J/A+A/688/A118 CFHT observations of starless core L 1498 (Lin+, 2024)
Deuterium fractionation of the starless core L 1498.
Lin S.-J., Lai S.-P., Pagani L., Lefevre C., Thieme J.T.
<Astron. Astrophys. 688, A118 (2024)>
=2024A&A...688A.118L 2024A&A...688A.118L (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Infrared
Keywords: ISM: abundances - ISM: clouds - ISM: kinematics and dynamics -
ISM: structure - ISM: individual objects: LDN 1498
Abstract:
Molecular deuteration is commonly seen in starless cores and is
expected to occur on a timescale comparable to that of the core
contraction. Thus, the deuteration serves as a chemical clock,
allowing us to investigate dynamical theories of core formation. We
aim to provide a 3D cloud description for the starless core L 1498
located in the nearby low-mass star-forming region Taurus and explore
its possible core formation mechanism. We carried out nonlocal thermal
equilibrium radiative transfer with multi-transition observations of
the high-density tracer N2H+ to derive the density and temperature
profiles of the L 1498 core. By combining these observations with the
spectral observations of the deuterated species, ortho-H2D+, N2D+,
and DCO+, we derived the abundance profiles for the observed species
and performed chemical modeling of the deuteration profiles across
L 1498 to constrain the contraction timescale. We present the first
ortho-H2D+ (110-111) detection toward L 1498. We find a peak
molecular hydrogen density of 1.6-0.3+3.0x105cm-3, a
temperature of 7.5-0.5+0.7K, and a N2H+ deuteration of
0.27-0.15+0.12 in the center. We derived a lower limit of the core
age for L 1498 of 0.16Ma, which is compatible with the typical
free-fall time, indicating that L 1498 likely formed rapidly.
Description:
This contains the near infrared observations of a cloud L 1498. The
observations cover the the wide filters J (1.25 micron),
H (1.65 micron), and Ks (2.16 micron) and are taken with the CFHT
WIRCAM instrument. Seeing conditions were typically 0.8", and the
on-source integration times were typically 0.5 to 1 hour per filter.
The Sky-Target-Sky (STS) dithering mode was conducted to subtract the
atmospheric infrared emission and preserve the extended scattered
light from the source. Data reduction was performed at the TERAPIX
center using a specific reduction method to recover the extended
emission.
Objects:
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RA (2000) DE Designation(s)
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04 10 52.97 +25 10 18.0 L 1498 = [LM99] L1498
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 118 6 List of of CFHT fits images
fits/* . 6 Individual CFHT fits 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 F3.1 arcsec/pix scale Scale of the image
24- 27 I4 --- Nx Number of pixels along X-axis
29- 32 I4 --- Ny Number of pixels along Y-axis
34- 39 I6 Kibyte size Size of FITS file
41- 64 A24 --- FileName Name of FITS file, in subdirectory fits
66-118 A53 --- Title Title of the FITS file
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Acknowledgements:
Sheng-Jun Lin, shengjunlin(at)asiaa.sinica.edu.tw
(End) Patricia Vannier [CDS] 17-Jun-2024