H$\alpha$ Emission of the H\,II region BSF8

Previous abstract Next abstract

Session 30 -- Star Formation, Molecular Clouds and HII Regions
Display presentation, Tuesday, 31, 1994, 9:20-6:30

[30.02] H$\alpha$ Emission of the H\,II region BSF8

S. P. Milster, F. Scherb (University of Wisconsin)

\ \ Imaging observations of faint Galactic H$\alpha$ emission from the warm ionized medium have been carried out with a dual-etalon, 150\,mm-diameter, Fabry-Perot spectrometer and a CCD camera. The FWHM velocity resolution is $12\rm\,km\,s^{-1}$ (0.25\,\AA ) and the field of view is normally $0.\!\!^{\circ}8$ but can be increased to about $2.\!\!^{\circ}0$ The spatial resolution of the images is 1--2$'$.

\ \ A high velocity ($v_{\rm LSR} \cong -50\rm\,km\,s^{-1}$) feature was discovered near $l=96^{\circ}$, $b=0^{\circ}$. The feature was identified as an H\,II region listed as BSF8 by Fich (Ap.J.S., 86, 475 (1993)), who carried out observations in the radio continuum. It was first cited by Blitz, Fich and Stark in Ap.J.S., 49, 183 (1982).

\ \ An H$\alpha$ data cube of BSF8 shows that it has a diameter of about $12'$, with an average surface brightness of $\cong$ 13\,Rayleighs and a peak surface brightness of $\cong$ 32\,Rayleighs. The spatially integrated emission has a velocity FWHM of $\cong 32\rm\,km\,s^{-1}$. The signal to noise ratio (SNR) for one pixel near the peak of the line is $\cong 13$. The high SNR is achieved due to the narrow passband of the Fabry-Perot which reduces the contribution from the diffuse background.

\ \ The $2.\!\!^{\circ}0$ field of view, relatively good spatial resolution, and high spectral resolution would be useful for conducting searches for faint H\,II regions near the galactic plane, where the relatively bright, diffuse background (H$\alpha$ and continuum) normally would obscure such objects in searches at lower spectral and spatial resolution.

Tuesday program listing