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Title: Astrochemical Properties of Planck Cold Clumps

Abstract

We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N{sub 2}H{sup +} distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC{sub 3}N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N{sub 2}H{sup +} emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN{sup 13}C, N{sub 2}D{sup +}, and cyclic-C{sub 3}H{sub 2} toward nine clumps. The detection rate of N{sub 2}D{sup +} is 50%. Furthermore, we observed the NH{sub 3} emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (≲20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N{sub 2}H{sup +} core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N{sub 2}D{sup +}. These two clumps are most likely on the verge of star formation. We introduce the chemical evolutionmore » factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.« less

Authors:
; ; ;  [1]; ; ; ;  [2];  [3]; ;  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12];  [13] more »; ; ; « less
  1. National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  2. Korea Astronomy and Space Science Institute, Daedeokdaero 776, Yuseong, Daejeon 305-348 (Korea, Republic of)
  3. Department of Astronomy, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  4. Academia Sinica Institute of Astronomy and Astrophysics, 11F of Astronomy-Mathematics Building, AS/NTU. No.1, Section 4, Roosevelt Rd, Taipei 10617, Taiwan (China)
  5. Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB (United Kingdom)
  6. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)
  7. Department of Astronomy, Peking University, 100871, Beijing (China)
  8. National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China)
  9. NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
  10. European Southern Observatory (Germany)
  11. IRAP, CNRS (UMR5277), Universite Paul Sabatier, 9 avenue du Colonel Roche, BP 44346, F-31028, Toulouse Cedex 4 (France)
  12. Department of physics, University of Helsinki, FI-00014, Helsinki (Finland)
  13. Department of Physics, Kagoshima University, 1-21-35, Korimoto, Kagoshima, 890-0065 (Japan)
Publication Date:
OSTI Identifier:
22661326
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 228; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMMONIA; CLOUDS; COSMIC DUST; DETECTION; GHZ RANGE; GRAVITATIONAL COLLAPSE; MOLECULAR IONS; MOLECULES; NITRILES; PROTOSTARS; RADIO TELESCOPES; STARS

Citation Formats

Tatematsu, Ken’ichi, Sanhueza, Patricio, Nguyễn Lu’o’ng, Quang, Hirota, Tomoya, Liu, Tie, Choi, Minho, Kang, Miju, Kim, Kee-Tae, Ohashi, Satoshi, Liu, Sheng-Yuan, Hirano, Naomi, Thompson, Mark A., Fuller, Gary, Wu, Yuefang, Li, Di, Francesco, James Di, Wang, Ke, Ristorcelli, Isabelle, Juvela, Mika, Shinnaga, Hiroko, E-mail: k.tatematsu@nao.ac.jp, Collaboration: JCMT Large Program “SCOPE” collaboration, TRAO Key Science Program “TOP” collaboration, and and others. Astrochemical Properties of Planck Cold Clumps. United States: N. p., 2017. Web. doi:10.3847/1538-4365/228/2/12.
Tatematsu, Ken’ichi, Sanhueza, Patricio, Nguyễn Lu’o’ng, Quang, Hirota, Tomoya, Liu, Tie, Choi, Minho, Kang, Miju, Kim, Kee-Tae, Ohashi, Satoshi, Liu, Sheng-Yuan, Hirano, Naomi, Thompson, Mark A., Fuller, Gary, Wu, Yuefang, Li, Di, Francesco, James Di, Wang, Ke, Ristorcelli, Isabelle, Juvela, Mika, Shinnaga, Hiroko, E-mail: k.tatematsu@nao.ac.jp, Collaboration: JCMT Large Program “SCOPE” collaboration, TRAO Key Science Program “TOP” collaboration, & and others. Astrochemical Properties of Planck Cold Clumps. United States. doi:10.3847/1538-4365/228/2/12.
Tatematsu, Ken’ichi, Sanhueza, Patricio, Nguyễn Lu’o’ng, Quang, Hirota, Tomoya, Liu, Tie, Choi, Minho, Kang, Miju, Kim, Kee-Tae, Ohashi, Satoshi, Liu, Sheng-Yuan, Hirano, Naomi, Thompson, Mark A., Fuller, Gary, Wu, Yuefang, Li, Di, Francesco, James Di, Wang, Ke, Ristorcelli, Isabelle, Juvela, Mika, Shinnaga, Hiroko, E-mail: k.tatematsu@nao.ac.jp, Collaboration: JCMT Large Program “SCOPE” collaboration, TRAO Key Science Program “TOP” collaboration, and and others. Wed . "Astrochemical Properties of Planck Cold Clumps". United States. doi:10.3847/1538-4365/228/2/12.
@article{osti_22661326,
title = {Astrochemical Properties of Planck Cold Clumps},
author = {Tatematsu, Ken’ichi and Sanhueza, Patricio and Nguyễn Lu’o’ng, Quang and Hirota, Tomoya and Liu, Tie and Choi, Minho and Kang, Miju and Kim, Kee-Tae and Ohashi, Satoshi and Liu, Sheng-Yuan and Hirano, Naomi and Thompson, Mark A. and Fuller, Gary and Wu, Yuefang and Li, Di and Francesco, James Di and Wang, Ke and Ristorcelli, Isabelle and Juvela, Mika and Shinnaga, Hiroko, E-mail: k.tatematsu@nao.ac.jp and Collaboration: JCMT Large Program “SCOPE” collaboration and TRAO Key Science Program “TOP” collaboration and and others},
abstractNote = {We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N{sub 2}H{sup +} distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC{sub 3}N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N{sub 2}H{sup +} emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN{sup 13}C, N{sub 2}D{sup +}, and cyclic-C{sub 3}H{sub 2} toward nine clumps. The detection rate of N{sub 2}D{sup +} is 50%. Furthermore, we observed the NH{sub 3} emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (≲20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N{sub 2}H{sup +} core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N{sub 2}D{sup +}. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.},
doi = {10.3847/1538-4365/228/2/12},
journal = {Astrophysical Journal, Supplement Series},
number = 2,
volume = 228,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • Here, we present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with the Early Release Compact Source Catalogue (ERCSC) and which contained 915 high signal-to-noise sources. It is based on the Planck 48-month mission data that are currently being released to the astronomical community. The PGCC catalogue is an observational catalogue consisting exclusively of Galactic cold sources. The three highest Planck bands (857, 454, and 353 GHz) have been combinedmore » with IRAS data at 3 THz to perform a multi-frequency detection of sources colder than their local environment. After rejection of possible extragalactic contaminants, the PGCC catalogue contains 13188 Galactic sources spread across the whole sky, i.e., from the Galactic plane to high latitudes, following the spatial distribution of the main molecular cloud complexes. The median temperature of PGCC sources lies between 13 and 14.5 K, depending on the quality of the flux density measurements, with a temperature ranging from 5.8 to 20 K after removing the sources with the top 1% highest temperature estimates. Using seven independent methods, reliable distance estimates have been obtained for 5574 sources, which allows us to derive their physical properties such as their mass, physical size, mean density, and luminosity.The PGCC sources are located mainly in the solar neighbourhood, but also up to a distance of 10.5 kpc in the direction of the Galactic centre, and range from low-mass cores to large molecular clouds. Because of this diversity and because the PGCC catalogue contains sources in very different environments, the catalogue is useful for investigating the evolution from molecular clouds to cores. Finally, it also includes 54 additional sources located in the Small and Large Magellanic Clouds.« less
  • A mapping survey of 51 Planck cold clumps projected on the Orion complex was performed with J = 1-0 lines of {sup 12}CO and {sup 13}CO with the 13.7 m telescope at the Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5 Multiplication-Sign 10{sup 21} cm{sup -2}, with an average value of (2.9 {+-} 1.9) Multiplication-Sign 10{sup 21} cm{sup -2}. The mean excitation temperatures of these clumps range from 7.4 to 21.1 K, with an average value of 12.1 {+-} 3.0 K and the average three-dimensional velocity dispersion {sigma}{sub 3D} in thesemore » molecular clumps is 0.66 {+-} 0.24 km s{sup -1}. Most of the clumps have {sigma}{sub NT} larger than or comparable to {sigma}{sub Therm}. The H{sub 2} column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857 GHz of the dust emission. By analyzing the distributions of the physical parameters, we suggest that turbulent flows can shape the clump structure and dominate their density distribution on large scales, but not function on small scales due to local fluctuations. Eighty-two dense cores are identified in the molecular clumps. The dense cores have an average radius and local thermal equilibrium (LTE) mass of 0.34 {+-} 0.14 pc and 38{sup +5}{sub -30} M{sub Sun }, respectively. The structures of low column density cores are more affected by turbulence, while the structures of high column density cores are more affected by other factors, especially by gravity. The correlation of velocity dispersion versus core size is very weak for the dense cores. The dense cores are found to be most likely gravitationally bounded rather than pressure confined. The relationship between M{sub vir} and M{sub LTE} can be well fitted with a power law. The core mass function here is much flatter than the stellar initial mass function. The lognormal behavior of the core mass distribution is most likely determined by internal turbulence.« less
  • A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of {sup 12}CO, {sup 13}CO, and C{sup 18}O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with {sup 12}CO and {sup 13}CO emission, and 68% of the sample has C{sup 18}O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located withinmore » 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of T{sub d} . Line width analysis shows that the majority of ECC clumps are low-mass clumps. Column densities N{sub H{sub 2}} span from 10{sup 20} to 4.5 Multiplication-Sign 10{sup 22} cm{sup -2} with an average value of (4.4 {+-} 3.6) Multiplication-Sign 10{sup 21} cm{sup -2}. N{sub H{sub 2}} cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance ratio of the {sup 13}CO to C{sup 18}O in these clumps is 7.0 {+-} 3.8, higher than the terrestrial value. Dust and gas are well coupled in 95% of the clumps. Blue profile asymmetry, red profile asymmetry, and total line asymmetry were found in less than 10% of the clumps, generally indicating that star formation is not yet developed. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC H II candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold astronomy.« less
  • We present the first survey of dense gas toward Planck Galactic Cold Clumps (PGCCs). Observations in the J = 1–0 transitions of HCO{sup +} and HCN toward 621 molecular cores associated with PGCCs were performed using the Purple Mountain Observatory’s 13.7 m telescope. Among them, 250 sources were detected, including 230 cores detected in HCO{sup +} and 158 in HCN. Spectra of the J = 1–0 transitions from {sup 12}CO, {sup 13}CO, and C{sup 18}O at the centers of the 250 cores were extracted from previous mapping observations to construct a multi-line data set. The significantly low detection rate of asymmetric double-peaked profiles,more » together with the good consistency among central velocities of CO, HCO{sup +}, and HCN spectra, suggests that the CO-selected Planck cores are more quiescent than classical star-forming regions. The small difference between line widths of C{sup 18}O and HCN indicates that the inner regions of CO-selected Planck cores are no more turbulent than the exterior. The velocity-integrated intensities and abundances of HCO{sup +} are positively correlated with those of HCN, suggesting that these two species are well coupled and chemically connected. The detected abundances of both HCO{sup +} and HCN are significantly lower than values in other low- to high-mass star-forming regions. The low abundances may be due to beam dilution. On the basis of an inspection of the parameters given in the PGCC catalog, we suggest that there may be about 1000 PGCC objects that have a sufficient reservoir of dense gas to form stars.« less
  • Following the recent report of the first identification of methyl acetate (CH{sub 3}COOCH{sub 3}) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110more » K and 120 K.« less