http://bear.ras.ucalgary.ca/abstracts/1990/1990.html (Einblicke ins Internet, ~06/1995)
H I spectrum of the symbiotic nova HM Sge
LEAHY, D. A., TAYLOR, A. R., YOUNG, G.
Astronomical Journal , vol. 99, June 1990, p. 1926-1929. Research supported by NSERC.
Abstract: VLA observations are used to measure the H I spectrum of the symbiotic nova HM Sge. It is found that the H I column density to HM Sge is 4 x 10 to the 20th/sq cm and that the upper limit to the mass of circumstellar H I is 0.008 D-squared solar mass, with D equal to the distance to HM Sge in kparsecs. In addition, the spectrum of the quasar O V + 168 is used to show that the total Galactic H I column density in the direction of HM Sge is 9.5 x 10 to the 20th/sq cm. The implications of these results on the interpretation of other observations of HM Sge are discussed.
Circumnebular neutral hydrogen in planetary nebulae
TAYLOR, A. R., GUSSIE, G. T., POTTASCH, S. R.
Astrophysical Journal, Part 1 , vol. 351, March 10, 1990, p. 515-521. Research supported by NSERC.
Abstract: Centimeter line observations of six compact planetary nebulae are reported. Circumnebular atomic hydrogen absorption has been observed in NGC 6790, NGC 6886, IC 418, IC 5117, and BD +30 deg 3639, while H I was not observed to a high upper limit in NGC 6741. Hydrogen was also detected in emission from BD +30 deg 3639. The expansion velocities of the circumnebular envelopes are similar to the expansion velocities observed for the ionized nebula. The optical depth of circumnebular H I appears to decrease with increasing linear radius of the ionized nebulae, indicating that these nebulae are ionization bounded and that the amount of atomic hydrogen decreases as young nebulas evolve.
The collective radio properties of symbiotic stars
SEAQUIST, E. R., TAYLOR, A. R.
Astrophysical Journal, Part 1 , vol. 349, Jan. 20, 1990, p. 313-327.
Abstract: Radio measurements of symbiotic stars are reported which extend the search for radio emission and provide multifrequency and multiepoch measurements of previously detected stars. The results show no evidence that there are time variations in excess of about 30 percent over a period of several years in the detected stars. The radio flux densities are correlated with brightness in the IR, especially at the longer IR wavelengths where dust emission dominates. It is confirmed that symbiotics with the latest red giant spectral types are the most luminous radio emitters. The D-types are the most radio-luminous. Virtually all detected stars with measurements at more than one frequency exhibit a positive spectral index, consistent with optically thick thermal bremsstrahlung. The binary separation for a number of radio-emitting symbiotics is estimated, and it is found that the distribution of inferred binary separations is dramatically different for IR D-types than for S-types.
X-ray variability in transient X-ray sources
DE MARTINO, D., WATERS, L. B. F. M., HABETS, G. M. H. J., TAYLOR, A. R.
Nuovo Cimento C, Serie 1 , vol. 13 C, Mar.-Apr. 1990, p. 471-479.
Abstract: The X-ray variability of transient X-ray binaries is analyzed in terms of the orbital motion of the neutron star, centrifugal inhibition of accretion and of the variable moss loss rate due to activity of the optical counterpart. The systems A0535 + 26 and V0332 + 53 are studied in this respect.
A radio survey of IRAS-selected Be stars
TAYLOR, A. R., DOUGHERTY, S. M., WATERS, L. B. F. M., BJORKMAN, K. S.
Astronomy and Astrophysics , vol. 231, no. 2, May 1990, p. 453-458. Research supported by NSERC.
Abstract: Results are presented of an extensive radio survey of 21 Be stars, observed with VLA on December 4, 1987, July 2, 1988, and September 28, 1988, that have strong emission in the 12-60-micron IRAS photometric bands. For most of the stars, simultaneous observations of the H-alpha line were also obtained to estimate the level of emission from circumstellar gas. A clear correlation was found between the radio data and H-alpha luminosity, indicating that the same process is responsible for both the radio and the hydrogen line emissions. In all cases, there was a turn down in the continuum spectrum of the emission excess between the FIR and the radio data, suggesting a change in the structure of the circumstellar disk outside the FIR region. It is suggested that, in at least some cases, the circumstellar disks of Be stars extend to very large distances from the star.
Papers presented at conferences (not included in conference
proceedings)
Radioastron: The Science
Taylor, A.R.
1990 Canadian Astronomical Society meeting, Calgary (invited).
Search for IR Variability in Be Stars
Dougherty, S.M, Taylor, A.R. and Clark, T.A.
1990 Canadian Astronomical Society meeting, Calgary.
HI Observations of the Young Planetary Nebula BD+30 3639
Dewdney, P. Likkel, L., Taylor, A.R. and Gussie, G.
1990 Canadian Astronomical Society meeting, Calgary.
Circumnebular Neutral Hydrogen in Planetary Nebulae
Gussie, G.T. and Taylor, A.R.
1990 Canadian Astronomical Society meeting, Calgary.
CH Cygni: A Precessing Radio Jet
Taylor, A.R. and Seaquist, E.R.
1990 Canadian Astronomical Society meeting, Calgary.
Identification of Discrete Sources in the WSRT 327 MHz Galactic
Plane Survey
van Leeuwen, J.A., Taylor, A.R., Wallace, B.J. and Penfold, J.E.
1990 Canadian Astronomical Society meeting, Calgary.
Supernova Remnants in the WSRT 327 MHz Galactic Plane Survey
Wallace, B.J., Taylor, A.R. and Goss, W.M.
1990 Canadian Astronomical Society meeting, Calgary.
Two New Position Sensors for Telescope Auto-guiding via Main Beam
Haslett, J.W., Condon, R.J., Gonnason, W.R., Singaravelan, S., Trofimenkoff, F.N., Milone, E.F., Babott, F.M., Clark, T.A. and Taylor, A.R.
1990 Canadian Astronomical Society meeting, Calgary.
Prepared by
Glen Young;
young@bear.ras.ucalgary.ca