ESA Science & Technology - Publication Archive
The massive cluster of galaxies Abell 2219 (z=0.228) with two spectacular gravitational lensing arcs was observed at 14.3mu (hereafter 15mu) with the Infrared Space Observatory and results were published by Barvainis et al.(1999). These observations have been reanalyzed using a method specifically designed for the detection of faint sources that had been applied to other clusters.
Five new sources were detected and the resulting cumulative total of ten sources all have optical counterparts. The mid-infrared sources are identified with three cluster members, three foreground galaxies, an Extremely Red Object, a star and two galaxies of unknown redshift. The spectral energy distributions (SEDs) of the galaxies are fit with models from a selection, using the program GRASIL. Best-fits are obtained, in general, with models of galaxies with ongoing star formation. Infrared luminosities and star formation rates are obtained for six sources_ the cluster members and the foreground galaxies. For the three cluster members the infrared luminosities derived from the model SEDs are between 5.7x10e10 L_sol and 1.4x10e11 L_sol, corresponding to infrared star formation rates between 10 and 24 M_sol/yr. The two cluster galaxies that have optical classifications are in the Butcher-Oemler region of the colour-magnitude diagramme. The three foreground galaxies have infrared luminosities between 1.5x10E10 L_sol and 9.4x10e10 L_sol, yielding infrared star formation rates between 3 and 16 M_sol/yr. Two of the foreground galaxies are located in two foreground galaxy enhancements (Boschin et al.2004). Including Abell 2219, six distant clusters of galaxies have been mapped with ISOCAM and luminous infrared galaxies (LIRGs) have been found in three of them. The presence of LIRGs in Abell 2219 strengthens the association between luminous infrared galaxies in clusters and recent or ongoing cluster merger activity.
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The European Space Agency performed several observing campaigns to observe the Leonid meteor stream. In November 1999, the ESA meteor group was stationed at two locations in Southern Spain, in November 2001 at two stations close to Broome in North-Western Australia. Double-station observations with LLTV systems were conducted. The data was recorded on S-VHS video tapes. The tapes were digitized using automatic detection software. Meteor heights, velocities and radiants were computed. This paper shows the results for the two maximum nights. The radiants determined in 1999 show a very large scatter due to unfortunate observing geometry and inaccurate position determination since one of the cameras was moving because of the wind. The 2001 data is excellent and the radiant was determined to be at RA = 153.96°±0.3° and Dec = 21.09°±0.2°. The error bars for individual meteor radiants are about 0.2° to 0.4°. This demonstrates that is indeed possible to determine good radiant positions using totally automated tools. Orbits, on the other hand, are not well defined due to the fact that the velocity of individual meteors shows large errors. Reasons for this are described.
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