J/A+A/636/A65 DG Tau B ALMA observations (Garufi+, 2020)
ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT).
I. CO, CS, CN, and H2CO around DG Tau B.
Garufi A., Podio L., Codella C., Rygl K., Bacciotti F., Facchini S.,
Fedele D., Miotello A., Teague R., Testi L.
<Astron. Astrophys. 636, A65 (2020)>
=2020A&A...636A..65G 2020A&A...636A..65G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Radio continuum ; Radio lines
Keywords: stars: pre-main sequence - protoplanetary disks
Abstract:
The chemical composition of planets is determined by the distribution
of the various molecular species in the protoplanetary disk at the
time of their formation. To date, only a handful of disks have been
imaged in multiple spectral lines with high spatial resolution. As
part of a small campaign devoted to the chemical characterization of
disk-outflow sources in Taurus, we report on new ALMA Band 6 (1.3mm)
observations with 0.15" (20au) resolution toward the embedded young
star DG Tau B. Images of the continuum emission reveals a dust disk
with rings and, putatively, a leading spiral arm. The disk, as well as
the prominent outflow cavities, are detected in CO, H2CO, CS, and
CN; instead, they remain undetected in SO2, HDO, and CH3OH. From
the absorption of the back-side outflow, we inferred that the disk
emission is optically thick in the inner 50au. This morphology
explains why no line emission is detected from this inner region and
poses some limitations toward the calculation of the dust mass and the
characterization of the inner gaseous disk. The H2CO and CS emission
from the inner 200au is mostly from the disk, and their morphology is
very similar. The CN emission significantly differs from the other two
molecules as it is observed only beyond 150au. This ring-like
morphology is consistent with previous observations and the
predictions of thermochemical disk models. Finally, we constrained the
disk-integrated column density of all molecules. In particular, we
found that the CH3OH/H2CO ratio must be smaller than ∼2, making
the methanol non-detection still consistent with the only such ratio
available from the literature (1.27 in TW Hya).
Description:
ALMA observations of DG Tau B were performed during Cycle 4 in August
2017 in an extended configuration with baselines ranging from 17m to
3.7km. The total integration time amounted to 88-minutes. The bandpass
was calibrated with the quasar J0510+1800, and phase calibration was
performed every 8 minutes using the quasar J0438+3004. The correlator
setup included 12 high-resolution (0.122MHz) spectral windows (SPWs)
covering 12 molecular transitions of six molecules: 12CO, H2CO,
CN, HDO, CH3OH, and SO2, plus one 1.875GHz broad SPW for continuum
emission (and including a strong CS spectral line).
Objects:
----------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------
04 27 04.69 +26 06 16.0 DG Tau = V* DG Tau
----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 128 4 Information on fits images
fits/* . 4 Fits images
--------------------------------------------------------------------------------
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 "date" Obs.date Observation date
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
87-128 A42 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Antonio Garufi, agarufi(at)arcetri.astro.it
(End) Patricia Vannier [CDS] 02-Apr-2020