J/A+A/577/L2 Barnard 1b-N and 1b-S nascent bipolar outflows (Gerin+, 2015)
Nascent bipolar outflows associated with the first hydrostatic core
candidates Barnard 1b-N and 1b-S.
Gerin M., Pety J., Fuente A., Cernicharo J., Commercon B., Marcelino N.
<Astron. Astrophys. 577, L2 (2015)>
=2015A&A...577L...2G 2015A&A...577L...2G
ADC_Keywords: Molecular clouds ; Radial velocities
Keywords: ISM: clouds - ISM: jets and outflows -
ISM: individual objects: Barnard 1b - stars: formation
Abstract:
In the theory of star formation, the first hydrostatic core (FHSC)
phase is a critical step in which a condensed object emerges from a
prestellar core. This step lasts about one thousand years, a very
short time compared with the lifetime of prestellar cores, and
therefore is hard to detect unambiguously. We present IRAM Plateau de
Bure observations of the Barnard 1b dense molecular core, combining
detections of H2CO and CH3OH spectral lines and dust continuum at 2.3"
resolution (∼500AU). The two compact cores B1b-N and B1b-S are
detected in the dust continuum at 2mm, with fluxes that agree with
their spectral energy distribution. Molecular outflows associated with
both cores are detected. They are inclined relative to the direction
of the magnetic field, in agreement with predictions of collapse in
turbulent and magnetized gas with a ratio of mass to magnetic flux
somewhat higher than the critical value, µ∼2-7. The outflow
associated with B1b-S presents sharp spatial structures, with ejection
velocities of up to ∼7km/s from the mean velocity. Its dynamical age
is estimated to be ∼2000yr. The B1b-N outflow is smaller and slower,
with a short dynamical age of ∼1000yr. The B1b-N outflow mass,
mass-loss rate, and mechanical luminosity agree well with theoretical
predictions of FHSC. These observations confirm the early evolutionary
stage of B1b-N and the slightly more evolved stage of B1b-S.
Description:
The two fits file correspond to the merging of the PdBI and single
dish data. The projection center is RA 03:33:21.300, DEC 31:07:34.00,
a position in between B1b-N and B1b-S. We observed a mosaic of seven
pointings that followed a hexagonal compact pattern with nearest
neighbors separated by half the primary beam, providing a roughly
circular field of view of 70" diameter at 2mm.
Objects:
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RA (2000) DE Designation(s)
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03 33 21.3 +31 07 27 B1b-N = [HKM99] B1-bN
03 33 21.3 +31 07 28 B1b-S = [HKM99] B1-bS
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 120 2 List of FITS datacubes
fits/* . 2 Individual FITS 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 Center right ascension (J2000)
10- 18 F9.5 deg DEdeg Center declination (J2000)
20- 23 F4.2 arcsec/pix Scale [0.49] Scale of the image
25- 27 I3 --- Nx [155] Number of pixels along X-axis
29- 31 I3 --- Ny [155] Number of pixels along Y-axis
33- 35 I3 --- Nz [150/618] Number of slices
37- 46 F10.6 GHz Freq [145.12/145.61] Central frequency
48- 55 F8.4 km/s V.min Lower value of radial velocity interval
57- 63 F7.4 km/s V.max Upper value of radial velocity interval
65- 71 F7.3 m/s dV Channel spacing
73- 77 I5 Kibyte size Size of the fits file
79- 91 A13 --- FileName Name of the FITS file in subdirectory fits
93-120 A28 --- Title Title of the file
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Acknowledgements:
Maryvonne Gerin, maryvonne.gerin(at)lra.ens.fr
(End) Patricia Vannier [CDS] 27-Apr-2015