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The HR 1614 Group and HIPPARCOS Astrometry
Eggen, Olin J.
The evidence for the existence of the important HR 1614 supercluster and group of rare rich CN stars is examined with the use of Hipparcos astrometry. Group membership is supported by Hipparcos parallaxes except for two stars for which available evidence suggests uncertainty in the Hipparcos values.
An Absence of Gaps in the Main-Sequence Population of Field Stars
Yanny, Brian; Newberg, Heidi Jo
Using high-precision parallaxes from the Hipparcos catalog, we construct H-R diagrams for two samples of bright stars. The first is a magnitude-limited sample that is over 90% complete and uses uniform photometry from the Catalog of WBVR Magnitudes of Northern Sky Bright Stars (δ>-14deg). This sample shows a smooth distribution of st…
Interplanetary Lyman α remote sensing with the Ulysses Interstellar Neutral Gas Experiment
Pryor, Wayne R.; Ajello, Joseph M.; Witte, Manfred
The Ulysses neutral gas instrument obtained celestial sphere maps of interplanetary Lyman α emission from neutral hydrogen in 1991-1996. These maps are unique because the spacecraft was located at a wide range of heliocentric ecliptic latitudes. Eleven of these maps are compared with the predictions of an interstellar wind hydrogen model previousl…
HIPPARCOS based astrometric analysis of M 3 and M 92 fields: optical identification of X-ray and radio sources, space motions of globular clusters M 3 and M 92 and a galactic orbit of the sdB star PG 1716+426
Geffert, M.
We present positions and proper motions with respect to the Hipparcos system of stars in the fields of the globular clusters M 3 and M 92. The data were used for the optical identification of X-ray and radio sources, a new determination of the absolute proper and space motions of the globular clusters M 3 and M 92. Moreover, we derived an accurate…
Lyalpha absorption in the nearby Universe: the sightline to Q1821+643
Bowen, David V.; Pettini, Max; Boyle, Brian J.
We present the first results of a survey designed to understand the origin of Lyalpha-forest absorption systems at low redshift. Using the WYFFOS and HYDRA multifibre spectrographs on the William Herschel and Wisconsin Indiana Yale NOAO (WIYN) telescopes, we have identified 51 galaxies brighter than b_j:=:18.5 within 30 arcmin of the sightline of …
Tentative Detection of Circumstellar CO2 from the AGB Star R Crateris
Ryde, N.; Eriksson, K.; Gustafsson, B. +2 more
We report on and discuss the detection of an emission feature at 14.98 µm from the oxygen-rich, semi-regularly pulsating Asymptotic Giant Branch star R Crateris, a feature which we suggest to be due to the <Stack> 0 1 </Stack> Q-branch of circumstellar CO2. We also suggest a reasonable excitation mechanism, which …
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 …