scholarly journals The Morphology and Physics of the Local Interstellar Medium

1996 ◽  
Vol 152 ◽  
pp. 261-268 ◽  
Author(s):  
Fredrick C. Bruhweiler
Keyword(s):  
Interstellar Medium ◽  
Radiation Field ◽  
Special Role ◽  
Low Density ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Density Region ◽  
Direct Measurements ◽  
Extreme Uv ◽  
Local Cloud

We are finally on the threshold of obtaining a coherent morphological and physical picture for the local interstellar medium (LISM), especially the region within 300 pc of the Sun. The EUVE is playing a special role in revealing this picture. This instrument can provide direct measurements of the the radiation field that photoionizes both hydrogen and helium. It also can yield direct measurements of the column densities of hydrogen, but especially He I and He II toward nearby white dwarfs. These observations suggest that the ionization in the Local Cloud, the cloud in which the Sun is embedded, is not in equilibrium, but in a recombination phase. Heuristic calculations imply that the the present ionization is due to the passage of shocks, at times greater than 3 × 106 years ago. The origin of these shocks are probably linked to the supernova which was responsible for the expanding nebular complex of clouds know as the Loop I supernova remnant, of which the Local Cloud is a part, extreme- UV radiation field, that which ionizes both hydrogen and helium in the LISM. Of the ISM within 300 pc, the volume appears to be predominantly filled by hot (106 K) coronal gas. This gas is laced with six largescale shell structures with diameters ~100−150 pc including the long-recognized radio loops, Loop I−IV, as well as the Orion-Eridanus and Gum Nebulae are identified. An idea that has evolved in the literature for over two decades is that the kinematically-linked OB associations representing Gould’s Belt, plus the gas and dust of Lindblad’s Ring, require that previous supernova activity and stellar winds carved out a 400–600 pc diameter cavity some 3 to 6 × 107 yr ago. This activity produced a pre-existing low density region, into which the present young loop structures have expanded. The outer boundaries of the identified expanding loop structures, inside this preexisting cavity, delineate the periphery of the the mis-named “local interstellar bubble.” Thus, this picture naturally explains some of the problems often associated with the presence of this low density region exterior to Loop I.

scholarly journals The Intrinsic Properties of the Local Interstellar Medium

1997 ◽  
Vol 166 ◽  
pp. 29-32 ◽  
Author(s):  
Olivia Puyoo ◽  
Lotfi Ben Jaffel
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
Interstellar Cloud ◽  
Actual State ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Intrinsic Properties ◽  
Hydrogen Density ◽  
Self Consistent ◽  
Local Cloud

AbstractWe propose a new method to constrain the actual state of the interstellar cloud that surrounds the solar system. Using Voyager UVS Lyman-α sky maps and the powerful principle of invariance, we derive the H distribution all along the spacecraft path. Provided current models of the heliopause interface between the solar and the interstellar winds, we extrapolate this distribution to farther distances from the Sun and infer in a self consistent way key parameters of the local cloud. Our findings are a high interstellar hydrogen density of ~ 0.24 cm−3 and a weak ionization .

scholarly journals Observations of Local Interstellar Mg I and Mg II

1984 ◽  
Vol 81 ◽  
pp. 64-66 ◽  
Author(s):  
F. Bruhweiler ◽  
W. Oegerle ◽  
E. Weiler ◽  
R. Stencel ◽  
Y. Kondo
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Upper Limits

AbstractWe have combined Copernicus and IUE observations of 5 stars within 50 pc of the Sun to study the ionization of magnesium in the local interstellar medium (LISM). The high resolution Copernicus spectrometer was used to detect interstellar Mg I 2852 in the spectra of α Gru, α Eri, and α Lyr, while placing upper limits on Mg I in the spectra of α CMa and α PsA. Observations of Mg II 2795, 2802 for these stars were also obtained with IUE and Copernicus. The column densities of Mg I and Mg II are used to place constraints on the temperature of the LISM.

scholarly journals Heating of the Interstellar Medium by Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 385-392
Author(s):  
Donald P. Cox
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Low Density ◽  
The Sun ◽  
X Ray ◽  
Interstellar Material ◽  
X Ray Background

We observe the heating of interstellar material in young supernova remnants (SNR). In addition, when analyzing the soft X-ray background we find evidence for large isolated regions of apparently hot, low density material. These, we infer, may have been heated by supernovae. One such region seems to surround the Sun. This has been modeled as a supernova remnant viewed from within. The most reasonable parameters are ambient density no ~ 0.004 cm−3, radius of about 100 pc, age just over 105 years (Cox and Anderson 1982).

scholarly journals Observations of [OI]63 μm line emission in main-sequence galaxies at z ∼ 1.5

2020 ◽  
Vol 499 (2) ◽  
pp. 1788-1794
Author(s):  
J Wagg ◽  
M Aravena ◽  
D Brisbin ◽  
I Valtchanov ◽  
C Carilli ◽  
...  
Keyword(s):  
Field Strength ◽  
Interstellar Medium ◽  
Radiation Field ◽  
Uv Radiation ◽  
Main Sequence ◽  
Line Emission ◽  
The Other ◽  
Low Density ◽  
Star Forming ◽  
Neutral Gas

ABSTRACT We present Herschel–PACS spectroscopy of four main-sequence star-forming galaxies at z ∼ 1.5. We detect [OI]63 μm line emission in BzK-21000 at z = 1.5213, and measure a line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$ L⊙. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G ∼ 320G0, and gas density, n ∼ 1800 cm−3, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [O i]63 μm line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (1.1\pm 0.2)\times 10^9$ L⊙. We find that the implied luminosity ratio, $L_{\rm [O\, {\small I}]63\, \mu m}/L_{\rm IR}$, of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z ∼ 6. The high [O i]63 μm line luminosities observed in BzK-21000 and the z ∼ 1−3 dusty and sub-mm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas.

scholarly journals Kinematical Structure of the Local Interstellar Medium

1997 ◽  
Vol 166 ◽  
pp. 195-198
Author(s):  
R. Génova ◽  
J. E. Beckman ◽  
J. Rodríguez Álamo
Keyword(s):  
Interstellar Medium ◽  
Velocity Vector ◽  
Galactic Center ◽  
Galactic Plane ◽  
The Sun ◽  
Local Interstellar Medium

AbstractObservations of interstellar Na I in the spectra of 93 stars within 315 pc from the Sun show that it lies in a tunnel of gas moving away from Scorpio-Centaurus and is surrounded by gas moving toward the Galactic center.Gas approaches the Sun from Scorpio-Centaurus expanding from (r, l, b)=(160 pc, 313°7, +28°2) with LSR velocity 15.3 km s−1. The radius of this shell is 153 pc.We identify these clouds:D: velocity vector (υd, ld, bd)=(+7.2 km s−1, 305°1, −13°5), above and below the Galactic plane (GP) in the range of Galactic longitudes 357°–55°.C: velocity vector (υc, lc, bc)=(+11.5 km s−1, 349°0, −35°2), above and below the GP in the range 30°≤l≤110°.M: velocity vector (υm, lm, bm)=(+21.9 km s−1, 34°2, +1°5), above and below the GP in the range 100°≤l≤130°.P: velocity vector (υp, lp, bp)=(+13.8 km s−1, 244°9, +5°4), above and below the GP from l~120° to the limit of our data at l~210°.E: velocity vector (υe, le, be)=(+16.8 km s−1, 208°4, +6°2) in the range 160°≤l≤185° and −10°≤b≤–35°.A: velocity vector (υa, la, ba)=(+12.9 km s−1, 73°6, −5°6) towards the Galactic anti-center, below the GP.I: velocity vector (υi, li, bi)=(+37.7 km s−1, 132°8, −64°3) towards the Galactic anti-center, above the GP.

scholarly journals Study of the LISM Using Pulsar Scintillation

1997 ◽  
Vol 166 ◽  
pp. 211-214
Author(s):  
N.D.R. Bhat ◽  
Y. Gupta ◽  
A.P. Rao
Keyword(s):  
Interstellar Medium ◽  
Radio Telescope ◽  
Density Fluctuations ◽  
Solar Neighborhood ◽  
Dispersion Measure ◽  
Low Density ◽  
Local Interstellar Medium ◽  
Local Bubble ◽  
Scattering Material ◽  
Scattering Strength

AbstractWe 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.

Neutral component of the local interstellar medium

2019 ◽  
Vol 91 (2) ◽  
pp. 272-280 ◽  
Author(s):  
Wojciech Konior ◽  
Romana Ratkiewicz ◽  
Jan Kotlarz
Keyword(s):  
Interstellar Medium ◽  
Impact Ionization ◽  
Current Knowledge ◽  
Experimental Investigations ◽  
Interstellar Space ◽  
The Sun ◽  
Neutral Component ◽  
Local Interstellar Medium ◽  
Hydrogen Atoms ◽  
Content Type

Purpose This paper aims to review the current knowledge about the neutral component of the local interstellar medium (LISM), which due to the resonant charge exchange, photoionization and electron impact ionization processes has a profound impact on the heliosphere structure. Design/methodology/approach This work is based on the heliospheric literature review. Findings The summary of four major effects of neutral hydrogen atoms penetrating solar wind (SW), i.e. the disappearance of the complicated flow structure; the emergence of “hydrogen wall” in front of the heliopause (HP); decreasing distance of termination shock (TS), HP and bow shock (BS) layer from the Sun; and recently discovered by the Interstellar Boundary Explorer mission, a region of enhanced energetic neutral atom (ENA) emission seen in all sky maps as a ribbon. Practical implications In the context of constantly developing space technologies in aerospace engineering and prospective deep space missions, there is a need of general reviews about the interstellar space surroundings of the Sun and gathering the knowledge to help in theoretical, numerical and experimental investigations such as the optimization of the scientific equipment and spacecraft structure to work in specific conditions. Originality/value The survey encapsulate basic and relevant processes playing an important role in the physics of the nearest surroundings of the Sun and the latest results of numerical and experimental investigations focused on the neutral LISM component and its influence on the heliosphere, which is strongly desired in future works. Until now, not many of such reviews have been done.

scholarly journals Interstellar Scintillation Studies of Pulsars and Distribution of Scattering Plasma in the Local Interstellar Medium

2001 ◽  
Vol 182 ◽  
pp. 171-174
Author(s):  
N.D. Ramesh Bhat ◽  
Yashwant Gupta ◽  
A. Pramesh Rao ◽  
P.B. Preethi
Keyword(s):  
Interstellar Medium ◽  
Radio Telescope ◽  
Plasma Turbulence ◽  
Solar Neighborhood ◽  
Component Model ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Local Bubble ◽  
Interstellar Scintillation

AbstractPulsar 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.

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