J/A+A/682/A81 CORE Sample NIKA2 and SMA images (Beuther+, 2024)
Density distributions, magnetic field structures and fragmentation in
high-mass star formation.
Beuther H., Gieser C., Soler J.D., Zhang Q., Rao R., Semenov D., Henning T.,
Pudritz R., Peters T., Klaassen P., Beltran M.T., Palau A., Moeller T.,
Johnston K.G., Zinnecker H., Urquhart J., Kuiper R., Ahmadi A.,
Sanchez-Monge A., Feng S., Leurini S., Ragan S.E.
<Astron. Astrophys. 682, A81 (2024)>
=2024A&A...682A..81B 2024A&A...682A..81B (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Radio sources ; Magnetic fields
Keywords: stars: formation - stars: massive - stars: protostars - ISM: clouds -
dust, extinction - ISM: magnetic fields
Abstract:
The fragmentation of high-mass star-forming regions depends on a
variety of physical parameters, including the density, magnetic field
and turbulent gas properties.
We evaluate the importance of the density and magnetic field
structures in relation to the fragmentation properties during
high-mass star formation.
Observing the large pc-scale Stokes I mm dust continuum emission with
the IRAM 30m telescope and the intermediate-scale (<0.1pc) polarized
submm dust emission with the Submillimeter Array toward a sample of 20
high-mass star-forming regions allows us to quantify the dependence of
the fragmentation behaviour of these regions depending on the density
and magnetic field structures.
Based on the IRAM 30m data, we infer density distributions
n∝r-p of the regions with typical power-law slopes p around
∼1.5. There is no obvious correlation between the power-law slopes of
the density structures on larger clump scales (∼1pc) and the number of
fragments on smaller core scales (<0.1pc). Comparing the large-scale
single-dish density profiles to those derived earlier from
interferometric observations at smaller spatial scales, we find that
the smaller-scale power-law slopes are steeper, typically around ∼2.0.
The flattening toward larger scales is consistent with the
star-forming regions being embedded in larger cloud structures that do
not decrease in density away from a particular core. Regarding the
magnetic field, for several regions it appears aligned with
filamentary structures leading toward the densest central cores.
Furthermore, we find different polarization structures with some
regions exhibiting central polarization holes whereas other regions
show polarized emission also toward the central peak positions.
Nevertheless, the polarized intensities are inversely related to the
Stokes I intensities, following roughly a power law slope of
{rpop.to}S-0.62I. We estimate magnetic field strengths between
∼0.2 and ∼4.5 mG, and we find no clear correlation between magnetic
field strength and the fragmentation level of the regions. Comparison
of the turbulent to magnetic energies shows that they are of roughly
equal importance in this sample. The mass-to-flux ratios range between
∼2 and ∼7, consistent with collapsing star-forming regions.
Finding no clear correlations between the present-day large-scale
density structure, the magnetic field strength and the smaller-scale
fragmentation properties of the regions, indicates that the
fragmentation of high-mass star-forming regions may not be affected
strongly by the initial density profiles and magnetic field
properties. However, considering the limited evolutionary range and
spatial scales of the presented CORE analysis, future research
directions should include density structure analysis of younger
regions that better resemble the initial conditions, as well as
connecting the observed intermediate-scale magnetic field structure
with the larger-scale magnetic fields of the parental molecular
clouds.
Description:
All 20 CORE regions were observed with New IRAM KIDs Array 2 (NIKA2)
on the IRAM 30m telescope between December 2019 and February 2020
(project 143-19).
The CORE sample was observed with the Submillimeter Array over a
period of several years. The first few regions were observed in the
winter term 2018/2019 and the last sources in September 2021.
Altogether, our observing campaign covered 17 CORE regions while the
remaining three CORE regions were already observed with the SMA in
earlier campaigns.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 20 CORE Sample (Beuther et al., 2018A&A...617A.100B 2018A&A...617A.100B)
list.dat 143 100 List of fits images
fits/* . 100 Individual fits images
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Source Source name
17 A1 --- n_Source [a] Note (1)
19- 20 I2 h RAh Right ascension (J2000)
22- 23 I2 min RAm Right ascension (J2000)
25- 29 F5.2 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 42 F5.2 arcsec DEs Declination (J2000)
44- 48 F5.1 km/s Vlsr LSR velocity
50- 52 F3.1 kpc D Distance
54- 57 F4.1 10+4Lsun L Luminosity
59- 60 I2 --- Ncores Number of cores
62- 72 A11 --- SName Short name
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Note (1): a: Archival SMA data from Chen et al. (2012ApJ...751L..13C 2012ApJ...751L..13C);
Frau et al. (2014A&A...567A.116F 2014A&A...567A.116F, Cat. J/A+A/567/A116);
Palau et al. (2021ApJ...912..159P 2021ApJ...912..159P).
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- SName Short name
13- 21 F9.5 deg RAdeg Right Ascension of center (J2000)
22- 30 F9.5 deg DEdeg Declination of center (J2000)
32- 34 I3 --- Nx Number of pixels along X-axis
36- 38 I3 --- Ny Number of pixels along Y-axis
40- 60 A21 "datime" Obs.date Observation date
62- 72 E11.6 Hz Freq ? Observed frequency
74- 76 I3 Kibyte size Size of FITS file
78-103 A26 --- FileName Name of FITS file, in subdirectory fits
105-143 A39 --- Title Title of the FITS file
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Acknowledgements:
Henrik Beuther, beuther(at)mpia.de
(End) Patricia Vannier [CDS] 22-Nov-2023