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First results from a photometric infrared survey for Vega-like disks around nearby main-sequence stars.
Waters, L. B. F. M.; Kessler, M. F.; Siebenmorgen, R. +12 more
We have undertaken a survey for Vega-like disks around nearby main-sequence stars by making photometric measurements with ISOPHOT at four wavelengths between 25 and 180µm. Our goal is to establish how common Vega-like disks are, and how their presence depends on the fundamental properties of main-sequence stars (mass, age, rotation etc.). He…
Nuclear disks of gas and dust in Fanaroff-Riley type I radio host galaxies: 3C 402N and NGC 7052.
de Juan, L.; Colina, L.; Golombek, D.
A nuclear disk of gas and dust is detected in the host galaxy of the Fanaroff-Riley type I (FR-I) radio source 3C 402N, using pre-COSTAR HST/FOC images, and high spatial resolution ground-based broad-band and Hα+[NII] narrow-band images. The physical properties of the nuclear disk in the B2 2116+26 host galaxy (NGC 7052) are also presented. On ave…
Discovery of a Nova in the Virgo Galaxy M100
Livio, Mario; Madore, Barry F.; Stetson, Peter B. +5 more
We present the V and I light curves of a nova discovered in the disk of the spiral galaxy M100, located in the Virgo Cluster. In spite of the fact that the light curve is not well sampled around maximum light and the reddening to the nova is not accurately known, by adopting the maximum magnitude versus rate of decline relation by Della Valle &…
Are the pulses of the Crab pulsar modulated?
Cadez, A.; Galicic, M.
We present the results of optical Crab pulsar observations which were designed to search for short-time variations in pulsar's light-curve. Hubble Space Telescope (High Speed Photometer) data and photometric data obtained at the Asiago 1.82m telescope using a specially designed stroboscopic chopper have been analysed and compared. We find a very w…
The extreme-ultraviolet spectrum of the central star of the planetary nebula NGC 1360
Dreizler, Stefan; Drake, Jeremy J.; Werner, Klaus +1 more
We have used the Extreme Ultraviolet Explorer (EUVE) to obtain the first EUV spectrum of the central star of a planetary nebula, that of NGC 1360. The photospheric spectrum shows continuum absorption edges due to O^4+ as well as absorption-line features. NLTE model atmospheres including line blanketing by iron-group elements can match the general …
A new HST image of Cygnus A .
Sparks, W. B.; Macchetto, F.; Miley, G. K. +2 more
We present a new HST image of Cygnus A, taken in the V-band. This image includes both continuum and lines of [0III], and shows the major, northwestern and southeastern components, together with the weaker central component. Filamentary structure is present at this resolution of 0.045". This structure runs generally parallel to the radio jet and ma…
Hubble Space Telescope Observations of Interstellar Lines in Three High-Latitude Stars
Jenkins, Edward B.; Wallerstein, George
To study changes in the gas-phase abundances of elements in the Galactic halo, we have used the Goddard High Resolution Spectrograph instrument on the Hubble Space Telescope to observe interstellar absorption lines of O I, Mg II, Al II, Al III, Si II, S II, Fe II, and Ni II in the spectra of three stars at high Galactic latitudes: HD 22586, HD 497…
The high latitude pass of ULYSSES: energetic particle observations with EPAC.
Keppler, E.; Korth, A.; Fraenz, M. +4 more
We report on observations of energetic particles (EP) during the ascent of ULYSSES to the south pole, on the fast pass from south to north and in the first few months after the north polar pass. After it left the ecliptic plane the spacecraft moved periodically into a corotating (26 days period) fast solar wind stream and observed the accelerated …
Ulysses assessment of the Jovian planetary field
Dougherty, M. K.; Balogh, A.; Smith, E. J. +1 more
The magnetic field measurements made by the Ulysses dual fluxgate/vector helium magnetometer during the day of closest approach to Jupiter in February 1992 are reported. The data are compared to a model which describes the field in terms of an internal spherical harmonic component together with an external current sheet field. The sensitivity of t…
On the spread of ages among the young stars in the LMC association NGC 1948.
Bomans, D. J.; de Boer, K. S.; Vallenari, A. +2 more
The ages of the young associations located at the border of the supergiant shell LMC4 are essential parameters to understand the formation and the evolution of that supergiant shell. We present spectra in the UV and the optical wavelength range of eleven stars in NGC 1948 in order to establish the location of the top of the main sequence more accu…