a luminous blue variable candidate (lbvc) was recently recognized south of the pistol hii region near the galactic center. luminosity estimates for this star range between 10^6.3 and 10^7 lsun, which may make this the brightest star known in the galaxy (eta car is 10^6.6 lsun). these estimates do rely, however, on the lbvc being located physically in the galactic center, i.e. at a distance of about 8.5kpc. there is also evidence, morphological and energetic, that the pistol consists of ejecta from the lbvc and that it is being ionized by that star (now also known as the pistol star). the pistol lies just 15 south of the well known quintuplet cluster (afgl 2004), named after the 5 dusty cocoon stars dominating the mid-ir emission, but which also contains many hot stars, specifically at least eight wr stars (4 wn and 4 wc), and over a dozen ob stars. due to their proximity (at least in projection) to the pistol, these stars may be partly responsible for ionizing the pistol, and in fact it is not inconceivable that the pistol star originated in the quintuplet. many of the above conjectures require that pistol, pistol star the quintuplet be physically in the galactic center, and to be physically close to each other. our goal is to obtain new estimates of the extinction to these sources (via the silicate absorption feature for the stars, and via hydrogen recombination lines for the hii region) to study whether they are indeed close to each other along the line of sight. we will also observe a suite of mid-ir fine structure lines in the pistol hii region. this will provide a measure of the elemental abundance (to test the theory that the pistol hii region was ejected from the pistol star), as well as a measure of the hardness of the exciting radiation.
Instrument
CAM04 , SWS01
Temporal Coverage
1998-03-05T14:47:39Z/1998-03-13T14:12:09Z
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, MONETI et al., 1999, 'THE NATURE OF THE PISTOL comma ITS STAR comma AND THE QUINTUPLET: CAM-CVF AND SWS SPECTROSCOPY', 1.0, European Space Agency, https://doi.org/10.5270/esa-hhqqjt1
