Search Publications
First Astronomical Images Sharpened with Adaptive Optics Using a Sodium Laser Guide Star
McLeod, B. A.; Hooper, E. J.; Angel, J. R. P. +7 more
Adaptive optics with a sodium resonance laser guide star was used at the Multiple Mirror Telescope (MMT) in 1996 April to image the core of the globular cluster M13 (NGC 6205). A 23" field was recorded in the Ks band with image resolution of 0.51", when the uncorrected resolution was 0.72". Global tilt, not sensed by the laser, was meas…
Principal component analysis of two ultraviolet emission-lines in 18 active galactic nuclei
Courvoisier, T. J. -L.; Turler, M.
We apply a principal component analysis (PCA) to the spectra of each of the 18 Seyfert 1-like objects observed more than 15 times by the international ultraviolet explorer (IUE) from 1978 until the end of 1991. PCA allows us to decompose the Lyalpha and Civl\ emission-lines of each object into two components with uncorrelated variations. We find t…
Detection of fine-structure line emission from carbon-rich and oxygen-rich AGB stars by the ISO SWS
Ohnaka, K.; Tsuji, T.; Aoki, W.
We detected five forbidden lines of iron, silicon and sulfur in red giants by the ISO SWS. [FeI] 24mu m emission was detected in two carbon stars, TX Psc and WZ Cas, and [SI] 25.2mu m emission was also detected in TX Psc, while none of these emission lines were detected in an oxygen-rich giant, 30g Her. On the other hand, the [FeII] 26mu m, [SiII]…
Constraints on the Radial Velocity Curve of HDE 245770 = A0535+26
Wang, Z. X.; Gies, D. R.
We present new radial velocity measurements from IUE high-dispersion spectra of HDE 245770, the Be companion of the X-ray transient binary system, A0535+26. We formally derive the semiamplitude of the star's binary motion by fitting the UV and published radial velocity measurements with the other orbital parameters fixed according to the neutron s…
A search for hidden white dwarfs in theROSATEUV survey - II. Discovery of a distant DA+F6/7V binary system in a direction of low-density neutral hydrogen
Barstow, M. A.; Holberg, J. B.; Burleigh, M. R.
The ROSAT Wide Field Camera (WFC) survey of the extreme ultraviolet (EUV) has provided us with evidence for the existence of a previously unidentified sample of hot white dwarfs in unresolved, detached binary systems. These stars are invisible at optical wavelengths due to the close proximity of their much more luminous companions (spectral type K…
Energetic ion populations and periodicities near Jupiter
Balogh, A.; Sarris, E. T.; Anagnostopoulos, G. C. +2 more
The HISCALE experiment, during Ulysses' approach to Jupiter, observed a ~10 hour periodic softening in ion spectrum outside the plasma sheet that (1) is not related to the approach of the plasma sheet, (2) is in phase with the «clock» relativistic electron modulation, and (3) is related to flux increase at low energies (<=200 keV) and flux decr…
EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO - I. Line Emission and Time Dependence
Harrison, R. A.; Wilhelm, K.; Fredvik, T. +8 more
EUV spectra of a medium-size sunspot and its surroundings, NOAA 7981, were obtained on 2 August 1996 with the Coronal Diagnostic Spectrometer (CDS) and the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on the Solar and Heliospheric Observatory (SOHO). The spectral lines formed in the transition region and corona show considerable str…
Eclipsing phenomena of the symbiotic star CH Cygni
Iijima, Takashi
Eclipsing phenomena of the inner binary with a period of 756 d in the triple symbiotic system CH Cyg may have been detected in detailed spectrophotometric observations. The eclipse of the hot component by the red giant started on 1994 October 11 and finished between 1995 January 8 and 18. The ingress duration was less than one day. The radius of t…
The Complete Spectral Energy Distribution and the Atmospheric Properties of the Helium-Rich White Dwarf MCT 0501-2858
Vennes, Stéphane; Polomski, Elisha F.; Chayer, Pierre +3 more
We analyze high-dispersion ultraviolet spectroscopic observations of the peculiar helium-rich white dwarf MCT 0501-2858. Ultraviolet spectra obtained during the 1996 November ORFEUS-SPAS II mission show the complete He II (n=2) line series as well as narrow heavy-element lines; the spectrum constrains the effective temperature (68,600 +/- 1800 K) …
Solid CO_2 towards NGC7538 IRS1
Leto, G.; Strazzulla, G.; Nisini, B. +2 more
We report the observation of the young infrared source NGC7538 IRS1 with the Short Wavelength Spectrometer (SWS) onboard the ISO satellite in the 2.4-45 mu m range. The spectrum exhibits several absorption features due to silicates and to molecular species frozen on the refractory dust. In particular the stretching and bending mode of solid CO_2 h…