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High-Resolution Infrared Imaging of the Compact Nuclear Source in NGC 4258
Chary, R.; Scoville, N. Z.; Matthews, K. +4 more
We present high-resolution imaging of the nucleus of NGC 4258 from 1 to 18 µm. Our observations reveal that the previously discovered compact source of emission is unresolved even at the near-infrared resolution of ~0.2" FWHM, which corresponds to about 7 pc at the distance of the galaxy. This is consistent with the source of emission being …
Supergranulation rotation
Schou, Jesper; Beck, John G.
Simple convection models estimate the depth of supergranulation at approximately 7500 km which suggests that supergranules would rotate at the rate of the plasma in the outer 1% of the solar radius. The supergranulation rotation obtained from MDI dopplergrams shows that supergranules rotate faster than the outer 5% of the convection zone and show …
Identification of comet Hyakutake's extremely long ion tail from magnetic field signatures
Balogh, André; Jones, Geraint H.; Horbury, Timothy S.
Observations of the varying orientations of comet tails led to the suggestion of the existence of the solar wind-a continuous outflow of ionized material from the Sun. It is now well established that gas from comets is ionized by several processes and joins the solar wind, forming an ion (plasma) tail that points away from the Sun. The plasma envi…
Hubble Space Telescope Observations and Photoionization Modeling of the LINER Galaxy NGC 1052
Kraemer, S. B.; Crenshaw, D. M.; Bruhweiler, F. C. +2 more
We present a study of available Hubble Space Telescope (HST) spectroscopic and imaging observations of the low-ionization nuclear emission-line region (LINER) galaxy NGC 1052. The WFPC2 imagery clearly differentiates extended nebular Hα emission from that of the compact core. Faint Object Spectrograph (FOS) observations provide a full set of optic…
The Nature of Associated Absorption and the Ultraviolet-X-Ray Connection in 3C 288.1
Shields, Joseph C.; Netzer, Hagai; Hamann, Frederick W.
We discuss new Hubble Space Telescope spectroscopy of the radio-loud quasar 3C 288.1. The data cover ~590 to ~1610 Å in the quasar rest frame. They reveal a wealth of associated absorption lines (AALs) with no accompanying Lyman-limit absorption. The metallic AALs range in ionization from C III and N III to Ne VIII and Mg X. We use these data and …
The Nature of the Halo Population of NGC 5128 Resolved with NICMOS on the Hubble Space Telescope
Charlot, Stéphane; Graham, James R.; Liu, Michael C. +1 more
We present the first infrared (IR) color-magnitude diagram (CMD) for the halo of a giant elliptical galaxy. The CMD for the stars in the halo of NGC 5128 (Centaurus A) was constructed from Hubble Space Telescope NICMOS observations of the WFPC2 CHIP-3 field of Soria et al. to a 50% completeness magnitude limit of [F160W]=23.8. This field is locate…
The structure and momentum of multiple collimated outflows in the protoplanetary nebula Frosty Leo
Sahai, R.; Bujarrabal, V.; Castro-Carrizo, A. +1 more
We have discovered multiple jet-like features in the inner regions of the protoplanetary nebula (PPN) Frosty Leo, in optical images obtained with the Hubble Space Telescope. Frosty Leo is only the second PPN (after CRL2688) and the first oxygen-rich one, to show well-focussed jets close to the equatorial plane. The nebula consists of two bright co…
Global and local bias in the FK5 from the Hipparcos data
Mignard, F.; Frœschlé, M.
Extensive analyses of the FK5 Catalogue with respect to the Hipparcos reference frame have been made in order to determine the overall and local corrections to be applied to any FK5-based secondary frame. The global rotation in position and proper motion is significant, and for the latter, interpreted in term of lack of inertiality of the FK5 fram…
Imaging of the protoelliptical NGC 1700 and its globular cluster system
Forbes, Duncan A.; Brodie, Jean P.; Kissler-Patig, Markus +1 more
An excellent candidate for a young elliptical, or `protoelliptical' galaxy is NGC 1700. Here we present new B-, V- and I-band imaging using the Keck telescope, and reanalyse existing V- and I-band images from the Hubble Space Telescope. After subtracting a model of the galaxy from the Keck images, NGC 1700 reveals two symmetric tidal tail-like str…
Radiometric Validation of the Midcourse Space Experiment's (MSX) Point Source Catalogs and the MSX Properties of Normal Stars
Cohen, Martin; Hammersley, Peter L.; Egan, Michael P.
We describe our methods to validate the absolute calibration of the infrared (IR) radiometry of the Midcourse Space Experiment (MSX) Point Source Catalog, version 1.2 (PSC1.2). These are based upon stars drawn from our current all-sky network of absolute calibrators and upon other stars that also support the calibration of ESA's Infrared Space Obs…