Description of source "05358+3543" from Rodriguez-Garza et al. (2017)


This source is part of the star-forming complex S233IR located at a distance of 1.8 kpc (Snell et al. 1990). S233IR contains two young embedded clusters in different evolutionary states separated by 0.5 pc. They are labeled as the northeast (NE) and southwest (SW) clusters, with estimated ages of 2 Myr and 3 Myr, respectively (Porras et al. 2000). Several star formation tracers are present in the NE cluster: H2O and OH masers (Tofani et al. 1995; Argon et al. 2000; Beuther et al. 2002d), intense Class II 6.6 GHz methanol masers (256 Jy; Menten 1991; Szymczak et al. 2000), and at least three highly collimated jets revealed from shocked H2 emission (Qiu et al. 2008; Porras et al. 2000). Three millimeter sources and possibly four molecular outflows are found in this cluster (mm1, mm2, and mm3; outflows A, B, C, and D: Beuther et al. 2002a). Outflow A is a large-scale (∼1 pc) highly collimated CO outflow possibly powered by mm1; outflow B is a high-velocity CO outflow, and outflow C is observed mainly in SiO emission. In marked contrast, the SW cluster—which harbors the IRAS source—does not show any of the star formation activity described above. No radio continuum emission at 3.6 cm was detected toward either cluster (S02).

Our observations were centered on the IRAS source in the SW cluster where one maser spot was detected; the NE cluster is outside our primary beam, although two maser spots were detected here (see Figure 1). The largest primary beam correction factors reported in Table 4 were applied to this source. In total, three methanol maser spots were detected; the one detected toward the SW cluster is coincident with SiO emission from the southern lobe of outflow C and also with an extended green feature that appears to be emanating from the SW cluster in a NW–SE direction. The other two in the NE cluster are either coincident with the inner knots of outflow A or with the tip of the southeastern lobe of outflow B. One of these two masers is also coincident with H2 emission (knot N4A: Porras et al. 2000 bow shock 1: Varricatt et al. 2010; Beuther et al. 2002a). In contrast to the Class II, H2O, and OH masers that are projected near the center of the NE cluster (Porras et al. 2000), the Class I masers are located at the borders of the star formation regions.

Litovchenko et al. (2011) made single-dish observations of 44 GHz masers in this source. Their pointing was centered toward the NE cluster and did not detect emission. Their primary beam covers the complete area where we detect two bright masers of 24.72 and 5.01 Jy. Their nondetection suggests variability.