G24.78+0.08 A1 ALMA images and datacubes

DOI

Hyper-compact (HC) or ultra-compact HII regions are the first manifestations of the radiation feedback from a newly born massive star. Therefore, their study is fundamental to understanding the process of massive (>=8M_{sun}) star formation. We employed Atacama Large Millimeter/submillimeter Array (ALMA) 1.4mm Cycle 6 observations to investigate at high angular resolution (~0.050, corresponding to 330au) the HC HII region inside molecular core A1 of the high-mass star-forming cluster G24.78+0.08. We used the H30{alpha} emission and different molecular lines of CH_3_CN and ^13^CH_3_CN to study the kinematics of the ionized and molecular gas, respectively. At the center of the HC HII region, at radii <~500au, we observe two mutually perpendicular velocity gradients, which are directed along the axes at PA=39{deg} and PA=133{deg}, respectively. The velocity gradient directed along the axis at PA=39{deg} has an amplitude of 22km/s/mpc, which is much larger than the other;s, 3km/s/mpc. We interpret these velocity gradients as rotation around, and expansion along, the axis at PA=39{deg}. We propose a scenario where the H30{alpha} line traces the ionized heart of a disk-jet system that drives the formation of the massive star (~20M{sun}) responsible for the HC HII region. Such a scenario is also supported by the position-velocity plots of the CH_3_CN and ^13^CH_3_CN lines along the axis at PA=133{deg}, which are consistent with Keplerian rotation around a 20M{sun}_ star. Toward the HC HII region in G24.78+0.08, the coexistence of mass infall (at radii of ~5000au), an outer molecular disk (from ~500au), and an inner ionized disk (<~500au) indicates that the massive ionizing star is still actively accreting from its parental molecular core. To our knowledge, this is the first example of a molecular disk around a high-mass forming star that, while becoming internally ionized after the onset of the HII region, continues to accrete mass onto the ionizing star.

Cone search capability for table J/A+A/650/A142/list (List of fits images and datacubes)

Identifier
DOI http://doi.org/10.26093/cds/vizier.36500142
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/A+A/650/A142
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/650/A142
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/650/A142
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/A+A/650/A142
Provenance
Creator Moscadelli L.; Cesaroni R.; Beltran M.T.; Rivilla V.M.
Publisher CDS
Publication Year 2021
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Galactic and extragalactic Astronomy; Interstellar medium; Natural Sciences; Observational Astronomy; Physics