VLA H92-ALPHA AND H115-BETA RECOMBINATION LINE OBSERVATIONS OF THE GALACTIC-CENTER H-II REGIONS - THE SICKLE (G0.18-0.04) AND THE PISTOL (G0.15-0.05)

The Very Large Array has been used in the CnB and DnC configurations t o observe the remarkable Galactoc center sources, the Sickle and the P istol, near l = 0 degrees.18, b = -0 degrees.04. These H II regions ha ve an unusual morphology and may be physically associated with the lin ear nonthermal filaments at l - 0.18, which appear to intersect the so urces. The H92 alpha (8.31 GHz) and H115 beta (8.43 GHz) radio recombi nation lines arising from these sources have been observed with angula r resolutions of 6'' and 9'', respectively. In addition, there is a pr obable detection of the helium line in the Pistol (Y+ similar to 14% /- 6%), while in the Sickle, no helium lines were detected with an upp er limit of Y+ similar to 5% (3 sigma). A complex velocity field has b een observed in both sources. The LSR velocity in the Sickle varies fr om 0 to 75 km s(-1) with an average velocity of similar to 35 km s(-1) ; the average velocity of the Pistol is similar to 115 km s(-1). The r ecombination line properties of the Sickle and the Pistol (FWHM line w idths, line-to-continuum ratios, beta-to-alpha ratio) are consistent w ith photoionization from hot stars. The beta-to-alpha line ratio of si milar to 0.35 +/- 0.07 over most of the Sickle and Pistol does nut dif fer significantly from the LTE value of 0.28. The average LTE electron temperature, T-e, for the Sickle (similar to 5500 K) is similar to t ypical Galactic center H II regions, and T-e for the Pistol is somewh at lower (similar to 3600 K). An additional H II component in the line profiles of three legions of the Sickle in which the nonthermal filam ents are present suggests that an interaction between the ionized gas and the nonthermal filaments is occurring. The probable detection of H e92 alpha in the Pistol and the nondetection in the Sickle may be due to a difference in the radiation field of the ionizing sources.