2017A&A...605A..61B


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.19CET16:50:19

2017A&A...605A..61B - Astronomy and Astrophysics, volume 605A, 61-61 (2017/9-1)

Multiplicity and disks within the high-mass core NGC 7538IRS1. Resolving cm line and continuum emission at ∼0.06'' x 0.05'' resolution.

BEUTHER H., LINZ H., HENNING T., FENG S. and TEAGUE R.

Abstract (from CDS):

Context. High-mass stars have a high degree of multiplicity and most likely form via disk accretion processes. The detailed physics of the binary and disk formation are still poorly constrained.
Aims. We seek to resolve the central substructures of the prototypical high-mass star-forming region NGC 7538IRS1 at the highest possible spatial resolution in line and continuum emission to investigate the protostellar environment and kinematics.
Methods. Using the Karl G. Jansky Very Large Array (VLA) in its most extended configuration at ∼24GHz has allowed us to study the NH3 and thermal CH3OH emission and absorption as well as the cm continuum emission at an unprecedented spatial resolution of 0.06''x0.05'', corresponding to a linear resolution of ∼150AU at a distance of 2.7kpc.
Results. A comparison of these new cm continuum data with previous VLA observations from 23yr ago reveals no recognizable proper motions. If the emission were caused by a protostellar jet, proper motion signatures should have been easily identified. In combination with the high spectral indices S∝να (α between 1 and 2), this allows us to conclude that the continuum emission is from two hypercompact HII regions separated in projection by about 430AU. The NH3 spectral line data reveal a common rotating envelope indicating a bound high-mass binary system. In addition to this, the thermal CH3OH data show two separate velocity gradients across the two hypercompact HII regions. This indicates two disk-like structures within the same rotating circumbinary envelope. Disk and envelope structures are inclined by ∼33°, which can be explained by initially varying angular momentum distributions within the natal, turbulent cloud.
Conclusions. Studying high-mass star formation at sub-0.1'' resolution allows us to isolate multiple sources as well as to separate circumbinary from disk-like rotating structures. These data show also the limitations in molecular line studies in investigating the disk kinematics when the central source is already ionizing a hypercompact HII region. Recombination line studies will be required for sources such as NGC 7538IRS1 to investigate the gas kinematics even closer to the protostars.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: formation - stars: massive - stars: individual: NGC 7538IRS1 - stars: rotation - instrumentation: interferometers - instrumentation: interferometers

VizieR on-line data: <Available at CDS (J/A+A/605/A61): list.dat fits/*>

Status at CDS : Objects in title, abstract, text, figures, and all or part of small table(s) being processed in SIMBAD.

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2548 2
2 3C 84 Sy2 03 19 48.1597607660 +41 30 42.114155434   13.10 12.48 11.09   ~ 3601 3
3 RAFGL 4176 IR 13 43 01.704 -62 08 51.23           ~ 94 0
4 IRAS 17216-3801 IR 17 25 06.517 -38 04 00.44           ~ 24 0
5 EGO G011.92-0.61 of? 18 13 58.1 -18 54 17           ~ 37 0
6 [WBN74] NGC 7538 IRS 3 Y*? 23 13 43.646 +61 28 14.02           ~ 64 0
7 [WBN74] NGC 7538 IRS 1 Y*O 23 13 45.318 +61 28 11.69           ~ 371 3
8 [WBN74] NGC 7538 IRS 2 Y*? 23 13 45.474 +61 28 19.87           ~ 72 0
9 NVSS J233921+601012 Rad 23 39 21.12520569 +60 10 11.8492190           ~ 16 1

    Equat.    Gal    SGal    Ecl

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2021.01.19-16:50:19

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