ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C$_2$H$_5$CN, CH$_3$OCHO and CH$_3$OH lines
Sheng-Li Qin, Tie Liu, Xunchuan Liu, Paul F. Goldsmith, Di Li, Qizhou Zhang, Hong-Li Liu, Yuefang Wu, Leonardo Bronfman, Mika Juvela, Chang Won Lee, Guido Garay… 展开作者
Sheng-Li Qin, Tie Liu, Xunchuan Liu, Paul F. Goldsmith, Di Li, Qizhou Zhang, Hong-Li Liu, Yuefang Wu, Leonardo Bronfman, Mika Juvela, Chang Won Lee, Guido Garay, Yong Zhang, Jinhua He, Shih-Ying Hsu, Zhi-Qiang Shen, Jeong-Eun Lee, Ke Wang, Ningyu Tang, Mengyao Tang, Chao Zhang, Yinghua Yue, Qiaowei Xue, Shang-Huo Li, Yaping Peng, Somnath Dutta, Ge Jixing, Fengwei Xu, Longfei Chen, Tapas Baug, Lokesh dewanggan, Anandmayee Tej
Hot cores characterized by rich lines of complex organic molecules are considered as ideal sites for investigating the physical and chemical environments of massive star formation. We present a search for hot cores by using typical nitrogen- and oxygen-bearing complex organic molecules (C$_2$H$_5$CN, CH$_3$OCHO and CH$_3$OH), based on ALMA Three-millimeter Observations of Massive Star-forming regions (ATOMS). The angular resolutions and line sensitivities of the ALMA observations are better than 2 arcsec and 10 mJy/beam, respectively. A total of 60 hot cores are identified with 45 being newly detected, in which the complex organic molecules have high gas temperatures ($>$ 100 K) and small source sizes ($<$ 0.1 pc). So far this is the largest sample of hot cores observed with similar angular resolution and spectral coverage. The observations have also shown nitrogen and oxygen differentiation in both line emission and gas distribution in 29 hot cores. Column densities of CH$_3$OH and CH$_3$OCHO increase as rotation temperatures rise. The column density of CH$_3$OCHO correlates tightly with that of CH$_3$OH. The pathways for production of different species are discussed. Based on the spatial position difference between hot cores and UC~H{\sc ii} regions, we conclude that 24 hot cores are externally heated while the other hot cores are internally heated. The observations presented here will potentially help establish a hot core template for studying massive star formation and astrochemistry.
Orion KL is one of the prime templates of astrochemical and prebiotic chemical studies. We wish to explore more organic molecules with increasing complexity in this region. In particular, we have searched for one of the most complex organic molecules detected in space so far, ethyl formate (C$_{2}$H$_{5}$OCHO). This species is the next step in chemical complexity after the simplest member of esters (methyl formate, CH$_{3}$OCHO). The mechanisms leading to its formation are still poorly known. We have used high angular resolution ($\sim$ 1.$^{\prime\prime}$5) ALMA observations covering a large …
The studies of the complex molecular emission lines in millimeter and submillimeter wavelengths towards the hot molecular cores demonstrate valuable details about the chemical complexity in the interstellar medium (ISM). We presented the first detection of the rotational emission lines of the complex organic molecule methyl formate (CH$_{3}$OCHO) towards the hot molecular core region IRAS 18566+0408 using the high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) band 3 observation. The estimated column density of CH$_{3}$OCHO using the rotational diagram analysis was (4.1$\pm$0.1…
We present a pilot, untargeted extragalactic carbon monoxide (CO) emission-line survey using ALMACAL, a project utilizing ALMA calibration data for scientific purposes. In 33 deep (Texp > 40 min) ALMACAL fields we report six CO emission-line detections above S/N > 4, one-third confirmed by MUSE observations. With this pilot survey, we probe a cosmologically significant volume of ~10^5 cMpc^3, widely distributed over many pointings in the southern sky, making the survey largely insusceptible to the effects of cosmic variance. We derive the redshift probability of the CO detections using probabi…
The distribution of gas and metals in the circumgalactic medium (CGM) plays a critical role in how galaxies evolve. The MUSE-ALMA Halos survey combines MUSE, ALMA and HST observations to constrain the properties of the multi-phase gas in the CGM and the galaxies associated with the gas probed in absorption. In this paper, we analyse the properties of galaxies associated with 32 strong \ion{H}{i} Ly-$α$ absorbers at redshift $0.2 \lesssim z \lesssim 1.4$. We detect 79 galaxies within $\pm 500$ \kms \!of the absorbers in our 19 MUSE fields. These associated galaxies are found at physical distanc…
ALMAGAL VIII. Early phases of triggered star formation in source AG286.0716$-$1.8229
INAF-Istituto di Astrofisica e Planetologia Spaziale（意大利国家天体物理研究所空间天文与行星物理学研究所）；I. Physikalisches Institut, Universität zu Köln（科隆大学第一物理研究所）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；INAF-Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Max-Planck-Institute for Extraterrestrial Physics (MPE)（马克斯·普朗克地外物理研究所）；Laboratory for the study of the Universe and eXtreme phenomena (LUX), Observatoire de Paris（巴黎天文台宇宙及极端现象实验室）；Dipartimento di Fisica, Università di Roma Tor Vergata（罗马托尔维加塔大学物理系）；Institut de Ciències de l’Espai (ICE), CSIC（空间科学研究所（CSIC））
We present high angular resolution 1.1mm continuum and spectroscopic ALMA observations of the well-known massive proto-cluster Mon R 2 IRS 3.The continuum image at 1.1mm shows two components, IRS 3 A and IRS 3 B, that are separated by $\sim$0.65$"$. We estimate that IRS 3 A is responsible of $\sim$80 % of the continuum flux, being the most massive component. We explore the chemistry of IRS 3 A based on the spectroscopic observations. In particular, we have detected intense lines of S-bearing species such as SO, SO$_2$, H$_2$CS and OCS, and of the Complex Organic Molecules (COMs) methyl formate…
To date, about two dozen low-mass embedded protostars exhibit rich spectra with lines of complex organic molecule (COM). These protostars seem to possess different enrichment in COMs. However, the statistics of COM abundance in low-mass protostars are limited by the scarcity of observations. This study introduces the Perseus ALMA Chemistry Survey (PEACHES), which aims at unbiasedly characterizing the chemistry of COMs toward the embedded (Class 0/I) protostars in the Perseus molecular cloud. Of 50 embedded protostars surveyed, 58% of them have emission from COMs. A 56%, 32%, and 40% of the pro…
Investigating the physical and chemical structures of massive star-forming regions is critical for understanding the formation and the early evolution of massive stars. We performed a detailed line survey toward six dense cores named as MM1, MM4, MM6, MM7, MM8, and MM11 in G9.62+0.19 star-forming region resolved in ALMA band 3 observations. Toward these cores, about 172 transitions have been identified and attributed to 16 species including organic Oxygen-, Nitrogen-, Sulfur-bearing molecules and their isotopologues. Four dense cores MM7, MM8, MM4, and MM11 are line rich sources. Modeling of t…
We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH$_3$OCH$_3$) and methyl formate (CH$_3$OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs together with their parent species methanol (CH$_3$OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures ($T_{\rm rot}\sim130$ K) and total column densities ($N_{\rm rot}\sim10^{16}$ cm$^{-2}$) have been calculated for each source based on multiple transitions of CH$_3…
We present high-resolution (synthesised beam size 0."088x0."083 or 25x23 pc$^2$) Atacama Large Millimetre/submillimetre Array (ALMA) $^{12}$CO(2-1) line and 236 GHz continuum observations, as well as 5 GHz enhanced Multi-Element Radio Linked Interferometer Network (e-MERLIN) continuum observations, of NGC 0708; the brightest galaxy in the low-mass galaxy cluster Abell 262. The line observations reveal a turbulent, rotating disc of molecular gas in the core of the galaxy, and a high-velocity, blue-shifted feature ~0."4 (~113 pc) from its centre. The sub-millimetre continuum emission peaks at th…
We characterize the ionized gas outflows in 15 low-redshift star-forming galaxies, a Valparaíso ALMA Line Emission Survey (VALES) subsample, using MUSE integral field spectroscopy and GAMA photometric broadband data. We measure the emission-line spectra by fitting a double-component profile, with the second and broader component being related to the outflowing gas. This interpretation is in agreement with the correlation between the observed star-formation rate surface density ($Σ_{\mathrm{SFR}}$) and the second-component velocity dispersion ($σ_{\mathrm{2nd}}$), expected when tracing the feed…
We present ALMA, NOEMA, and IRAM-30m/EMIR observations of the high-density tracer molecules HCN, HCO+, and HNC in three of the brightest lensed dusty star-forming galaxies at z~3-3.5, part of the Planck's Dusty GEMS sample, to probe the gas reservoirs closely associated with their exceptional levels of star formation. We obtain robust detections of ten emission lines between J_up=4 and 6, as well as several additional flux upper limits. In PLCK_G244.8+54.9, the brightest source at z=3.0, the HNC(5-4) line emission at 0.1" resolution, together with other spatially-integrated line profiles, sugg…
Complex organic molecules with three carbon atoms are found in the earliest stages of star formation. In particular, propenal (C$_2$H$_3$CHO) is a species of interest due to its implication in the formation of more complex species and even biotic molecules. This study aims to search for the presence of C$_2$H$_3$CHO and other three-carbon species such as propylene (C$_3$H$_6$) in the hot corino region of the low-mass protostellar binary IRAS 16293--2422 to understand their formation pathways. We use ALMA observations in Band 6 and 7 from various surveys to search for the presence of C$_3$H$_6$…
Spectuner-D1: Spectral Line Fitting of Interstellar Molecules Using Deep Reinforcement Learning
Zhejiang Laboratory（浙江实验室）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；University of Chinese Academy of Sciences（中国科学院大学）；I. Physikalisches Institut, Universität zu Köln（科隆大学第一物理研究所）
We present a detailed analysis of the high-angular resolution (0.''037, corresponding to 5 au) observations of the 1.25 mm continuum and $^{12}$CO $2-1$ emission from the disk around the T Tauri star AS 209. AS 209 hosts one of the most unusual disks from the DSHARP sample, the first high angular resolution ALMA survey of disks (Andrews et al. 2018), as nearly all of the emission can be explained with concentric Gaussian rings. In particular, the dust emission consists of a series of narrow and closely spaced rings in the inner $\sim$60 au, two well-separated bright rings in the outer disk, ce…
We have analyzed the Atacama Large Millimeter/submillimeter Array (ALMA) cycle 2 data of band 6 toward the G345.4938+01.4677 massive young protostellar object (G345.5+1.47 MYSO) in the IRAS 16562--3959 high-mass star-forming region with an angular resolution of $\sim 0.3"$, corresponding to $\sim 760$ au. We spatially resolve the central region which consists of three prominent molecular emission cores. A hypercompact (HC) H$_{\rm {II}}$ region (Core A) and two molecule-rich cores (Core B and Core C) are identified using the moment zero images of the H30$α$ line and a CH$_{3}$OH line, respecti…
The collapse of the protostellar envelope results in the growth of the protostar and the development of a protoplanetary disk, playing a critical role during the early stages of star formation. Characterizing the gas infall in the envelope constrains the dynamical models of star formation. We present unambiguous signatures of infall, probed by optically thick molecular lines, toward an isolated embedded protostar, BHR 71 IRS1. The three dimensional radiative transfer calculations indicate that a slowly rotating infalling envelope model following the "inside-out" collapse reproduces the observa…
Magnetic fields in Massive Star-Forming Regions (MagMaR). VIII. Magnetic field overrun by gravity in GGD 27's accretion streamers
Institut de Ciències de l’Espai (ICE-CSIC)（太空科学研究所）；Instituto Argentino de Radioastronomía（阿根廷无线电天文学研究所）；Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata（拉普拉塔国立大学天文与地球物理科学学院）；Academia Sinica Institute of Astronomy and Astrophysics（中央研究院天文及天文物理研究所）；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究学院）；Department of Astronomy, School of Science, The University of Tokyo（东京大学理学部天文学系）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学射电天文学与天体物理研究所）；Joint ALMA Observatory（ALMA联合观测站）；National Radio Astronomy Observatory（美国国家射电天文台）；Max Planck Institute for Astronomy（马克斯·普朗克天体物理学研究所）
Massive star-forming regions exhibit an extremely rich and diverse chemistry, which in principle provides a wealth of molecular probes, as well as laboratories for interstellar prebiotic chemistry. Since the chemical structure of these sources displays substantial spatial variation among species on small scales (${\lesssim}10^4$ au), high angular resolution observations are needed to connect chemical structures to local environments and inform astrochemical models of massive star formation. To address this, we present ALMA 1.3 mm observations toward OB cluster-forming region G10.6-0.4 (hereaft…
