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Full-Text Articles in Astrophysics and Astronomy
Evidence Signalling The Start Of Enhanced Counterjet Flow In The Symbiotic System R Aquarii, A. G. Michalitsianos, M. Perez, Menas Kafatos
Evidence Signalling The Start Of Enhanced Counterjet Flow In The Symbiotic System R Aquarii, A. G. Michalitsianos, M. Perez, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
The velocity structure of strong far-UV emission lines observed in the symbiotic variable R Aqr suggests the start of new jet activity which will probably culminate in the appearance of a series of intense nebular emission knots within a decade. This is indicated by a systematic redward wavelength drift of emission lines, which we have followed with the International Ultraviolet Explorer (IV E) since the discovery of the brilliant northeast jet emission knots more than 10 years ago. The C IV λλ1548, 1550 resonance lines, which previously showed a prominent blue asymmetric wing that extended to velocities in excess -200 …
Variable Ultraviolet Emission In Sy Muscae, A. G. Michalitsianos, Menas Kafatos
Variable Ultraviolet Emission In Sy Muscae, A. G. Michalitsianos, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Following the enhancement in ultraviolet flux which we reported previously, we have continued monitoring the symbiotic variable SY Muscae with the International Ultraviolet Explorer (JUE). Over the course of one year, the prominent emission lines of N v, 0 v, C rv, He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region, as suggested from the Sim] :\1892 and Cm] :\1909 intensity ratio. Our data is consistent with a sudden ejection event in which material expelled from the surface of a hot Teff …
Ultraviolet Observations Of Four Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, R. W. Hobbs
Ultraviolet Observations Of Four Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, R. W. Hobbs
Mathematics, Physics, and Computer Science Faculty Articles and Research
Observations were obtained with the International Ultraviolet Explorer (IUE) of four symbiotic stars. The UV spectra of YY Her, SY Mus, CL Sco, and BX Mon are characterized by varying degrees of thermal excitation. We have analyzed these low resolution spectra in terms of line-blanketed model atmospheres of early A, B, and F type stars in order to identify the nature of the hot companion in these systems. The expected emission from early main sequence stars does not fully explain the observed distribution of UV continuum energy over the entire IUE spectral range (1200-3200 A). More likely the observed continuum …
Radio And Optical Observations Of The R Aquarii Jet, R. J. Sopka, G. Herbig, Menas Kafatos, A. G. Michalitsianos
Radio And Optical Observations Of The R Aquarii Jet, R. J. Sopka, G. Herbig, Menas Kafatos, A. G. Michalitsianos
Mathematics, Physics, and Computer Science Faculty Articles and Research
VLA observations at 6 cm and Lick Observatory optical plates of R Aquarii indicate the existence of a jetlike feature extending 7" -10" from the central star. A wide field map at 6 cm shows an unresolved compact radio source which lies close to the axis defined by the jet at a distance of ~ 3' from R Aqr. Episodic mass transfer in this symbiotic variable could explain the erratic outbursts that R Aqr is known to undergo. Formation of an accretion disk and the accompanying radio-optical jet may characterize the observed outbursts in this system.
A Brightening Of The Symbiotic Variable Sy Muscae, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, G. Wallerstein
A Brightening Of The Symbiotic Variable Sy Muscae, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, G. Wallerstein
Mathematics, Physics, and Computer Science Faculty Articles and Research
The symbiotic variable SY Muscae has been observed with IUE in September 1980 and June 1981 and in the photographic region in May 1981. The entire ultraviolet spectrum brightened between September and June by about a factor of 5. The spectrum shows high excitation including emission from N v and high electron density, about 10^10 cm^-3 as determined from various line ratios in the ultraviolet. The optical spectrum is dominated by permitted lines; even [0 m] is very weak again indicating high density in the ionized region. The increase in ultraviolet continuum and line emission may be due to enhanced …