grs 1915+105 was discovered in aug 1992 with the watch all-sky x-ray monitor on board the granat satellite. the source has been since then one of the brightest objects in the x-ray sky, highly variable in all wavelenghts, from gamma-rays to radio. at a distance of 12 kpc, the absorption towards the source is almost 30 magnitudes, putting the object well beyond the reach of optical telescopes. the uniqueness of grs 1915+105 is that it shows superluminal motion, following a bright radio outburst seen in march 1994 - the first such case in our galaxy. grs 1915+105 is a binary system in which a massive black hole (with perhaps 33 solar mases) is accreting mass from a nearby companion. the companion class is still unclear, but it could be a high-mass object, on the basis of observations performed in aug 1995, that revealed the near-ir reverberation of an energetic radio-outburst. the jet was also observed in the k-band in july 1995. near-ir spectroscopy indicates the presence of strong emission lines (he i 2.06 um and br-gamma 2.16 um) during the high activity periods. it has been recently noticed (autumn 1997) that grs 1915+105 is undergoing a new strong outburst in x-rays and radio frequencies. taking into account that the outbursts observed so far do not last for more than 1-2 months, we request ir observations with iso during discretionary time in order to observe the object in the course of this current outburst. the fact that iso is in orbit provides a unique opportunity to observe this object during this active period, thus completing the iso observations already performed during a more quiet state. we expect to find a variable source in the cam energy range, brighter than in the previous iso observation. we also intend to extend the ground-based jhk measurements (1.0-2.4 um) to 17 um in order to detect in a full cvf spectrum the h recombination lines, and the ar ii (7.05 um), ne ii (12.93 u...m) and ne iii (15.7 um) emission lines. a deep cam observation at 15 um will allow us to search for faint mid-ir emission along the jet. the detection of the source in the far-ir with phot (up to 200 um), will give support to the hypothesis that the far infrared emission is the consequence of heating, by the high energy photons, of the surrounding dust ejected by the companion. the requested observations will help to clarify the poorly known nature of the emission mechanisms of grs 1915+105, the most energetic source in the galaxy. only iso has the necessary sensitivity to perform them.
Instrument
CAM01 , CAM04 , PHT03 , PHT22
Temporal Coverage
1997-11-05T21:08:20Z/1997-11-06T01:20:42Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's 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, 1998, Too: The Nature Of The Superluminal Galactic Source Grs 1915+105 Iso Observations During The Oct 1997 X-Ray And Radio-Outburst, 1.0, European Space Agency, https://doi.org/10.5270/esa-usbqdks
