Search Publications
Evaluating Possible Heating Mechanisms Using the Transition Region Line Profiles of Late-Type Stars
Ayres, Thomas R.; Wood, Brian E.; Linsky, Jeffrey L.
Our analysis of high-resolution Goddard High-Resolution Spectrograph (GHRS) spectra of late-type stars shows that the Si IV and C IV lines formed near 105 K can be decomposed into the sum of two Gaussians, a broad component and a narrow component. We find that the flux contribution of the broad components is correlated with both the C I…
HST, radio and infrared observations of 28 3CR radio galaxies at redshift z~ - I. The observations
Best, P. N.; Longair, M. S.; Roettgering, H. J. A.
Hubble Space Telescope images are presented of a sample of 28 3CR radio galaxies with redshifts in the range 0.6<z<1.8, together with maps at comparable angular resolution of their radio structure, taken using the Very Large Array. Infrared images of the fields, taken with the United Kingdom InfraRed Telescope, are also presented. The optica…
The LINER Nucleus of M87: A Shock-excited Dissipative Accretion Disk
Dopita, Michael A.; Sutherland, Ralph S.; Ford, Holland C. +4 more
We present long-baseline Faint Object Spectrograph (FOS) spectra of the nuclear accretion disk in M87 (NGC 4486), offset from the nucleus by 0.6" (42.7 pc) in order to avoid the nuclear continuum. Even so close to the nucleus, the optical spectrum has the appearance of a normal LINER galaxy. We show that the presence of strong UV emission lines pr…
Absorption by Highly Ionized Interstellar Gas Along Extragalactic and Galactic Sight Lines
Sembach, Kenneth R.; Savage, Blair D.; Lu, Limin
We present intermediate resolution (FWHM ∼10-20 km s-1) Goddard High Resolution Spectrograph observations of Galactic C IV and N V absorption along the sight lines to Fairall 9, Mrk 509, PKS 2155-304, and NGC 5548. These observations also provide measures of Si II and S II along the sight lines. Recent measurements of Si IV absorption f…
Planetary Nebulae in the Globular Cluster PAL 6 and NGC 6441
Henry, R. B. C.; Kwitter, K. B.; Morse, Jon A. +2 more
Jacoby & Fullton (1998, in preparation) recently surveyed the Galactic globular cluster system for planetary nebulae and identified excellent candidates in the disk clusters Pal 6 and NGC 6441. Velocities, abundances, and central star properties for these two nebulae are derived. There is a 0.5% probability that the nebula in Pal 6 is a chance…
Origin and Evolution of Coronal Streamer Structure During the 1996 Minimum Activity Phase
Llebaria, A.; Michels, D. J.; Paswaters, S. E. +17 more
We employ coronal extrapolations of solar magnetograph data to interpret observations of the white-light streamer structure made with the LASCO coronagraph in 1996. The topological appearance of the streamer belt during the present minimum activity phase is well described by a model in which the Thomson-scattering electrons are concentrated around…
Detection of Zonal Shear Flows beneath the Sun's Surface from f-Mode Frequency Splitting
Kosovichev, A. G.; Schou, J.
We report on the first successful measure of the zonal variations of the Sun's differential rotation (so-called torsional oscillations) by helioseismology. Using new helioseismic data from the Michelson Doppler Imager on board SOHO, we have detected zonal flow bands with velocity variation of 5 m s-1 at a depth of 2-9 Mm beneath the sur…
SUMER Observations Confirm the Dynamic Nature of the Quiet Solar Outer Atmosphere: The Internetwork Chromosphere
Judge, P. G.; Wilhelm, K.; Carlsson, Mats
On 1996 March 12, during the commissioning phase of the SOHO mission, we obtained observations of the quiet-Sun with the SUMER instrument. The observations were sequences of 15-20 s exposures of ultraviolet emission-line profiles and of the neighboring continua. These data contain signatures of the dynamics of the solar chromosphere that are uniqu…
RAPID - The Imaging Energetic Particle Spectrometer on Cluster
Livi, S.; Grande, M.; Woch, J. +30 more
Hubble Space Telescope Images of the HH 111 Jet.
Hartigan, Patrick; Bally, John; Reipurth, Bo +2 more
We have observed the classic Herbig-Haro jet HH 111 with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope (\HST) through narrow-band filters isolating Hα and [S II]lambda lambda6716 ,6731 emission. The new images fully resolve the body of the jet into a series of small bow shocks, which we conclude form as fast jet material …