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Mid-Infrared Observations of the Mira Circumstellar Environment
Fazio, Giovanni G.; Marengo, Massimo; Karovska, Margarita +4 more
This Letter presents results from high angular resolution mid-IR imaging of the Mira AB circumbinary environment using the Mid-InfraRed Array Camera MIRAC3 at the NASA Infrared Telescope Facility. We resolved the dusty circumstellar envelope at 9.8, 11.7, and 18 µm around Mira A (ο Ceti) and measured the size of the extended emission. Strong…
Field line diffusion in solar wind magnetic turbulence and energetic particle propagation across heliographic latitudes
Veltri, P.; Zimbardo, G.; Pommois, P.
The transport of energetic particles in the heliosphere is strongly influenced by the magnetohydrodynamic turbulence found in the solar wind. This turbulence causes a magnetic field line random walk, which can explain the Ulysses observations at high heliographic latitudes of particles accelerated at corotating interaction regions (CIRs). A three-…
Modeling the Interstellar Medium-Stellar Wind Interactions of λ Andromedae and ɛ Indi
Zank, Gary P.; Wood, Brian E.; Müller, Hans-Reinhard
A numerical study is presented of the interaction between the partially ionized interstellar medium (ISM) and the stellar wind of the very active RS CVn-type binary star λ And (G8 IV-III+?). Similar to results found for the heliosphere-ISM interaction, a termination shock, a tangential discontinuity (the ``astropause''), and a bow shock are found …
An HST Study of Jovian Chromophores
Simon-Miller, Amy A.; Gierasch, Peter J.; Banfield, Don
A principal components analysis was performed on Hubble Space Telescope WFPC2 images of Jupiter from October 1995 and October 1996. Global maps in the F410M, F555W, F673N, and F953N filters were analyzed. These are continuum wavelengths in Jupiter's spectrum, sensitive to reflection from the visible cloud deck. The primary principal components cor…
Chandra Detection of the Radio and Optical Double Hot Spot of 3C 351
Bondi, M.; Brunetti, G.; Comastri, A. +4 more
In this Letter, we report a Chandra X-ray detection of the double northern hot spot of the radio quasar 3C 351. The hot spot has also been observed in the optical with the Hubble Space Telescope (R band) and with the 3.5 m Telescopio Nazionale Galileo (B band). The radio-to-optical and X-ray spectra are interpreted as the results of the synchrotro…
Deep colour-magnitude diagrams of LMC field stars imaged with HST
Santiago, B. X.; Gilmore, G. F.; Johnson, R. A. +2 more
We present deep photometry (V<~26) in V and I bands obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope for 7 fields ~5° away from the Large Magellanic Cloud centre. The fields contain, typically, 2000 stars each. Isochrones were fitted to the colour-magnitude diagrams in order to identify different star popu…
Electron density variations during ultraviolet transient events
Doyle, J. G.; Madjarska, M. S.; Teriaca, L.
% High-resolution temporal observations performed with the SUMER spectrometer on SOHO provide an opportunity to investigate the electron density variations in the `quiet-Sun' solar transition region due to UV transient events. Two datasets obtained in the density sensitive lines belonging to the O iv 1400 Å multiplet were searched for such events,…
On the Evolution of the Solar Photospheric and Coronal Magnetic Field
Schrijver, Carolus J.; Handy, Brian N.
The Extreme Ultraviolet Imaging Telescope (EIT) and the Michelsen Doppler Imager (MDI) instruments on the Solar and Heliospheric Observatory (SOHO) ran a coordinated observing campaign over the dates 1997 August 10-14. MDI generated 1.2" resolution magnetograms (0.6" pixels) of the solar photosphere at a nominal cadence of one minute while EIT obs…
Hubble Space Telescope Imagery and Canada-France-Hawaii Telescope Fabry-Perot Two-dimensional Spectroscopy in Hα of the Ejected Nebula M1-67: Turbulent Status
Moffat, Anthony F. J.; Joncas, Gilles; Grosdidier, Yves +2 more
Bright circumstellar nebulae around massive stars are potentially useful to derive time-dependent mass-loss rates and hence constrain the evolution of the central stars. A key case in this context is the relatively young ejection-type nebula M1-67 around the runaway Population I Wolf-Rayet star WR 124 (=209 BAC), which exhibits a WN 8 spectrum. Wi…
Multiwavelength Studies of Hercules X-1 during Short High and Anomalous Low States: On-again, Off-again
McCray, R.; O'Brien, K.; Boroson, B. +4 more
We present results from multiwavelength observations of the Hercules X-1 system during a short high state (SHS) and during an anomalous low state (ALS). The magnitude of deviation from spin-up appears to be positively correlated with duration of the ALS. Such a correlation is consistent with an interpretation of the ALS in terms of a change in mas…