scholarly journals Probing Protoplanetary Disk Winds with C ii Absorption

2021 ◽  
Vol 921 (2) ◽  
pp. 181
Author(s):  
Ziyan Xu ◽  
Gregory J. Herczeg ◽  
Christopher M. Johns-Krull ◽  
Kevin France
Keyword(s):  
Wind Velocity ◽  
Hubble Space Telescope ◽  
Line Emission ◽  
Wind Model ◽  
Disk Wind ◽  
T Tauri ◽  
Fast Wind ◽  
Slow Wind ◽  
Far Ultraviolet ◽  
Absorption Features

Abstract We present an analysis of wind absorption in the C ii λ1335 doublet toward 40 classical T Tauri stars with archival far-ultraviolet (FUV) spectra obtained by the Hubble Space Telescope. Absorption features produced by fast or slow winds are commonly detected (36 out of 40 targets) in our sample. The wind velocity of the fast wind decreases with disk inclination, which is consistent with expectations for a collimated jet. Slow wind absorption is mostly detected in disks with intermediate or high inclination, without a significant dependence of wind velocity on disk inclination. Both the fast and slow wind absorption are preferentially detected in FUV lines of neutral or singly ionized atoms. The Mg ii λ λ2796, 2804 lines show wind absorption consistent with the absorption in the C ii lines. We develop simplified semi-analytical disk/wind models to interpret the observational disk wind absorption. Both fast and slow winds are consistent with expectations from a thermal-magnetized disk wind model and are generally inconsistent with a purely thermal wind. Both the models and the observational analysis indicate that wind absorption occurs preferentially from the inner disk, which offers a wind diagnostic in complement to optical forbidden line emission that traces the wind in larger volumes.

scholarly journals Effect of ambient wind velocity on Planetary Nebula morphology

1997 ◽  
Vol 180 ◽  
pp. 224-224
Author(s):  
Vikram V. Dwarkadas ◽  
Roger A. Chevalier ◽  
John M. Blondin
Keyword(s):  
Wind Velocity ◽  
Ambient Medium ◽  
Asymptotic Giant Branch ◽  
Density Contrast ◽  
Expansion Velocity ◽  
Ambient Wind ◽  
Pn Velocity ◽  
Fast Wind ◽  
Self Similar ◽  
Slow Wind

Planetary Nebulae (PNe) are formed by the interaction of the fast wind from a post-Asymptotic Giant Branch Star with the slow ambient wind from a previous epoch. If the two interacting winds have constant properties, the velocity of the PN shell tends towards a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNe in the self-similar stage (Dwarkadas et al. 1996). We have investigated the contribution of the ambient wind velocity to PN morphology, which has hitherto not received much attention since the work of Kahn & West (1985). We find that the nebular morphology is a consequence of the density contrast between pole and equator in the ambient medium, the steepness of the density profile and the velocity of the ambient wind; classification of PNe purely on the basis of the first two factors may be misleading. In particular, the ratio of ambient wind velocity to PN velocity is important in determining whether the nebula shows a bulge or a cusp at the equator. A high density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. As long as the external wind velocity is small compared to the expansion velocity of the nebula, the PNe tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, inclusion of an asymmetric velocity profile in the slow wind, with the velocity increasing towards the pole, can lead to a bipolar nebula if the equatorial velocity is sufficiently low. Preliminary results with a slow wind velocity increasing towards the equator (as is found in calculations of common envelope evolution) show that the nebulae tend to be more oblate, which is not often observed in nature. Representative results for shapes of PNe using various values of the relevant parameters are presented.

scholarly journals Outflows and Accretion in Young Stellar Objects

2004 ◽  
Vol 219 ◽  
pp. 599-610 ◽  
Author(s):  
Nuria Calvet
Keyword(s):  
Observational Evidence ◽  
Young Stellar Objects ◽  
Opening Angle ◽  
Wide Angle ◽  
Wind Model ◽  
Stellar Objects ◽  
Disk Wind ◽  
T Tauri ◽  
Fu Ori ◽  
Temperature Enhancement

Outflows in young stellar objects are powered by accretion, and ∼ 0.1 of the accreted material is lost in the outflow. Observational evidence is analyzed in the context of models for the origin of the wind. Winds in FU Ori objects are clear examples of disk winds. In Classical T Tauri stars, there is evidence for the existence of a wide angle wind at scales < 100 AU, which supports the X-wind model prediction that narrow jets are the result of density/temperature enhancement towards the axis of the system. However, recent HST observations of the DG Tau jet indicate that the opening angle of the wind is more confined than predicted by the X-wind model, in better agreement with disk wind theories.

scholarly journals The nuclear environment of the NLS1 Mrk 335: Obscuration of the X-ray line emission by a variable outflow

2019 ◽  
Vol 490 (1) ◽  
pp. 683-697 ◽  
Author(s):  
M L Parker ◽  
A L Longinotti ◽  
N Schartel ◽  
D Grupe ◽  
S Komossa ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Large Fraction ◽  
Broad Band ◽  
Line Emission ◽  
X Ray ◽  
High Energies ◽  
Low Energies ◽  
Gas Cooling ◽  
Nuclear Environment ◽  
Absorption Features

ABSTRACT We present XMM–Newton, NuSTAR, Swift, and Hubble Space Telescope observations of the Narrow-line Seyfert 1 galaxy Mrk 335 in a protracted low state in 2018 and 2019. The X-ray flux is at the lowest level so far observed, and the extremely low continuum flux reveals a host of soft X-ray emission lines from photoionized gas. The simultaneous UV flux drop suggests that the variability is intrinsic to the source, and we confirm this with broad-band X-ray spectroscopy. The dominance of the soft X-ray lines at low energies and distant reflection at high energies, is therefore due to the respective emission regions being located far enough from the X-ray source that they have not yet seen the flux drop. Between the two XMM–Newton spectra, taken 6 months apart, the emission line ratio in the O vii triplet changes drastically. We attribute this change to a drop in the ionization of intervening warm absorption, which means that the absorber must cover a large fraction of the line emitting region, and extend much further from the black hole than previously assumed. The HST spectrum, taken in 2018, shows that new absorption features have appeared on the blue wings of C iii*, Ly α, N v, Si iv, and C iv, likely due to absorbing gas cooling in response to the low flux state.

scholarly journals Accretion Disk Winds in Cataclysmic Variables

1996 ◽  
Vol 158 ◽  
pp. 253-256
Author(s):  
Christian Knigge ◽  
Janet E. Drew ◽  
Keith O. Mason
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Cataclysmic Variables ◽  
Line Profiles ◽  
Line Flux ◽  
Wind Model ◽  
Disk Wind ◽  
Eclipse Observations ◽  
Fast Wind ◽  
Slow Moving

AbstractWe present preliminary results of a modelling campaign based on HST eclipse observations of the wind-formed C IV resonance line in the eclipsing nova-like variable UX UMa. Within the framework of a simple kinematic accretion disk wind model, we are currently able to reproduce the shapes (but not the strengths) of the observed line profiles away from and during eclipse, as well as the behaviour of the integrated line flux light curve. The most important aspect of our modelling is that it suggests the presence of a vertically extended, relatively dense and slow moving transition region between the disk photosphere and the fast wind.

scholarly journals The Disk Wind Model of the Broad Line Region of Active Galactic Nuclei

1997 ◽  
Vol 163 ◽  
pp. 615-619
Author(s):  
J. Chiang ◽  
N. Murray
Keyword(s):  
Active Galactic Nuclei ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Wind Model ◽  
Disk Wind ◽  
Reverberation Mapping ◽  
Broad Absorption Line ◽  
Broad Emission ◽  
Line Region ◽  
Dynamical Features

AbstractIn a fashion similar to winds in O stars, the AGN disk winds may be responsible for the broad, blue-shifted absorption of resonance lines which characterize the Broad Absorption Line QSOs. The dynamical features of the disk wind may also account for many of the properties of the broad emission lines of AGN. Although the velocity field of the material responsible for the line emission is primarily that of the accretion disk, the presence of an accelerated radial wind influences the line formation so that single-peaked profiles are generic. Further, the recent reverberation mapping response of NGC 5548 is also qualitatively explained by these same radiative transfer effects.

scholarly journals The Kinematics of Quasar Broad Emission Line Regions Using a Disk-Wind Model

2017 ◽  
Vol 34 ◽  
Author(s):  
Suk Yee Yong ◽  
Rachel L. Webster ◽  
Anthea L. King ◽  
Nicholas F. Bate ◽  
Matthew J. O’Dowd ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Profile ◽  
Inclination Angle ◽  
Opening Angle ◽  
Line Profiles ◽  
Wind Model ◽  
Disk Wind ◽  
Reverberation Mapping ◽  
Broad Emission ◽  
Line Region

AbstractThe structure and kinematics of the broad line region in quasars are still unknown. One popular model is the disk-wind model that offers a geometric unification of a quasar based on the viewing angle. We construct a simple kinematical disk-wind model with a narrow outflowing wind angle. The model is combined with radiative transfer in the Sobolev, or high velocity, limit. We examine how angle of viewing affects the observed characteristics of the emission line. The line profiles were found to exhibit distinct properties depending on the orientation, wind opening angle, and region of the wind where the emission arises.At low inclination angle (close to face-on), we find that the shape of the emission line is asymmetric, narrow, and significantly blueshifted. As the inclination angle increases (close to edge-on), the line profile becomes more symmetric, broader, and less blueshifted. Additionally, lines that arise close to the base of the disk wind, near the accretion disk, tend to be broad and symmetric. Single-peaked line profiles are recovered for the intermediate and equatorial wind. The model is also able to reproduce a faster response in either the red or blue sides of the line profile, consistent with reverberation mapping studies.

scholarly journals A Hubble Space Telescope STIS Observation of VW Hydri at the Exact Far-Ultraviolet Onset of an Outburst

2004 ◽  
Vol 614 (1) ◽  
pp. L61-L64 ◽  
Author(s):  
Edward M. Sion ◽  
F. H. Cheng ◽  
Boris T. Gänsicke ◽  
Paula Szkody
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Far Ultraviolet

scholarly journals Photoionisation effects in hydrodynamical simulations of planetary nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 350-351
Author(s):  
L. Hernández-Martínez ◽  
D. Estrella ◽  
P. F. Velázquez ◽  
A. Esquivel ◽  
A. C. Raga
Keyword(s):  
Proper Motion ◽  
Planetary Nebulae ◽  
Numerical Results ◽  
Accelerated Expansion ◽  
Central Source ◽  
Fast Wind ◽  
Hα Emission ◽  
Hydrodynamical Simulations ◽  
Slow Wind

AbstractWe explored the photoionisation effects on both the proper motion and emission of planetary nebulae NGC 6302, by means of hydrodynamical simulations. We used the GUACHO code, which includes the photoionisation due to central source (Esquivel et al. 2009, Esquivel & Raga 2013). We model these PNe considering an interacting stellar fast wind with and ejected toroidally shaped slow wind (Uscanga et al. 2014). Synthetic Hα emission maps were obtained from our numerical results in order to do a comparison between the cases with and without photoionisation. Using a wavelets fittering method on our results for the ionisation case, we do not find an increase in the proper motion velocities, however we can see an accelerated expansion in both cases. For the ionisation case the Hα emission presents an increase.

scholarly journals Hubble Space Telescope observations of Europa in and out of eclipse

2010 ◽  
Vol 9 (4) ◽  
pp. 265-271 ◽  
Author(s):  
W.B. Sparks ◽  
M. McGrath ◽  
K. Hand ◽  
H.C. Ford ◽  
P. Geissler ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Broad Band ◽  
Line Emission ◽  
Optical Emission ◽  
High Energy ◽  
High Energy Particle ◽  
Wide Field ◽  
Particle Radiation ◽  
Space Telescope ◽  
Solar Blind

AbstractEuropa is a prime target for astrobiology and has been prioritized as the next target for a National Aeronautics and Space Administration flagship mission. It is important, therefore, that we advance our understanding of Europa, its ocean and physical environment as much as possible. Here, we describe observations of Europa obtained during its orbital eclipse by Jupiter using the Hubble Space Telescope. We obtained Advanced Camera for Surveys Solar Blind Channel far ultraviolet low-resolution spectra that show oxygen line emission both in and out of eclipse. We also used the Wide-Field and Planetary Camera-2 and searched for broad-band optical emission from fluorescence of the surface material, arising from the very high level of incident energetic particle radiation on ices and potentially organic substances. The high-energy particle radiation at the surface of Europa is extremely intense and is responsible for the production of a tenuous oxygen atmosphere and associated FUV line emission. Approximately 50% of the oxygen emission lasts at least a few hours into the eclipse. We discuss the detection limits of the optical emission, which allow us to estimate the fraction of incident energy reradiated at optical wavelengths, through electron-excited emission, Cherenkov radiation in the ice and fluorescent processes.

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