Time-Variable Radio Recombination Line Emission in W49A. (arXiv:2010.04656v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pree_C/0/1/0/all/0/1">C. G. De Pree</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilner_D/0/1/0/all/0/1">D. J. Wilner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kristensen_L/0/1/0/all/0/1">L. E. Kristensen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galvan_Madrid_R/0/1/0/all/0/1">R. Galván-Madrid</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goss_W/0/1/0/all/0/1">W. M. Goss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Klessen_R/0/1/0/all/0/1">R. S. Klessen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Low_M/0/1/0/all/0/1">M.-M. Mac Low</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peters_T/0/1/0/all/0/1">T. Peters</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robinson_A/0/1/0/all/0/1">A. Robinson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sloman_S/0/1/0/all/0/1">S. Sloman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rao_M/0/1/0/all/0/1">M. Rao</a>
We present new Jansky Very Large Array (VLA) images of the central region of
the W49A star-forming region at 3.6~cm and at 7~mm at resolutions of 0farcs15
(1650 au) and 0farcs04 (440 au), respectively. The 3.6~cm data reveal new
morphological detail in the ultracompact ion{H}{2} region population, as well
as several previously unknown and unresolved sources. In particular, source A
shows elongated, edge-brightened, bipolar lobes, indicative of a collimated
outflow, and source E is resolved into three spherical components. We also
present VLA observations of radio recombination lines at 3.6~cm and 7~mm, and
IRAM Northern Extended Millimeter Array (NOEMA) observations at 1.2~mm. Three
of the smallest ultracompact ion{H}{2} regions (sources A, B2 and G2) all show
broad kinematic linewidths, with $Delta$V$_{FWHM}gtrsim$40~km~s$^{-1}$. A
multi-line analysis indicates that broad linewidths remain after correcting for
pressure broadening effects, suggesting the presence of supersonic flows.
Substantial changes in linewidth over the 21 year time baseline at both 3.6 cm
and 7 mm are found for source G2. At 3.6 cm, the linewidth of G2 changed from
31.7$pm$1.8 km s$^{-1}$ to 55.6$pm$2.7 km s$^{-1}$, an increase of
$+$23.9$pm$3.4 km s$^{-1}$. The G2 source was previously reported to have
shown a 3.6~cm continuum flux density decrease of 40% between 1994 and 2015.
This source sits near the center of a very young bipolar outflow whose
variability may have produced these changes.
We present new Jansky Very Large Array (VLA) images of the central region of
the W49A star-forming region at 3.6~cm and at 7~mm at resolutions of 0farcs15
(1650 au) and 0farcs04 (440 au), respectively. The 3.6~cm data reveal new
morphological detail in the ultracompact ion{H}{2} region population, as well
as several previously unknown and unresolved sources. In particular, source A
shows elongated, edge-brightened, bipolar lobes, indicative of a collimated
outflow, and source E is resolved into three spherical components. We also
present VLA observations of radio recombination lines at 3.6~cm and 7~mm, and
IRAM Northern Extended Millimeter Array (NOEMA) observations at 1.2~mm. Three
of the smallest ultracompact ion{H}{2} regions (sources A, B2 and G2) all show
broad kinematic linewidths, with $Delta$V$_{FWHM}gtrsim$40~km~s$^{-1}$. A
multi-line analysis indicates that broad linewidths remain after correcting for
pressure broadening effects, suggesting the presence of supersonic flows.
Substantial changes in linewidth over the 21 year time baseline at both 3.6 cm
and 7 mm are found for source G2. At 3.6 cm, the linewidth of G2 changed from
31.7$pm$1.8 km s$^{-1}$ to 55.6$pm$2.7 km s$^{-1}$, an increase of
$+$23.9$pm$3.4 km s$^{-1}$. The G2 source was previously reported to have
shown a 3.6~cm continuum flux density decrease of 40% between 1994 and 2015.
This source sits near the center of a very young bipolar outflow whose
variability may have produced these changes.
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