Search Publications
The IUE MEGA Campaign: The Rotationally Modulated Wind of zeta Puppis
Howarth, Ian D.; Massa, Derck; Prinja, Raman K.
We discuss 16 days of intensive IUE observations of the Si IV doublet ( lambda 1400) in the spectrum of the O4 I(n)f star zeta Pup. The data show continuous variability throughout the greater part of the blueshifted absorption. Time series analysis of these data reveals significant power at periods of 19.2 hr and 5.2 days, which we identify with t…
Limits on the Hubble Constant from the HST Distance of M100
Ford, H. C.; Ferrarese, L.; Bresolin, F. +15 more
Because M100 is in the Virgo cluster, our recent measurement of its distance has an impact on the calibration of all of the extragalactic secondary distance indicators which reach beyond Virgo and define the expansion rate. We examine the consequences of a 17 Mpc M100 distance, questioning its consistency with supernova and other distances.
T…The Morphology of the Narrow-Line Region of Markarian 3
Boksenberg, A.; Capetti, A.; Sparks, W. B. +2 more
We present the results of Hubble Space Telescope observations of the Seyfert 2 galaxy Mrk 3. Images were taken with the Faint Object Camera and Wide Field Planetary Camera with filters centered on the emission lines [O II] λ3727, [O III] λ5007, Hα, and Hγ.
The narrow-line region (NLR) of Mrk 3 has a striking S-shaped morphology extending over…The Origin of the Rings around SN 1987A: an Evaluation of the Interacting-Winds Model
Martin, Crystal L.; Arnett, David
The origin of the nebulosity around SN 1987A is investigated using two-dimensional, hydrodynamic calculations of the interaction of the progenitor's stellar winds. The collision of the final blue supergiant (BSG) wind with a highly flattened red supergiant (RSG) wind expelled earlier produces a double-lobed bubble of shocked BSG wind confined by a…
The Transition Regions of Capella
Ayres, Thomas R.; Brown, Alexander; Wood, Brian E. +3 more
We have used the Goddard High Resolution Spectrometer (GHRS) to observe the spectoscopic binary system Capella (G8 III + G1 III). Exposures with the G140L, G140M, G160M, G200M, and echelle gratings provide emission line profiles with unprecedented signal-to-noise and spectral resolving power (lambda/Delta-lambda) up to 92,000. Multi-Gaussin fits t…
Evidence for Rapid Rotation of the Carbon Star V Hydrae
Morris, Mark; Barnbaum, Cecilia; Kahane, Claudine
The carbon star V Hya is known to have a bipolar circumstellar outflow and an unusual photospheric spectrum. After measuring the changes in the photospheric velocity and carrying out a spectral broadening analysis over 10 photometric phases, we conclude that rotation due to spin-up by a companion in a common envelope configuration is the most comp…
Hubble Space Telescope and R-Band Eclipse Maps of the UX Ursae Majoris Accretion Disk
Horne, Keith; Baptista, R.; Mason, K. O. +2 more
Hubble Space Telescope time-resolved spectroscopic and ground-based R-band photometric data of UX UMa during eclipse are presented and discussed. The spectroscopy covers the C IV λ1550 and He II λ1640 spectral regions. The eclipses in the UV continuum are deep, nearly reaching the zero level at mid-eclipse phases. Sharp ingress and egress features…
Si/O Abundance Ratios in Extragalactic H II Regions from Hubble Space Telescope UV Spectroscopy
Terlevich, E.; Garnett, D. R.; Skillman, E. D. +5 more
We have measured the Si III] intercombination doublet at 1883 A and 1892 A in seven extragalactic H II regions using the Faint Object Spectrograph on the Hubble Space Telescope. These measurements were used to derive the Si/C and Si/O gas phase abundance ratios in the ionized gas. We find that Si/O shows no systematic variation with O/H over the r…
Vibrationally Excited H 2, HCl, and NO + in the Diffuse Clouds toward zeta Ophiuchi
van Dishoeck, Ewine F.; Federman, S. R.; Lambert, David L. +2 more
Absorption lines from vibrationally excited H2 and from HCl were detected in the ultraviolet spectrum of Zeta Oph with the Hubble Space Telescope (HST). Improved upper limits on NO(+) absorption were obtained as well. The data were analyzed with an updated version of a chemical model for diffuse clouds (van Dishoeck & Black 1986) as a guide to…
The Hubble Space Telescope Sample of Radio-loud Quasars: The LY alpha /H beta Ratio
Ferland, G. J.; Browne, I. W. A.; Netzer, Hagai +5 more
We have used the first Hubble Space Telescope Faint Object Spectrograph spectra of our sample of radio- loud quasars, and quasi-simultaneous ground-based spectrophotometry, to investigate the intensity ratio Lyα/Hβ, whose small observed values are one of the outstanding problems of active galactic nuclei research. The present sample of 20 quasars …