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1.
Werner Lohmann 《Astrophysics and Space Science》1974,27(1):227-231
According to the tangential method the productAR
0 is determined with 145.7 km s–1 from measurements of the line profiles of the 21-cm line of the neutral hydrogen by Weaver and Williams (1973). The recent individual measurements of Oort's constantA and of the distanceR
0 of the Sun from the galactic centre yields 138.5 km s–1. The mean value 142.1 kms–1 leads toA=14.56 km s–1 kpc–1 andR
0=9.76 kpc. At the galactocentric distanceR nearR
0 the angular velocity is represented by (R)=25.84–2.98 (R–9.76)+0.075 (R–9.76)2. The mass of the Galaxy amounts to 1-92×1011 .
Herrn Kollegen Prof. Dr W. Gleisberg zum 70. Geburtstag am 26.12.1973 gewidmet.
Mitteilungen Serie A. 相似文献
Herrn Kollegen Prof. Dr W. Gleisberg zum 70. Geburtstag am 26.12.1973 gewidmet.
Mitteilungen Serie A. 相似文献
2.
Werner Lohmann 《Astrophysics and Space Science》1974,29(1):61-62
According to the Bottlinger law the mass of M33 is determined with (1.29±0.23)×1010
M from measurements of the velocities of the neutral hydrogen by Warneret al. (1973).
Mitteilungen Serie A. 相似文献
Mitteilungen Serie A. 相似文献
3.
We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the solar
wind velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of
23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic
ray intensity based on the heliolongitudinally dependent solar wind velocity. A consistent, divergence-free interplanetary
magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the solar
wind velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure
does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on
observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally
obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient
of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation
parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the solar wind velocity
V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic
ray intensity mainly is caused by this basic modulation effect. 相似文献
4.
Normalisation des systèmes linéaires canoniques et application au problème restreint des trois corps
An algorithm is given for normalizing conservative linear Hamiltonian systems. This one generalizes Siegel's method to the cases where the eigenvalues are multiple. We obtain by a canonical transformation a normal form of two blocks, one of which is the upper Jordan form, and the other, the lower Jordan form. We select real solutions from the solutions of these equations, and we apply the result to the restricted three body problem in the vicinity of the triangular points for Routh's critical mass ratio.
n est la matrice unité d'ordren,O n est la matrice nulle d'ordren. 相似文献
n est la matrice unité d'ordren,O n est la matrice nulle d'ordren. 相似文献
5.
We impose the requirement that the spatial distribution of pulsars deduced from their dispersion measures using a model of
the galactic electron density (n
e
) should be consistent with cylindrical symmetry around the galactic centre (assumed to be 10 kpc from the Sun). Using a carefully
selected subsample of the pulsars detected by the II Molonglo Survey (II MS), we test a number of simple models and conclude
that (i) the effective mean 〈ne〉) for the whole galaxy is 0.037-0.012
+0.020 cm-3, (ii) the scale height of electrons is greater than 300 pc and probably about 1 kpc or more, and (iii) there is little evidence
for variation of ne with galactic radius RGC for RGc ≳ 5 kpc. Further, we make a detailed analysis of the contribution to ne from H II regions. Combining the results of a number of relatively independent calculations, we propose a model for the galactic
electron density of the formn
e
(z) = 0.030 + 0.020 exp (- |z|/70) cm-3 where z(pc) is the height above the galactic plane and the second term describes the contribution from H II regions. We believe
the statistical uncertainties in the parameters of this model are quite small. 相似文献
6.
W. Gtz 《Astronomische Nachrichten》1986,307(6):371-378
The noteworthy deviations and differences given in the individual values of the metal abundance of open clusters were studied. It could be shown that the metal abundance of open clusters, which are situated in or near the galactic plane (|z| ≦ 0.3 Kpc) are not only correlated wiht the galactocentric distance (RGC ) but also with the galactic longitude l of the clusters. This correlation is not given in the open clusters of high |z|-distances. There, the metal abundance is connected as well with the galactocentric radius (RGC ) as with the distances of the objects form the galactic plane. 相似文献
7.
Werner Lohmann 《Astrophysics and Space Science》1980,72(2):439-446
In star clusters and in galaxy clusters the exponentn of the generalized law of Schuster statistically decreases with increasing masses
of the clusters or increasing numbersL of their members. In most casesn(gal. cl.) is smaller thann(st. cl.). It is confirmed, that in larger galaxy clusters the brighter members are somewhat more concentrated at the center than the fainter members.
Mitteilungen Serie A. 相似文献
Mitteilungen Serie A. 相似文献
8.
It is shown that the lists of Shakhbazian Compact Galaxy Groups (SCGGs) are not complete. The number of the detected groups in the strip between b = ±30° and b = ±20° is by four to five times smaller than expected. The most probable reason is that during the search for SCGGs it was hard to distinguish images of compact galaxies from that of stars on the POSS prints in dense areas of the sky at lower galactic latitudes. There is some deficit of the detected groups between 60° and 40° of the north galactic latitudes. The surface density of SCGGs in the southern galactic hemisphere between b = −50° and b = −30° is by about three times less than it is expected. Obviously, the southern sky has not been searched properly. The list of Hickson's groups is complete down to galactic latitude ±30°. However, some excess of HCGs is found in the southern hemisphere, where the surface density of the found groups is by about two times higher than that of in the northern hemisphere. 相似文献
9.
An empirical relation which relates the 408 MHz galactic continuum background temperature (408GCBT) to dispersion measures, position and radio-luminosity of 325 pulsars is obtained by means of multple stepwise regression analysis. This relation showns that pulsars may be considered as galactic probes for the distribution of 408GCBT and interstellar electron density (IED) in interstellar medium (ISM).Peculiar pulsars (O-C±2.5) point out galactic regions where the observedT
408 are higher (or lower) andn
e
lower (or higher) than the averaged ones.Normal pulsars (–2.5T
408 andn
e
are in agreement, on, the average.Standard pulsars (O-C±0.05) show galactic regions where observed and computedT
408 andn
e
are in good agreement. Recent models of pulsar disk systems, suggested by Michel and Dessler (1981) could justify the conclusions drawn for peculiar pulsars having O-C>2.5. 相似文献
10.
Teruaki Ohnishi 《Astrophysics and Space Science》1973,25(1):217-238
A model of galaxy with an active nucleus is investigated; The cloud in the galactic disc accretes on the core. The core temperature and hence the core luminosity becomes high because of the kinetic energy release by the accreting gas cloud. Then the gas and dust in the core is ejected outward by the radiation pressure from resonance line scattering, forms a sort of halo around the core and subsequently falls on the galactic plane. The gas and dust subsisted from star formation accretes again on the nucleus to provoke another explosion. So these processes are cyclic throughout the life of the galaxy.According to this model, the period of explosion depends only on the temperatureT of the system in such a manner as(y)=2.7×106
T
1/2. This relation can well explain the observed time scales for galactic explosions. On the other hand, the time dependence of heavy elements abundance, of the redshift of distant galaxy and of galactic luminosity is investigated. The redshift dependence of galactic distribution is also examined. It has become clear that this model can lead the inconsistent results with observational facts. The other problems concerning with galaxies or metagalaxies should be treated along this line. 相似文献
11.
J. P. Vallée 《Astrophysics and Space Science》1993,207(1):109-117
Large ( > 100 pc) interstellar magnetic bubbles are necessary in the cosmic-ray-driven fast galactic dynamo, as pioneered by Parker in 1992. In a first part, a look is made at the available data on nearby (< 1000 pc) large interstellar magnetic bubbles. Here the magnetic field strengthB in a large shell of densityn around an OB association is found to be a few times greater than that outside in the general interstellar medium, varying typically likeB ~n, as expected for a shocked medium. In a second part, some tests are made of the predictions about interstellar magnetic bubbles made by the theory of a cosmic-ray driven fast galactic dynamo. The bubble tests generally support the idea of a cosmic-ray-driven fast galactic dynamo for the Milky Way. 相似文献
12.
Wolfgang Kundt 《Astrophysics and Space Science》1990,172(1):109-134
An attempt is made to present all the relevant observations of our galactic centre and to explain them by means of a working scheme that involves a minimum number ofad hoc assumptions.In this scheme, the central engine is Sgr A*, a supermassive star of some 103
M
and surface temperature 3.6×104 K in Keplerian rotation, fuelled by the strongly magnetized disk. It drives both a non-thermal (pair-plasma) wind and a thermal wind. Interactions with the central star cluster and with the circumnuclear disk give rise to the thermal vortex Sgr A West and to the non-thermal spill-over bubble Sgr A East. The relativistic pair plasma escapes supersonically through the galactic chimney into the galactic twin jets, as in Seyfert galaxies. 相似文献
13.
Singh P. R. Saad Farid A. I. Singh A. K. Pant T. K. Aly Ayman A. 《Astrophysics and Space Science》2021,366(5):1-6
We are considering the spacetime described by the metric proposed by Mannheim and Kazanas. The effective potential and the circular orbits are discussed. The rotational velocity derived from the geodesics equation agrees with the observed flat galactic rotation curves. Finally, solutions to the Gordon equation for massless bosons evolving in this spacetime are obtained in terms of Heun general functions.
相似文献14.
15.
W. J. Baggaley 《Earth, Moon, and Planets》2004,95(1-4):197-209
Dust is an important component of galactic stucture and the cyclic processing of particulate matter leads to stellar and planetary
formation. Though astronomical methods using analysis of dust-penetrating starlight can provide some limited information about
the dust, the prospect of its in-situ sampling within the Solar System by spacecraft and its remote sensing by ground-based techniques open up a new field in galactic
exploration. 相似文献
16.
J. Tschauner 《Celestial Mechanics and Dynamical Astronomy》1971,3(2):189-196
Zusammenfassung Die Gleichungen der Bewegung des kleinen Körpers in der Nähe der DreieckspunkteL
4,L
5 des elliptischen eingeschränkten Dreikörperproblems werden mit Hilfe eíner eínfachen Transformation explizit in zwei unabhängige Komponenten aufgespalten, welche den bekannten Bewegungsfamiliedd unde des Kreisfalles entsprechen. Aufgrund dieser Zerlegung wird für die Bewegung im elliptischen Fall eine erste Stabilitätsgrenze berechnet, welche die Ergebnisse anderer Autoren präzisiert.Die Arbeit wurde vom Bundesministerium für Bildung und Wissenschaft in Bonn gefördert. Der Verfasser dankt dem Ministerium für die erwiesene Unterstützung.
Herrn Prof. Dr. L. Merz, TH München, zum 65. Geburtstag gewidmet 相似文献
A simple transformation is used to divide explicitly the equations of motion of an infinitesimal body in the neighborhood of the triangular pointsL 4,L 5 in the elliptic restricted Three-Bony-Problem into two independent components corresponding to the well-known families of motiond ande in the circular case. This separation immediately gives a first stability constraint for the elliptic case which is more exact than the results prior given by other authors.The work presented in this paper was supp orted by the Federal Ministry of Scientific Research in Bonn, Germany. The author gratefully acknowledges the sponsorship granted by the Ministry.
Herrn Prof. Dr. L. Merz, TH München, zum 65. Geburtstag gewidmet 相似文献
17.
We interpret the puzzling-ray bursts as emitted by cooling sparks from the surface of spasmodically accreting, old neutron stars. Their spiky, anisotropic radiation is oriented w.r.t. the galactic disk via interstellar accretion, whose orbital angular momentum tends to counteralign with the galactic spin; in this way, larger source numbers in directions of the galactic disk are compensated by smaller beaming probabilities, resulting in a near-isotropic arrival distribution, as observed by BATSE. The source distances range between 10 pc and 500 pc. Their radiated energies are of order 1035 erg, corresponding to accreted clumps (blades) of typical mass 1015 g per burst. Magnetic surface field strengths range between 1010 and 1012 G, somewhat weaker than those of newborn neutron stars. 相似文献
18.
The infrared J, K-photometry of the 2MASS catalog has been used to identify red clump giants as well as to determine the distances to them
and the interstellar extinction. Color-magnitude diagrams plotted for ten sky regions situated mostly near the galactic plane
have been analyzed. Applying the maximum likelihood technique, the parameters of distribution of a number of red clump giants
over their J-K color index have been determined; on the basis of these parameters, stars of this type to K = 11
m
have been identified. According to the reddening of identified stars, the K-band extinction in the direction of the regions under study has been estimated. The value of the extinction and its variation
with galactic latitude and longitude are in agreement with the extinction calculated by the model of Arenou et al. 相似文献
19.
Andrea Merloni Sebastian Heinz Tiziana Di Matteo 《Astrophysics and Space Science》2005,300(1-3):45-53
We examine the disc-jet connection in stellar mass and supermassive black holes by investigating the properties of their compact
emission in the hard X-ray and radio bands. We compile a sample of ∼100 active galactic nuclei with measured mass, 5 GHz core
emission, and 2–10 keV luminosity, together with eight galactic black holes with a total of ∼50 simultaneous observations
in the radio and X-ray bands. Using this sample, we study the correlations between the radio (LR) and the X-ray (LX) luminosity and the black hole mass (M). We find that the radio luminosity is correlated with both M and LX, at a highly significant level. We show how this result can be used to extend the standard unification by orientation scheme
to encompass unification by mass and accretion rate. 相似文献
20.
This paper presents the RCGP catalogue of more than 0.5 million candidate red clump stars with the limiting magnitude K
s
= 9.5
m
. These stars are selected from the PPMX catalogue as the most probable red clump members by analyzing the color-reduced proper
motion diagrams built from the proper motions given in PPMX and J, K
s
-photometry given in the 2MASS catalogue. Reddening of the selected stars is used to find extinction in the K
s
-band and to consider it in the further analysis. The two-dimensional galactic rotation model generalized by Ogorodnikov is
used to investigate the tangential velocity field of the selected red clump members, most of which are thin disk stars located
within 1.5 kpc from the sun. The values of kinematic parameters and solar components are determined as a function of stellar
heights above the galactic equatorial plane and their heliocentric distances. 相似文献