the purpose of this proposal is to search for the infrared signature of graphite dust in the interstellar medium, to resolve the currently still questionable origin of the 2200 angstrom extinction feature. graphite has been suggested as an interstellar dust component, since it posseses a strong absorption peak at 2200 a, which is a prominent observed feature in the interstellar extinction curve. however, except for this feature, there has been no other major reasons to adopt graphite as an interstellar dust constituent. furthermore, other candidate material, such as standard coal or polycyclic aromatic hydrocarbons (pahs), have strong absorption features at 2200 a, and can also be potential carriers of this feature. as a result, despite 30 years of continuing research, the identification of the 2200 a feature is still controversial. however, iso is uniquely capable of resolving this issue, since graphite is distinguished from other candidate material by the presence of two infrared-active resonances at 11.52 and 6.30 microns (draine 1984, apj, 277, l71). of the two, the 11.52 feature is the stronger one. we therefore propose to search for the feature in absorption along the line of sight of a heavily obscured (in the visible) bright source at infrared wavelengths.
Instrument
SWS02
Temporal Coverage
1997-02-22T13:54:24Z/1997-02-22T14:43:14Z
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, Dwek et al., 1998, 'A SEARCH FOR THE INFRARED SIGNATURE OF GRAPHITE GRAINS THE 11.52 MICRON GRAPHITIC ABSORPTION FEATURE TOWARDS THE G.C.', 1.0, European Space Agency, https://doi.org/10.5270/esa-p53nrcc
