HH-34

PR Photo 40b/99 shows a three-colour composite of the young object
Herbig-Haro 34 (HH-34), now in the protostar stage of evolution. It is
based on CCD frames obtained with the FORS2 instrument in imaging
mode, on November 2 and 6, 1999.

This object has a remarkable, very complicated appearance that
includes two opposite jets that ram into the surrounding interstellar
matter. This structure is produced by a machine-gun-like blast of
"bullets" of dense gas ejected from the star at high velocities
(approaching 250 km/sec). This seems to indicate that the star
experiences episodic "outbursts" when large chunks of material fall
onto it from a surrounding disk.

HH-34 is located at a distance of approx. 1,500 light-years, near the
famous Orion Nebula, one of the most productive star birth
regions. Note also the enigmatic "waterfall" to the upper left, a
feature that is still unexplained.

PR Photo 40c/99 is an enlargement of a smaller area around the central
object.

Technical information: Photo 40b/99 is based on a composite of three
images taken through three different filters: B (wavelength 429 nm;
Full-Width-Half-Maximum (FWHM) 88 nm; exposure time 10 min; here
rendered as blue), H-alpha (centered on the hydrogen emission line at
wavelength 656 nm; FWHM 6 nm; 30 min; green) and S II (centrered at
the emission lines of inonized sulphur at wavelength 673 nm; FWHM 6
nm; 30 min; red) during a period of 0.8 arcsec seeing. The field shown
measures 6.8 x 6.8 arcmin and the images were recorded in frames of
2048 x 2048 pixels, each measuring 0.2 arcsec.  The Full Resolution
version shows the original pixels. North is up; East is left.

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