Polarization measurements with ISOPHOT: performance and first results
Abstract
ISOPHOT provided unique polarization capabilities in the FIR. The 1 σ accuracy of linear polarization is 1% for sources with total fluxes of few Jy. For the first time the polarization of a quasar was measured: 3C 279 showed a high polarization of 23% half a year after a γ-ray flare with a decrease to 6.5% one year later, but with equal total flux. A consistent polarization of 8% between 25 and 170 μm was found for the Crab nebula. It is considerably lower than expected from mm-polarization measurements. This could indicate the presence of unpolarized IR emission from lines and/or dust. This interpretation is not unambiguous, however, as the angle of polarization in the IR differs from that in the radio. The non-detection of polarization for asteroids with highly elongated shapes places new constraints on their surface properties.
- Publication:
-
The Universe as Seen by ISO
- Pub Date:
- March 1999
- Bibcode:
- 1999ESASP.427...77K
- Keywords:
-
- POLARIZATION;
- INSTRUMENTATION: POLARIMETERS;
- TECHNIQUES: POLARIMETRIC;
- MINOR PLANETS;
- ASTEROIDS;
- ISM: SUPERNOVA REMNANTS;
- QUASARS: INDIVIDUAL: 3C 279