J/A+A/666/A191 L1451-mm SiO line and CH3OH maser detections (Wakelam+, 2022)
Confirmation of the outflow in L1451-mm: SiO line and CH3OH maser detections.
Wakelam V., Coutens A., Gratier P., Vidal T.H.G., Vaytet N.
<Astron. Astrophys. 666, A191 (2022)>
=2022A&A...666A.191W 2022A&A...666A.191W (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Masers
Keywords: astrochemistry - stars: protostars - ISM: molecules -
ISM: individual objects: L1451-mm - stars: low-mass
Abstract:
The observational counterpart of theoretically predicted first
hydrostatic cores (FHSC) have been hunted in the interstellar medium
for nearly two decades now. Distinguishing them from other types of
more evolved but still embedded objects remains a challenge as these
objects have a short lifetime, are small, and embedded in a dense
cocoon. One possible lead is through the characterization of outflows
launched by these objects, which are supposed to be low velocity and
small in extent.
We observed the L1451-mm FHSC candidate with the NOEMA interferometer
(and complementary IRAM 30m data) in order to study the emission of
several molecules.
Among the targeted molecules, we detected lines of c-C3H2,
CH3OH, CS, C34S, SO, DCN, DCO+, H2CO, HC3N, HDCO, and SiO. One
of the methanol lines appear to be a maser line. Both the detection of
this Class I maser and SiO line in L1451- mm support the presence of
low velocity and compact outflow. The excitation conditions of the
thermal lines of methanol are also compatible with shocks (H2
density of ∼3Å*106cm-3 and temperature larger than 40K).
Although the presence of such low velocity outflow is theoretically
predicted by some models of FHSC, these models also predict the shock
temperature to be below 20K, i.e. not evaporating methanol. In
addition, the predicted velocities would not erode the grains and
release silicon in the gas-phase. We then conclude that these new
observations favor the hypothesis that L1451- mm would be at a very
early proto-stellar stage launching an outflow nearly on the plan of
the sky with a higher velocity that what is observed.
Description:
The datacubes for spectral observations are give in the following
format: name_frequency.fits. If name is "NOEMA" they are only NOEMA
data while if name is "merged" they are NOEMA+30m merged data.
Frequency are in MHz and correspond to the the central frequency of
the band. For the NOEMA data, we also provide the continuum LSB and
USB data.
Objects:
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RA (2000) DE Designation(s)
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03 25 09.5 +30 23 51 L1451-mm = NAME LDN 1451-mm
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 115 41 List of fits datacubes and images
fits/* . 41 Individual fits datacubes and images
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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)
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- 30 I3 --- Nz ? Number of slices
32- 37 I6 m/s bVRAD ? Lower value of VRAD interval for the datacubes
39- 43 I5 m/s BVRAD ? Upper value of VRAD interval for the datacubes
45- 47 I3 m/s dVRAD ? VRAD resolution
49- 54 I6 Kibyte size Size of FITS file
56- 79 A24 --- FileName Name of FITS file, in subdirectory fits
81-115 A35 --- Title Title of the FITS file
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Acknowledgements:
Valentine Wakelam, valentine.wakelam(at)u-bordeaux.fr
(End) Patricia Vannier [CDS] 03-Aug-2022