Search Publications
Water Production of Comets 2P/Encke and 81P/Wild 2 Derived from SWAN Observations during the 1997 Apparition
Schmidt, W.; Bertaux, J. -L.; Lallement, R. +5 more
The water production rates of comets 2P/Encke and 81P/Wild 2 during their 1997 apparitions have been estimated from Lyman-α observations of the SWAN instrument and compared to previously published values. 2P/Encke was detected 28 times from few days preperihelion to 1.4 AU postperihelion with a perihelion water production rate QH 2…
A complete relativistic ionized accretion disc in Cygnus X-1
Young, A. J.; Fabian, A. C.; Ross, R. R. +1 more
The galactic black hole candidate Cygnus X-1 is observed to be in one of two X-ray spectral states: either the low/hard (low soft X-ray flux and a flat power-law tail) or high/soft (high blackbody-like soft X-ray flux and a steep power-law tail) state. The physical origin of these two states is unclear. We present here a model of an ionized accret…
Solar cycle variations in the electron heat flux: Ulysses observations
Lin, Naiguo; Gary, S. Peter; Scime, Earl E. +2 more
Solar wind observations by the Ulysses spacecraft now include nearly ten years of continuous ion and electron measurements. In this study, we report detailed measurements of the electron heat flux in the solar wind. In particular, we examine the heat flux measurements for long-term correlations with wave activity and solar wind speed. We find that…
The Heliospheric Magnetic Field at Solar Maximum: Ulysses Observations
Balogh, André; Smith, Edward J.
At solar maximum, the large-scale structure of the heliospheric magnetic field (HMF) reflects the complexity of the Sun's coronal magnetic fields. The corona is characterised by mostly closed magnetic structures and short-lived, small coronal holes. The axis of the Sun's dipole field is close to the solar equator; there are also important contribu…
The first XMM-Newton spectrum of a high redshift quasar - PKS 0537-286
Tiengo, A.; Boller, Th.; O'Brien, P. T. +6 more
We present XMM-Newton observations of the high redshift (z=3.104), radio-loud quasar PKS 0537-286. The EPIC CCD cameras provide the highest signal-to-noise spectrum of a high-z quasar to date. The EPIC observations show that PKS 0537-286 is extremely X-ray luminous (LX =2 1047 erg s-1), with an unusually hard X-ray…
Circumnuclear Spiral Arms and Starburst Rings in Magnetized Barred Spiral Galaxies
Fan, Zuhui; Lou, Yu-Qing; Yuan, Chi +1 more
The Seyfert galaxy NGC 1097 has a prominent bar and a luminous circumnuclear starburst ``ring.'' Magnetic fields as revealed by nonthermal radio continuum emissions correlate well with the optical barred spiral structure on large scales, have a gross enhancement overlapping with the optical/infrared ``ring,'' and show a trailing swirl around and w…
The Massive Star Content of NGC 6822: Ground-Based andHubble Space Telescope Photometry
Massey, Philip; Bianchi, Luciana; Romaniello, Martino +1 more
We investigate the massive star population of NGC 6822 with ground-based UBV photometry covering the whole of the galaxy and HST WFPC2 photometry with filters F255W, F336W, F439W, and F555W of two fields containing very rich and crowded OB associations. The four-band WFPC2 photometry is used to derive Teff and E(B-V). H-R diagrams are c…
Gas-Phase Polycyclic Aromatic Hydrocarbons in Absorption toward Protostellar Sources?
Bregman, Jesse D.; Temi, Pasquale
One of the major criticisms of identifying the infrared emission bands with polycyclic aromatic hydrocarbon (PAH) molecules has been the lack of a match between laboratory spectra of individual PAHs and the emission features. Part of the difficulty arises from the complexity of modeling the emission mechanism with an a priori unknown mixture of io…
Four years of Ulysses dust data: 1996-1999
Krüger, H.; Srama, R.; Hamilton, D. P. +17 more
The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse ( i=79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU). Between January 1996 and December 1999 the spacecraft was beyond 3 AU from the Sun and crossed the ecliptic plane at aphelion in May 1998. In this 4-yr period 218 dust impacts were recorded with the dust detector …
Possible contribution of different energy sources to the production of organics in Titan's atmosphere
Coll, P.; Raulin, F.; Navarro-González, R. +1 more
A quantitative comparison of the products arising from the irradiation of a Titan's simulated atmosphere is presented. The energy sources used represent some of the main events that occur in the satellite's atmosphere. All of the compounds identified are classified in the hydrocarbon and nitrile chemical families. Almost all of the detected compou…