Study of the bipolar jet of the YSO Th 28 with VLT/SINFONI: Jet morphology and H2_2 emission

$Context.$ The YSO Th 28 possesses a highly collimated jet, which clearly exhibits an asymmetric brightness of its jet lobes at optical and NIR wavelengths. There may be asymmetry in the jet plasma parameters in opposite jet lobes (e.g. electron density, temperature, and outflow velocity). $Aims.$ We examined the Th 28 jet in a 3"x3" where the jet material is collimated and accelerated. Our goal is to map the morphology and determine its physical parameters to determine the physical origin of such asymmetries. $Methods.$ We present $JHK$-spectra of Th 28 obtained with the SINFONI on the (VLT, ESO) in June-July 2015. $Results.$ The [Fe II] emission originates in collimated jet lobes. Two new axial knots are detected at 1" in the blue lobe and 1".2 in the red lobe. The H$_2$ radiation is emitted from an extended region with a radius of $\gtrsim270$ au, which is perpendicular to the jet. The PV diagrams of the bright H$_2$ lines reveal faint H$_2$ emission along both jet lobes as well. The compact and faint H I emission (Pa$\beta$ and Br$\gamma$) comes from two regions, namely from a spherical region around the star and from the jet lobes. The size of the jet launching region is derived as 0".015 ($\sim$3 au at 185 pc), and the initial opening angle of the Th 28 jet is $\sim28^0$, which makes this jet substantially less collimated than most jets from other CTTs. $Conclusions.$ The emission in [Fe II], H$_2$, and H I lines suggests a morphology in which the ionised gas in the disc appears to be disrupted by the jet. The resolved disc-like H$_2$ emission most likely arises in the disc atmosphere from shocks caused by a radial uncollimated wind. The asymmetry of the [Fe II] photocentre shifts with respect to the jet source arises in the immediate vicinity of the driving source of Th28 and suggests that the observed brightness asymmetry is intrinsic as well.Comment: 18 pages, 14 figure

A search for temperature and density variations in NGC 7027 with the Hubble Space Telescope

We observed the young planetary nebula NGC 7027 with the HST Imaging Spectrograph (STIS) in long-slit mode at five slit positions along the major axis of the nebula, over the wavelength range from 3000 to ~10,000 Å. We used dereddened line ratios to determine line-of-sight average values for (1) He^(++) and He^+ ionization fractions from He II λ4686 and He I λ5876; (2) electron density from both [S II] (λ6716/λ6731) and [Ar IV] (λ4711/λ4740); and (3) temperature from [O III] (λ4959 + λ5007)/λ4363. The He^(++)/H^+ ratio varies across the nebula, with values up to 0.06 over the central parts, falling off to 0.03 at offsets of 5"-6" from the central star. The line-of-sight mean densities vary by factors of ~5 on angular scales as small as ~1". The average electron temperatures are generally consistent with a constant = 13,800 ± 2000 K within the uncertainties, except for ~2% of measured pixels where T_e > 18,000 K. The variations of density along the slits are not obviously correlated with variations in extinction. The ionization structure of the nebula varies on both large and small scales. [O I] λ6300, Hα, and He II λ4686 intensity profiles along each slit appear to trace ionization gradients at Hα peaks, with the highest ionization on the side toward the central star and lowest ionization on the far side. These structures may result from effects of stellar radiation, shocks from a fast stellar wind, or some combination of the two processes

Against all odds? Forming the planet of the HD196885 binary

HD196885Ab is the most "extreme" planet-in-a-binary discovered to date, whose orbit places it at the limit for orbital stability. The presence of a planet in such a highly perturbed region poses a clear challenge to planet-formation scenarios. We investigate this issue by focusing on the planet-formation stage that is arguably the most sensitive to binary perturbations: the mutual accretion of kilometre-sized planetesimals. To this effect we numerically estimate the impact velocities $dv$ amongst a population of circumprimary planetesimals. We find that most of the circumprimary disc is strongly hostile to planetesimal accretion, especially the region around 2.6AU (the planet's location) where binary perturbations induce planetesimal-shattering $dv$ of more than 1km/s. Possible solutions to the paradox of having a planet in such accretion-hostile regions are 1) that initial planetesimals were very big, at least 250km, 2) that the binary had an initial orbit at least twice the present one, and was later compacted due to early stellar encounters, 3) that planetesimals did not grow by mutual impacts but by sweeping of dust (the "snowball" growth mode identified by Xie et al., 2010b), or 4) that HD196885Ab was formed not by core-accretion but by the concurent disc instability mechanism. All of these 4 scenarios remain however highly conjectural.Comment: accepted for publication by Celestial Mechanics and Dynamical Astronomy (Special issue on EXOPLANETS

Investigations of the Young Stellar Object Th 28

This work explores the young stellar object Th 28 (V1190 Sco), which belongs to the class T Tauri. The analysis of observations in the near infrared range using the SINFONI integral field spectrograph of the European Southern Observatory VLT telescope is presented.Исследован молодой звездный объект Th 28 (V1190 Sco), относящийся к классу Т Тельца. Представлен анализ наблюдений в ближнем инфракрасном диапазоне с использованием спектрографа интегрального поля SINFONI телескопа VLT Европейской южной обсерватории.Работа выполнена при поддержке гранта РНФ 18-72-10132

ODRL Policy Modelling and Compliance Checking

This paper addresses the problem of constructing a policy pipeline that enables compliance checking of business processes against regulatory obligations. Towards this end, we propose an Open Digital Rights Language (ODRL) profile that can be used to capture the semantics of both business policies in the form of sets of required permissions and regulatory requirements in the form of deontic concepts, and present their translation into Answer Set Programming (via the Institutional Action Language (InstAL)) for compliance checking purposes. The result of the compliance checking is either a positive compliance result or an explanation pertaining to the aspects of the policy that are causing the noncompliance. The pipeline is illustrated using two (key) fragments of the General Data Protect Regulation, namely Articles 6 (Lawfulness of processing) and Articles 46 (Transfers subject to appropriate safeguards) and industrially-relevant use cases that involve the specification of sets of permissions that are needed to execute business processes. The core contributions of this paper are the ODRL profile, which is capable of modelling regulatory obligations and business policies, the exercise of modelling elements of GDPR in this semantic formalism, and the operationalisation of the model to demonstrate its capability to support personal data processing compliance checking, and a basis for explaining why the request is deemed compliant or not

Powder Bed Layer Characteristics: The Overseen First-Order Process Input

A discrete element powder model is used in conjunction with a finite volume melting model on the first layer of a powder bed selective laser melting process

The Kuiper Belt and Other Debris Disks

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade