The stellar population and complex structure of the bright-rimmed cloud IC 1396N

Abstract

Context. IC 1396N is a bright-rimmed cloud associated with an intermediate-mass star-forming region, where a number of HerbigHaro objects, H 2 jet-like features, CO molecular outflows, and millimeter compact sources have been observed. Aims. We study the complex structure of the IC 1396N core and the molecular outflows detected in the region in detail and reveal the presence of additional YSOs inside this globule. Methods. We carried out a deep survey of the IC 1396N region in the J, H, K broadband filters and deep high-angular resolution observations in the H 2 narrowband filter with NICS at the TNG telescope. The completeness limits in the 2MASS standard are K s ∼ 17.5, H ∼ 18.5, and J ∼ 19.5. Results. A total of 736 sources have been detected in all three bands within the area where the JHK images overlap. There are 128 sources detected only in HK , 67 detected only in K , and 79 detected only in JH. We found only a few objects exhibiting a near-infrared excess and no clear signs of clustering of sources towards the southern rim. In the case of triggered star formation in the southern rim of the globule, this could be very recent, because it is not shown through Near-Infrared imaging alone. The H 2 emission is complex and knotty and shows a large number of molecular hydrogen features spread over the region, testifying to recent starformation activity throughout the whole globule. This emission is resolved into several chains or groups of knots that sometimes show a jet-like morphology. The shocked cloudlet model scenario previously proposed to explain the V-shaped morphology of the CO molecular outflow powered by the intermediate-mass YSO BIMA 2 seems to be confirmed by the presence of H 2 emission at the position of the deflecting western clump. New possible flows have been discovered in the globule, and some of them could be very long. In particular, the YSO BIMA 3 could be powering an old and poorly collimated outflow.

Triggered Star Formation

“…There are class III and class II stars around the rim and class I/0 stars inside. Beltrán et al (2009) did a JHK survey of the same bright rim and found few NIR-excess sources and no signs of clustering toward the southern part of the rim. They also found no color or age gradient in the north-south direction.…”

Dissecting an intermediate-mass protostar

“…Classified as a class 0/I borderline source, this young protostar is associated with a very energetic bipolar outflow. In addition, near-infrared images by Nisini et al (2001) and Beltrán et al (2009) identified a collimated 2.12 μm H 2 jet. The outflows and envelope of this protostar were firstly mapped by Codella et al (2001) and Beltrán et al (2002Beltrán et al ( , 2004b using BIMA and OVRO.…”

Close encounters of the protostellar kind in IC 1396N

“…Deep sub-arcsecond 2.12 μm H 2 1-0 S(1) line emission observations carried out with the TNG telescope (Beltrán et al 2009) resolved the emission features spread throughout the region into several chains of knots. In a few cases, these strands of H 2 knots have a jet-like morphology, which suggests that they could trace different flows Beltrán et al 2009).…”

“…In a few cases, these strands of H 2 knots have a jet-like morphology, which suggests that they could trace different flows Beltrán et al 2009). Towards the northern part of the globule, Nisini et al (2001) proposed that some of these knots could be associated with the CO molecular outflow discovered by Codella et al (2001), and Beltrán et al (2009) suggested that strand of knots located at both sides of the IR-dark "tail" could be associated with each other and be part of long flows with lengths ranging Based on observations carried out with the IRAM Plateau de Bure. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).…”

“…The "tail" was also mapped in the continuum at 2.7 mm to search for the possible outflow powering sources that according to Beltrán et al (2009) should be hidden there. In this letter, we present the first results of this study, which confirm the scenarios proposed by Beltrán et al (2009), including the collision of two of these flows.…”