2020ApJ...904..139S -
Astrophys. J., 904, 139-139 (2020/December-1)
NGC 7538 IRS1 – an O star driving an ionized jet and giant N-S outflow.
SANDELL G., WRIGHT M., GUSTEN R., WIESEMEYER H., REYES N., MOOKERJEA B. and CORDER S.
Abstract (from CDS):
NGC 7538 IRS 1 is a very young embedded O star driving an ionized jet and accreting mass with an accretion rate >10–4 M☉ yr–1, which is quenching the hypercompact H II region. We use SOFIA GREAT data, Herschel PACS and SPIRE archive data, SOFIA FORCAST archive data, Onsala 20 m and CARMA data, and JCMT archive data to determine the properties of the O star and its outflow. IRS 1 appears to be a single O star with a bolometric luminosity >1 x 105 L☉, i.e., spectral type O7 or earlier. We find that IRS 1 drives a large molecular outflow with the blueshifted northern outflow lobe extending to ∼280'' or 3.6 pc from IRS 1. Near IRS 1 the outflow is well aligned with the ionized jet. The dynamical timescale of the outflow is ∼1.3 x 105 yr. The total outflow mass is ∼130 M☉. We determine a mass outflow rate of 1.0 x 10–3 M☉ yr–1, roughly consistent with the observed mass accretion rate. We observe strong high-velocity [C II] emission in the outflow, confirming that strong UV radiation from IRS 1 escapes into the outflow lobes and is ionizing the gas. Many O stars may form like low-mass stars, but with a higher accretion rate and in a denser environment. As long as the accretion stays high enough to quench the H II region, the star will continue to grow. When the accretion rate drops, the H II region will rapidly start to expand.
Abstract Copyright:
© 2020. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Radio jets - Compact H II region - Giant molecular clouds - Star formation - O stars - Stellar accretion - Stellar accretion disks
Status at CDS
:
Examining the need for a new acronym.
Simbad objects:
13
Full paper
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