scholarly journals Planckearly results. XXI. Properties of the interstellar medium in the Galactic plane

2011 ◽  
Vol 536 ◽  
pp. A21 ◽  
Author(s):  
◽  
A. Abergel ◽  
P. A. R. Ade ◽  
N. Aghanim ◽  
M. Arnaud ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Galactic Plane

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 Microwave Interstellar Medium Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust

2004 ◽  
Vol 617 (1) ◽  
pp. 350-359 ◽  
Author(s):  
Douglas P. Finkbeiner ◽  
Glen I. Langston ◽  
Anthony H. Minter
Keyword(s):  
Interstellar Medium ◽  
Galactic Plane

scholarly journals Search for and study of pulsars with the Nançay Radio Telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 386-387
Author(s):  
Franck Octau ◽  
Grégory Desvignes ◽  
Ismaël Cognard ◽  
David Champion ◽  
Patrick Lazarus ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Radio Telescope ◽  
Galactic Plane ◽  
Strong Field ◽  
Sampling Time ◽  
Current Status ◽  
Black Widow ◽  
Gravitation Wave ◽  
Tests Of Gravity

AbstractSince the discovery of the first pulsar in 1967, over 2500 pulsars have been discovered. Pulsars enable a broad range of studies: from the study of the properties of the interstellar medium and of pulsar magnetospheres to tests of gravity in the strong-field regime and the characterisation of the cosmological gravitation wave background. These reasons are the main drive for searching for more pulsars. A blind pulsar survey, named SPAN512, was initiated with the Nançay Radio Telescope in 2012. Conducted at 1.4 GHz with a sampling time of 64μs and 500-kHz frequency channels, SPAN512 was designed to search for fast and distant pulsars in the Galactic plane. Here we describe the current status of the survey and present the latest discovery, PSR J2055+3829, a 2.08-ms pulsar in a black widow system.

scholarly journals G54.4–0.3 — Multi-Frequency Investigation of an SNR in Interaction with the ISM

1996 ◽  
Vol 169 ◽  
pp. 627-628
Author(s):  
N. Junkes
Keyword(s):  
Interstellar Medium ◽  
Northern Hemisphere ◽  
Supernova Remnant ◽  
Galactic Plane ◽  
Point Sources ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Shell Type ◽  
Fir Spectra

G54.4–0.3 is an extended shell-type supernova remnant (SNR) in the Galactic plane. We selected this source as a candidate for the interaction of SNRs with the interstellar medium on the base of an investigation of cool IRAS point sources in the direction of SNRs. We found a statistical excess of IRAS sources with FIR spectra similar to young stellar objects (Td ≈ 25 − 45 K) in the vicinity of G54.4–0.3 and a number of other SNRs in the northern hemisphere (Junkes & Fürst 1992).

scholarly journals A Close Look at the Galactic Ecosystem: the Canadian Galactic Plane Survey

2009 ◽  
Vol 5 (H15) ◽  
pp. 804-804
Author(s):  
Roland Kothes ◽  
Tom L. Landecker
Keyword(s):  
Life Cycle ◽  
Interstellar Medium ◽  
Galactic Plane ◽  
Dynamic Range ◽  
Galactic Disk ◽  
Density Waves ◽  
Spiral Density Waves ◽  
Infrared Surveys

AbstractEnergy and mass interchanges in the interstellar medium are driven by the life-cycle of stars. They appear in our own Galaxy over a broad range of scales, from point-like injection from stars to global input on the scale of spiral density waves. Understanding this Galactic Ecosystem requires observations of the different phases of the ISM over this large angular dynamic range. The Canadian Galactic Plane Survey (CGPS) is a project to combine radio, millimeter, and infrared surveys of the Galactic plane, providing arcminute-scale images of all major components of the interstellar medium over a large portion of the Galactic disk.

scholarly journals Long-term Monitoring of Molonglo Calibrators

2000 ◽  
Vol 17 (1) ◽  
pp. 72-82 ◽  
Author(s):  
B. M. Gaensler ◽  
R. W. Hunstead
Keyword(s):  
Interstellar Medium ◽  
Light Curve ◽  
Time Scales ◽  
Galactic Plane ◽  
Line Of Sight ◽  
Radio Sources ◽  
Before And After ◽  
Long Term Monitoring ◽  
Term Monitoring

AbstractBefore and after every 12 hour synthesis observation, the Molonglo Observatory Synthesis Telescope (MOST) measures the flux densities of ∼5 compact extragalactic radio sources, chosen from a list of 55 calibrators. From 1984 to 1996, the MOST made some 58,000 such measurements. We have developed an algorithm to process this dataset to produce a light curve for each source spanning this thirteen-year period. We find that 18 of the 55 calibrators are variable, on time scales between one and ten years. There is the tendency for sources closer to the Galactic Plane to be more likely to vary, which suggests that the variability is a result of refractive scintillation in the Galactic interstellar medium. The sources with the flattest radio spectra show the highest levels of variability, an effect possibly resulting from differing orientations of the radio axes to the line of sight.

scholarly journals Polarization Gradient Study of Interstellar Medium Turbulence Using the Canadian Galactic Plane Survey

2017 ◽  
Vol 835 (2) ◽  
pp. 210 ◽  
Author(s):  
C. A. Herron ◽  
J. Geisbuesch ◽  
T. L. Landecker ◽  
R. Kothes ◽  
B. M. Gaensler ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Galactic Plane ◽  
Polarization Gradient

scholarly journals The SEDIGISM survey: First Data Release and overview of the Galactic structure

2020 ◽  
Vol 500 (3) ◽  
pp. 3064-3082 ◽  
Author(s):  
F Schuller ◽  
J S Urquhart ◽  
T Csengeri ◽  
D Colombo ◽  
A Duarte-Cabral ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Large Scale ◽  
Galactic Plane ◽  
Structural Features ◽  
Galactic Centre ◽  
Molecular Gas ◽  
Spiral Arms ◽  
Star Forming ◽  
Wide Range ◽  
Data Release

ABSTRACT The SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey used the APEX telescope to map 84 deg2 of the Galactic plane between ℓ = −60° and +31° in several molecular transitions, including 13CO (2 – 1) and C18O (2 – 1), thus probing the moderately dense (∼103 cm−3) component of the interstellar medium. With an angular resolution of 30 arcsec and a typical 1σ sensitivity of 0.8–1.0 K at 0.25 km s−1 velocity resolution, it gives access to a wide range of structures, from individual star-forming clumps to giant molecular clouds and complexes. The coverage includes a good fraction of the first and fourth Galactic quadrants, allowing us to constrain the large-scale distribution of cold molecular gas in the inner Galaxy. In this paper, we provide an updated overview of the full survey and the data reduction procedures used. We also assess the quality of these data and describe the data products that are being made publicly available as part of this First Data Release (DR1). We present integrated maps and position–velocity maps of the molecular gas and use these to investigate the correlation between the molecular gas and the large-scale structural features of the Milky Way such as the spiral arms, Galactic bar and Galactic Centre. We find that approximately 60 per cent of the molecular gas is associated with the spiral arms and these appear as strong intensity peaks in the derived Galactocentric distribution. We also find strong peaks in intensity at specific longitudes that correspond to the Galactic Centre and well-known star-forming complexes, revealing that the 13CO emission is concentrated in a small number of complexes rather than evenly distributed along spiral arms.

scholarly journals How Important is Neutral Carbon to an Understanding of the Dense Interstellar Medium?

1996 ◽  
Vol 169 ◽  
pp. 469-478
Author(s):  
D.T. Jaffe
Keyword(s):  
Interstellar Medium ◽  
Large Scale ◽  
Galactic Plane ◽  
Recent Analysis ◽  
Know How ◽  
Neutral Gas ◽  
Trace Species ◽  
Ultraviolet Photons ◽  
Trace Constituents ◽  
The Relationship

In virtually all of the dense interstellar medium, H2 is the most abundant form of hydrogen, but it is not directly observable in the bulk of the gas. As a result, we are forced to use trace constituents of the gas as surrogates when we want to know the distribution of material in the dense ISM. Most commonly, we employ the lowest few rotational transitions of CO and its isotopes as the trace species. One of the most hotly debated issues in the study of the molecular ISM is the extent to which one can trust CO or isotopic CO lines to reflect reliably the underlying H2 distribution (see Shier, Rieke, & Rieke (1994), Sodroski et al. (1995) for recent comments on the I(12CO)/N(H2) ratio and Lada et al. (1994) for a recent analysis of the relationship between isotopic CO and total cloud column densities). CO becomes increasingly unreliable as a tracer of H2 as the average column density between cloud surfaces exposed to ultraviolet photons and the shielded centers of clouds becomes smaller. Young stars in the galactic plane perfuse atomic and molecular clouds with far–UV (λ > 91 nm) radiation. This radiation tends to dissociate CO more readily than it dissociates H2 (Van Dishoeck & Black 1988). The differences in susceptibility of H2 and CO to photodissociation may lead to the existence of significant portions of the molecular medium where the usual trace species are underabundant or even absent. In addition, there is dense H I at the cloud boundaries, immediately outside the molecular material. In the UV–illuminated cloud surfaces, the gas-phase carbon is in the form of C I or C II. It is important, therefore, to determine the amount and location of large-scale C I emission if one hopes to know how much molecular and dense atomic gas is missing from studies using CO as a tracer and to what extent photodissociation is responsible for the absence of this CO. We discuss here some of the relevant theoretical and observational work on the relationship between C II, C I, CO and H2. Our principal aim is to see if and how observations of C I might help us to improve our knowledge of the distribution of dense neutral gas in the Milky Way.

scholarly journals Theoretical Problems in the Interstellar Medium

1992 ◽  
Vol 9 ◽  
pp. 109-114
Author(s):  
J. Michael Shull
Keyword(s):  
Interstellar Medium ◽  
Galactic Plane ◽  
Line Emission ◽  
Diffuse Emission ◽  
Ionization Source ◽  
Vertical Support ◽  
Gas Layer ◽  
Intercloud Medium ◽  
Small Dust ◽  
Theoretical Developments

AbstractI review recent theoretical developments in the structure, heating, and ionization of the interstellar medium. Among the unsolved issues are: the vertical support of the gas layer; the ionization source for the H+ layer and diffuse line emission above the Galactic plane; the physics of stochastic heating of small dust grains and the resulting infrared spectra. Turbulent mixing may play an important role in the intercloud medium and diffuse emission above the disk. I conclude with some possible analogies between the intergalactic medium and the interstellar medium.

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