Showing papers on "Spiral galaxy published in 1971"
TL;DR: In this article, a computer model for dynamical evolution of isolated disks of stars with initial velocity dispersions corresponding to Toomre criterion is presented, noting instability relative to large scale modes.
Abstract: Computer model for dynamical evolution of isolated disks of stars with initial velocity dispersions corresponding to Toomre criterion, noting instability relative to large scale modes
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TL;DR: In this article, the possible existence of strong magnetic fields in stars is discussed and a method of constructing highly distorted models of magnetic, rotating stars is developed, where a force-free outer boundary condition is necessary for stars with both poloidal and toroidal fields at the surface.
Abstract: The possible existence of strong magnetic fields in stars is discussed and a method of constructing highly distorted models of magnetic, rotating stars developed. For stars with both poloidal and toroidal fields at the surface a force-free outer boundary condition is necessary. Non-linear solutions of the force-free equations must be used. The force-free equations and the structure equations for a white dwarf are solved simultaneously by a finite difference method.
22 citations
TL;DR: In this article, spectral types and photometry are reported for numerous stars in Sco OB-1 and in the foreground of the association, showing no evidence for a recently reported correlation between absolute magnitude and color excess.
Abstract: New spectral types and photometry are reported for numerous stars in Sco OB-1 and in the foreground of the association. The new data permit reddening in the local spiral arm to be subtracted out in a discussion of reddening in the gas and dust of an adjacent spiral arm. The reddening that occurs within the association Sco OB-1 itself appears to be normal and to have R = 3. Infrared fluxes indicate no deviations (in the reddening law from the ultraviolet to 2.2 μ) from the law for the local spiral arm in Scorpio. The new data show no evidence for a recently reported correlation between absolute magnitude and color excess.
TL;DR: In this paper, the results of an n-body calculation, containing about 12,000 particles, were shown as a motion picture, where some of the particles were treated as gas, obeying a special dissipative dynamics, the rest as stars.
Abstract: Results of an n-body calculation, containing about 120000 particles, were shown as a motion picture. Some of the particles are treated as ‘gas’, obeying a special dissipative dynamics, the rest as ‘stars’. The system was started as pure ‘gas’, and ‘stars’ were made out of the ‘gas’ in a manner closely mimicking real galaxies. Spiral density wave patterns appear in the ‘gas’, and last for about 3 ‘galactic rotations’ without substantial change of form. Various experiments are described that have been undertaken in an attempt to learn the roles of various parts of the system in the maintenance of spiral patterns.
TL;DR: Spiral galaxy NGC 4569 member of Virgo cluster, using measurements of central velocity field, rotation and density estimates as discussed by the authors, is a member of the Virgo Cluster.
Abstract: Spiral galaxy NGC 4569 member of Virgo cluster, using measurements of central velocity field, rotation and density estimates
TL;DR: In this paper, four-color Str6mgren photometry was used to show that the blue-straggler and horizontal-branch stars in the old galactic cluster M 67 do not have low surface gravities and that they are more massive than the cluster stars at the main-sequence turnoff.
Abstract: Four-color Str6mgren photometry shows that the ' blue-straggler" and "horizontal-branch" stars in the old galactic cluster M 67 do not have low surface gravities and that they are more massive than the cluster stars at the main-sequence turnoff. Therefore they are not highly evolved single stars, but most probably close-binary systems in various stages of evolution with mass transfer, as suggested by MeCrea. Key words: galactic clusters - photometry - blue-straggler stars - horizontal-branch stars
TL;DR: In this article, the authors conjecture that the highly obscured galaxy IC342 might be associated with Maffei 1 and Mafei 2 (refs. 1 and 2) and show that IC342 is the fourth largest (after M31, M33 and M101) spiral galaxy known.
Abstract: I SUGGEST in this report that the highly obscured galaxy IC342 might be associated with Maffei 1 and Maffei 2 (refs. 1 and 2). IC342 is the fourth largest (after M31, M33 and M101) spiral galaxy known. It is separated from Maffei 1 by less than 12° which, at a distance of 2 M parsec (Mpc), would correspond to a projected separation of only 0.4 Mpc. Available data on Maffei 1 and on IC342 are compared in Table 1.
TL;DR: In this article, the density wave theory of galactic spirals is applied to the distribution of space velocity distributions, gravitation field strength and vertex deviation for nearby young stars, using density wave theories of galaxies.
Abstract: Statistical space velocity distributions, gravitation field strength and vertex deviation for nearby young stars, using density wave theory of galactic spirals
TL;DR: In this paper, the spectral properties of field horizontal-branch stars were investigated using objective-prism spectroscopy (APS) spectrograms and they were shown to have spectral characteristics similar to those of some known blue horizontal branch stars.
Abstract: Ten relatively bright field stars are listed that have spectral characteristics similar to those of some known blue horizontal-branch stars. Key words: field horizontal-branch stars objective-prism spectroscopy
TL;DR: In this paper, the authors discuss the theoretical aspects of spiral structure in galaxies outside our own and leave it largely to Professor Lin to speak about observations on other spiral galaxies and their relevance for possible theoretical interpretations.
Abstract: Does our Galaxy possess spiral structure and, if so, can this structure be traced observationally with some degree of confidence? This is the major question to which I shall address myself tonight. Following my talk, Professor Lin will speak about the theoretical aspects of spiral structure. I shall be very brief in my references to spiral structure in galaxies outside our own and leave it largely to Professor Lin to speak about observations on other spiral galaxies and their relevance for possible theoretical interpretations. A year ago, my good and distinguished friend Professor B. A. Vorontsov-Velyaminov chided me in his address at the Basel Symposium for having been too eager to accept the fact that observation suggests that our Galaxy really possesses spiral structure. I hope to show in my Discourse that for our Galaxy we have indeed evidence for the presence of an underlying structure of spiral features.
Journal Article•
Journal Article•
01 Jan 1971
TL;DR: In this article, the Magellanic clouds were observed using the synchrotron mechanism and measurements of the intensity, spectra, and polarization of this radio emission can tell us about these two invisible constituents which are found both in extended regions (spiral arms) and in discrete sources (supernova remnants).
Abstract: A galaxy is made up of a number of different ingredients: stars, gas, magnetic fields and cosmic rays. This talk will be about observations of the radio continuum emission from the Magellanic Clouds which is produced by the synchrotron mechanism when the last two ingredients are mixed together. Measurements of the intensity, spectra, and polarization of this radio emission can tell us something about these two invisible constituents which we know from radio observations of our Galaxy are found both in extended regions (spiral arms) and in discrete sources (supernova remnants).