Condensations Expelled from the Stars, and Pairs of Stars, Connected with Bright Filaments

During several surveys of high-quality film-copies of the ESO B, R, ESO/SRC J, and EJ plates, except other young unstable objects (HH objects, star-forming regions, cometary nebulae) were found also two types of other unstable objects. 1. Bright condensations, connected with stars by bright filaments. 2. Pairs of stars, connected with each other by bright filaments. The objects of first type are mostly seen in infrared, on 2MASS K images. Due to their infrared colours, two of condensations and half of all stars can have thick dust discs.

New Herbig–Haro objects and outflows in the Mon R1 association

ABSTRACT We present the results of a narrow-band Hα and [S ii] imaging survey of the Mon R1 association performed with the 1-m Schmidt telescope at Byurakan Observatory. Our observations covered a 1° field near the centre of the association. As a result of this study, 20 new Herbig–Haro knots were discovered, some of which form collimated outflows. Among the most extended ones are HH 1203 and HH 1196, which have a length of 1 pc or even more. During the search for the probable sources of HH objects, several new nebulous stars were found. A list of all nebulous stellar objects in the Mon R1 area under study is presented, with detailed descriptions of the most interesting ones. The near-infrared data from the GLIMPSE360 and WISE surveys revealed several more objects related to Mon R1, some of which had optical counterparts, as well as helped to identify at least three probable H2 collimated flows from the deeply embedded pre-main-sequence objects. The probable members of Mon R1 were selected by their distances; their bolometric luminosities and extinctions were estimated. Among the outflow sources, three embedded objects with luminosities greater than 10 L⊙ were found. The mean distance to the Mon R1 complex is estimated as 715 pc.

Multifrequency study of HH 137 and HH 138: discovering new knots and molecular outflows with Gemini and APEX

ABSTRACT We present a multiwavelength study of two Herbig–Haro (HH) objects (137 and 138) that may be associated. We use Gemini H2 (2.12 μm) and K (2.2 μm) images, as well as Atacama Pathfinder EXperiment molecular line observations and Spitzer image archives. Several H2 knots, linked to the optical chain of knots of HH 137, are identified in the Gemini and Spitzer 4.5 μm images. New shock excited regions related to the optical knots delineating HH 138 are also reported. In addition, a bright 4.5 μm 0.09 pc-long arc-shaped structure, roughly located mid-way between HH 137 and HH 138, is found to be associated with two Spitzer Class I/II objects, which are likely to be the exciting stars. These sources are almost coincident with a high-density molecular clump detected in 12CO(3 − 2), 13CO(3 − 2), C18O(3 − 2), HCO+(3 − 2), and HCN(3 − 2) molecular lines with an local thermodynamic equilibrium (LTE) mass of 36 M⊙. The 12CO(3 − 2) emission distribution over the observed region reveals molecular material underlying three molecular outflows. Two of them (outflows 1 and 2) are linked to all optical knots of HH 137 and HH 138 and to the H2 and 4.5 μm shock emission knots. In fact, the outflow 2 shows an elongated 12CO blue lobe that coincides with all the H2 knots of HH 137, which end at a terminal H2 bow shock. We propose a simple scenario that connects the outflows to the dust clumps detected in the region. A third possible outflow is located to the north-east projected towards a secondary weak and cold dust clump.

Saw-type shock fronts in several HII regions of southern hemisphere

Radiation shock fronts at the heads of non adiabatic cooling jets are considered. Decay of these shock fronts leads to the origin of groups of HH objects, and of groups of bright condensations in the jets expelled from the nuclei of galaxies, e.g. from the nucleus of NGC5128. Several examples of saw-type radiation shock fronts, found in the Southern Hemisphere, are presented.

Development of jets, outflows and HH objects

The entrainment of molecular material through a mixing layer along the walls of a HH jet beam has been modeled analytically (Cantó & Raga 1991; Stahler 1994) and numerically (Taylor & Raga 1995; Lim et al. 1999). However, when full radiative jet simulations are carried out, the molecular, environmental material remains within a dense shell which follows the shape of the leading bow shock. Because of this, no molecular material reaches the outer boundary of the jet beam, and therefore no “side-entrainment” of molecular gas into the fast jet beam takes place.