Search Publications
Streaming Motions toward the Supermassive Black Hole in NGC 1097
Robinson, Andrew; Marconi, Alessandro; Axon, David J. +5 more
We have used GMOS-IFU and high-resolution HST-ACS observations to map, in unprecedented detail, the gas velocity field and structure within the 0.7 kpc circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear evidence of radial streaming motions associated with spiral structures leading to the unresolved (<3.5 pc) nucleus, w…
Survey of large-amplitude flapping motions in the midtail current sheet
Nakamura, R.; Sergeev, V. A.; Baumjohann, W. +5 more
<P style="line-height: 20px;"> We surveyed fast current sheet crossings (flapping motions) over the distance range 10-30 RE in the magnetotail covered by the Geotail spacecraft. Since the local tilts of these dynamic sheets are large and variable in these events, we compare three different methods of evaluating current sheet norma…
The sky distribution of positronium annihilation continuum emission measured with SPI/INTEGRAL
Knödlseder, J.; Shrader, C. R.; Schanne, S. +15 more
We present a measurement of the sky distribution of positronium (Ps) annihilation continuum emission obtained with the SPI spectrometer on board ESA's INTEGRAL observatory. The only sky region from which significant Ps continuum emission is detected is the Galactic bulge. The Ps continuum emission is circularly symmetric about the Galactic centre,…
Discovery of two new satellites of Pluto
Stern, S. A.; Weaver, H. A.; Mutchler, M. J. +6 more
Pluto's first known satellite, Charon, was discovered in 1978. It has a diameter (~1,200km) about half that of Pluto, which makes it larger, relative to its primary, than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful, but they were not sensitive to objects <~150km in diameter and …
A Long-Period, Violently Variable X-ray Source in a Young Supernova Remnant
Caraveo, P. A.; Bignami, G. F.; Tiengo, A. +2 more
Observations with the Newton X-ray Multimirror Mission satellite show a strong periodic modulation at 6.67 +/- 0.03 hours of the x-ray source at the center of the 2000-year-old supernova remnant RCW 103. No fast pulsations are visible. If genetically tied to the supernova remnant, the source could either be an x-ray binary, composed of a compact o…
A maximum-likelihood method for fitting colour-magnitude diagrams
Naylor, Tim; Jeffries, R. D.
We present a maximum-likelihood method for fitting two-dimensional model distributions to stellar data in colour-magnitude space. This allows one to include (for example) binary stars in an isochronal population. The method also allows one to derive formal uncertainties for fitted parameters, and assess the likelihood that a good fit has been foun…
Photometric analysis of 1 Ceres and surface mapping from HST observations
Parker, Joel Wm.; Stern, S. Alan; Russell, Christopher T. +5 more
The highest resolution (pixel scale 30 km) images of Ceres to date have been acquired by the Advanced Camera for Surveys onboard Hubble Space Telescope, through three wide band filters, centered at 535, 335, and 223 nm, covering more than one rotation of Ceres. The lightcurve at 535 nm agrees with earlier observations at V-band [Tedesco, E.F., Tay…
SPICAM on Mars Express: Observing modes and overview of UV spectrometer data and scientific results
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +13 more
This paper is intended as an introduction to several companion papers describing the results obtained by the SPICAM instrument on board Mars Express orbiter. SPICAM is a lightweight (4.7 kg) UV-IR dual spectrometer dedicated primarily to the study of the atmosphere of Mars. The SPICAM IR spectrometer and its results are described in another compan…
X-ray nature of the LINER nuclear sources
Guerrero, M. A.; González-Martín, O.; Márquez, I. +2 more
We report the results from a homogeneous analysis of the X-ray (Chandra ACIS) data available for a sample of 51 LINER galaxies selected from the catalogue by Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187) and representative of the population of bright LINER sources. The nuclear X-ray morphology has been classified by their nuclear co…
Spitzer 70 and 160 µm Observations of the Extragalactic First Look Survey
Im, M.; Frayer, D. T.; Surace, J. A. +33 more
We present 70 and 160 µm observations from the Spitzer extragalactic First Look Survey (xFLS). The data reduction techniques and the methods for producing co-added mosaics and source catalogs are discussed. Currently, 26% of the 70 µm sample and 49% of the 160 µm-selected sources have redshifts. The majority of sources with redsh…