Engineering topics

Panagia, N.

Publications and source records attributed to Panagia, N..

24 records · Page 2

NASA NTRS1982

The interstellar spectrum of the supernova 1980k in NGC 6946

Bright supernovae in external galaxies offer a rare opportunity to probe the intervening interstellar media over very extended path-lengths, including the disk and halo of the Galaxy and the parent galaxy of the supernova. SN 1980k was discovered in NGC 6946 on 1980 October 29. In the first month after discovery, high resolution optical and ultraviolet observations were obtained to exploit the supernova as a probe of the intervening interstellar media. The obtained data are discussed. In the spectra, absorption lines were observed of Mg I, Mg II, Fe II, Mn II, Ca II and Na I. The absorption lines are attributed to the intervening interstellar media distributed over the very extended line of sight sampled, of order 7 Mpc. These lines are wider and stronger than any previously measured in the quiescent interstellar gas in the halo and disk of the Milky Way and of external galaxies

Pettini, M.↗

NASA NTRS1982

IUE and Einstein observations of NGC5204

The use of both the Einstein and IUE observations of NGC5204 to test some of the hypotheses put forward as a result of an X-ray survey of blue peculiar late type galaxies is discussed. In particular the hypothesis that binary X-ray sources of Pop I progenitors are responsible for most of the X-ray emission, is strengthened by the IUE short wavelength spectrum of NGC5204. This spectrum suggests a number of OB stars in agreement with the inferred from the X-ray luminosity. It also shows an ultraviolet excess in agreement with the large X-ray to blue flux ratio.

Fabbiano, G.↗

NASA NTRS1981

IUE and ground-based observations of mass-loss in the Magellanic Clouds

Ground based and IUE observations of hot stars in the large and small Magellanic Clouds were carried out to investigate the mass loss process in these objects and to search for differences with galactic hot stars. Preliminary results show that in a large proportion of the stars observed the mass loss process is taking place. A mechanism for acceleration of the wind in OB stars is proposed.

Macchetto, F.↗

NASA NTRS1981

Observations of supernova 1979c in M 100

The IUE observations of supernova 1979c in M 100 are presented and discussed. The main results are: (1) the bulk of the energy is in the form of continuous emission which is radiated by the main SN envelope; (2) the absorption features originate mostly in both the disks and the haloes of our Galaxy and M 100; and (3) the emission lines are produced in a highly ionized shell which has a radius greater than twice the radius of the main envelope and consists of compressed circumstellar material in which the abundance ratio N/C is about 30 times higher than solar.

Panagia, N.↗

NASA NTRS1981

Observations of the nucleus of M100

The galaxy M100 = NGC 4321 is a spiral galaxy in which a bright Type II Supernova was discovered on April 19, 1979. Its spectral evolution was followed with IUE for more than two months (refs. 1,2). At all epochs, the spectrum was dominated by continuous radiation on which emission and absorption features were superimposed. The equivalent width of most of the absorption features appeared not to vary with time suggesting that they originated in the interstellar media of M100 and our own galaxy.

Panagia, N.↗

NASA NTRS1974

Dust in H2 regions

The effects of dust inside H2 regions were studied by means of theoretical models of dusty nebulae. Infrared observations were analyzed and clear evidence was found that the emitting dust is mostly mixed with the ionized gas. Some information about the amount, distribution, and properties of dust grains was also derived.

Panagia, N.↗