J/A+A/673/A143 IRAS 16293-2422 molecular environment (Kahle+, 2023)
The molecular environment of the solar type protostar IRAS 16293-2422.
Kahle K.A., Hernandez-Gomez A., Wyrowski F., Menten K.M.
<Astron. Astrophys. 673, A143 (2023)>
=2023A&A...673A.143K 2023A&A...673A.143K (SIMBAD/NED BibCode)
ADC_Keywords: Protostars ; YSOs ; Spectroscopy ; Infrared sources
Keywords: ISM: molecules - stars: individual: IRAS 16293-2422
Abstract:
Studying the physical and chemical processes leading to the formation
of low-mass stars is crucial for understanding the origin of our Sun
and the Solar System. In particular, analyzing the emission and
absorption lines from molecules to derive their spatial distribution
in the envelopes of young stellar objects is a fundamental tool to
obtain information on the kinematics and chemistry at the very early
stages of star formation.
In this work we aim to examine in detail the spatial structures and
molecular abundances of material surrounding the very well-known low-
mass binary protostar IRAS 16293-2422 and the prestellar core 16293E,
which are embedded in the Lynds 1689 N dark cloud. This analysis is
performed to obtain information on the physical and chemical
properties of these young objects and their interaction with the
molecular outflows present across the region.
We have used the LAsMA heterodyne array installed on the Atacama
Pathfinder EXperiment (APEX) 12 meter submillimeter telescope to image
a region of about 0.12x0.12pc2 around IRAS 16293-2422 and 16293E and
to study their molecular environment covering 45.6GHz in a frequency
range from 277GHz to 375GHz. We have also used the APEX FLASH+
receiver to observe and search for molecular lines in a frequency
range between 476GHz to 493GHz.
We have identified 144 transitions from 36 molecular species,
including isotopologues. This is the first time that such a large
number of species have been mapped at large scales simultaneously in
this region. The maps reveal the envelope to have a complex morphology
around the cloud cores and the emission peaks known as E1, E2, W1, W2,
and HE2, including the outflow structure arising from IRAS 16293-2422.
Using several transitions of para-H2CO, we have derived new lower
limits for the kinetic temperatures toward IRAS 16293-2422 and the
surrounding emission peaks. Based on these temperatures, new column
densities for all detected species were derived around the cloud cores
and all emission peaks using the radiative transfer codes CLASS-Weeds,
CASSIS, and RADEX. We derived H2 volume densities in Lynds 1689 N
based on ortho-H2CO transitions with different upper level energies,
varying between 5x106cm-3 and 63K at IRAS 16293-2422 to values on
the order of 1x106cm-3 and 35K at the other emission peaks.
Our new observations further confirm the scenario of an outflow
arising from IRAS 16293-2422 interacting with the prestellar core
16293E. This is inferred from the velocity and linewidth gradient
shown by several deuterated species closer to the outflow-core
interaction region in 16293E. We observe a large-scale velocity
gradient across the molecular cloud which coincides with the rotation
of the envelope around IRAS 16293-2422 reported previously in the
literature. A comparison with JCMT SCUBA-2 450 micrometer dust
continuum maps and our data suggests that emission peak W2 may be
related to a colder dust source rather than a shocked region. The
newly derived column densities and temperatures for different species,
combined with the molecular spatial distribution in all sources,
indicate clear chemical differences between the protostellar source,
the prestellar core and the shocked positions as a result of the
diverse physical conditions at different locations in this region.
Description:
We have used the LAsMA heterodyne array installed on the Atacama
Pathfinder EXperiment (APEX) 12 meter submillimeter telescope to image
a region of about 0.12x0.12pc2 around IRAS 16293-2422 and 16293E and
to study their molecular environment covering 45.6GHz in a frequency
range from 277GHz to 375GHz.
The data was reduced using the CLASS program, which is part of the
GILDAS software package. We produced cubes of each detected transition
and created velocity-integrated intensity maps that cover the full
line profile. For some transitions, additional maps cover only the
blue or red-shifted emission (the systematic cloud velocity is 4km/s).
The file names correspond to the figure labels in Appendix J and the
species displayed in the fits file. For example, the file 03aN2H+.fit
contains the velocity-integrated intensity map of N2H+ shown in
Fig. J.3a.
File names of maps displayed in the main part of the paper are
indicated by a leading m in the file name. Their subfigures are
described as t (top), m (middle), and b (bottom). The file names are
restricted to 8+3 characters, due to which fits files of HC-13-O+
abbreviate this species as HC13O. Information about the respective
transition rest frequency, integration interval, and species (CDMS
notation) can be found in the fits headers.
Objects:
---------------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------------
16 32 22.8 -24 28 38.7 IRAS 16293-2422 = NAME IRAS 16293
16 32 28.5 -24 29 02.0 16293E = NAME IRAS 16293E
---------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 162 131 List of fits maps
fits/* . 131 Individual fits maps
--------------------------------------------------------------------------------
See also:
J/A+A/544/L7 : IRAS 16293-2422 ALMA maps (Pineda+, 2012)
J/A+A/585/A112 : IRAS 16293-2422 spectrum (Martin-Domenech+, 2016)
J/A+A/631/A137 : IRAS 16293-2422 CH3CCH spectral cubes (Calcutt+, 2019)
J/A+A/626/A93 : IRAS 16293-2422 spectral cubes (van der Wiel+, 2019)
J/A+A/633/A7 : IRAS 16293-2422 spectral cubes (van 't Hoff+, 2020)
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- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 29 I2 Kibyte size Size of FITS file
31- 42 A12 --- FileName Name of FITS file, in subdirectory fits
44-162 A119 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Angelique Kahle, kakahle(at)mpifr-bonn.mpg.de
(End) Patricia Vannier [CDS] 23-Dec-2022