Search Publications
Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express
Kallio, E.; Fedorov, A.; Budnik, E. +42 more
The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the mart…
Detection of a Red Supergiant Progenitor Star of a Type II-Plateau Supernova
Smartt, Stephen J.; Mattila, Seppo; Gilmore, Gerard F. +4 more
We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion, and subsequent HST images confirm the positional coincidence of the supernova with a single resolved star tha…
Three-Dimensional Polarimetric Imaging of Coronal Mass Ejections
Davila, Joseph M.; Moran, Thomas G.
We present three-dimensional reconstructions of coronal mass ejections (CMEs), which were obtained through polarization analysis of single-view images recorded with the use of the Large Angle and Spectrometric Coronagraph (LASCO) C2 coronagraph on board the Solar and Heliospheric Observatory (SOHO) spacecraft. Analysis of a loop-like CME shows a c…
Jupiter's Atmospheric Composition from the Cassini Thermal Infrared Spectroscopy Experiment
Smith, M. D.; Strobel, D. F.; Lellouch, E. +39 more
The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of a…
Phase-Resolved Spectroscopy of Geminga Shows Rotating Hot Spot(s)
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +2 more
Isolated neutron stars are seen in x-rays through their nonthermal and/or surface thermal emissions. X-ray Multimirror Mission-Newton observations of the Geminga pulsar show a 43-electron volt spectrum from the whole neutron star surface, as well as a power-law component above 2 kiloelectron volts. In addition, we have detected a hot (170 electron…
Cassini Imaging of Jupiter's Atmosphere, Satellites, and Rings
Dones, Luke; West, Robert A.; Porco, Carolyn C. +21 more
The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as the spacecraft encountered the giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. We also describe previously unseen emissions arising fro…
A Young White Dwarf Companion to Pulsar B1620-26: Evidence for Early Planet Formation
Richer, Harvey B.; Hansen, Brad M.; Stairs, Ingrid H. +2 more
The pulsar B1620-26 has two companions, one of stellar mass and one of planetary mass. We detected the stellar companion with the use of Hubble Space Telescope observations. The color and magnitude of the stellar companion indicate that it is an undermassive white dwarf (0.34 +/- 0.04 solar mass) of age 480 × 106 +/- 140 × 106
Radio Emission from an Ultraluminous X-ray Source
Kaaret, Philip; Zezas, Andreas; Corbel, Stephane +1 more
The physical nature of ultraluminous x-ray sources is uncertain. Stellar-mass black holes with beamed radiation and intermediate black holes with isotropic radiation are two plausible explanations. We discovered radio emission from an ultraluminous x-ray source in the dwarf irregular galaxy NGC 5408. The x-ray, radio, and optical fluxes as well as…
Geminga's Tails: A Pulsar Bow Shock Probing the Interstellar Medium
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +5 more
We report the X-ray Multimirror Mission-Newton European Photon Imaging Camera observation of two elongated parallel x-ray tails trailing the pulsar Geminga. They are aligned with the object's supersonic motion, extend for ~2', and have a nonthermal spectrum produced by electron-synchrotron emission in the bow shock between the pulsar wind and the …
The Sun and Heliosphere at Solar Maximum
Krupp, N.; Balogh, A.; Geiss, J. +9 more
Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun's rotation axis. Magnetic fields, solar wind,…