A Q-band line survey towards Orion KL using the Tianma radio telescope

Abstract

We have conducted a line survey towards Orion KL using the Q-band receiver of Tianma 65 m radio telescope (TMRT), covering 34.8--50 GHz with a velocity resolution between 0.79 km s${}^{-1}$ and 0.55 km s${}^{-1}$ respectively. The observations reach a sensitivity on the level of 1-8 mK, proving that the TMRT is sensitive for conducting deep line surveys. In total, 597 Gaussian features are extracted. Among them, 177 radio recombination lines (RRLs) are identified, including 126, 40 and 11 RRLs of hydrogen, helium and carbon, with a maximum $\Delta n$ of 16, 7, and 3, respectively. The carbon RRLs are confirmed to originate from photodissociation regions with a $V_{\mathrm{LSR}}\sim$9 km s${}^{-1}$. In addition, 371 molecular transitions of 53 molecular species are identified. Twenty-one molecular species of this survey were not firmly detected in the Q band by Rizzo et al. (2017), including species such as H${}_2$CS, HCOOH, C${}_2$H${}_5$OH, H${}_2^{13}$CO, H${}_2$CCO, CH${}_3$CHO, CH${}_2$OCH${}_2$, HCN $v_2=1$, and CH${}_3$OCHO $v_t=1$. In particular, the vibrationally excited states of ethyl cyanide (C${}_2$H${}_5$CN $v$13/$v$21) are for the first time firmly detected in the Q band. NH${}_3$ (15,15) and (16,16) are identified, and they are so far the highest transitions of the NH${}_3$ inversion lines detected towards Orion KL. All the identified lines can be reproduced by a radiative transfer model.

51 pages, 18 figures, accepted by ApJS

References in corpus (22)

• The distance to the Orion Nebula
• The SCUBA Legacy Catalogue: Continuum Objects Detected by SCUBA
• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• The chemistry and spatial distribution of small hydrocarbons in UV-irradiated molecular clouds: the Orion Bar PDR
• Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH${}_2$CN) in TMC-1
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- I. Survey description and a first look at G9.62+0.19
• Modelling the sulphur chemistry evolution in Orion KL
• Ro-vibrational excitation of an organic molecule (HCN) in protoplanetary disks
• 13C Isotopic Fractionation of HC3N in Star-Forming Regions -Low-Mass Star Forming Region L1527 and High-Mass Star Forming Region G28.28-0.36-
• Low Frequency Carbon Radio Recombination Lines I: Calculations of Departure Coefficients
• A study of dynamical processes in the Orion KL region using ALMA-- Probing molecular outflow and inflow
• Sulfur-bearing molecules in Orion KL
• A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz
• Carbon-Chain Molecules in Molecular Outflows and Lupus I Region--New Producing Region and New Forming Mechanism
• A search for cloud cores affected by shocked carbon chain chemistry in L1251
• Hunting for the elusive methylene radical
• Inverted level populations of hydrogen atoms in ionized gas
• A spectroscopic survey of Orion KL between 41.5 and 50 GHz
• A particular carbon-chain-producing region: L1489 starless core
• Determining electron temperature and density in a H II region by using the relative strengths of hydrogen radio recombination lines
• A FAST Survey of HINSA in PGCCs Guided by HC3N

Cited by in corpus (5)

• First Detection of Radio Recombination Lines of Ions Heavier than Helium
• Sulfur oxides tracing streamers and shocks at low mass protostellar disk-envelope interfaces
• The LMT 2 millimeter receiver system (B4R). II. Science demonstration observations toward Orion-KL/OMC-1
• The ALMA-QUARKS survey: Extensive detection of acetamide in multiple high-mass star-forming regions
• The SOFIA Massive (SOMA) Star Formation Q-band Follow-up. II. Hydrogen Recombination Lines Toward High-Mass Protostars