S316p.105 — New VLA Observations of Massive Protostars: A Search for Jets

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Viviana Rosero2, Peter Hofner1, Mark Claussen3

Institution(s): 1. New Mexico Tech, 2. New Mexico Tech and NRAO, 3. NRAO

Molecular outflows appear to be an ubiquitous phenomena among stars of all masses. However, to date only a handful of sources with disks and collimated jets have been detected in young massive objects (YMOs). It is not clear if the lack of detections are due to intrinsic properties of YMOs or due to observational disadvantages. We have performed a survey of ~60 YMOs with unprecedented sensitivity, using the Karl G. Jansky Very Large Array (VLA) to achieve ~3-10 microJy RMS in C and K-band images (about 10-100 times more sensitive than previous efforts). The sample is composed of the earliest stages of massive star formation: hot molecular cores and infrared dark cloud cores. Moreover, all the sources show signatures of massive star formation such as methanol and water masers and outflow phenomena. This study provides a sample of jet candidates which is a valuable basis for a follow up search for associated disks.
In this contribution we present our observational results from the survey. We have a high detection rate of weak radio continuum emission from the YMOs in our sample, most of which were previously undetected. In addition to the jet scenario, we are analyzing which other processes could be producing the radio emission; some of the detections appear to be from non-thermal emission, and others could be associated with ultra-compact HII regions. Before the upgrade of the VLA, most of the HII regions detected were B0 type stars (or earlier). Hence, these highly sensitive sample of YSOs open a new door of results, from HII regions associated with late B-type stars to very weak, collimated ionized jets associated to very early YMOs.