Nova Envelope Research Articles

Grain Formation in Nova Envelopes

Grain formation in ejected envelopes of novae is investigated. The solar abundance is assumed as one of the typical examples that C/O is smaller than unity. Then, magnesium silicate is proved to be the first main condensate. We estimate the number density c1 (t1) of monomers (SiO molecules for our case) at the beginning of condensation to beabout 105 cm for ΔM = 3 x 10-4 M⊙and Vexp = 1000 km sec-1 (ΔM is the ejected mass and V exp is the expansion velocity).

Secular Mass Loss from Cataclysmic Variables

The mass loss from cataclysmic binaries seems an important and worth studying phenomenon for a number of reasons. It is probably enough to mention only two of them:(a) Whenever we can directly observe the ejected material, determine its amount and the rate of mass loss, as well as its chemical composition (this being the case of the expanding envelopes of novae), we are getting a good insight into the basic physical mechanisms responsible for the observed phenomena.(b) The mass loss (together with the mass transfer) and the loss of the orbital angular momentum are related directly to the dynamical evolution of a binary system and - indirectly - to the evolution of its components.

Non Uniformity Expected in Nova Ejection

It is shown that according to the model of continued ejection of nova envelopes by radiation pressure, discrete clouds are probably formed. Their properties are discussed.

La distance de la Nova Delphini 1967

The good agreement found between the observed flux of radio emission of the Nova Delphini 1967 and that calculated theoretically enables us to deduce the angular diameter of the Nova's envelope. This result, when combined with the known linear diameter of the envelope, gives a distance of the order of 885 pc for Nova Delphini.

The Chemical Composition of the Envelopes of Novae

AbstractThere are two methods to study the chemical composition of the envelopes ejected by novae: (a) the analysis of the absorption spectra of novae; (b) the analysis of emission lines during the nebular stage.

On the time-dependent principle of invariance in a semi-infinite medium

For a semi-infinite medium in which the particle mean free time is much greater than the mean survival time of a photon (e.g,, envelopes of novae, planetary nebulae, and cosmic clouds), a radiative transfer theory is derived that tekes into account the irreversible leakage of radiation from the system. The time-dependent diffusion problem posed by this theory is solved by means of a transient scattering function. The explicit form of the integral equation for this scattering function is obtained. (T,F.H.)

A Study of Emission-Line Intensities in Some Bright Northern Wolf-Rayet Stars.

view Abstract Citations (35) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Study of Emission-Line Intensities in Some Bright Northern Wolf-Rayet Stars. Aller, Lawrence H. Abstract From a study of emission-line intensities in a number of bright Woif-Rayet stars excitation tempera- tures of their atmospheric envelopes are estimated. These temperatures turn out to be very high and de- pend upon the ionization potential of the ion employed-in the sense that the higher the ionization po- tential, the higher the resultant temperature. The emission lines in the Woif-Rayet stars probably do not arise from the primary mechanism, i.e., photoionization and subsequent recapture of electrons, but rather from the absorption of high-frequency radiation emerging from the lower layers. On the basis of certain plausible assumptions an attempt is made to find the chemical composition of the atmospheric layers. In the carbon stars helium is estimated to be about fifty times as abundant as oxygen and fifteen times as abundant as carbon, while in the nitrogen stars helium appears to be about twenty times as abundant as nitrogen and three hundred times as abundant as carbon. The estimate of the abundance of helium with respect to other gases is very uncertain. The nuclei of BD+30°3639 and NGC 40 seem to be typical carbon stars. The nucleus of NGC 6543, which contains both nitrogen and carbon, seems to show a rela- tively small range of ionization. The chemical composition of the Woif-Rayet stars seems to be more closely related to that of the super- novae than to the envelopes of ordinary novae, which appear to have roughly the same composition, on the average, as the planetary nebulae and normal stars. The electron densities in the radiating layers of a Woif-Rayet star appear to be of the order of 1Oh1~~1O12 electrons/cm3, much greater than the electron densities in the envelope of a nova. The background spec- trum of the star is sufficiently intense to blot out any forbidden lines that may appear Publication: The Astrophysical Journal Pub Date: March 1943 DOI: 10.1086/144508 Bibcode: 1943ApJ....97..135A full text sources ADS | data products SIMBAD (1)

NOTE ON THE ELECTRON DENSITY IN THE ENVELOPES OF NOVAE

NOTE ON THE ELECTRON DENSITY IN THE ENVELOPES OF NOVAE