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1981

Articles 1 - 7 of 7

Full-Text Articles in Stars, Interstellar Medium and the Galaxy

Preliminary Report On Iue Spectra Of Crab Nebula, K. Davidson, T. R. Gull, S. P. Maran, T. P. Stecher, Menas Kafatos, V. L. Trimble Jan 1981

Preliminary Report On Iue Spectra Of Crab Nebula, K. Davidson, T. R. Gull, S. P. Maran, T. P. Stecher, Menas Kafatos, V. L. Trimble

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

The Crab Nebula is marginally observable with the IUE. Observations of the optically brightest filamentary regions, made with IUE in August 1979, show the C IV x1549, He II x1640, and C III] x1909 emission lines. The intensities of these lines have been compared with visual-wavelength data. It appears that carbon is not overabundant in the Crab; carbon/- oxygen is approximately "normal" oxygen is slightly scarcer than "normal" as a fraction of the total mass.

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Iue Observations Of Two Late Type Stars Bx Mon (M4 + Pec) And Tv Gem (M1 Iab), Andrew G. Michalitsianos, R. W. Hobbs, Menas Kafatos Jan 1981

Iue Observations Of Two Late Type Stars Bx Mon (M4 + Pec) And Tv Gem (M1 Iab), Andrew G. Michalitsianos, R. W. Hobbs, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

IUE observations of two late type stars BX Mon and TV Gem have been obtained that reveal the emission properties in the ultraviolet of subluminous companions. Analysis of the continuum emission observed from BX Mon suggests the companion is a middle A III star. High excitation emission lines observed between 1200 A and 2000 A (C IV, Si Ill], C III ) that generally do not typify emission observed in either late M type variables or A type stars are also detected. It is suggested that these strong high-excitation lines arise in a large volume of gas heated by non-radiation …

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Ingress Observations Of The 1980 Eclipse Of The Symbiotic Star Ci Cygni, R. E. Stencel, Andrew G. Michalitsianos, Menas Kafatos, Alexander A. Boyarchuk Jan 1981

Ingress Observations Of The 1980 Eclipse Of The Symbiotic Star Ci Cygni, R. E. Stencel, Andrew G. Michalitsianos, Menas Kafatos, Alexander A. Boyarchuk

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

One of the major results from the IUE may prove to be the new knowledge gained by studies of the ultraviolet spectra of symbiotic stars. Symbiotics combine spectral features of a cool M giant-like photosphere with strong high excitation emission lines of nebular origin, superposed. An excellent pre-UV review has been given by Swings (i). The UV spectra are dominated by intense permitted and semi-forbidden emission lines and weak continua indicative of hot compact objects and accretion disks. Two symbiotics, AR Pay and CI Cyg are thought to be eclipsing binaries, and we have begun IUE observations during the predicted …

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Iue Observations And Interpretation Of The Symbiotic Star Rw Hya, Menas Kafatos, Andrew G. Michalitsianos Jan 1981

Iue Observations And Interpretation Of The Symbiotic Star Rw Hya, Menas Kafatos, Andrew G. Michalitsianos

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

IUE observations of the high excitation symbiotic star RW Hya (gM2 + pec) have been obtained. Analysis of the intense UV continuum observed between II00 A to 2000 A suggests this star is a binary system in which the secondary is identified as a hot subdwarf with T _. _I0 D K. We deduce a distance to the system of ~1000 pc. The UV spectrum consists of mainly semi-forbidden and allowed transition lines of which the ClV (1548 A, 1550 A) emission lines are particularly strong, and UV continuum at both shorter and longer wavelengths. Strong forbidden lines seem to …

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Iue Observations Of Circumstellar Emission From The Late Type Variable R Aqr (M7 + Pec), R. W. Hobbs, Andrew G. Michalitsianos, Menas Kafatos Jan 1981

Iue Observations Of Circumstellar Emission From The Late Type Variable R Aqr (M7 + Pec), R. W. Hobbs, Andrew G. Michalitsianos, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

As part of a program to observe circumstellar emission from late type stars, IUE observations of R Aqr (M7 + pec) have been obtained in low dispersion. Strong permitted, semi-forbidden and forbidden emission lines are seen, superimposed on a bright ultraviolet continuum. We deduce that the strong emission line spectrum that involves C III], C IV, Si III], [0 II] and [0 lll] probably arises from a dense compact nebula the size of which is comparable to the orbital radius of the binary system of which R Aqr is the primary star. The low excitation emission lines of Fe II, …

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Superbubbles, T. R. Gull, F. C. Bruhweiler, Menas Kafatos, S. Sofia Jan 1981

Superbubbles, T. R. Gull, F. C. Bruhweiler, Menas Kafatos, S. Sofia

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

Individual massive stars with Mbol < -6 have huge stellar winds that create interstellar bubbles. Stars with masses greater than 8Mo (4Mo?) are considered supernova progenitors. These massive stars are numerous in OB associations where few supernova remnants are detected. Model calculations describing the evolution of an association show: i) that large, hot cavities are formed by pushing the ambient gas into neutral shells; 2) that the shell radii change with galactocentric radius, 3) that only thirty percent of the interstellar medium is in the form of supercavities and 4) that a consequence is that only a small fraction of supernovae form supernova remnants. These results have strong bearing on interpretation of interstellar studies being done by IUE and by HEAO-B.

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Oh Emission In The Direction Of Tv Gem And Bi Cyg, L. W. Brown, R. W. Hobbs, A. G. Michalitsianos, Menas Kafatos Jan 1981

Oh Emission In The Direction Of Tv Gem And Bi Cyg, L. W. Brown, R. W. Hobbs, A. G. Michalitsianos, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

OH maser main-line emission at 1665 MHz has been detected in the direction of two late-type supergiants, TV Gem (Mllab) and BI Cyg (M3Iab), with the 43-m telescope and 18-cm receiver at NRAO-Green Bank. Detection of two new OH maser sources here is particularly interesting in view of the relatively small number of late-type supergiants that are known as molecular radio sources or associated in close proximity with OH emission clouds. The infrared, ultraviolet, and radio properties of these stars are discussed briefly.

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