Search Publications
The Ultraviolet Color Gradient in the Late-Type Spiral Galaxy M33
O'Connell, Robert W.; Bohlin, Ralph C.; Landsman, Wayne B. +3 more
The ultraviolet surface brightness and color distributions for the late-type spiral galaxy M33 are derived from images at 1520 and 2490 A that were obtained by the Ultraviolet Imaging telescope (UIT) on the Astro Spacelab mission. although the surface brightness shows a general decline with radius, the dominant spiral arms cause significant deviat…
The Luminosity of the Double-Mode Cepheid Y Carinae
Evans, Nancy R.
IUE spectra of the double-mode Cepheid Y Carinae have been used to determine the spectral type of the binary companion. From the companion spectral type (B9.O V), the absolute magnitude of the Cepheid is found to be -2.94 mag, with an estimated uncertainty of +/-0.3. This luminosity is in good agreement with that from the period-luminosity-color r…
A Spectroscopic Search for Colliding Stellar Winds in O-Type Close Binary Systems. II. Plaskett's Star (HD 47129)
Wiggs, Michael S.; Gies, Douglas R.
New evidence for colliding winds in the massive O-type binary system Plaskett's star is reported. High S/N ratio spectra of the H-alpha and He I 6678 emission lines are presented, and their orbital phase-related variations are examined in order to derive the locations and motions of the high-density gas in the system. Radial velocity cures for sev…
EXOSAT Observations of the Be/X-Ray Binary 4U 2206+54
Saraswat, Priyamvada; Apparao, Krishna M. V.
We present the X-ray observations of the Be star binary system 4U 2206 + 54 made with the EXOSAT satellite during the period 1983-1985. The observations were carried out on three occasions, each separated by roughly a year. The source was active during the 1983 and 1985 observations and several short duration flares were observed. The spectrum, du…
Spatially Resolved Ultraviolet Spectroscopy of the Liner Galaxy NGC 3998
Filippenko, A. V.; Branduardi-Raymont, G.; Reichert, G. A. +3 more
We report results of recent IUE observations of the low-ionization nuclear emission-line region (LINER) galaxy NGC 3998. Spatial structure in the long-wavelength emission is apparent; the spatial profiles in the LWP images show a two-component structure, with an unresolved central component superposed on extended underlying emission. We have used …
Carbon and Nitrogen Abundances Determined from Transition Layer Lines
Mena-Werth, Jose; Boehm-Vitense, Erika
The possibility of determining relative carbon, nitrogen, and silicon abundances from the emission-line fluxes in the lower transition layers between stellar chromospheres and coronae is explored. Observations for main-sequence and luminosity class IV stars with presumably solar element abundances show that for the lower transition layers Em = BT<…
The Structure of the Inner Arcsecond of R Aquarii Observed with the Hubble Space Telescope
Burgarella, Denis; Paresce, Francesco
The inner arcsec of R Aquarii has been observed with the Faint Object Camera on the Hubble Space Telescope. A simple and reliable linear deconvolution method is used to resolve the two features, designated C1 and C2 from radio observations, into several condensations. C1 is composed of four objects, designated C1a, C1b located at 0.099 arcsec from…
A VLA 3.6 Centimeter Survey of N-Type Carbon Stars
Brown, Alexander; Luttermoser, Donald G.
The results are presented of a VLA-continuum survey of 7 N-type carbon stars at 3.6 cm. Evidence exists for hot plasma around such stars; the IUE satellite detected emission lines of singly ionized metals in the optically brightest carbon stars, which in solar-type stars indicate the existence of a chromosphere. In the past, these emission lines w…
Possible First Detection of Ultraviolet Pulses from an Intermediate Polar: V603 Aquila
Udalski, A.; Schwarzenberg-Czerny, A.; Monier, R.
We report possible independent detection of a pulsation in the UV continuum radiation of the intermediate polar star, V603 Aql, at 2.2 sigma level. Since the period of the pulsation of 62.9 minutes is very close to the period of X-ray and optical modulations discovered earlier, its detection combined with previous data confirms reality of UV, X-ra…
The Origin of the Far-Ultraviolet Continuum in Solar and Stellar Flares
Bromage, G. E.; Doyle, J. G.; Phillips, K. J. H.
A continuum in the far-ultraviolet region observed in IUE spectra of dMe stars in a flaring state is discussed and compared with that observed in solar flares. Similar continuous emission observed in solar flare far-ultraviolet spectra has been identified with neutral silicon recombination radiation excited by intense lines. This also appears to b…