Search Publications

An Analysis of the Statistics of the Hubble Space Telescope Kuiper Belt Object Search

Brown, Michael E.; Kulkarni, Shrinivas R.; Liggett, Timothy J.

We calculate statistical limits to the detection of Kuiper belt objects in the Hubble Space Telescope (HST) data of Cochran et al., in which they report the discovery of a population of Halley-sized objects in Pluto-like orbits. Detection of a population of faint objects in these data is limited by the number of false objects that appear owing onl…

Restoration of Long-Exposure Full-Disk Solar Intensity Images

Duvall, T. L.; Jefferies, S. M.; Toner, C. G.

We describe an algorithm for restoring full-disk solar intensity images blurred by a smooth, quasi-stationary point-spread function (PSF). For Earth-based observations, this type of data can be obtained by using exposure times that are much longer than the redistribution time of the atmosphere. Using simulated data for a wide range of observing co…

The Age of the Globular Cluster M68

Castellani, V.; Brocato, E.; Piersimoni, A.

Relying on the accurate color-magnitude diagram (CMD) presented by Walker in 1994, we use the fitting of moderately hot horizontal-branch models to the observed CMD to derive suitable information regarding both cluster reddening and distance modulus and to discuss theoretical predictions constraining the absolute age of the metal-poor Galactic glo…

The Mass of the Classical Cepheid V350 SGR

Bohm-Vitense, E.; Evans, N. R.; Carpenter, K. +2 more

Two medium resolution spectra of the hot companion of the Cepheid V350 Sgr have been obtained with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope. Comparison of these spectra (in the wavelength range 1840 to 1880 \AA) with the spectrum of $\alpha$ Lyr shows that V350 Sgr B has a projected rotation velocity which may be …

Infrared Photometry of 487 Sources in the Inner Regions of NGC 5128 (Centaurus A)

Minniti, Dante; Alonso, M. Victoria

We study the sources present in the inner 3 kpc region of NGC 5128 (Cen A), most of which are star clusters of different ages. Photometry of archival Hubble Space Telescope WFPC images (F675W filter) is complemented with IR photometry (JHK' filters) obtained with the IRAC2B infrared array camera at the ESO/MPI 2.2 m telescope. From IR color maps w…

An active K0 IV-V star and a hot white dwarf (EUVE J0702+129) in a wide binary.

Doyle, J. G.; Christian, D. J.; Mathioudakis, M. +1 more

We present far ultraviolet and optical spectroscopy of the Extreme Ultraviolet Explorer (EUVE) survey source EUVE J0702+129 revealing a composite K0 star plus DA white dwarf spectrum. The International Ultraviolet Explorer spectra show continuum emission from a hot white dwarf (Teff=30-40,000K) and a rising contribution from the K0 star at λ>25…

Detection of a Satellite Orbiting The Nucleus of Comet Hale–Bopp (C/1995 O1)

Sekanina, Z.

This paper reports on the detection of a satellite around the principal nucleus of comet Hale-Bopp. As shown elsewhere, a successful morphological model for the comet's dust coma necessitates the postulation of overlapping jet activity from a comet pair. The satellite has been detected digitally on images taken with the Hubble Space Telescope's Wi…

Wind variability of B supergiants. II. The two-component stellar wind of γ Arae.

Howarth, I. D.; Massa, D.; Prinja, R. K. +2 more

The stellar wind of the rapidly rotating early-B supergiant, γ Ara, is studied using time series, high-resolution IUE spectroscopy secured over ~6 days in 1993 March. Results are presented based on an analysis of several line species, including N V, C IV, Si IV, Si III, C II, and Al III. Comparisons of the time-averaged wind line morphology of γ A…

The Joint Science Operations Centre

Chaizy, P. A.; Dimbylow, T. G.; Hapgood, M. A. +4 more

ISO-SWS Observations of NGC 1068

Lutz, D.; Genzel, R.; Sturm, E. +2 more

We present a first analysis of 2.4-45µm spectra of NGC 1068 obtained with the Short Wavelength Spectrometer SWS on board the Infrared Space Observatory ISO. The measured fine-structure line fluxes can be fit successfully by a simple photoionization model invoking an EUV bump in the ionizing continuum, similar to the case of the Circinus galaxy. Di…