Showing papers on "White dwarf published in 1970"
189 citations
TL;DR: Magnetic fields of DA dwarfs observed with photoelectric polarimeter, noting no magnetic fields observable as mentioned in this paper. But no magnetic field was observed in the DA-D dwarfs.
Abstract: Magnetic fields of DA dwarfs observed with photoelectric polarimeter, noting no fields observable
99 citations
TL;DR: The star BD +16° 516 (a = 3h44^5, O = + 16° 57 (1900), V = 9.6) is noted as a spectroscopic binaiy by Wilson (1963) in the General Catalogue of Stellar Radial Velocities as mentioned in this paper.
Abstract: The star BD +16° 516 (a = 3h44^5, O = +16° 57 (1900), V = 9.6) is noted as a spectroscopic binaiy by Wilson (1963) in the General Catalogue of Stellar Radial Velocities (No. 2196). This conclusion is based upon five spectrograms obtained at the Mount Wilson Observatory between 1942 and 1945, at a reciprocal dispersion of 80 Â/mm. The listed range of observed velocities for these spectrograms is 242 km/sec. Spectrograms of this star obtained at the Kitt Peak National Observatory at 39 Â/mm show single, rotationally broadened lines of a K0 V star with strong emission lines of singly ionized calcium, and an unusually strong ultraviolet continuum. In Figure 1 a portion of an intensity tracing of one of these spectrograms is reproduced, showing the strength of the Ca n emission. Five spectrograms have been obtained so far, all of which show positive radial velocities, and with a maximum recorded radial velocity of + 180 km/sec.
71 citations
TL;DR: In this article, thermal and vibrational energy losses due to URCA shells in stellar interiors are calculated for semidegenerate, relativistic electrons and analytical expressions are derived for more general cases calculated with a computer.
Abstract: Thermal and vibrational energy losses due to URCA shells in stellar interiors are calculated. Analytic expressions are derived for semidegenerate, relativistic electrons. Results are given for more general cases calculated with a computer. The calculations are carried out for a large number of nuclei that may contribute to URCA energy losses in various stages of stellar evolution. An illustration is given of the cooling and vibrational damping of a white dwarf. For a central Fermi energy ≳5 MeV, the internal temperature of the star should be reduced to the order of 106 K and the relative vibrational amplitude should be reduced to the order of 10−5 on a time scale of 109 yr. URCA shells are present, the URCA neutrino energy loss dominates in the temperature region up to about 2×109 K.
55 citations
45 citations
40 citations
TL;DR: In this paper, the electron-neutrino weak interaction and beat decay coupling constants were found nearly equal, describing astrophysical tests based on white dwarf stars luminosity intervals.
Abstract: Electron-neutrino weak interaction and beat decay coupling constants found nearly equal, describing astrophysical tests based on white dwarf stars luminosity intervals
31 citations
Journal Article•
31 citations
Journal Article•
19 citations
16 citations
TL;DR: In this paper, the neutrino synchrotron radiation for a completely relativistic electron gas in the presence of large magnetic field is computed according to the photon-neutrino coupling theory of weak interactions.
Abstract: The neutrino synchrotron radiation for a completely relativistic electron gas in the presence of large magnetic field is computed according to the photon neutrino coupling theory of weak interactions. The radiation is also estimated for the non-relativistic case. The neutrino luminosity of several model white dwarfs are computed according to the photon-neutrino coupling theory and compared with that of the current-current coupling theory. It is shown that, according to the photonneutrino coupling theory, the neutrino luminosity is greater than the photon luminosity and, therefore, most likely to have astrophysical significance in the evolution of stars with large electron energies and potentially large magnetic field, such as white dwarfs.
TL;DR: Low mass star evolution from helium burning to white dwarf, describing red giant and mass loss stages in model as discussed by the authors, is described in detail in this paper. But the model is based on the same model as the one described in this article.
Abstract: Low mass star evolution from helium burning to white dwarf, describing red giant and mass loss stages in model
01 Jan 1970
TL;DR: The thermal imbalance effect on stellar pulsational stability using linear quasi-adiabatic pulsation theory has been studied in this article, where the authors used a linear QA approach.
Abstract: Thermal imbalance effect on stellar pulsational stability using linear quasi-adiabatic pulsation theory
01 Jan 1970
TL;DR: In this paper, a close examination of the evidence shows that those with the most certain optical identifications, Scorpio X-1 and Cygnus X-2, have very few features in common.
Abstract: In developing models for the point X-ray sources the general aim has been to find a common explanation for all such objects. However, important observational differences have already become apparent among the systems having optical identifications. A close examination of the evidence shows that those with the most certain optical identifications, Scorpio X-1 and Cygnus X-2, have very few features in common and, in fact, the model proposed here for Cyg X-2 can probably be excluded for Sco X-1.
TL;DR: Sco XR-1 optical intensity power spectra oscillations searched for in pulsar frequencies and fundamental radial mode vibrations in white dwarfs and neutron stars were found in this article.
Abstract: Sco XR-1 optical intensity power spectra oscillations searched for in pulsar frequencies and fundamental radial mode vibrations in white dwarfs and neutron stars
TL;DR: The photon-neutrino coupling theory of weak interactions as presented by Bandyopadhyay is definitely excluded by the astrophysical data for white dwarfs and red supergiants as discussed by the authors.
Abstract: The photon-neutrino coupling theory of weak interactions as presented by Bandyopadhyay is definitely excluded by the astrophysical data for white dwarfs. Furthermore, it is impossible to adjust the photon-neutrino coupling constant so as to reproduce simultaneously the pertinent astrophysical data for white dwarfs and red supergiants.
TL;DR: There is reason to believe that the pronounced feature that was found at approximately 0.006 Hz in the power spectrum of the immediately postflare data sample can be explained in terms of the acoustic oscillations of a hot, bounded plasma atmosphere in the strong gravitational field of a dense underlying star.
Abstract: IN a recent report1 we presented evidence for the existence of short-term periodic variations in the optical “flickering” of Sco X-l following a large (optical) flare on the night of April 3, 1967 We now have reason to believe that the pronounced feature that was found at approximately 0006 Hz in the power spectrum of the immediately postflare data sample (610–1,109 of the photometric observations by Sandage et al2) can be explained in terms of the acoustic oscillations of a hot, bounded plasma atmosphere in the strong gravitational field of a dense underlying star