J/A+A/631/A64 Barn 335 ALMA datacubes (Bjerkeli+, 2019)
Kinematics around the B335 protostar down to au scales.
Bjerkeli P., Ramsey J.P., Harsono D., Calcutt H., Kristensen L.E.,
van der Wiel M.H.D., Jorgensen J.K., Muller S., Persson M.V.
<Astron. Astrophys. 631, A64 (2019)>
=2019A&A...631A..64B 2019A&A...631A..64B (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Interstellar medium
Keywords: stars: formation - stars: protostars - ISM: jets and outflows -
accretion, accretion disks
Abstract:
The relationship between outflow launching and the formation of
accretion disks around young stellar objects is still not entirely
understood, which is why spectrally and spatially resolved
observations are needed. Recently, the Atacama Large Millimetre/
sub-millimetre Array (ALMA) carried out long-baseline observations
towards a handful of young sources, revealing connections between
outflows and the inner regions of disks. Here we aim to determine the
small-scale kinematical and morphological properties of the outflow
from the isolated protostar B335 for which no Keplerian disk has, so
far, been observed on scales down to 10au. We used ALMA in its
longest-baseline configuration to observe emission from CO
isotopologues, SiO, SO2, and CH3OH. The proximity of B335 provides
a resolution of ∼3au (0.03"). We also combined our long-baseline data
with archival observations to produce a high-fidelity image covering
scales up to 700 au (7"). 12CO has an X-shaped morphology with arms
∼50au in width that we associate with the walls of an outflow cavity,
similar to what is observed on larger scales. Long-baseline continuum
emission is confined to <7au from the protostar, while short- baseline
continuum emission follows the 12CO outflow and cavity walls.
Methanol is detected within ∼30au of the protostar. SiO is also
detected in the vicinity of the protostar, but extended along the
outflow. The 12CO outflow does not show any clear signs of rotation
at distances ≥30au from the protostar. SiO traces the protostellar
jet on small scales, but without obvious rotation. CH3OH and SO2
trace a region <16au in diameter, centred on the continuum peak, which
is clearly rotating. Using episodic, high-velocity, 12CO features,
we estimate the launching radius of the outflow to be<0.1au and
dynamical timescales of the order of a few years.
Description:
This data collection contains seven spectral cubes and one spectrum.
The observational setup and details concerning calibration, data
combination and imaging is presented in Sec. 2 and Table 1 of the
paper. For the long-baseline spectral line cubes, the continuum was
subtracted in the UV domain using only the line free channels. The the
APEX 12 spectrum, the median of the line free channels were
subtracted. For the combined 12CO cube, no baseline subtraction was
made. The fits cubes delivered here are listed below (relevant
ALMA/APEX project id's are in parentheses):
1. B335CONTcombined.fits: Combined 1.3mm continuum
(2013.1.00879, 2016.1.01552, 2017.1.00288)
2. B335_CONT.fits: Long-baseline 1.3mm continuum (2017.1.00288)
3. B335_APEX.fits: APEX 12CO single dish data (O-087.F-9314A)
4. B335CO21combined.fits: Combined 12CO cube
(2013.1.00879, 2016.1.01552, 2017.1.00288)
5. B335_SPW1.fits: Long baseline 12CO cube (2017.1.00288)
6. B335_SPW2.fits: Long baseline CH3OH, SiO and SO2 cube (2017.1.00288)
7. B335_SPW3.fits: Long baseline C18O cube (2017.1.00288)
8. B335_SPW4.fits: Long baseline 13CO cube (2017.1.00288)
For the long-baseline spectral line cubes (5,6,7,8), the continuum was
subtracted in the UV domain using only the line free channels. For the
APEX 12CO spectrum (3), the median of the line free channels were
subtracted. For the combined 12CO cube (1), no baseline subtraction
was made.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
19 36 55 +07 34.4 Barn 335 = LDN 663
-----------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 183 8 List of fits files
fits/* . 8 Individual fits files
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See also:
J/A+A/475/281 : Herbig-Haro flows in B335 (Galfalk+, 2007)
Byte-by-byte Description of file: list.dat
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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- 33 I4 --- Nz ? Number of slices
35- 57 A23 "datime" Obs.date Observation date
59- 65 F7.3 GHz bFREQ ? Lower value of frequency interval
67- 73 F7.3 GHz BFREQ ? Upper value of frequency interval
75- 82 F8.1 Hz dFREQ ? Frequency resolution
84- 91 I8 Kibyte size Size of FITS file
93-115 A23 --- FileName Name of FITS file, in subdirectory fits
117-183 A67 --- Title Title of the FITS file
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Acknowledgements:
Per Bjerkeli, per.bjerkeli(at)bjerkeli.se
(End) Patricia Vannier [CDS] 30-Sep-2019