb is a spectroscopic binary ($M_{\rm{bin}}=4\,M_\odot$) surrounded by two low-mass companions at large separations. Its circumbinary disk is highly substructured, featuring numerous spiral arms and a large cavity observed in infrared (IR) scattered light. We analyzed the CO line channel and intensity moment maps. By fitting a Keplerian model to the line channel emission, we identified the residual motions and conducted a line spectra analysis. We resolved an asymmetric continuum crescent on top of a dust ring at 0.39" (138 au), colocated with the IR ring. The CO molecule line emissions trace a smaller cavity in gas, whose edge aligns with the inner rim of the ring detected in H$\alpha$ emission at 0.20" (65 au). The $^{12}$CO line emission and kinematics trace highly non-Keplerian motions ($\sim0.1\Delta\upsilon_{\rm kep}$), and these CO spiral features align well with the spiral structures in scattered light. The $^{12}$CO line spectra analysis reveals a streamer above the southeastern disk plane, likely falling onto the disk. The $^{13}$CO and C$^{18}$O kinematics largely follow the disk's underlying Keplerian rotation, while $^{13}$CO exhibits tentative signs of anticyclonic vortex flows at the continuum crescent location. Our multimolecular line study suggests that the circumbinary disk of HD 34700A is highly perturbed in its upper layers, possibly warped and influenced by infalling material. While late-stage infall may account for the IR spirals and the formation of the vortex through Rossby wave instability, an embedded massive companion within the cavity may also contribute to these features.

astro-ph.EP↗

arXiv2024

The GRAVITY young stellar object survey XIV : Investigating the magnetospheric accretion-ejection processes in S CrA N

The dust- and gas-rich protoplanetary disks around young stellar systems play a key role in star and planet formation. While considerable progress has recently been made in probing these disks on large scales of a few tens of astronomical units (au), the central au needs to be more investigated. We aim at unveiling the physical processes at play in the innermost regions of the strongly accreting T Tauri Star S CrA N by means of near-infrared interferometric observations. The K-band continuum emission is well reproduced with an azimuthally-modulated dusty ring. As the star alone cannot explain the size of this sublimation front, we propose that magnetospheric accretion is an important dust-heating mechanism leading to this continuum emission. The differential analysis of the Hydrogen Br$\gamma$ line is in agreement with radiative transfer models combining magnetospheric accretion and disk winds. Our observations support an origin of the Br$\gamma$ line from a combination of (variable) accretion-ejection processes in the inner disk region.

astro-ph.SR↗

arXiv2024

The SPHERE view of the Chamaeleon I star-forming region

We used VLT/SPHERE to observe 20 systems in the Cha I cloud in polarized scattered light in the near-infrared. We combined the scattered light observations with existing literature data on stellar properties and with archival ALMA continuum data to study trends with system age and dust mass. We also connected resolved near-infrared observations with the spectral energy distributions of the systems. In 13 of the 20 systems included in this study we detected resolved scattered light signals from circumstellar dust. For the CR Cha, CT Cha, CV Cha, SY Cha, SZ Cha, and VZ Cha systems we present the first detailed descriptions of the disks in scattered light. The observations found typically smooth or faint disks, often with little substructure, with the notable exceptions of SZ Cha, which shows an extended multiple-ringed disk, and WW Cha, which shows interaction with the cloud environment. New high S/N K- band observations of the HD 97048 system in our survey reveal a significant brightness asymmetry that may point to disk misalignment and subsequent shadowing of outer disk regions, possibly related to the suggested planet candidate in the disk. We resolve for the first time the stellar binary in the CS Cha system. Multiple wavelength observations of the disk around CS Cha have revealed that the system contains small, compact dust grains that may be strongly settled, consistent with numerical studies of circumbinary disks. We find in our sample that there is a strong anti-correlation between the presence of a (close) stellar companion and the detection of circumstellar material with five of our seven nondetections located in binary systems.

astro-ph.GA↗

arXiv2021

A multiwavelength analysis of the spiral arms in the protoplanetary disk around WaOph 6

[Full abstract in the paper] In recent years, protoplanetary disks with spiral structures have been detected in scattered light, millimeter continuum, and CO gas emission. The mechanisms causing these structures are still under debate. A popular scenario to drive the spiral arms is the one of a planet perturbing the material in the disk. However, if the disk is massive, gravitational instability is usually the favored explanation. Multiwavelength studies could be helpful to distinguish between the two scenarios. So far, only a handful of disks with spiral arms have been observed in both scattered light and millimeter continuum. We aim to perform an in-depth characterization of the protoplanetary disk morphology around WaOph 6 analyzing data obtained at different wavelengths, as well as to investigate the origin of the spiral features in the disk. We present the first near-infrared polarimetric observations of WaOph 6 obtained with SPHERE at the VLT and compare them to archival millimeter continuum ALMA observations. We traced the spiral features in both data sets and estimated the respective pitch angles. We discuss the different scenarios that can give rise to the spiral arms in WaOph 6. We tested the planetary perturber hypothesis by performing hydrodynamical and radiative transfer simulations to compare them with scattered light and millimeter continuum observations.

astro-ph.EP↗