Search Publications
Missions
Journals
Publication Years
Far-Ultraviolet Continuum of G-Type Stars: A Signature of the Temperature Minimum Region
Morossi, C.; Malagnini, M. L.; Franchini, M.
The main results of a program of systematic comparison between observed and computed UV spectral energy distributions of field G-type stars are illustrated. We constructed the UV observed energy distributions for 53 G stars, starting from the IUE Uniform Low Dispersion Archive (ULDA) and computed the corresponding theoretical fluxes by using the a…
The Solar Wind - Inner Heliosphere
McComas, D. J.; Goldstein, B. E.; Neugebauer, M. +3 more
The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulyss…
Ulysses observations of a ``density hole'' in the high-speed solar wind
McComas, D. J.; Forsyth, R. J.; Riley, Pete +1 more
Ulysses observations at mid and high heliographic latitudes have revealed a solar wind devoid of the large variations in density, temperature, and speed that are commonly observed at low latitudes. One event, however, observed on May 1, 1996, while Ulysses was located at ~3.7AU and 38.5°, stands out in the plasma data set. The structure, which is …
Localised neutral hydrogen absorption towards the radio jet of Markarian 6
Mundell, C. G.; Holloway, A. J.; Pedlar, A. +1 more
We present 0.15'' (56 pc) resolution MERLIN observations of neutral hydrogen (Hi) lambda 21cm absorption detected towards the arcsecond-scale radio jet of the Seyfert 1.5 galaxy Markarian 6. Absorption is detected only towards a bright, compact radio feature located, in projection, 380 pc north of the likely location of the optical nucleus. Based …
Spatiotemporal Correlations and Turbulent Photospheric Flows from SOHO/MDI Velocity Data
Tarbell, T.; Lawrence, J. K.; Cadavid, A. C. +2 more
Time series of high-resolution and full-disk velocity images obtained with the Michelson Doppler Imager (MDI) instrument on board SOHO have been used to calculate the spacetime spectrum of photospheric velocity flow. The effects of different methods for filtering acoustic oscillations have been carefully studied. It is found that the spectra show …
The HIPPARCOS proper motion link to the extragalactic reference system using NPM and SPM
Kozhurina-Platais, V.; Lindegren, L.; Platais, I. +9 more
We describe the use of the Lick Northern Proper Motion (NPM) program and its southern-sky complement, the Yale/San Juan Southern Proper Motion (SPM) program, to determine the Hipparcos proper motion link to the extragalactic reference system defined by galaxies. In total ~ 9,100 Hipparcos stars were chosen for the NPM link solution and ~ 4,100 for…
Hubble Space Telescope Wide Field Planetary Camera 2 Imaging of UGC 12695: A Remarkably Unevolved Galaxy at Low Redshift
Impey, C. D.; Bothun, G. D.; O'Neil, Karen +1 more
Utilizing the F814W and F300W filters, short-exposure Hubble Space Telescope Wide Field Planetary Camera 2 images were taken of UGC 12695, a nearby (z ~ 0.021) low surface brightness disk galaxy. UGC 12695 has an unusual morphology, consisting of a Y-shaped nucleus surrounded by a faint spiral arm with a number of bright H ii regions interspersed …
The Sirius Supercluster and Missing Mass near the Sun
Eggen, Olin J.
The Hipparcos results confirm some 50 members of the Sirius supercluster in the Bright Star Catalogue. The resulting, well-defined color-luminosity array indicates an age of 4 x 10^8 yr from conventional (no overshoot) models. A comparison of the luminosity function obtained from members in the Bright Star Catalogue, unbiased as to proper motion, …
Large Variations in the Winds of Single Cool Giants: λ Velorum and γ Crucis
Carpenter, K. G.; Mullan, D. J.; Robinson, R. D.
UV spectra of the ``noncoronal'' single K supergiant λ Vel and of the single M giant γ Cru obtained with IUE and the Hubble Space Telescope at various epochs indicate that the profiles of many lines formed in the wind exhibit striking alterations in shape with time. We parameterize the wind profiles in terms of an empirical optical depth τemp…
Discovery of a Luminous White Dwarf in a Young Star Cluster in the Large Magellanic Cloud
Elson, Rebecca A. W.; Sigurdsson, Steinn; Hurley, Jarrod +2 more
We have identified a candidate ~1-2×105 yr old luminous white dwarf in NGC 1818, a young star cluster in the Large Magellanic Cloud. This discovery strongly constrains the boundary mass Mc at which stars stop forming neutron stars and start forming white dwarfs, to Mc>~7.6 Msolar.