Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userKinematics of the ring-like nebula SuWt 2
106
0
0.0
(
0
)
Authors
D. Jones
Ask ChatGPT about the research
No Arabic abstract
We present the first detailed spatio-kinematical analysis and modelling of the Southern planetary nebula SuWt 2. This object presents a problem for current theories of planetary nebula formation and evolution, as it is not known to contain a central post-main sequence star. Deep narrowband [NII]6584 images reveal the presence of faint bipolar lobes emanating fromthe edges of the nebular ring. Longslit observations of the H-alpha and [NII]6584 emission lines were obtained using EMMI on the 3.6-m ESO-NTT. The spectra reveal the nebular morphology as a bright torus encircling the waist of an extended bipolar structure. By deprojection, the inclination of the ring is found to be 68$degr$ $pm$ 2$degr$ (c.f. ~90$degr$ for the double A-type binary believed to lie at the centre of the nebula), and the ring expansion velocity is found to be 28 km/s. Our findings are discussed with relation to possible formation scenarios for SuWt 2. Through comparison of the nebular heliocentric systemic velocity, found here to be -25 $pm$ 5 km/s, and the heliocentric systemic velocity of the double A-type binary, we conclude that neither component of the binary could have been the nebular progenitor. However, we are unable to rule out the presence of a third component to the system, which would have been the nebula progenitor.
rate research
Read More
To gain a more complete understanding of the dynamics of the GK Per (1901) remnant faint-object high-resolution echelle spectroscopic observations and imaging were undertaken covering the knots which comprise the nova shell and the surrounding nebulosity. New imaging from the Aristarchos telescope in Greece and long-slit spectra from the MES instrument at the San Pedro Martir observatory in Mexico were obtained, supplemented with archival observations from several other optical telescopes. Position-velocity arrays are produced of the shell, and also individual knots, and are then used for morpho-kinematic modelling with the shape code. Evidence is found for the interaction of knots with each other and with a wind component, most likely the periodic fast wind emanating from the central binary system. We find that a cylindrical shell with a lower velocity polar structure gives the best model fit to the spectroscopy and imaging. We show in this work that the previously seen jet-like feature is of low velocity. The individual knots have irregular tail shapes; we propose here that they emanate from episodic winds from ongoing dwarf nova outbursts by the central system. The nova shell is cylindrical and the symmetry axis relates to the inclination of the central binary system. Furthermore, the cylinder axis is aligned with the long axis of the bipolar planetary nebula in which it is embedded. Thus, the central binary system is responsible for the bipolarity of the planetary nebula and the cylindrical nova shell. The gradual planetary nebula ejecta versus sudden nova ejecta is the reason for the different degrees of bipolarity. We propose that the jet feature is an illuminated lobe of the fossil planetary nebula that surrounds the nova shell.
In this article, we present the multi-viewpoint and multi-wavelength analysis of an atypical solar jet based on the data from Solar Dynamics Observatory, SOlar, and Heliospheric Observatory, and Solar TErrestrial RElations Observatory. It is usually believed that the coronal mass ejections (CMEs) are developed from the large scale solar eruptions in the lower atmosphere. However, the kinematical and spatial evolution of the jet on 2013 April 28 guide us that the jet was clearly associated with a narrow CME having a width of approx 25 degrees with a speed of 450 km/s. To better understand the link between the jet and the CME, we did the coronal potential field extrapolation from the line of sight magnetogram of the AR. The extrapolations present that the jet eruption follows exactly the same path of the open magnetic field lines from the source region which provides the route for the jet material to escape from the solar surface towards the outer corona.
The link between the shaping of bipolar planetary nebulae and their central stars is still poorly understood. The kinematics and shaping of the multipolar nebula M 1-75 are hereby investigated, and the location and nature of its central star are briefly discussed. Fabry-Perot data from GHaFAS on the WHT sampling the Doppler shift of the [N II] 658.3 nm line are used to study the dynamics of the nebula, by means of a detailed 3-D spatio-kinematical model. Multi-wavelength images and spectra from the WFC and IDS on the INT, and from ACAM on the WHT, allowed us to constrain the parameters of the central star. The two pairs of lobes, angularly separated by ~22 degrees, were ejected simultaneously approx. ~3500-5000 years ago, at the adopted distance range from 3.5 to 5.0 kpc. The larger lobes show evidence of a slight degree of point symmetry. The shaping of the nebula could be explained by wind interaction in a system consisting of a post-AGB star surrounded by a disc warped by radiative instabilities. This requires the system to be a close binary or a single star which engulfed a planet as it died. On the other hand, we present broad- and narrow-band images and a low S/N optical spectrum of the highly-reddened, previously unnoticed star which is likely the nebular progenitor. Its estimated V-I colour allows us to derive a rough estimate of the parameters and nature of the central star.
We present the first detailed spatio-kinematical analysis and modelling of the planetary nebula HaTr 4, one of few known to contain a post-common-envelope central star system. Common envelope evolution is believed to play an important role in the shaping of planetary nebulae, but the exact nature of this role is yet to be understood. High spatial- and spectral- resolution spectroscopy of the [OIII]5007 nebular line obtained with VLT-UVES are presented alongside deep narrowband Ha+[NII]6584 imagery obtained using EMMI-NTT, and together the two are used to derive the three-dimensional morphology of HaTr 4. The nebula is found to display an extended ovoid morphology with an enhanced equatorial region consistent with a toroidal waist - a feature believed to be typical amongst planetary nebulae with post-common-envelope central stars. The nebular symmetry axis is found to lie perpendicular to the orbital plane of the central binary, concordant with the idea that the formation and evolution of HaTr 4 has been strongly influenced by its central binary.
ALMA has observed a plethora of ring-like structures in planet forming discs at distances of 10-100 au from their host star. Although several mechanisms have been invoked to explain the origin of such rings, a common explanation is that they trace new-born planets. Under the planetary hypothesis, a natural question is how to reconcile the apparently high frequency of gap-carving planets at 10-100 au with the paucity of Jupiter mass planets observed around main sequence stars at those separations. Here, we provide an analysis of the new-born planet population emerging from observations of gaps in discs, under the assumption that the observed gaps are due to planets. We use a simple estimate of the planet mass based on the gap morphology, and apply it to a sample of gaps recently obtained by us in a survey of Taurus with ALMA. We also include additional data from recent published surveys, thus analysing the largest gap sample to date, for a total of 48 gaps. The properties of the purported planets occupy a distinctively different region of parameter space with respect to the known exo-planet population, currently not accessible through planet finding methods. Thus, no discrepancy in the mass and radius distribution of the two populations can be claimed at this stage. We show that the mass of the inferred planets conforms to the theoretically expected trend for the minimum planet mass needed to carve a dust gap. Finally, we estimate the separation and mass of the putative planets after accounting for migration and accretion, for a range of evolutionary times, finding a good match with the distribution of cold Jupiters.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
