J/A+A/635/A94 HD141569A system ALMA and NOEMA data cubes (Di Folco+, 2020)
An ALMA/NOEMA study of gas dissipation and dust evolution in the 5 Myr-old
HD141569A hybrid disc.
Di Folco, E., Pericaud, J., Dutrey A., Augereau J.C., Chapillon E.,
Guilloteau S., Pietu V., Boccaletti A.
<Astron. Astrophys. 635, A94 (2020)>
=2020A&A...635A..94D 2020A&A...635A..94D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, emission
Keywords: accretion, accretion disks - methods: observational -
techniques: interferometric - protoplanetary disks -
stars: pre-main sequence - radio lines: stars
Abstract:
The study of gas-rich debris discs is fundamental to characterising
the transition between protoplanetary discs and debris discs. Aims. We
determine the physical parameters of the brightest gas-rich debris
disc orbiting HD 141569A.
We analyse images from the NOrthern Extended Millimeter Array (NOEMA)
and the Atacama Large Millimeter/submillimeter Array (ALMA) in 12CO,
13CO J=2-1, and 13CO J=1-0 transitions. We incorporate ALMA
archival data of the 12CO J=3-2 transition and present continuum
maps at 0.87mm, 1.3mm, and 2.8mm. We use simple parametric laws
with the Diskfit code and MCMC exploration to characterise the gas
disc parameters and report a first attempt to characterise its
chemical content with IRAM-30m.
The continuum emission is equally shared between a compact (<50au) and
a smooth, extended dust component (∼350 au). Large millimetre grains
seem to dominate the inner regions, while the dust spectral index is
marginally larger in the outer region. The 12CO is optically thick,
while 13CO is optically thin with tau13CO∼0.15 (C18O is not
detected). The 13CO surface density is constrained to be one order
of magnitude smaller than around younger Herbig Ae stars, and we
derive a gas mass M12CO=10-1M☉. We confirm the presence of a
small CO cavity (RCO=17±3au), and find a possibly larger radius
for the optically thin 13CO J=2-1 transition (35±5au). We show
that the observed CO brightness asymmetry is coincident with the
complex ring structures discovered with VLT/SPHERE in the inner 90au.
The 12CO temperature T0(100au)∼30K is lower than expected for a
Herbig∼A0 star, and could be indicative of subthermal excitation.
With the largest amount of dust and gas among hybrid discs, HD141569A
shows coincident characteristics of both protoplanetary discs (central
regions), and debris discs at large distance. Together with its
morphological characteristics and young age, it appears to be a good
candidate to witness the transient phase of gas dissipation, with an
apparently large gas-to-dust ratio (G/D>100) favouring a faster
evolution of dust grains.
Description:
NOEMA Observations. HD141569 was observed with NOEMA during three runs
from December 2014 to April 2016. The 12CO J=2-1 transition at
230.538 GHz was mapped with the 7D and 7C configurations (7 antennas)
of the IRAM array, with an angular resolution of 2.4x1.2'' (baseline
lengths from 15 to 192m, natural weighting). The spectral setup used a
narrow band (20MHz bandwidth, resolution 0.20km/s). Excellent
conditions are noteworthy for one track, with precipitable water
vapour inferior to 1.5mm, and a 15° mean phase rms.
In winter 2014/2015, we also obtained 13CO J=2-1 (220.399GHz)
observations. The 6C and 7D configuration antennas were used with a
total on-source time of 12.7h. We reached a 2.3''x1.2'' angular
resolution (baseline lengths from 15 to 176m) and used the same
spectral resolution as for 12CO J=2-1.
The WIDEX correlator provided 4GHz bandwidth during the observations
of the 12CO and 13CO. Combining the two observations at 1.3mm, we
obtained a 2.1''x1.0'' beam for the continuum map.
ALMA observations. We obtained ALMA observations in Band 3
(84-116GHz). The data were recorded in August 2015 for the 13CO
J=1-0 (110.201GHz) and C18O J=1-0 (115.271GHz) transitions during
two runs with 39 and 44 antennas respectively (project 2013.1.00883,
PI. Pericaud). The spatial resolution was 0.76''x0.56'' (baselines up
to 1.55 km), and the spectral resolution 0.2km/s. The data was
collected with relatively poor weather conditions (PWV∼4mm).
In addition, we collected archival raw data from the project
2012.1.00698.S (PI. Boley) to complement our analysis in Band7
(275-373GHz), which includes the 12CO J=3-2 line at 345.796GHz.The
observations carried out with 32 antennas provide a resolution of
0.43''x0.35'' (baselines up to 650m), and a spectral resolution of
0.8km/s.
We used the CASA package to calibrate the ALMA data, and we carried
out the imaging and analysis of all NOEMA and ALMA observations with
the GILDAS software. The imaging was performed with natural weighting
for both ALMA and NOEMA.
Objects:
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RA (2000) DE Designation(s)
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15 49 57.75 -03 55 16.3 HD 141569 = HIP 77542
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 129 9 List of fits images and datacubes
fits/* . 9 Individual fits images 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)
11- 19 F9.5 deg DEdeg Declination of center (J2000)
21- 24 I4 --- Nx Number of pixels along X-axis
26- 29 I4 --- Ny Number of pixels along Y-axis
31- 32 I2 --- Nz Number of slices for the datacubes
34- 51 E18.13 Hz Freq Observed frequency
53- 58 F6.3 km/s bRV ? Lower value of radial velocity for datacubes
60- 66 F7.3 km/s BRV ? Upper value of radial velocity for datacubes
68- 73 F6.3 km/s dRV ? Radial Velocity increment for the datacubes
75- 79 I5 Kibyte size Size of FITS file
81- 92 A12 --- FileName Name of FITS file, in subdirectory fits
94-129 A36 --- Title Title of the FITS file
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Acknowledgements:
Emmanuel Di Folco, emmanuel.di-folco(at)u-bordeaux.fr
(End) Emmanuel Di Folco [Uni. Bordeaux], Patricia Vannier [CDS] 11-Mar-2020