J/A+A/686/A162 NGC 1333-SE DCO+ and H13CO+ datacubes (Pineda+, 2024)
Probing the physics of star formation (ProPStar) I. First resolved maps of the
electron fraction and cosmic-ray ionization rate in NGC 1333.
Pineda J.E., Sipila O., Segura-Cox D.M., Valdivia-Mena M.T., Neri R.,
Kuffmeier M., Ivlev A.V., Offner S.S.R., Maureira M.J., Caselli P.,
Spezzano S., Cunningham N., Schmiedeke A., Chen M.
<Astron. Astrophys. 686, A162 (2024)>
=2024A&A...686A.162P 2024A&A...686A.162P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Molecular data ; Interferometry ; Radio sources
Keywords: astrochemistry - techniques: interferometric -
stars: formation - ISM: abundances - cosmic rays - ISM: molecules
Abstract:
Electron fraction and cosmic-ray ionization rates in star-forming
regions are important quantities in astrochemical modeling and are
critical to the degree of coupling between neutrals, ions, and
electrons, which regulates the dynamics of the magnetic field.
However, these are difficult quantities to estimate.
We aim to derive the electron fraction and cosmic-ray ionization rate
maps of an active star-forming region.
We combined observations of the nearby NGC 1333 star-forming region
carried out with the NOEMA interferometer and IRAM 30-m single dish to
generate high spatial dynamic range maps of different molecular
transitions. We used the DCO+ and H13CO+ ratio (in addition to
complementary data) to estimate the electron fraction and produce
cosmic-ray ionization rate maps.
We derived the first large-area electron fraction and cosmic-ray
ionization rate resolved maps in a star-forming region, with typical
values of 10-6.5 and 10-16.5s-1, respectively. The maps present
clear evidence of enhanced values around embedded young stellar
objects (YSOs). This provides strong evidence for locally accelerated
cosmic rays. We also found a strong enhancement toward the northwest
region in the map that might be related either to an interaction with
a bubble or to locally generated cosmic rays by YSOs. We used the
typical electron fraction and derived a magnetohydrodynamic (MHD)
turbulence dissipation scale of 0.054pc, which could be tested with
future observations.
We found a higher cosmic-ray ionization rate compared to the canonical
value for N(H2)=1021-1023cm-2^ of 10-17s-1 in the region,
and it is likely generated by the accreting YSOs. The high value of
the electron fraction suggests that new disks will form from gas in
the ideal-MHD limit. This indicates that local enhancements of
ζ(H2), due to YSOs, should be taken into account in the
analysis of clustered star formation.
Description:
We present the original cubes used to obtain the results from the
paper. These are the combined NOEMA and 30m data cubes of DCO+ (1-0)
and H13CO+ (1-0) from project S21AD and 090-21 (PI: J. E. Pineda).
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
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03 29 10.0 +31 14 00 NGC 1333-SE
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 155 4 List of fits maps and datacubes
fits/* . 4 Individual fits maps and datacubes
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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- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 32 I3 --- Nz ? Number of slices for the datacubes
34- 41 F8.2 m/s bVRAD ? Lower value of VRAD for the datacubes
43- 49 F7.1 m/s BVRAD ? Upper value of VRAD for the datacubes
51- 57 F7.3 m/s dVRAD ? VRAD resolution for the datacubes
59- 64 I6 Kibyte size Size of FITS file
66- 99 A34 --- FileName Name of FITS file, in subdirectory fits
101-155 A55 --- Title Title of the FITS file
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Acknowledgements:
Jaime E. Pineda, jpineda(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 13-Mar-2024