scientific abstract one of the major discoveries made by iras was finding the presence of a far-infrared excess around the standard star vega (alpha lyrae) and around a number of other similar main sequence stars. the infrared excess has been interpreted as due to a disk of dust particles left over from the formation of such stars. the lws will be used to study the dust disks around a number of these stars, in particular obtaining grating spectra to look for the 44 micron and 62 micron ice bands in emission from the cool disks. fabry-perot scans will also be obtained at the wavelengths of a number of ionic fine structure lines in the case of beta pictoris, the only star in the sample for which the disk has been imaged and studied spectroscopically at non-infrared wavelengths. a latex file containing fuller details of this proposal is available from mjb@star.ucl.ac.uk. observation summary grating spectra are needed to look for dust features in the disks, and to investigate fully which lines are present. beta pic will be observed with the fp as well, since optical and uv observations have already indicated the presence of emitting gas around this system. the fp observations will enhance the detectability of weaker lines seen against the dust continuum, as well as providing velocity (and thus dynamical) information about gas in the disk. 8.1 hours of lws guaranteed (spacecraft) time are allocated to this programme. if stars in the orion-hole are observable (i.e. a spring launch), 324.5 minutes will be used for full lws grating scans of eight stars and 121.2 minutes will be used for full sws fast grating scans of four stars. 51.1 minutes will be used for lws fp scans of the spectrum of beta pictoris at the wavelengths of six fine structure lines, these are: cii (157.7um), nii (121.9um), oi (63.2, 145.5um), feiii (51.7um) and feii (51.3um). if stars in the sagittarius-hole are observable (i.e. an autumn launch), 446.2 minutes will be used for full lws grating scans of ^en stars and 30.3 minutes will be used for a full sws fast grating scans of one star (complementary sws scans of the remaining stars are being obtained by the sws consortium). the priority 1 lws guaranteed spacecraft time allocated to this programme is 3.21 hours if the orion-hole is observable, or 3.38 hours if the sgr-hole is observable.
Instrument
LWS01 , LWS02 , SWS01
Temporal Coverage
1996-06-04T13:14:51Z/1998-03-27T21:29:43Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, Barlow et al., 1999, 'Spectroscopic Observations of Vega-Excess Systems ', 1.0, European Space Agency, https://doi.org/10.5270/esa-139s4nx
