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Mass Segregation in the Globular Cluster NGC 6397

Cool, Adrienne M.; King, Ivan R.; Sosin, Craig

Our deep HST images of the center of the globular cluster NGC 6397 are almost devoid of faint stars, implying that these stars must be much less concentrated to the cluster center than the brighter stars. This difference is an expected consequence of energy exchanges through stellar encounters, which give higher velocities to lower mass stars and …

The structure and evolution of the Nova V1974 Cygni shell from HST observations.

Paresce, F.; Livio, M.; Korista, K. +1 more

The Faint Object Camera on the refurbished Hubble Space Telescope (HST) observed Nova Cygni 1992 (V1974 Cyg) on three separate occasions in the first five months of 1994 through a series of interference and narrow band filters sensitive to the emission lines of OIII, OII, Hβ, Lyman α, HeII, NeIII, NeV, MgII, and NIV. Two objective prism images in …

The Abundances of Pt, Au, and HG in the Chemically Peculiar HgMn-Type Stars kappa CANCRI and chi LUPI

Wahlgren, Glenn M.; Brage, Tomas; Leckrone, David S. +2 more

Echelle mode spectra obtained with the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope (HST) have been used to determine the abundances of the heavy elements Pt, Au, and Hg in the chemically peculiar HgMn-type stars kappa Cancri and chi Lupi. The abundances were determined by fitting observed line profiles with synth…

The Unusual Quasar PG 1407+265

Elvis, Martin; Wilkes, Belinda J.; McDowell, Jonathan C. +4 more

PG 1407+265, discovered in the Palomar-Green Survey (Schmidt & Green 1983), was identified as a z ∼ 1 radio-quiet quasar on the basis of a single weak line. Further observations over a wide wavelength range confirm the identification but reveal the object to have unusual emission-line properties. Broad Hα is the only strong emission line with …

Discovery of two hot DO white dwarfs exhibiting ultrahigh-excitation absorption lines.

Rauch, T.; Werner, K.; Dreizler, S. +3 more

We report on the detection of two faint blue stars (HE0504-2408 and HS0713+3958) discovered by the Hamburg Schmidt surveys whose spectra are dominated by broad and shallow metal absorption lines from ultrahighly excited ionization stages (CV, CVI/NVI, NVII/OVII, OVIII, NeIX, NeX) with ionization energies ranging from 392eV to 1362eV. Detailed non-…

Radio and Emission-Line Jets in the Type 2 Seyfert Galaxy Markarian 1066 (UGC 2456)

Mulchaey, John; Bower, Gary; Morse, Jon A. +3 more

Fundamental parameters of Wolf-Rayet stars. IV. Weak-lined WNE stars.

Hillier, D. J.; Crowther, P. A.; Smith, L. J.

A detailed study of 3 `weak-lined' Galactic WN3-4 stars (WR46=HD104994, WR128=HD187282 and WR152=HD211564) has been carried out based on new ultraviolet, optical and infrared spectroscopy. Tailored analyses, using the WR standard model, allow determinations of stellar parameters and chemical abundances based on the observed hydrogen, helium, carbo…

Hubble Space Telescope FOS Spectroscopy of the Ultrashort-Period Dwarf Nova WZ Sagittae: The Underlying Degenerate

Szkody, Paula; Sion, Edward M.; Hubeny, Ivan +4 more

Two consecutive Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra of the exposed white dwarf in the ultrashort-period, high-amplitude, dwarf nova WZ Sge, reveal a rich absorption line spectrum of neutron carbon and ionized metals, the Stark-broadened Lyman-alpha absorption wing, the H2 quasi-molecular Lyman-alpha 'satellite' abs…

β Pictoris: evidence of light variations.

Deleuil, M.; Ferlet, R.; Vidal-Madjar, A. +4 more

We have analyzed β Pictoris photometric measurements obtained from La Silla by the Geneva Observatory from 1975 to 1992. These data show evidence of variations in the brightness of the star, with no color dependency. Here, we demonstrate that the light variations are present on long as well as on short time scales. On a long time scale, we show th…

Structures in the polar solar wind: Plasma and field observations from Ulysses

Balogh, A.; McComas, D. J.; Forsyth, R. J. +5 more

Ulysses has frequently observed solar wind structures lasting from several hours to several days since it passed into the region of solar wind emanating from the southern polar coronal hole at ~36°S. In addition to previously reported Alfven waves and coronal mass ejections, two other sorts of structures are routinely evident. This paper provides …