Astrospheres, stellar winds, and the interstellar medium

Heliophysics ◽  
2016 ◽  
pp. 56-79
Author(s):  
Brian E. Wood ◽  
Jeffrey L. Linsky
Keyword(s):  
Interstellar Medium ◽  
Stellar Winds

scholarly journals The Violent Interstellar Medium of Nearby Dwarf Galaxies

1999 ◽  
Vol 16 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Gamma Ray ◽  
Dwarf Galaxies ◽  
Young Star ◽  
Stellar Winds ◽  
Star Forming ◽  
Star Forming Regions ◽  
Supernova Explosions ◽  
High Velocity Clouds ◽  
Ob Associations

AbstractHigh resolution HI observations of nearby dwarf galaxies (most of which are situated in the M81 group at a distance of about 3·2 Mpc) reveal that their neutral interstellar medium (ISM) is dominated by hole-like features most of which are expanding. A comparison of the physical properties of these holes with the ones found in more massive spiral galaxies (such as M31 and M33) shows that they tend to reach much larger sizes in dwarf galaxies. This can be understood in terms of the galaxy's gravitational potential. The origin of these features is still a matter of debate. In general, young star forming regions (OB-associations) are held responsible for their formation. This picture, however, is not without its critics and other mechanisms such as the infall of high velocity clouds, turbulent motions or even gamma ray bursters have been recently proposed. Here I will present one example of a supergiant shell in IC 2574 which corroborates the picture that OB associations are indeed creating these structures. This particular supergiant shell is currently the most promising case to study the effects of the combined effects of stellar winds and supernova explosions which shape the neutral interstellar medium of (dwarf) galaxies.

scholarly journals Massive stars shaping the ISM: H I holes and shells in nearby galaxies

1999 ◽  
Vol 193 ◽  
pp. 636-644
Author(s):  
Elias Brinks ◽  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Dwarf Galaxy ◽  
Massive Stars ◽  
Neutral Hydrogen ◽  
Neutral Medium ◽  
Stellar Winds ◽  
X Ray ◽  
Left Behind ◽  
Neutral Gas ◽  
Nearby Galaxies

Neutral hydrogen (H I) is a magnificent tool when studying the structure of the interstellar medium (ISM) as it is relatively easily observable and can be mapped at good spatial and velocity resolution with modern instruments. Moreover, it traces the cool (∼ 100 K) and warm (∼ 5000 K) neutral gas which together make up about 60%, or the bulk, of the ISM. The currently accepted picture is that stellar winds and subsequent supernovae are the origin for the clearly defined holes or bubbles within the more or less smooth neutral medium. The H I can therefore serve indirectly as a tracer of the hot interstellar medium (HIM) left behind after the most massive stars within an OB association have gone off as supernovae. A splendid example is the dwarf galaxy IC 2574 for which we discuss H I, optical and X-ray observations.

scholarly journals Search for HI Bubbles Around WR Stars: WR 149

1996 ◽  
Vol 169 ◽  
pp. 619-620
Author(s):  
C. Cappa de Nicolau ◽  
V.S. Niemela ◽  
U. Herbstmeier ◽  
B. Koribalski
Keyword(s):  
Interstellar Medium ◽  
Neutral Hydrogen ◽  
Gas Bubbles ◽  
Stellar Winds ◽  
Hydrogen Distribution ◽  
Neutral Gas ◽  
Rayet Star

The interaction of strong stellar winds with the interstellar medium creates large cavities or interstellar bubbles surrounded by expanding outer shells. 21-cm line (HI) observations have revealed the presence of such neutral gas bubbles around several WR stars (e.g. Niemela & Cappa de Nicolau 1991 and references therein; Dubner et al. 1992).Continuing our search for HI bubbles around WR stars, we have analyzed the neutral hydrogen distribution in the vicinity of the Wolf-Rayet star WR149, a highly reddened WN6-7 star located at 6.5 kpc in the direction (l,b) = (89.°53,+0.°65).

scholarly journals Low temperature gas phase reaction rate coefficient measurements: Toward modeling of stellar winds and the interstellar medium

2019 ◽  
Vol 15 (S350) ◽  
pp. 382-383
Author(s):  
Niclas A. West ◽  
Edward Rutter ◽  
Mark A. Blitz ◽  
Leen Decin ◽  
Dwayne E. Heard
Keyword(s):  
Low Temperature ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Building Blocks ◽  
Rate Coefficients ◽  
Stellar Winds ◽  
Phase Reaction

AbstractStellar winds of Asymptotic Giant Branch (AGB) stars are responsible for the production of ∼85% of the gas molecules in the interstellar medium (ISM), and yet very few of the gas phase rate coefficients under the relevant conditions (10 – 3000 K) needed to model the rate of production and loss of these molecules in stellar winds have been experimentally measured. If measured at all, the value of the rate coefficient has often only been obtained at room temperature, with extrapolation to lower and higher temperatures using the Arrhenius equation. However, non-Arrhenius behavior has been observed often in the few measured rate coefficients at low temperatures. In previous reactions studied, theoretical simulations of the formation of long-lived pre-reaction complexes and quantum mechanical tunneling through the barrier to reaction have been utilized to fit these non-Arrhenius behaviours of rate coefficients.Reaction rate coefficients that were predicted to produce the largest change in the production/loss of Complex Organic Molecules (COMs) in stellar winds at low temperatures were selected from a sensitivity analysis. Here we present measurements of rate coefficients using a pulsed Laval nozzle apparatus with the Pump Laser Photolysis - Laser Induced Fluorescence (PLP-LIF) technique. Gas flow temperatures between 30 – 134 K have been produced by the University of Leeds apparatus through the controlled expansion of N2 or Ar gas through Laval nozzles of a range of Mach numbers between 2.49 and 4.25.Reactions of interest include those of OH, CN, and CH with volatile organic species, in particular formaldehyde, a molecule which has been detected in the ISM. Kinetics measurements of these reactions at low temperatures will be presented using the decay of the radical reagent. Since formaldehyde and the formal radical (HCO) are potential building blocks of COMs in the interstellar medium, low temperature reaction rate coefficients for their production and loss can help to predict the formation pathways of COMs observed in the interstellar medium.

scholarly journals Chemical enrichment from Wolf-Rayet stellar winds

1999 ◽  
Vol 193 ◽  
pp. 218-226
Author(s):  
Georges Meynet
Keyword(s):  
Angular Velocity ◽  
Interstellar Medium ◽  
Mass Loss ◽  
Solar Nebula ◽  
Cosmic Ray ◽  
Stellar Winds ◽  
Chemical Enrichment ◽  
Galactic Cosmic Ray ◽  
Loss Rates

Stellar winds contribute together with supernovae explosions to the chemical enrichment of the interstellar medium. We recall how the metallicity dependence of the stellar winds implies a metallicity dependence of the stellar yields. We show that an increase of the initial angular velocity has different effects than an increase of the mass loss rates. Wolf-Rayet stars appear as important sources of 19F and 26Al. They are the favoured candidates for the 22Ne anomaly observed in the Galactic cosmic ray sources. They may also have injected into the proto-solar nebula short-lived radionuclides as 26Al, 36Cl, 41Ca, 107Pd and 205Pb.

scholarly journals HI Bubbles around NGC 6888

1996 ◽  
Vol 169 ◽  
pp. 617-618
Author(s):  
C. Cappa de Nicolau ◽  
C. Rogers ◽  
G. Dubner ◽  
N. St.-Louis
Keyword(s):  
Interstellar Medium ◽  
Stellar Winds ◽  
Interstellar Gas ◽  
Ring Nebula ◽  
Optical Ring

The interstellar bubbles are generally the result of the interaction of strong stellar winds with the surrounding material. HI voids and shells have been disclosed around several WR stars in our Galaxy (e.g. Niemela & Cappa de Nicolau 1991, Dubner et al. 1992). We report here an analysis of the interstellar medium in the vicinity of the WR star HD 192163 = WR 136 and the optical ring nebula NGC 6888 based on HI observations. Our aim is to look for the traces left in the cold interstellar gas by the action of the stellar winds of HD 192163.

scholarly journals The Surroundings of Gamma-Ray Bursts: Constraints on Progenitors

2005 ◽  
Vol 192 ◽  
pp. 441-450
Author(s):  
Roger A. Chevalier
Keyword(s):  
Interstellar Medium ◽  
Mass Loss ◽  
Massive Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Uniform Density ◽  
Stellar Winds ◽  
Wind Environment ◽  
Low Mass ◽  
Pulsar Wind

SummaryThe association of a supernova with a gamma-ray burst (GRB 030329) implies a massive star progenitor, which is expected to have an environment formed by pre-burst stellar winds. Although some sources are consistent with the expected wind environment, many are not, being better fit by a uniform density environment. One possibility is that this is a shocked wind, close to the burst because of a high interstellar pressure and a low mass loss density. Alternatively, there is more than one kind of burst progenitor, some of which interact directly with the interstellar medium. Another proposed environment is a pulsar wind bubble that has expanded inside a supernova, which requires that the supernova precede the burst.

scholarly journals Stochastic Starformation and Bubbles in the Large Magellanic Cloud

1984 ◽  
Vol 108 ◽  
pp. 89-90
Author(s):  
J. V. Feitzinger
Keyword(s):  
Interstellar Medium ◽  
Radiation Pressure ◽  
Hii Regions ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Shell Structures ◽  
Stellar Winds ◽  
Bubble Structure ◽  
Ring Nebulae

Nearly all places in the LMC where ring nebulae or shell structures in the neutral or ionized interstellar medium are observed, an OB association and/or WR-stars can be located (Braunsfurth, Feitzinger, 1983). Several mechanisms have been propsoed to generate shell or bubble structures: stellar winds, supernovae explosions, evolving HII regions, sequential starformation, collapsing hydrogen clouds interacting with stellar winds and radiation pressure. Ordered motions resulting in a shell or bubble structure are the result of almost any point like energy injection into the interstellar medium. Therefore all the mechanisms result in similar morphological structures, thus similar shapes can have heterogeneous origins.

scholarly journals Expanding bubbles in Orion A: [C II] observations of M 42, M 43, and NGC 1977

2020 ◽  
Vol 639 ◽  
pp. A2 ◽  
Author(s):  
C. H. M. Pabst ◽  
J. R. Goicoechea ◽  
D. Teyssier ◽  
O. Berné ◽  
R. D. Higgins ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Cosmological Parameters ◽  
Analytical Models ◽  
High Spectral Resolution ◽  
Expansion Velocity ◽  
Stellar Winds ◽  
Orion Nebula ◽  
Expansion Time

Context. The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to their strong radiation fields and stellar winds. Stellar feedback is one of the most crucial cosmological parameters that determine the properties and evolution of the interstellar medium in galaxies. Aims. We aim to understand the role that feedback by stellar winds and radiation play in the evolution of the interstellar medium. Velocity-resolved observations of the [C II] 158 μm fine-structure line allow us to study the kinematics of UV-illuminated gas. Here, we present a square-degree-sized map of [C II] emission from the Orion Nebula complex at a spatial resolution of 16′′ and high spectral resolution of 0.2 km s−1, covering the entire Orion Nebula (M 42) plus M 43 and the nebulae NGC 1973, 1975, and 1977 to the north. We compare the stellar characteristics of these three regions with the kinematics of the expanding bubbles surrounding them. Methods. We use [C II] 158 μm line observations over an area of 1.2 deg2 in the Orion Nebula complex obtained by the upGREAT instrument onboard SOFIA. Results. The bubble blown by the O7V star θ1 Ori C in the Orion Nebula expands rapidly, at 13 km s−1. Simple analytical models reproduce the characteristics of the hot interior gas and the neutral shell of this wind-blown bubble and give us an estimate of the expansion time of 0.2 Myr. M 43 with the B0.5V star NU Ori also exhibits an expanding bubble structure, with an expansion velocity of 6 km s−1. Comparison with analytical models for the pressure-driven expansion of H II regions gives an age estimate of 0.02 Myr. The bubble surrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis expands at 1.5 km s−1, likely due to the over-pressurized ionized gas as in the case of M 43. We derive an age of 0.4 Myr for this structure. Conclusions. We conclude that the bubble of the Orion Nebula is driven by the mechanical energy input by the strong stellar wind from θ1 Ori C, while the bubbles associated with M 43 and NGC 1977 are caused by the thermal expansion of the gas ionized by their central later-type massive stars.

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