Search Publications
PG 0009+036: a rapidly rotating normal B star in the galactic halo.
de Boer, K. S.; Heber, U.; Moehler, S. +1 more
We present the spectroscopic analysis of a rapidly rotating main sequence B star at high galactic latitude. From optical and ultraviolet spectra of PG 0009+036 we find for the atmospherical parameters T_eff_=14500K, logg=3.9, and a rotational velocity of vsini=320km/s. The effects of rotation on the fundamental parameters of the star are discussed…
Search for neutron star spin periods in X-ray bursts.
van der Klis, M.; Jongert, H. C.
We report a search for pulsations in 147 Type 1 X-ray bursts observed with EXOSAT in 10 X-ray burst sources. Instead of treating each burst separately, we incoherently averaged the power spectra of all of the bursts of a given burster to improve statistics. No periodicities were detected; 99% confidence upper limits on the modulation depths of pos…
HR 4289 - an X-ray luminous galaxy close to the bright star.
Schmitt, J. H. M. M.; Reimers, D.; Huensch, M.
Using new optical, UV and X-ray observations we show that the K5 III star HR 4289, formerly believed to be the only ROSAT All-Sky survey detection to the right of the coronal diving line, should not be identified with the X-ray source. Pointed ROSAT PSPC observations demonstrate that the X-ray source is slightly extended, and locate the X-ray sour…
The apsidal motion in extragalactic stars: the masses of the eclipsing binary HV 2274 in the Large Magellanic Cloud.
Claret, A.
Theoretical apsidal motion rates based on evolutionary stellar models are used to evaluate masses and radii of an extragalactic eclipsing binary (HV 2274) in the Large Magellanic Cloud. As radial velocity curves are not available, from the results of the analysis of the light curve and the detected apsidal motion it was possible to constrain the v…
HST observations of the PG 1159 type central star of K1-16.
Patriarchi, P.; Perinotto, M.
The central star of the planetary nebula K1-16, belonging to the class of the pulsating PG 1159 pre-white dwarfs, has been observed with the HST telescope using the GHRS in the zone of the CIV λ1550A doublet, to ascertain the reality and examine the properties of the exceptionally fast wind suggested to occur in this star by low resolution IUE obs…
An emission line region associated with 3C 273.
Meisenheimer, K.; Hippelein, H.; Roeser, H. J.
We have observed an extended emission line region about 4" to the South-East of 3C 273 in the light of the lines [OII]λ372.8nm and [OIII]λ500.7nm, with an overall linear dimension of ~20x10kpc and a brightness of ~10^-18^W/m^2^ in either line. HST images show the region to be split up into several knots. The line intensity ratios and colors are co…
A study of solar analogues in the ultraviolet.
Solano, E.; Wamsteker, W.; Fernley, J. +1 more
We have made a comparative study of the Sun and solar analogue stars using the published solar ultraviolet fluxes and IUE low dispersion spectra of the solar analogues. The Hyades dwarf HD 28099 (vB64) shows a flux excess below 2500A which is probably due to chromospheric activity since it is a relatively young star. HD 44594, 186408 (16CygA) and …
Faint Object Camera observations of complex nuclear structure in PKS 2158-380.
Boksenberg, A.; Blades, J. C.; Disney, M. J. +3 more
We present the results of Hubble Space Telescope observations of the nucleus of the narrow-line radio galaxy PKS 2158-380. Faint Object Camera images (taken before the December 1993 servicing mission) in bands centered near 3720A and 3420A show complex nuclear structure. The nucleus consists of three well resolved components of sizes ~0.3" (~0.28k…
Symmetry in discontinuity properties at the north and south heliographic poles: Ulysses.
Balogh, A.; Tsurutani, B. T.; Goldstein, B. E. +3 more
A study of directional discontinuities (DDs) that occurred during 4 days of the Ulysses north polar pass was conducted (461 directional discontinuities total) using magnetic field and plasma data. We find that the total number of directional discontinuities selected by the Tsurutani and Smith (1979) method are the same in the north and south polar…
The galactic warp in young stars proper motions.
Lattanzi, M. G.; Smart, R. L.
Using Monte Carlo simulations of the Galaxy parameters, we have investigated the expected effects of a galactic warp model on the proper motions of early type stars. The introduction of the warp into the Galaxy simulation appears very pronounced in galactic latitude proper motions, but unobservable in galactic longitude proper motions. The proper …