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Energy concentration and loss due to a violent collapsing bubble are essential phenomena to many applications such as cavitation erosion, biomedical ultrasonics, sonochemistry, cavitation cleaning and underwater explosions. It has been generally known that the energy of a bubble system is radiated away as an acoustic wave and dissipated by viscosity. However, there is no study in the scientific literature on the time history of the energy of a bubble system in a compressible flow. Here we have introduced the local energy of a non-spherical bubble system, consisting of the energy of the interior gas, the interface and the exterior liquid in the inner asymptotic region. The local energy determines the local bubble and flow dynamics, including the concentration of energy, stress and momentum. We obtain a simple formula for the radiated energy associated with acoustic radiation in terms of the bubble volume history. We perform calculations of the energy history for a transient bubble in a compressible liquid in an infinite domain, subject to buoyancy and near a rigid boundary, respectively. Our calculations show that the local energy of a transient bubble follows a step function in time, being nearly conserved for most of each cycle of oscillation but decreasing rapidly and significantly at bubble inception and at the end of collapse, due to the emission of steep pressure waves or shock waves. The loss of the local energy of the bubble system due to the emission of steep pressure waves and the associated damping of the bubble oscillation are diminished by buoyancy effects and decrease with the buoyancy parameter. Similarly, the loss of the local energy of a bubble system is diminished by the presence of a rigid boundary and decreases with the proximity of the bubble to the boundary. We also analyse the energy concentration of single bubble sonoluminescence in a standing acoustic wave.

The Sun is located inside an enormous local cavity filled with a million degree, ionized hydrogen gas and surrounded by a wall of dense and cold gas, this cavity is known as the Local Bubble (LB). Since the tempreture of Local Bubble is high, the typical singly-ionized atoms or molecules can not survive at this high tempreture. To overcome this problem we should probe the Local Bubble using species which survive under this condition so we have done a whole sky survey in north hemisphere by observing absorptions in the Diffuse Interstellar Bands (DIBs) for sight-lines with distance >300 pc. We have done 30 nights observation and have observed 473 bright stars. We found that the correlations between 5780 Å DIBs and Na I D doublets inside of the LB is much more than carriers outside of the LB.

The aim of the present study, based on literature data, is to find signatures of the giant radio continuum structure Loop III on the nearby interstellar medium, and search for molecular cloud and star formation, possibly triggered by its expansion. The preliminary results are as follows: (1) The 3D map of the Local Bubble, published by Lallement et al. (2003) suggests that Loop III is probably more distant than the early models had indicated. (2) The molecular clouds at high galactic latitudes in the 2nd Galactic quadrant are probably associated with the neutral/molecular wall of Loop III. (3) Star formation in Lynds 1333 and Lynds 1082 (GF 9) might have been triggered by the expansion of Loop III. (4) The supernova(e), whose explosion produced Loop III, might have been located in the SU Cas association.

Pulsar scintillation measurements from the Ooty Radio Telescope (ORT) are used to investigate the distribution of scattering in the Local Interstellar Medium (LISM; region of ≲ 1 kpc of the Sun), specifically the region in and around the Local Bubble. A 3-component model, where the Solar neighborhood is surrounded by a shell of enhanced plasma turbulence, is proposed for the LISM. Further, the Ooty data, along with those from Parkes and other telescopes are used for investigating the distribution of scattering towards the nearby Loop I Superbubble.

Results from new observations of pulsars using the Ooty Radio Telescope (ORT) are used for investigating the structure of the Local Interstellar Medium (LISM). The observations show anomalous scintillation effects towards several nearby pulsars, and these are modeled in terms of large-scale spatial inhomogeneities in the distribution of plasma density fluctuations in the LISM. A 3-component model, where the Solar neighbourhood is surrounded by a shell of enhanced plasma turbulence, is proposed for the LISM. The inferred scattering structure is strikingly similar to the Local Bubble. Further, analysis based on recent scintillation measurements show evidence for enhanced scattering towards pulsars located in the general direction of the Loop I Superbubble. The model for the LISM has been further extended by incorporating the scattering due to turbulent plasma associated with Loop I.

We present here the results from an extensive scintillation study of twenty pulsars in the dispersion measure (DM) range 3 – 35 pc cm−3 carried out using the Ooty Radio Telescope, to investigate the distribution of ionized material in the local interstellar medium (LISM). Our analysis reveals several anomalies in the scattering strength, which suggest that the distribution of scattering material in the solar neighborhood is not uniform. Our model suggests the presence of a low density bubble surrounded by a shell of much higher density fluctuations. We are able to put some constraints on geometrical and scattering properties of such a structure, and find it to be morphologically similar to the local bubble known from other studies.

In this contribution, we discuss some topics in the study of dust in the local interstellar medium. The spectrum of local clouds has recently been measured using ISO and COBE, confirming in general the models of excitation and cooling of dust illuminated by the the interstellar radiation field. We discuss in some detail the spatial correlation of interstellar dust and gas and the idea that infrared emission traces the total column density of the interstellar medium, with the particular application to the formation of H2. We also show that dust is present in the nearby Loop I shell, with properties similar to average, suggesting that the walls of the Local Bubble would also have relatively ‘normal’ dust content.

High latitude observations find C3+, N4+, and O5+, while shadowing by intervening hydrogen clouds indicates the presence of soft X-ray emitting gas in the halo of our galaxy. This paper reports on detailed hydrocode simulations of one of the possible source types: isolated supernova remnants evolving in the tenuous ambient medium of the halo. Their O5+ column densities are similar to those observed from the halo. The N4+, C3+, and X-ray properties are also simulated and discussed. The calculations may also be of interest for the Local Bubble, external galaxies, and non-thermal pressure estimations.

The Local Bubble (LB), a volume of roughly 100 pc radius filled with ionized gas of high temperature and low density, is not a unique object. It is obviously surrounded by several interstellar bubbles of similar properties. Some of them are as close as to undergo interaction with the LB. Our most prominent neighbour is the Loop I superbubble formed by the Sco-Cen OB association. It is shown that this huge shell is in collision with our Local Bubble. The product of this interaction is an annular cloud of dense neutral gas at the boundary between the two bubbles. Other examples for close neighbouring bubbles are the Gum nebula, the Eridanus bubble and possibly the two radio loops II and III.

We discuss details in the galactic HI distribution, which are relevant for studies of the Local Bubble. All results are based on the 21 cm Sky survey with the Large Pulkovo Radiotelescope. The antenna temperature scans were decomposed in two components and after the subtraction of the broad one two details in the residual are presented in this paper. The first is an estimate of the distance to the Sancisi-van Woerden filament in the Sco-Oph region. The second is the connection of a 21 cm feature in the southern galactic quadrant II with the negative-velocity elliptical brightness distribution around the South Pole of the Galaxy.

Modeling the Local Bubble is one of those activities fraught with danger. It is very easy to be too naive, to fail to consider the dependence of the model on assumptions about the nearby ambient state, or the likelihood of such a structure. It is similarly easy to become so caught up in the details of the vicinity that it is unclear where to begin a necessarily idealized modeling effort. And finally, it is important to remember that the data we have may in some cases be lying to us, and that we have not yet learned to read their facial expressions quite carefully enough.That said, I’ve tried in this paper to be helpful to those who may wish to take the risks. I surveyed the very most basic stories that the data seem to tell, and pointed out the standard coincidences that may be telling us a lot about what is happening, but may turn out once again to have been just coincidences. I’ve described 5 distinct conceptions that in one flavor or another pretty well survey the collection of mental images that have so far been carried by those who’ve attempted models. One may be right, or something entirely different may be more appropriate. It’s at least vital to realize that a conception comes first, followed by a simplified model of details. I’ve also included a long list of questions directed at observers. Some have partial answers, some one wouldn’t know today quite how to approach. But it is a list that students of the soft x-ray background, interstellar absorption lines, possible instrumentation, and the heliosphere may wish to review from time to time, just to see whether they can figure out how to be more helpful. There is another list for modelers, things the models must address, however-so-flimsily if necessary, because there are strong observational constraints (and stronger ones coming) on what can and cannot be present in the local ISM. To that I’ve added a few remarks concerning x-ray emission coming from beyond the Local Bubble, and another few on how x-ray emission from within the solar system might be contaminating what we see. That last bit is new, exciting, and possibly wrong, but it is an example of the ongoing wariness I believe one has to take toward the facts in the case. By the way, Dieter, it really was a great meeting.

Nearby late-B and early-A stars show clear IS absorptions in Mg II, C II and other lines (IUE spectra). Some of them, in the Sco Cen direction, also show absorption features at C IV and Si IV line wavelengths. We discuss the possible formation of these lines in an intermediate temperature gas region between the dense and cold H I wall and the hot ISM, a region that could be the collision interaction between the Local Bubble and the Loop I supershell. Some individual stellar spectra are presented and discussed.

The EURD instrument has been designed to measure diffuse emission in the extreme ultraviolet (350–1100 Å). This new design provides an unprecedented 4–5 Å spectral resolution and 200 photons/sec/cm2/sr sensitivity after only 100 hours of observations. One of the goals of this project is to search for spectral lines of highly ionized species from the high temperature component (105 – 106 K) of the interstellar medium that fills the Local Bubble. It is expected that EURD will detect lines due to a thermalized hot component of the interstellar medium, and it will also provide critical diagnostics of the physical properties of this gas. With EURD data we could also detect a spectral line due to the decay of massive neutrinos as well as study oxygen lines from the upper atmosphere airglow. EURD is on board the Spanish MINISAT-01 satellite.

Soft X-ray background data from the ROSATPSPC have been fitted by a model including emission from the local bubble, embedded hot gas within the disk, hot gas in the Galactic halo and extra-galactic emission, together with local and disk absorption. In all directions a halo component at 106.2 K (0.2 keV) is required for an acceptable fit. The halo emission measure shows spatial variability and the global trend suggests a disk-like planar rather than more extended spherical distribution. New values for the emission measure within the local bubble are derived.

Ultraviolet absorption lines from carbon atoms within a neutral cloud inside or near the edge of the Local Bubble can reveal the thermal pressure of the gas, since the relative populations of the fine-structure levels are determined by a balance between collisional excitation and radiative decay. Features from a C I multiplet appearing in the uv spectrum of the starδCyg (l= 79°,b= +10°,d= 52 pc) were observed with the echelle spectrograph of the Goddard High Resolution Spectrograph on HST. An interpretation of absorptions detected from the two lowest levels gives a thermal pressure range 102.7

The Diffuse X-ray Spectrometer (DXS) obtained spectra of the low energy X-ray (44 – 83 Å) diffuse background near the galactic plane from galactic longitudes 150° ≲ l ≲ 300° with ≲ 3 Å spectral resolution and ~ 15° angular resolution. Thus, DXS measured X-ray spectra that arise almost entirely from within the Local Bubble. The DXS spectra show emission lines and emission-line blends, indicating that the source of the X-ray emission is thermal – hot plasma in the Local Bubble. The measured spectra are not consistent with those predicted by standard coronal models, either with solar abundances or depleted abundances, over the temperature range 105 – 107 K. The measured spectra are also inconsistent with the predictions of various non-equilibrium models. A nearly acceptable fit to DXS spectra can be achieved using a hybrid model that combines the Raymond & Smith ionization balance calculation with recently calculated (by DAL) ionic emission lines.