scholarly journals An Aperture Synthesis Survey of the Galactic Plane

1974 ◽  
Vol 27 (5) ◽  
pp. 687 ◽  
Author(s):  
BB Jones ◽  
EA Finlay
Keyword(s):  
Brightness Temperature ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Absolute Temperature ◽  
Temperature Profiles ◽  
Contour Maps ◽  
Average Value ◽  
Low Surface Brightness ◽  
Carina Nebula ◽  
The Galaxy

The results of a survey already published have been used to construct contour maps and ruled surface diagrams of the brightness temperature at 29�9 MHz near the galactic plane between I = 225� and 30�. The angular resolution was 0�� 8 at the zenith, and the range of zenith angles involved was � 30�. Restoration of the background was achieved with the aid of a low resolution filled-aperture survey carried out by others. The brightness temperature scale was calibrated absolutely. The optical depth of the Galaxy in directions within 40� of latitude from the centre has been estimated by a method which relies only on the shapes of brightness temperature profiles and not on absolute temperature calibrations. If an electron temperature is assumed, r.m.s. electron densities can be deduced. The average value of the disc emissivity at 29�9 MHz and the value of its spectral index have been calculated from brightness temperature profiles observed at a number of different frequencies, calibrations being required for these purposes. About 29 discrete absorption regions have been observed and identified with optically observed HII regions, and the fact that these are all nearer than 4 kpc permits a choice between kinematic distances in two cases. The Carina nebula and RCW 108 lend themselves to the measurement of local emissivities, and values of these together with their implications have already been published. A number of previously unlisted nonthermal sources have been observed, many of which are objects of low surface brightness and probably are supernova remnants.

scholarly journals On a possible corrugation of the galactic plane

1970 ◽  
Vol 38 ◽  
pp. 147-150 ◽  
Author(s):  
C. M. Varsavsky ◽  
R. J. Quiroga
Keyword(s):  
Brightness Temperature ◽  
Solid Body ◽  
Rotation Curve ◽  
Galactic Plane ◽  
Maximum Temperature ◽  
Body Rotation ◽  
Maximum Brightness ◽  
Solid Body Rotation ◽  
The Galaxy ◽  
Sinusoidal Pattern

We have studied the rotation curve of the Galaxy at different heights below and above the equator. In the course of this work we noticed that the maximum brightness temperature of hydrogen oscillates around the galactic plane following a fairly sinusoidal pattern. It is further noticed that the maximum temperature of hydrogen occurs right on the plane in the regions where the rotation curve has a form indicating solid body rotation. A rotation curve based on points of maximum hydrogen temperature does not differ appreciably from a rotation curve measured on the galactic plane.

scholarly journals Extended Polarized Emission Structures in the Galactic Plane at 11 cm Wavelength

1990 ◽  
Vol 140 ◽  
pp. 63-64
Author(s):  
N. Junkes ◽  
E. Fürst ◽  
W. Reich
Keyword(s):  
Supernova Remnants ◽  
Spiral Structure ◽  
Galactic Plane ◽  
Radio Sources ◽  
Galactic Magnetic Field ◽  
Background Component ◽  
Polarized Emission ◽  
The Galaxy ◽  
Galactic Longitude ◽  
Thermal Background

Data from the Effelsberg Galactic plane survey at 11 cm wavelength have been used to produce a survey of polarized intensity in the first Galactic quadrant. Besides polarized sources (Supernova remnants and extragalactic objects) extended polarized emission features are visible, which are not connected to distinct radio sources. To decide whether these features reflect characteristics of the local field or the distant spiral structure of the Galaxy we performed an integration of polarized intensities as a function of Galactic longitude. An anticorrelation with the thermal background component suggests a distance of more than 6 kpc for some components of the polarized emission. This enables us to derive an upper limit for the uniform component of the Galactic magnetic field.

scholarly journals Radio Emission from Supernova Remnants

1996 ◽  
Vol 145 ◽  
pp. 333-340
Author(s):  
Richard G. Strom
Keyword(s):  
Cosmic Rays ◽  
Radio Emission ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Energy Content ◽  
Particle Energy ◽  
The Galaxy ◽  
Radio Frequencies ◽  
Shock Fronts

Most of the supernova remnants known in the Galaxy have only been detected at radio frequencies. The reason for this is absorption in the Galactic plane at both optical and X-ray wavelengths. All available evidence suggests that the shock fronts which accompany supernova remnants accelerate enough cosmic rays to GeV energies to produce readily detectable radio emission. This is fortunate, for it enables us to study remnants throughout the Galactic disk, although existing catalogues may be anywhere from 50 to 90 % incomplete. Cosmic rays and the magnetic fields in which they gyrate are the essential ingredients for producing the synchrotron radiation which is observed at radio frequencies. Various methods for estimating magnetic field strengths can be applied to a small number of remnants, and produce values not far from those based upon equipartition between the energy contents of particles and fields. From this, the particle energy content is derived for a number of objects.

scholarly journals A motion picture film of galactic 21-cm line emission

1970 ◽  
Vol 38 ◽  
pp. 122-125 ◽  
Author(s):  
G. Westerhout
Keyword(s):  
Galactic Plane ◽  
Line Emission ◽  
Neutral Hydrogen ◽  
Hydrogen Distribution ◽  
Motion Picture Film ◽  
Contour Maps ◽  
Latitude Range ◽  
The Galaxy ◽  
Line Survey ◽  
Line Work

Since 1964 we have been observing 21-cm line profiles in a new survey of the neutral hydrogen distribution in the neighborhood of the galactic plane with the 300-foot radio telescope of the National Radio Astronomy Observatory in Green Bank, W.Va. This is the largest telescope available for 21-cm line work; it has a beamwidth of 10 min of arc and is equipped with an excellent line receiver. Since it seems unlikely that an extensive hydrogen-line survey will be made with any larger telescope, we felt that for reference purposes a concerted effort should be made to obtain as many 21-cm data as possible pertaining to the structure of the Galaxy with this telescope. The data have been presented in the form of contour maps giving the intensity of the 21-cm line radiation as a function of right-ascension and velocity at constant declination. A series of contour maps was distributed to the astronomical community in 1966 as the first edition of the Maryland–Green Bank Galactic 21-cm Line Survey. The second edition, containing 1200 pages and approximately 1800 maps, was distributed in the summer and fall of 1969. It is expected that additional contour maps, completing the survey as originally planned, covering a latitude range from bII = +1° to −1°, lII = 11° to 235° (bII = +3° to −3° between lII = 100° and 145°), will be finished by the summer of 1970. Scans were made across the galactic equator with a stationary telescope, so that the declination is constant through each scan; the declination intervals varied from 4 to 6 min of arc. Eventually, we plan to cover a strip from bII = +5° to −5° between lII = 11° and 235°, containing 225000 independent points at intervals of 6 min of arc, with an effective beamwidth of 12.5 min of arc, a velocity resolution of 2 km s-1, and a total of 1.2 × 108 individual intensities.

scholarly journals Searching for Supernova Remnants

1998 ◽  
Vol 15 (1) ◽  
pp. 79-82 ◽  
Author(s):  
A. Walker ◽  
W. J. Zealey
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Galactic Plane ◽  
Chemical Properties ◽  
Optical Emission ◽  
Composite Image ◽  
Large Numbers ◽  
The Galaxy ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractThe UKST/AAO Galactic Plane Hα Survey has the potential to discover many new objects not visible on red plates taken in past surveys. Recent radio surveys have identified large numbers of new supernova remnants, very few of which have been optically identified. Here we will discuss our plans to use this survey to search for optical emission from both new and known supernova remnants. Observations of these objects in the optical and radio wavelengths will reveal important information about the physical and chemical properties of supernova remnants, and their role in the evolution of the galaxy. We also present a composite image of a newly discovered Hα shell around the Coalsack, named the Coalsack Loop. This object has been detected in radio emission and may represent the remains of an old supernova remnant.

scholarly journals Spatial Distribution of Pulsars and Supernova Remnants

1987 ◽  
Vol 40 (6) ◽  
pp. 837 ◽  
Author(s):  
AO Allakhverdiyev ◽  
OH Guseinov ◽  
IM Yusifov
Keyword(s):  
Spatial Distribution ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Close Binary System ◽  
Close Binary ◽  
Type I ◽  
Type Ii ◽  
Solar Mass ◽  
The Galaxy ◽  
Main Component

We show that the burst of Type I supernovas occurs about 108 years after the birth of the progenitor. This duration results in the main by the delay of the burst after the formation of a white dwarf of about one solar mass in a close binary system. The mass of the main component of this system is about 8M0 , and the mass of the secondary about 3M0 . These stars complete their evolution as Type I supernovas and are distributed along the galactic plane. Pulsars are formed about 107 years after the birth of their progenitors, and are accompanied by a Type II supernova. Pulsars therefore have an annular distribution in the Galaxy.

scholarly journals The Large-Scale Distribution of Synchrotron Emissivity in the Galaxy

1981 ◽  
Vol 94 ◽  
pp. 223-224 ◽  
Author(s):  
S. Kearsey ◽  
J. L. Osborne ◽  
S. Phillipps ◽  
C.G.T. Haslam ◽  
C. J. Salter ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Large Scale ◽  
Galactic Plane ◽  
Thermal Emission ◽  
Radio Continuum ◽  
3 Dimensional ◽  
The Galaxy ◽  
Dimensional Distribution ◽  
Alternative Approaches ◽  
Best Fit

The all-sky radio continuum map at 408 MHz presented at this symposium by Haslam et al. can be interpreted in terms of the large-scale 3-dimensional distribution of synchrotron emissivity in the Galaxy when due allowance is made for the thermal emission. Its derivation from a 2-dimensional map must involve a number of assumptions so it is instructive to compare the results of alternative approaches (described in detail in forthcoming papers by the present authors). In both cases the variation of emissivity in the galactic plane is obtained from the observed intensity profile at b=0o and then the z-variation is chosen to give the best fit to the complete map. The observed profile is shown in the figure with and without the contributions of catalogued supernova remnants and HII regions.

scholarly journals Optical and Radio Information

1968 ◽  
Vol 1 ◽  
pp. 206-209
Author(s):  
Hugh M. Johnson
Keyword(s):  
Cross Sections ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Optical Data ◽  
X Rays ◽  
Interstellar Gas ◽  
X Ray ◽  
The Galaxy ◽  
Ionization Cross Sections ◽  
Optical Astronomy

The six or eight optically identified X-ray sources comprise starlike objects and extended supernova remnants in the Galaxy, well as as a radio galaxy and a quasar. Both X-ray and radiofrequency radiation penetrate the entire galactic plane, but only two or three galactic radio sources have been identified with X-ray sources. This has led Hayakawa et al. to postulate that detectable X-ray sources are not farther than 1 kpc. However, other studies suggest that there is a cluster of a few intrinsically bright sources actually near the galactic nucleus and a scattering of weaker sources near the sun.The distances of X-ray sources can be estimated from extinction by interstellar gas or intergalactic gas on spectra above 10 Å, but the method ultimately depends on the radio and optical data of the gas. Conversely, interstellar densities of certain elements with large photo-ionization cross-sections may be determined from the absorption of X-rays, after calibration of source distances by the methods of optical astronomy.

scholarly journals The Ratan Galactic Plane Survey

1998 ◽  
Vol 179 ◽  
pp. 103-105
Author(s):  
S.A. Trushkin
Keyword(s):  
Spectral Data ◽  
Supernova Remnants ◽  
Milky Way ◽  
Galactic Plane ◽  
Radio Continuum ◽  
Radio Sources ◽  
Optical Identification ◽  
Source Distance ◽  
The Galaxy

Now in radio continuum surveys more than 10,000 radio sources have discovered in the Milky Way plane but the Galactic origin only of a small part of them has been determined. The problem comes from the absence of estimates of source distance and the optical identification even for bright radio sources, and the most of sources have not spectral data at 2-3 frequencies. As followed some hundreds of sources have not classified as thermal or non-thermal. Now we don't know the full number of supernova remnants (SNRs) in the Galaxy. The simple estimates show that a sample of Galactic SNRs is not full as for weak and extended (> 15′) as for bright and compact (< 3′) SNRs (Trushkin 1993).

scholarly journals Observations of Magnetic Fields in Galaxies

1992 ◽  
Vol 9 ◽  
pp. 81-86
Author(s):  
R. Wielebinski
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Large Scale ◽  
Galactic Plane ◽  
Building Blocks ◽  
Galactic Centre ◽  
Definitive Evidence ◽  
The Galaxy ◽  
The Universe

AbstractMagnetic fields are present in every corner of the Universe. The Earth, the Sun and most of the planets are known to possess dipolar magnetic fields. In the Galaxy many individual objects like stars, pulsars, bipolar nebulae and supernova remnants are found to have associated magnetic fields. It seems that the rotation plays a significant role in the ability of a cosmic object to develop a magnetic field. The magnetic field of the Galaxy is observed to be oriented along the galactic plane as evidenced by both optical and radio polarization observations. Radio maps of the Galactic centre reveal poloidal magnetic fields as ‘wisps’ or ‘strings’ around Sagittarius A. Observations of nearby galaxies give us remarkable information about the large-scale magnetic fields in these building blocks of the Universe. Magnetic fields play an important role in the formation of jets of radio galaxies. Further out, in clusters of galaxies, definitive evidence has been given for the existence of intergalactic magnetic fields.

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