Search Publications
A Keplerian disk around the Herbig Ae star HD 34282
Kahane, C.; Dutrey, A.; Piétu, V.
We report new millimeter observations of the circumstellar material surrounding the Herbig Ae A0.5 star HD 34282 performed with the IRAM array in CO ~ and in continuum at 1.3 mm. These observations have revealed the existence of a large Keplerian disk around the star. We have analysed simultaneously the line and continuum emissions to derive the p…
Month-Timescale Optical Variability in the M87 Jet
Perlman, Eric S.; Sparks, William B.; Macchetto, F. Duccio +2 more
A previously inconspicuous knot in the M87 jet has undergone a dramatic outburst and now exceeds the nucleus in optical and X-ray luminosity. Monitoring of M87 with the Hubble Space Telescope and Chandra X-Ray Observatory during 2002-2003, has found month-timescale optical variability in both the nucleus and HST-1, a knot in the jet 0.82" from the…
An absorption event in the X-ray light curve of NGC 3227
Uttley, P.; McHardy, I. M.; Lamer, G.
We have monitored the Seyfert galaxy NGC 3227 with the Rossi X-ray Timing Explorer (RXTE) since 1999 January. During late 2000 and early 2001 we observed an unusual hardening of the 2-10 keV X-ray spectrum which lasted several months. The spectral hardening was not accompanied by any correlated variation in flux above 8 keV. We therefore interpret…
The [Fe II] 1.644 Micron Emission in M82 and NGC 253: Is It a Measure of the Supernova Rate?
Rieke, George H.; Alonso-Herrero, Almudena; Rieke, Marcia J. +1 more
We present Hubble Space Telescope NICMOS [Fe II] 1.644 µm, Paα (1.87 µm), and continuum images of the starburst galaxies M82 and NGC 253 at an unprecedented spatial resolution. In both galaxies we detect [Fe II] compact sources superposed on a diffuse background in the disk of the galaxies, together with a component above and below the…
The DA+dMe eclipsing binary EC13471-1258: its cup runneth over ... just
Koester, D.; Stobie, R. S.; O'Donoghue, D. +5 more
The optical spectrum and light curve of EC13471-1258 show that it is an eclipsing binary with an orbital period of 3h 37m comprising a DA white dwarf and a dMe dwarf. Total eclipses of the white dwarf are observed lasting 14 min, with the partial phases lasting 54 s. On one occasion, two pre-eclipse dips were seen. Timings of…
An X-Ray Jet Discovered by Chandra in the z=4.3 Radio-selected Quasar GB 1508+5714
Schwartz, D. A.; Smith, Randall K.; Siemiginowska, Aneta +3 more
We report the Chandra discovery of an X-ray jet associated with the z=4.3 radio-loud quasar GB 1508+5714. The jet X-ray emission peaks ~2" to the southwest of the quasar core. We present archival Hubble Space Telescope Wide Field Planetary Camera 2 data of the quasar field that show no optical emission at the location of the X-ray jet. We discuss …
Cluster electric current density measurements within a magnetic flux rope in the plasma sheet
Balogh, A.; Owen, C. J.; Reme, H. +11 more
On August 22, 2001 all 4 Cluster spacecraft nearly simultaneously penetrated a magnetic flux rope in the tail. The flux rope encounter took place in the central plasma sheet, βi ~ 1-2, near the leading edge of a bursty bulk flow. The ``time-of-flight'' of the flux rope across the 4 spacecraft yielded Vx ~ 700 km/s and a diame…
Large amplitude solitary waves in and near the EarthÂ’s magnetosphere, magnetopause and bow shock: Polar and Cluster observations
André, M.; Cattell, C.; Dombeck, J. +6 more
Solitary waves with large electric fields (up to 100's of mV/m) have been observed throughout the magnetosphere and in the bow shock. We discuss observations by Polar at high altitudes ( ~ 4-8 RE ), during crossings of the plasma sheet boundary and cusp, and new measurements by Polar at the equatorial magnetopause and by Cluster near the bow shock…
INTEGRAL/SPI ground calibration
Knödlseder, J.; von Kienlin, A.; Bouchet, L. +30 more
Three calibration campaigns of the spectrometer SPI have been performed before launch in order to determine the instrument characteristics, such as the effective detection area, the spectral resolution and the angular resolution. Absolute determination of the effective area has been obtained from simulations and measurements. At 1 MeV, the effecti…
A Hubble Space Telescope Search for Lyman Continuum Emission from Galaxies at 1.1 < z < 1.4
Malkan, Matthew; Webb, Wayne; Konopacky, Quinn
If enough of their Lyman-limit continuum escapes, star-forming galaxies could be significant contributors to the cosmic background of ionizing photons. To investigate this possibility, we obtained the first deep imaging in the far-ultraviolet of 11 bright blue galaxies at intermediate redshift (1.1<z<1.4) with the Space Telescope Imaging Spe…