Astrophys. J., 899, 128-128 (2020/August-3)
The formation of a stellar association in the NGC 7000/IC 5070 complex: results from kinematic analysis of stars and gas.
KUHN M.A., HILLENBRAND L.A., CARPENTER J.M. and AVELAR MENENDEZ A.R.
Abstract (from CDS):
We examine the clustering and kinematics of young stellar objects (YSOs) in the North America/Pelican Nebulae, as revealed by Gaia astrometry, in relation to the structure and motions of the molecular gas, as indicated in molecular-line maps. The Gaia parallaxes and proper motions allow us to significantly refine previously published lists of YSOs, demonstrating that many of the objects previously thought to form a distributed population turn out to be nonmembers. The members are subdivided into at least six spatio-kinematic groups, each of which is associated with its own molecular cloud component or components. Three of the groups are expanding, with velocity gradients of 0.3-0.5 km s–1 pc–1, up to maximum velocities of ∼8 km s–1 away from the groups' centers. The two known O-type stars associated with the region, 2MASS J20555125+4352246 and HD 199579, are rapidly escaping one of these groups, following the same position-velocity relation as the low-mass stars. We calculate that a combination of gas expulsion and tidal forces from the clumpy distribution of molecular gas could impart the observed velocity gradients within the groups. However, on a global scale, the relative motions of the groups do not appear either divergent or convergent. The velocity dispersion of the whole system is consistent with the kinetic energy gained due to gravitational collapse of the complex. Most of the stellar population has ages similar to the freefall timescales for the natal clouds. Thus, we suggest the nearly freefall collapse of a turbulent molecular cloud as the most likely scenario for star formation in this complex.
© 2020. The American Astronomical Society. All rights reserved.
Star formation - Star forming regions - Stellar associations - Stellar kinematics - Space astrometry - Young stellar objects - T Tauri stars - Giant molecular clouds - Millimeter astronomy - OB stars
Status at CDS
Examining the need for a new acronym. // Large table(s) will be appraised for possible ingestion in VizieR.
View the reference in ADS
To bookmark this query, right click on this link: simbad:2020ApJ...899..128K and select 'bookmark this link' or equivalent in the popup menu