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J/A+A/606/A35       Barnard 1b-N and 1b-S 350GHz images          (Gerin+, 2017)

Evidence for disks at an early stage in class 0 protostars? Gerin M., Pety J., Commercon B., Fuente A., Cernicharo J., Marcelino N., Ciardi A., Lis D.C., Roueff E., Wootten H.A., Chapillon E. <Astron. Astrophys. 606, A35 (2017)> =2017A&A...606A..35G (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Photometry, millimetric/submm Keywords: stars: formation - ISM: clouds - submillimeter: ISM - ISM: individual objects: Barnard 1b - ISM: molecules Abstract: The formation epoch of protostellar disks is debated because of the competing roles of rotation, turbulence, and magnetic fields in the early stages of low-mass star formation. Magnetohydrodynamics simulations of collapsing cores predict that rotationally supported disks may form in strongly magnetized cores through ambipolar diffusion or misalignment between the rotation axis and the magnetic field orientation. Detailed studies of individual sources are needed to cross check the theoretical predictions. We present 0.06-0.1arcsec resolution images at 350GHz toward B1b-N and B1b-S, which are young class 0 protostars, possibly first hydrostatic cores. The images have been obtained with ALMA, and we compare these data with magnetohydrodynamics simulations of a collapsing turbulent and magnetized core. The submillimeter continuum emission is spatially resolved by ALMA. Compact structures with optically thick 350GHz emission are detected toward both B1b-N and B1b-S, with 0.2 and 0.35arcsec radii (46 and 80au at the Perseus distance of 230pc), within a more extended envelope. The flux ratio between the compact structure and the envelope is lower in B1b-N than in B1b-S, in agreement with its earlier evolutionary status. The size and orientation of the compact structure are consistent with 0.2arcsec resolution 32GHz observations obtained with the Very Large Array as a part of the VANDAM survey, suggesting that grains have grown through coagulation. The morphology, temperature, and densities of the compact structures are consistent with those of disks formed in numerical simulations of collapsing cores. Moreover, the properties of B1b-N are consistent with those of a very young protostar, possibly a first hydrostatic core. These observations provide support for the early formation of disks around low-mass protostars. Description: The data are provided as two separate FITS files, one for B1b-N and one for B1b-S. The data have been obtained with ALMA in continuum mode. Four continuum basebands with 2 GHz bandwidth, 128 channels each have been combined. Central sky frequencies on each band are 2336.5 and 338.4GHz in the lower side band and 3548.5 and 350.5GHz in the upper side band. The images have been produced by combining two observing sessions in two ALMA configurations C36-7 and C40-4, for a total of 30 minutes on source. The data processing and calibration is described in the article. The image units are Jy/beam. Objects: ------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------ 03 33 20.32 +31 07 21.5 Barnard 1b = [HKM99] B1-b ------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 97 2 List of fits images fits/* 0 2 Individual fits images
See also: J/A+A/577/L2 : Barnard 1b-N and 1b-S nascent bipolar outflows (Gerin+, 2015) J/A+A/606/L3 : Barnard 1b CO, NH2D and SO images (Fuente+, 2017) Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
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- 52 A23 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.sss) 54- 60 F7.3 GHz Freq Observed frequency 62- 66 I5 Kibyte size Size of FITS file 68- 85 A18 --- FileName Name of FITS file, in subdirectory fits 87- 97 A11 --- Title Title of the FITS file
Acknowledgements: Maryvonne Gerin, maryvonne.gerin(at)lra.ens.fr
(End) Patricia Vannier [CDS] 25-Aug-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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