Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/102940
Title: Transition from coherent cores to surrounding cloud in L1688
Authors: Choudhury, S.
Pineda, J. E.
Caselli, P.
Offner, S. S. R.
Rosolowsky, E.
Friesen, R. K.
Redaelli, E.
Chacón-Tanarro, A.
Shirley, Y.
Punanova, A.
Kirk, H.
Issue Date: 2021
Publisher: EDP Sciences
Citation: Transition from coherent cores to surrounding cloud in L1688 / S. Choudhury, J. E. Pineda, P. Caselli, et al. — DOI 10.1051/0004-6361/202039897 // Astronomy and Astrophysics. — 2021. — Vol. 648. — A114.
Abstract: Context. Stars form in cold dense cores showing subsonic velocity dispersions. The parental molecular clouds display higher temperatures and supersonic velocity dispersions. The transition from core to cloud has been observed in velocity dispersion, but temperature and abundance variations are unknown. Aims. We aim to measure the temperature and velocity dispersion across cores and ambient cloud in a single tracer to study the transition between the two regions. Methods. We use NH3 (1,1) and (2,2) maps in L1688 from the Green Bank Ammonia Survey, smoothed to 1′, and determine the physical properties by fitting the spectra. We identify the coherent cores and study the changes in temperature and velocity dispersion from the cores to the surrounding cloud. Results. We obtain a kinetic temperature map extending beyond dense cores and tracing the cloud, improving from previous maps tracing mostly the cores. The cloud is 4-6 K warmer than the cores, and shows a larger velocity dispersion (Δσv = 0.15-0.25 km s-1). Comparing to Herschel-based dust temperatures, we find that cores show kinetic temperatures that are ≈1.8 K lower than the dust temperature, while the gas temperature is higher than the dust temperature in the cloud. We find an average p-NH3 fractional abundance (with respect to H2) of (4.2 ± 0.2) × 10-9 towards the coherent cores, and (1.4 ± 0.1) × 10-9 outside the core boundaries. Using stacked spectra, we detect two components, one narrow and one broad, towards cores and their neighbourhoods. We find the turbulence in the narrow component to be correlated with the size of the structure (Pearson-r = 0.54). With these unresolved regional measurements, we obtain a turbulence-size relation of σv,NT ∝ r0.5, which is similar to previous findings using multiple tracers. Conclusions. We discover that the subsonic component extends up to 0.15 pc beyond the typical coherent boundaries, unveiling larger extents of the coherent cores and showing gradual transition to coherence over ∼0.2 pc. © S. Choudhury et al. 2021.
Keywords: ISM: INDIVIDUAL OBJECTS: L1688
ISM: KINEMATICS AND DYNAMICS
ISM: MOLECULES
STARS: FORMATION
AMMONIA
DISPERSIONS
DUST
TRACERS
TURBULENCE
COHERENT BOUNDARIES
DUST TEMPERATURES
GRADUAL TRANSITION
KINETIC TEMPERATURES
MOLECULAR CLOUDS
SUBSONIC VELOCITY
SUPERSONIC VELOCITIES
VELOCITY DISPERSION
VELOCITY
URI: http://hdl.handle.net/10995/102940
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85104988265
PURE ID: 21881180
532bfb02-66f5-4eae-9954-6690affd004f
ISSN: 46361
DOI: 10.1051/0004-6361/202039897
metadata.dc.description.sponsorship: Acknowledgemen. S.C., J.E.P., and P.C. acknowledge the support by the Max Planck Society. This material is based upon work supported by the Green Bank Observatory which is a major facility funded by the National Science Foundation operated by Associated Universities, Inc. A.C.-T. acknowledges the support from MINECO projects AYA2016-79006-P and PID2019-108765GB-I00. AP acknowledges the support from the Russian Ministry of Science and Higher Education via the State Assignment Project FEUZ-2020-0038. A.P. is a member of the Max Planck Partner Group at the Ural Federal University.
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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