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 Kinematics of Pulsars

1987 ◽  
Vol 125 ◽  
pp. 23-33
Author(s):  
A.G. Lyne
Keyword(s):  
Binary System ◽  
Supernova Remnants ◽  
Massive Stars ◽  
Normal Population ◽  
Hii Regions ◽  
Close Binary System ◽  
Close Binary ◽  
The Galaxy ◽  
Motion Measurements ◽  
Halo Population

Pulsars have a galactic radial distribution similar to that of many galactic populations such as HII regions, massive stars and supernova remnants. However they are generally much further from the plane of the Galaxy than these objects. Proper motion measurements sho that this is because they are typically moving with high velocities. The measurements also indicate that most pulsars were formed a few million years ago close to the plane, within the normal Population I regions. Some pulsars will escape from the Galaxy, although the majority will end up in a halo population. The origin of the high velocities is not clear at present but may be due either to some asymme try in the formation event or to the disruption of a close binary system.

scholarly journals Supernovae — Birthplace of Pulsars?

1981 ◽  
Vol 95 ◽  
pp. 403-416
Author(s):  
Roger A. Chevalier
Keyword(s):  
Neutron Star ◽  
Supernova Remnants ◽  
Massive Star ◽  
Type I ◽  
Type Ii ◽  
X Ray ◽  
The Core ◽  
The Galaxy ◽  
Recent Developments ◽  
Available Information

Recent developments in the theory of the light from supernovae indicate that while Type II supernovae probably involve the explosion of a massive star with an extended envelope, Type I supernovae may involve the total thermonuclear disruption of a white dwarf. The energy release in a Type II supernova is presumably related to the contraction of the core to a neutron star and pulsar formation is likely. The hypothesis that Type II supernovae leave pulsars while Type I supernovae do not leave compact remnants is shown to be consistent with the available information on X-ray sources containing neutron stars, young supernova remnants, and the distribution of pulsars in the galaxy. Some pulsars are probably formed in the explosion of a massive star that has lost its envelope. These events may not be accompanied by a bright supernova display.

scholarly journals Spatial distribution of exoplanet candidates based on Kepler and Gaia data

2020 ◽  
Vol 635 ◽  
pp. A191
Author(s):  
A. Maliuk ◽  
J. Budaj
Keyword(s):  
Spatial Distribution ◽  
Galactic Plane ◽  
Open Clusters ◽  
Field Of View ◽  
Solar Neighbourhood ◽  
Spatial Gradients ◽  
The Galaxy ◽  
Formation And Evolution ◽  
F Stars ◽  
Galactic Longitude

Context. Surveying the spatial distribution of exoplanets in the Galaxy is important for improving our understanding of planet formation and evolution. Aims. We aim to determine the spatial gradients of exoplanet occurrence in the Solar neighbourhood and in the vicinity of open clusters. Methods. We combined Kepler and Gaia DR2 data for this purpose, splitting the volume sampled by the Kepler mission into certain spatial bins. We determined an uncorrected and bias-corrected exoplanet frequency and metallicity for each bin. Results. There is a clear drop in the uncorrected exoplanet frequency with distance for F-type stars (mainly for smaller planets), a decline with increasing distance along the Galactic longitude l = 90°, and a drop with height above the Galactic plane. We find that the metallicity behaviour cannot be the reason for the drop of the exoplanet frequency around F stars with increasing distance. This might have only contributed to the drop in uncorrected exoplanet frequency with the height above the Galactic plane. We argue that the above-mentioned gradients of uncorrected exoplanet frequency are a manifestation of a single bias of undetected smaller planets around fainter stars. When we correct for observational biases, most of these gradients in exoplanet frequency become statistically insignificant. Only a slight decline of the planet occurrence with distance for F stars remains significant at the 3σ level. Apart from that, the spatial distribution of exoplanets in the Kepler field of view is compatible with a homogeneous one. At the same time, we do not find a significant change in the exoplanet frequency with increasing distance from open clusters. In terms of byproducts, we identified six exoplanet host star candidates that are members of open clusters. Four of them are in the NGC 6811 (KIC 9655005, KIC 9533489, Kepler-66, Kepler-67) and two belong to NGC 6866 (KIC 8396288, KIC 8331612). Two out of the six had already been known to be cluster members.

scholarly journals CSI in Supernova Remnants

2017 ◽  
Vol 12 (S331) ◽  
pp. 81-85
Author(s):  
You-Hua Chu
Keyword(s):  
Supernova Remnants ◽  
Hubble Space Telescope ◽  
Orbital Plane ◽  
Large Magellanic Cloud ◽  
Close Binary System ◽  
Close Binary ◽  
Binary Interaction ◽  
Space Telescope ◽  
Multi Wavelength ◽  
Mass Ejection

AbstractSupernovae (SNe) explode in environments that have been significantly modified by the SN progenitors. For core-collapse SNe, the massive progenitors ionize the ambient interstellar medium (ISM) via UV radiation and sweep the ambient ISM via fast stellar winds during the main sequence phase, replenish the surroundings with stellar material via slow winds during the luminous blue variable (LBV) or red supergiant (RSG) phase, and sweep up the circumstellar medium (CSM) via fast winds during the Wolf-Rayet (WR) phase. If a massive progenitor was in a close binary system, the binary interaction could have caused mass ejection in certain preferred directions, such as the orbital plane, and even bipolar outflow/jet. As a massive star finally explodes, the SN ejecta interacts first with the CSM that was ejected and shaped by the star itself. As the newly formed supernova remnant (SNR) expands further, it encounters interstellar structures that were shaped by the progenitor from earlier times. Therefore, the structure and evolution of a SNR is largely dependent on the initial mass and close binarity of the SN progenitor. The Large Magellanic Cloud (LMC) has an excellent sample of over 50 confirmed SNRs that are well resolved by Hubble Space Telescope, Chandra X-ray Observatory, and Spitzer Space Telescope. These multi-wavelength observations allow us to conduct stellar forensics in SNRs and understand the wide variety of morphologies and physical properties of SNRs observed.

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.

On the accretion of interstellar matter by stars

1940 ◽  
Vol 36 (3) ◽  
pp. 325-330 ◽  
Author(s):  
F. Hoyle ◽  
R. A. Lyttleton
Keyword(s):  
Stellar Evolution ◽  
Binary Systems ◽  
Galactic Plane ◽  
Small Mass ◽  
Average Density ◽  
Close Binary ◽  
Interstellar Matter ◽  
Satisfactory Description ◽  
Geological Evidence ◽  
The Galaxy

The rate of accretion of interstellar matter by stars as proposed in a previous paper is further discussed. It is shown that this amount, while sufficient for the evolution of the majority of stars, is insufficient by a factor of the order of 10 or more to give a satisfactory description of the general evolution of massive stars and close binary systems of small mass. Consideration of the possibility of increasing the rate of accretion for such exceptional stars leads to the conclusion that this can be carried out satisfactorily only by a corresponding increase in the density of the cloud. Although we were led to this view by considering all the factors involved in accretion and showing that only a change in the density could possibly produce the required increase, it is at once clear from the accretion formula, without detailed discussion of the other quantities involved, that the density is the only factor through which effects could be introduced that do not apply to all stars quite generally. By investigating the various factors in the galaxy affecting the density, it is shown that within 100 parsecs of the galactic plane, and also in local regions, the density may rise above 10−21 g. per c.c., which gives an increase of order 100 times the normal rate for stars lying in these regions. These suggestions receive independent corroboration from investigations by Jeans relating to extra-galactic nebulae which led to average densities also of order 10−21 g. per c.c., while a further argument from geological evidence shows that the average density of material along the sun's track must be higher than 10−21 g. per c.c. It remains to be seen whether future observations will succeed in confirming these suggestions indicated by the requirements of this theory of stellar evolution.

scholarly journals Survey of OH Masers at 1665 MHz. II. Galactic Longitude 340o to the Galactic Centre

1983 ◽  
Vol 36 (3) ◽  
pp. 361 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Ground State ◽  
Galactic Plane ◽  
Line Emission ◽  
State Transitions ◽  
Galactic Centre ◽  
Emission Sources ◽  
Type I ◽  
Type Ii ◽  
Formation Type ◽  
Galactic Longitude

The galactic plane from longitude 340� through the galactic centre to longitude + 2� has been searched for OH on the 1665 MHz transition. Forty-nine OH maser emission sources were detected and these have now been studied on all four OH ground-state transitions. Most of the masers are associated with regions of star formation (type I) while three may be examples of late-type stars (type II OH/IR) with unusually strong main-line emission

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.

HR Diagrams of Galaxies: Ages and Stages of Evolution

1978 ◽  
Vol 80 ◽  
pp. 247-257
Author(s):  
Beatrice M. Tinsley
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Stellar Populations ◽  
Young Star ◽  
Red Giants ◽  
Type I ◽  
Type Ii ◽  
Hubble Sequence ◽  
The Galaxy ◽  
Bright Blue

Baade (1944) based his concept of stellar populations in galaxies on the HR diagrams that he inferred from the magnitude at which their brightest stars could be resolved. His type I population had bright blue supergiants like those in the disk of the Milky Way, while the brightest stars in type II were the red giants found in globular clusters. He postulated that the Hubble sequence of galaxy types from irregulars to ellipticals contained increasing proportions of Population II relative to Population I, and that similar differences characterized nuclear bulges of spirals relative to their disks. A very important revision of this picture came with the discovery by Morgan and Mayall (1957; Morgan, 1956, 1959) that the integrated blue light of the nuclear bulges of M31 and the Galaxy is dominated by strong-lined CN giants, not by the weak-lined type found in globular clusters. On the basis of integrated spectra of galaxies, Morgan developed a revised population scheme, in which the extreme types are a young-star rich population, like Baade's extreme Population I, and a young-star deficient population, analogous to Population II but generally metal-rich. Different proportions of these two types are still thought to represent the main differences among stellar populations in different regions of galaxies.

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