Search Publications

Interstellar Gas in Low Mass Virgo Cluster Spiral Galaxies

Madden, Suzanne C.; Smith, Beverly J.

We have measured the strengths of the [C II] 158 mu m, [N II] 122 mu m, and CO (1 - 0) lines from five low blue luminosity spiral galaxies in the Virgo Cluster, using the Infrared Space Observatory and the NRAO 12m millimeter telescope. Two of the five galaxies have high L([C II])/L(CO) and L(FIR)/L(CO) ratios compared to higher mass spirals. Thes…

High-Resolution Imagery of BD + 30degree3639 and Its Dusty Halo

White, Stephen M.; Borkowski, Kazimierz J.; Harrington, J. Patrick +1 more

The planetary nebula BD +30\arcdeg3639 has been imaged by the Hubble Space Telescope through nine narrow-band filters. A high resolution radio map has been obtained with the VLA. Comparison of Hβ , Hα and radio images allow us to derive the point-to-point variations in both the extinction and the ratio of total to selective absorption. The extinct…

In-Flight Performance of the Virgo Luminosity Oscillations Imager Aboard SOHO

Appourchaux, Thierry; Andersen, Bo N.; Fröhlich, Claus +3 more

The Luminosity Oscillations Imager (LOI) is a part of the VIRGO instrument aboard the Solar and Heliospheric Observatory (SOHO). The scientific objective of the LOI experiment is to identify and characterize pressure and internal gravity oscillations of the Sun by observing the radiance variations. The LOI is a low-resolution imager with 12 pixels…

Observations of Doppler Shifts in a Solar Polar Coronal Hole

Wilhelm, K.; Mariska, J. T.; Warren, H. P.

Using observations from the Solar Ultraviolet Measurements of Emitted Radiation experiment flown on the Solar and Heliospheric Observatory spacecraft, we have measured Doppler wavelength shifts in the north polar coronal hole in the 1032 and 1038 Å emission lines of O VI and the 1036 and 1037 Å emission lines of C II relative to chromospheric emis…

Tomographic Separation of Composite Spectra. IV. The Physical Properties of the Massive Close Binary DH Cephei

Gies, Douglas R.; Penny, Laura R.; Bagnuolo, William G., Jr.

We present the results of a Doppler tomographic reconstruction of the UV spectra of the double-lined, O binary DH Cephei based on observations made with the International Ultraviolet Explorer. We describe cross-correlation methods we use to obtain precise radial velocities, and we present a radial velocity curve based on combined optical and UV me…

Resolution and Kinematics of Molecular Gas Surrounding the Cloverleaf Quasar at Z = 2.6 Using the Gravitational Lens

Yun, M. S.; Blandford, R. D.; Scoville, N. Z. +1 more

Gravitational lenses have long been advertised as primitive telescopes, capable of magnifying cosmologically distant sources. In this Letter we present new, 0.9" resolution CO (7-6) observations of the z = 2.56 Cloverleaf quasar (H1413+117) and spatially resolved images. By modeling the gravitational lens, we infer a size scale of 0.3" (~1 kpc) fo…

Improved Evidence for a Black Hole in M32 from HST/FOS Spectra. I. Observations

van der Marel, Roeland P.; Rix, Hans-Walter; de Zeeuw, P. Tim

We have obtained spectra through small apertures centered on the nuclear region and major axis of M32 with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). A detailed analysis and reduction of the data is presented, including (1) new calibrations and modeling of the FOS aperture sizes, point-spread function, and line-spread…

On the Origin of the Ultraviolet Continuum in Seyfert 2 Galaxies

Colina, Luis; Pérez, Enrique; Mas-Hesse, J. Miguel +4 more

High-resolution Hubble Space Telescope ultraviolet images of the Seyfert 2 galaxies NGC 1667, NGC 3982, NGC 5427, and NGC 5953, previously known to have circumnuclear star-forming rings, are presented.

The UV images of all four Seyfert 2 galaxies show the presence of several compact UV-bright knots at distances of ~0.7-2 kpc from the nucleus …

Keck Spectroscopy of Objects with Lens-like Morphologies in the Hubble Deep Field

Zepf, Stephen E.; Davis, Marc; Moustakas, Leonidas A.

We present spectroscopy from the Keck telescope of three sets of objects in the Hubble Deep Field (HDF) that have lens-like morphologies. In the case of J123641+621204, which is composed of four objects with similar colors and a mean separation of <~0.8", we find at least two distinct components at redshifts of z = 3.209 and z = 3.220 that are …

Radio Emission from Objects in the Hubble Deep Field

Fomalont, E. B.; Windhorst, R. A.; Richards, E. A. +2 more

A radio image that covers the Hubble deep field and flanking fields has been made using the VLA for 50 hr at a frequency of 8.4 GHz, a resolution of 6", and a 4.3 σ detection level of 12.2 µJy. All six radio sources detected in the deep field are identified with galaxies brighter than I = 24 mag, based on a radio/optical coincidence better t…