Wind-blown Bubble Research Articles

Kinetic efficiencies of stellar wind bubbles

The theoretical fraction of a stellar wind's energy converted into the kinetic energy of an expanding swept-up shell is 20 percent in the classical theory of stellar wind bubbles. Observational estimates of this conversion factor based on the amount of ionized material in wind-swept shells about Wolf-Rayet stars generally yield results of 1 percent. If there is a substantial amount of neutral material in the shell, it will not be counted and the kinetic efficiency will be underestimated. Presented here is a dynamical estimate which accounts for this neutral material in deducing the kinetic efficiencies of stellar wind bubbles. Bubbles classified as wind-blown shells have kinetic efficiencies in line with theoretical expectations for energy-conserving evolution in a homogeneous medium. Ringlike nebulae have significantly lower efficiencies, probably because they have been 'poisoned' by the photoevaporation of clouds engulfed during evolution into a cloudy substrate.

On the structure and stability of radiative shock waves

view Abstract Citations (125) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Structure and Stability of Radiative Shock Waves Bertschinger, E. Abstract The structure of a spherical, radiative, interstellar shock wave (e.g., a supernova remnant or a stellar wind bubble) is derived under the assumption that the cooling rate per unit volume has the form Λ ∝ ραTβ for T above a cutoff temperature Tc and Λ = 0 for T below Tc. In the limit of short cooling time and large isothermal cooling Mach number, the flow has an exact analytic solution. Three-dimensional linear stability analyses of the analytic solutions have been performed. The results demonstrate that the radiative phase of shock evolution cannot be adequately modeled as being spherically symmetric and that high spatial resolution is necessary to follow the growth of instabilities. Publication: The Astrophysical Journal Pub Date: May 1986 DOI: 10.1086/164151 Bibcode: 1986ApJ...304..154B Keywords: Dynamic Stability; Interstellar Matter; Shock Wave Propagation; Gas Cooling; Hydrodynamics; Spherical Waves; Stellar Winds; Strata; Supernova Remnants; Velocity Distribution; Astrophysics; HYDRODYNAMICS; INSTABILITIES; SHOCK WAVES full text sources ADS |

The remarkable kinematics of the WR wind-blown bubble RCW 58

On presente de nouvelles observations optiques et UV, de haute resolution, de haut rapport signal-bruit, de HD 96548, une etoile WN 8 entouree par la nebuleuse RCW 58 qui consiste en matiere ejectee par l'etoile et contenue dans une bulle. Le spectre presente des composantes d'absorption decalees vers le bleu dans un certain nombre de raies interstellaires provenant d'une variete d'ions. On discute de la correlation existant entre les vitesses des composantes et les potentiels d'ionisation

Radio wave scattering in the galactic disk

Electron density turbulence in the Galaxy causes radio sources to be broadened angularly by amounts that depend strongly on the direction of the source. Recent scattering measurements using very long baseline interferometry (VLBI)1 and interplanetary scintillations (IPS)2 of extragalactic sources, and interstellar scintillations (ISS) of pulsars3 are used here to constrain the distribution of scattering material in the Galaxy. Although ubiquitous, scattering material appears to be highly concentrated in a thin disk of ∼100 pc thickness and in clumps of 1–10 pc size probably associated with H II regions, stellar wind bubbles, and/or supernova shocks. Typical transverse velocities of scattering material are much smaller than typical pulsar velocities. We predict the scattering angle as a function of galactic latitude. The results imply a maximum observable surface brightness for incoherent sources of electron synchrotron radiation.

Photoionized stellar wind bubbles in a cloudy medium

The evolution of a stellar wind bubble in a cloudy medium of 1-10/cu cm mean density is investigated, allowing for the effects of the star's ionizing radiation. The dynamics of the bubble are governed by the effects of photoionization: weak winds produce bubbles which are confined by the pressure of the H II region, whereas strong winds produce bubbles whose size is determined by the photoevaporation and displacement of the clouds. Nebulae around massive stars begin with wind-blown shells, evolve into amorphous H II regions, then ring-like H II regions, then nebulae with stellar ejecta, and finally are swept up by a blast wave when the star explodes as a supernova. Part or all of the ring-like phase may be too faint to observe. Expanding H II shells with masses of the order of 10,000 solar masses are predicted around massive stars, and may account for the shells seen around the supernova remnants HB 21 and W44.

The Effect of Mass-Loss On the Evolution of HII Regions in the L.M.C.

Empirical calibrations based on prior studies of Galactic OB Stars are used to determine the integrated stellar wind mechanical luminosity (Lw) and the integrated Lyman continuum photon luminosity (S*) for 10 OB clusters in the L.M.C. These values of Lw and S*, together with narrow band H-α surface photometry of an overlapping sample of 15 L.M.C. HII regions, are used to show that the large shell-like HII regions, in the L.M.C. are stellar wind bubbles 3 to 5 million years old. In order to reproduce the general properties of these HII shells, a thick cushion of shocked stellar wind gas must have been present on the inside of the shell for most of the life time of the nebula, and the shell itself must be ram pressure confined by the HI/molecular cloud out of which it formed.

Galactic ring nebulae associated with Wolf-Rayet stars. VIII Summary and atlas

view Abstract Citations (142) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galactic ring nebulae associated with Wolf-Rayet stars. VIII. Summaryand atlas. Chu, Y. -H. ; Treffers, R. R. ; Kwitter, K. B. Abstract Photographs for ten galactic ring nebulae associated with WR stars are presented, and references are given to published photographs for other such nebulae. Every WR ring nebula suggested in the literature is discussed and reevaluated. Fabry-Perot data have been obtained for two new nebulae in order to diagnose their formation mechanisms. Seven stellar wind-blown bubble type (W type), two stellar ejecta type, four shell-structured H II region type (Rs type), and two amorphous region type nebulae are acknowledged. Most W-type nebulae are associated with early-type WN stars, while most Rs-type nebulae surround WC stars. The implications of statistical results for these ring nebulae are discussed. Publication: The Astrophysical Journal Supplement Series Pub Date: December 1983 DOI: 10.1086/190914 Bibcode: 1983ApJS...53..937C Keywords: Galactic Structure; Nebulae; Ring Structures; Wolf-Rayet Stars; Astronomical Catalogs; H Ii Regions; Stellar Winds; Astrophysics full text sources ADS | data products SIMBAD (42) Related Materials (7) Part 1: 1981ApJ...249..195C Part 2: 1981ApJ...249..586C Part 3: 1981ApJ...250..615C Part 4: 1982ApJ...254..562C Part 5: 1982ApJ...254..569T Part 6: 1982ApJ...254..578C Part 7: 1982ApJ...254..132T

W50 - a stellar-wind bubble in a three-phase interstellar medium?

L'interaction entre les jets relativistes de SS 433 et la nebuleuse radio W 50 est analysee sur la base d'observations recentes. On trouve que SS 433 pourrait etre entouree d'un milieu interstellaire nuageux, du type de celui decrit par le modele a 3 phases de McKee et Ostriker. W 50 est probablement une bulle interstellaire en expansion, entrainee par un fort vent stellaire du compagnon de SS 433 plutot qu'un reste de supernova

The W28 Supernova and the Surrounding Interstellar Medium

A large shell, 1.5 degrees in diameter, outlined by nebulosity and dust clouds has been found centred on the W28 supernova remnant. Obscuration has been studied over a 2 degree square area centred on W28. The W28 SNR is coincident with a region of reduced obscuration. The densest parts of the obscuration AB≥ 4m is coincident with the molecular clouds associated with M20 and the OH maser to the south of M20.The observed absorption is interpreted as being the result of the expansion of the W28 SNR into an older pre-existing SNR or stellar wind bubble.

Ring nebulae associated with of stars: Statistics, classification, origin

The ring nebulae associated with galactic Of stars is considered on the grounds of the list of Of nebulae proposed by lozinskaya and Lomovsky (1982). Taking into account the selection effects, about 80% of Of stars are shown to be associated withHii regions and about 30–50% of these regions have shell structures. Four types of nebulae associated with Of stars are resolved: amorphousHii regions, ring-likeHii regions, wind-blown bubbles, and stellar ejectas. These types appear to be identical to the morphology of nebulae around WR stars proposed by Chu (1981). Observational data are presented and the nature of a number of Of ring nebulae of different types is discussed.

Ultraviolet absorption by interstellar gas near the LMC star HD 36402 in the interstellar bubble N51D

Four interstellar absorption components associated with the immediate surroundings of the star are found in UV, high-dispersion IUE spectra of the LMC star HD 36402 in the N51D nebulosity. The 305 km/sec absorption is found to originate in low-density, 10,000 K gas, and the density and velocity structures agree with that derived from visual emission lines. From a fit of the observed Lyman-alpha profile, it is found that there is an N(H) of about 10 to the 20.2/sq cm in front of HD 36402, while the large N(H) of approximately 10 to the 21.3/sq cm from 21-cm data indicates most of the neutral gas to be behind N51D. An additional component shows N V, C IV and Si IV features which are stronger than is consistent with a wind-blown interstellar bubble, implying that there is additional absorption outside the bubble. Solar abundance ratios for the metals are suggested by the overall pattern of absorption line strength.

Galactic ring nebulae associated with Wolf-Rayet stars. V - The stellar wind-blown bubbles

Galactic ring nebulae associated with Wolf-Rayet stars. V - The stellar wind-blown bubbles

The nearest stellar wind bubble or fossil supernova remnant

A new series of ultra-deep, wide-angle Hα filter photographs at higher angular resolution than hitherto achieved, have been obtained covering the Orion-Taurus-Eridanus region. These reveal new, both diffuse and filamentary nebulosities near the Barnard Arc Nebula, which are correlated with Hi features in the region. Mechanisms capable of producing the observed features are discussed. Both a stellar wind bubble and a fossil supernova remnant are considered possible explanations, and would represent the nearest examples of these features to the Sun. Furthermore, nebulosity in this region has been photographed for the first time at [Nii]. The possible implications of this and other observations are discussed.

The Stellar Wind Bubble NGC2359 - Part One - CO VLA and Optical Observations

view Abstract Citations (38) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The stellar wind bubble NGC 2359. I. CO, VLA, and optical observations. Schneps, M. H. ; Haschick, A. D. ; Wright, E. L. ; Barrett, A. H. Abstract The symmetric ring nebula NGC 2359 ≡ S298 is believed to be an interstellar bubble blown by stellar winds from the Wolf-Rayet star HD 56925. Microwave observations of the nebula in CO and 13CO, and 20 cm VLA observations, are compared to narrow-band [O III] photographs of the region. Tile observations demonstrate for the first time that the stellar wind bubble is interacting with neutral material. Three CO clouds are observed, spread in velocity over 30 km s-1 and centered on the mean Hα velocity for the H II region. The CO velocities fall within the velocity range observed in the optical shell, suggesting that the neutral clouds may be driven to supersonic velocities by the stellar winds. At least one of the clouds appears to be in direct contact with the stellar wind bubble. To test for signs of recent star formation, a search was made for H2O maser emission, with negative results. Optical counterparts for two of the CO clouds have been identified on narrow-band filter photographs of the nebula. The high resolution 20 cm VLA observations resolve the filamentary structure of the shell, completing the bubble in regions obscured by the CO clouds. The VLA map agrees well with the optical photographs in regions which are free of CO. A search at 6 and 20 cm failed to reveal radio continuum emission from the W-R star at levels above 0.6 and 2.0 mJy, respectively, providing an upper limit for the mass-loss rate of Mdot = 7 × 10-5 Msun. Kinematic parameters inferred from the observations are compared to theoretical models for the evolution of stellar wind shells. It is shown that modest mass-loss rates can account for the supersonic motions observed in NGC 2359, even for models in which the stellar winds impact directly on the shell without the aid of a hot intermediate layer. Simple isotropic homogeneous models for the evolution of stellar wind shells produce serious inconsistencies when applied to NGC 2359. These assumptions are clearly violated in this object, which is bounded by dense neutral clouds in the east, and by low density ionized gas in the west. Pressure effects from the nonuniformly ionized ambient medium may contribute to the stellar wind pressures and modify the evolution of the nebula. Publication: The Astrophysical Journal Pub Date: January 1981 DOI: 10.1086/158582 Bibcode: 1981ApJ...243..184S full text sources ADS | data products SIMBAD (5)

Optical evidence for stellar wind bubbles in the Orion Nebula?

Optical evidence for stellar wind bubbles in the Orion Nebula?