Search Publications
The interstellar void in the direction to ɛ CMa: local clouds and hot gas.
Ferlet, R.; Vidal-Madjar, A.; Lemoine, M. +2 more
We analyse HST GHRS observations of the interstellar medium in the direction to ɛ CMa, the strongest EUV source in the sky, located in a region deficient in neutral gas. The line of sight contains three main absorption components resolved in the high resolution Ech B observations. Three weak components are also detected. We derive their heliocentr…
A detailed X-ray variability study of the Seyfert galaxy NGC 4051
Papadakis, I. E.; Lawrence, A.
We present a detailed and rigorous examination of the X-ray variability characteristics of the Seyfert galaxy NGC 4051, using the 1985 EXOSAT observation and our improved power spectrum modelling techniques. The Medium Energy (ME) power spectrum is adequately fitted by a power-law model, but the Low Energy (LE) spectrum is not. We find an excellen…
WFPC2 Imaging of the Circumstellar Nebulosity of HL Tauri
Casertano, Stefano; Ballester, Gilda E.; Krist, John E. +15 more
Planetary camera images of HL Tauri have been obtained through V-, R-, and I-band filters using the Wide Field and Planetary Camera 2 aboard the refurbished Hubble Space Telescope. These images show that HL Tauri is entirely reflection nebulosity at optical wavelengths, with no optical star visible to a limiting magnitude of V = 25.5. The optical …
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…
Was Fritz Zwicky's "Type V" SN 1961V a Genuine Supernova?
Filippenko, Alexei V.; Ho, Luis C.; Barth, Aaron J. +4 more
In 1989, Goodrich and collaborators suggested that SN 1961V, a very peculiar Type II (Zwicky's "Type V") supernova, was not the final explosion of a star at the end of its life, but rather the giant eruption of a massive, luminous blue variable, like n Car. To test this hypothesis, we have used the Hubble Space Telescope to obtain optical images o…
Properties of the WO Wolf-Rayet stars.
Barlow, M. J.; Storey, P. J.; Kingsburgh, R. L.
We present optical spectrophotometry for five WO Wolf-Rayet stars, three of them in our own Galaxy and one in each of the SMC and LMC. IUE ultraviolet spectrophotometry has also been obtained for the two Magellanic Cloud WO stars, including a high resolution spectrum for one of them. Quantitative spectral typing criteria are defined for WO subtype…
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…
Ultraviolet observations of galaxies in nearby clusters. III. Star-forming galaxies in the Coma cluster.
Laget, M.; Donas, J.; Milliard, B.
In a field of 1deg radius centered in the Coma cluster of galaxies, UV (λ=2000A) observations with a 40-cm balloon-borne imaging telescope (FOCA) have provided a list of 442 UV sources brighter than m_UV_=18, which are identified in the Godwin et al. (1983) catalogue. 254 are identified as galaxies, 178 as star-like objects and 10 as galaxy-star p…