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arXiv · 2401.03049

Radio Continuum and Water Maser Observations of the High-Mass Protostar IRAS 19035+0641 A

Tatiana M. Rodriguez·Emmanuel Momjian·Peter Hofner·Anuj P. Sarma·Esteban D. Araya
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Abstract

We present Very Large Array (VLA) 1.3 cm continuum and 22.2 GHz H$_2$O maser observations of the high-mass protostellar object IRAS 19035+0641 A. Our observations unveil an elongated bipolar 1.3 cm continuum structure at scales $\lesssim500\,$au which, together with a rising in-band spectral index, strongly suggests that the radio emission toward IRAS 19035+0641 A arises from an ionized jet. In addition, eight individual water maser spots well aligned with the jet axis were identified. The Stokes V spectrum of the brightest H$_2$O maser line ($\sim100\,$Jy) shows a possible Zeeman splitting and is well represented by the derivatives of two Gaussian components fitted to the Stokes I profile. The measured $B_{\mathrm{los}}$ are $123\,(\pm27)$ and $156\,(\pm8)\,$mG, translating to a pre-shock magnetic field of $\approx7\,$mG. Subsequent observations to confirm the Zeeman splitting showed intense variability in all the water maser spots, with the brightest maser completely disappearing. The observed variability in a one-year time scale could be the result of an accretion event. These findings strengthen our interpretation of IRAS 19035+0641 A as a high-mass protostar in an early accretion/outflow evolutionary phase.

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Tatiana M. Rodriguez, Emmanuel Momjian, Peter Hofner, Anuj P. Sarma, Esteban D. Araya. 2024-01-05. Radio Continuum and Water Maser Observations of the High-Mass Protostar IRAS 19035+0641 A. https://arxiv.org/abs/2401.03049

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