Search Publications
The Orbits of the Inner Neptunian Satellites from Voyager, Earth-based, and Hubble Space Telescope Observations
Jacobson, R. A.; Owen, W. M., Jr.
We present revised orbital elements for the six small Neptunian satellites discovered by Voyager 2. The elements have been determined from a fit to imaging data acquired by the Voyager 2 spacecraft and astrometric observations made at Earth-based observatories and by the Hubble Space Telescope. An assessment of the accuracy of the elements is prov…
The dependence of Langmuir wave amplitudes on position in Earth's foreshock
Gurnett, D. A.; Balogh, A.; Pickett, J. S. +3 more
We present the first results of Langmuir wave observations in the foreshock from the Cluster WBD Plasma Wave Receiver. When the data were binned by distance to the foreshock boundary, the Langmuir wave amplitude probability distributions followed the log-normal statistics predicted by stochastic growth theory for all regions of the foreshock. The …
Stellar activity and magnetism studied by optical interferometry
Jankov, S.; Kilbinger, M.; Lanz, T. +5 more
By means of numerical simulations, we investigate the ability of optical interferometry, via the fringe phase observable, to address stellar activity and magnetism. To derive abundance maps and stellar rotation axes, we use color differential interferometry which couples high angular resolution to high spectral resolution. To constrain magnetic fi…
Optical and infrared spectroscopic analysis of the post-AGB star candidate IRAS 19386+0155
Pereira, C. B.; Lorenz-Martins, S.; Machado, M.
This work reports high-resolution spectroscopic stellar parameters and abundance analysis of the post-AGB star IRAS 19386+0155. The analysis of the high resolution spectrum shows that it has an effective temperature of Teff=6800±100 K and a surface gravity of log g = 1.4±0.2. The abundance analysis reveals IRAS 19386+0155 to be a metal-…
The circumstellar environment of IRAS 16293-2422. ISO-LWS and SCUBA observations
Griffin, M.; Saraceno, P.; Correia, J. C.
We present far-infrared (FIR) continuum observations of the deeply embedded source IRAS 16293-2422 performed with the Long Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). We also report 450 and 850 µm mapping observations done with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell T…
Dual Flows with Supersonic Velocities in the Sunspot Transition Region
Wilhelm, K.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more
Observations of sunspot transition region lines that deviate significantly from a Gaussian shape are presented. Attention is given to ``dual flows,'' a line profile phenomenon in which two distinct velocities are observed within the same spatial resolution element. In 5 out of 12 sunspots we observe dual flows. Several emission line profiles are w…
Characteristic Scales of Chromospheric Oscillation Wave Packets
McIntosh, Scott W.; Smillie, Darren G.
We use wavelet transforms to study the characteristic time scales of chromospheric oscillation ``wave packets'' that are observed in Transition Region and Coronal Explorer (TRACE) ultraviolet continuum image time series. Using several data sets, we investigate the statistical, spatial, and temporal intermittence of the number, duration, mean frequ…
XMM-Newton study of the very young stellar cluster IC 348
Preibisch, T.; Zinnecker, H.
We analyze a XMM-Newton X-ray imaging observation of the very young stellar cluster IC 348 with an observing time of 12 h and a corresponding total (all detector) MOS-equivalent exposure time of 207 ks. Our observation is strongly affected by a very intense solar particle flare, due to which only the first half of the exposure time can be used for…
An X-Ray Investigation of the NGC 346 Field in the Small Magellanic Cloud. III. XMM-Newton Data
Corcoran, Michael F.; Stevens, Ian R.; Nazé, Yaël +2 more
We present new XMM-Newton results on the field around the NGC 346 star cluster in the SMC. This continues and extends previously published work on Chandra observations of the same field. The two XMM-Newton observations were obtained, respectively, 6 months before and 6 months after the previously published Chandra data. Of the 51 X-ray sources det…
Two long-period X-ray pulsars detected in the SMC field around XTE J0055-727
Pietsch, W.; Haberl, F.; Schartel, N. +2 more
An XMM-Newton target of opportunity observation of the field around the transient 18.37 s pulsar