HH object

HH object

short for Herbig–Haro object.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
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However, this particular HH object was unique from most others of its kind as it appears on its own rather than as a pair. 
The star can produce erratic outbursts when more matter is falling in, and these moments are recorded as brighter knots or blobs within the HH object, which travel along the jet over the years.
Models of photoionized HH flows [43] predict that the Te along an HH object is of about the typical value of a gas in photoionization equilibrium--about [10.sup.4] K--but shows a localized increase at the leading working surface of the bow shock due to shock heating.
It is noted that up to today IFS has been used to investigate physical, chemical and structural properties of the MIF, HH objects, and proplyds.
The spatial distribution maps of emission line fluxes, dust extinction, electron density and temperatures, and the He and O abundances were obtained by these authors and allowed them to detect the effects of well-known morphologies in Orion such as the Bright Bar, the Dark Bay, or prominent HH objects. A relation between the He abundance and the ionization structure that was interpreted as possible deviations of the case B recombination theory was also found.
In last decades, and especially after the launch of the HST, many outflows such as HH objects or collimated jets have been identified in the central part of the Orion Nebula (see e.g., [40-42]).
He has made measurements of both the star and the surface brightness of the nebula close by in the region of HH-215--the most recently generated HH object associated with PV Cep.
HH objects are formed when shockwaves created by material ejected by a new star plow into surrounding nebulosity; the interaction causes the light of hydrogen atoms and sulfur ions to glow.
She is investigating emission from HH objects to see if there is enough X-radiation behind the C-shocks to produce OH via the Wardle mechanism.
To finish, we will show a scientific application of this observational technique: 3D spectroscopy of photoionized HH objects in the Orion nebula--the case of HH 202--[2].