Proper motions of embedded protostellar jets in Serpens

Abstract

Aims. We determine the proper motion of protostellar jets around Class 0 and Class I sources in an active star forming region in Serpens. Methods. Multi-epoch deep images in the 2.122 μm line of molecular hydrogen, v = 1−0 S(1), obtained with the near-infrared instrument NOTCam on a timescale of 10 years, are used to determine the proper motion of knots and jets. K-band spectroscopy of the brighter knots is used to supply radial velocities, estimate extinction, excitation temperature, and H 2 column densities towards these knots. Results. We measure the proper motion of 31 knots on different timescales (2, 4, 6, 8, and 10 years). The typical tangential velocity is around 50 km s −1 for the 10-year baseline, but for shorter timescales, a maximum tangential velocity up to 300 km s −1 is found for a few knots. Based on morphology, velocity information, and the locations of known protostars, we argue for the existence of at least three partly overlapping and deeply embedded flows, one Class 0 flow and two Class I flows. The multi-epoch proper motion results indicate time-variable velocities of the knots, for the first time directly measured for a Class 0 jet. We find in general higher velocities for the Class 0 jet than for the two Class I jets. While the bolometric luminosites of the three driving sources are about equal, the derived mass flow rateṀ out is two orders of magnitude higher in the Class 0 flow than in the two Class I flows.

Identifying Variability in Deeply Embedded Protostars with ALMA and CARMA

“…Ser-emb 11 and 17 have both been suggested as candidate driving sources for outflows seen in 2.122 µm H 2 by Spitzer Djupvik et al (2016). Outflows are also seen closer to each source in CO (J = 2 → 1) Hull et al (2014).…”

“…Ser-emb 1 is the Class 0 source with the lowest bolometric temperature (39K) in Serpens Main (Enoch et al 2009), suggesting it is also the least evolved. A N-S oriented bi-polar jet likely originating from Ser-emb 1 is seen in 2.122 µm H 2 emission (Djupvik et al 2016). N-S oriented CO outflows are also seen emanating directly from the source in CO (J = 2 → 1) Hull et al (2014).…”