J/ApJ/871/251ivo://CDS.VizieR/J/ApJ/871/251doi:10.26093/cds/vizier.18710251CDSPeng Y.Rivilla V.M.Zhang LiGe J.X.Zhou B.2020-10-12T12:26:20Z2020-08-10T11:22:11ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frinterstellar-mediummolecular-physicsradio-astronomyOrion 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 (~1.5") ALMA observations covering a large bandwidth from 214 to 247GHz. We have detected 82 unblended lines of C_2_H_5_OCHO (49 and 33 of the trans- and gauche- conformers, respectively). The line images showed that C2H5OCHO arises mainly from the compact ridge and the hot core-southwest regions. The derived rotational temperatures and column densities are 122+/-34K, (0.9+/-0.3)x10^16^cm^-2^ for the hot core-SW, and 103+/-13K, (0.6+/-0.3)x10^16^cm^-2^ for the compact ridge. The comparison of spatial distribution and abundance ratios with chemically related molecules (methyl formate, ethanol, and formic acid) indicates that C_2_H_5_OCHO is likely formed on the surface of dust grains by addition of CH_3_ to functional-group radicals (CH_2_OCHO) derived from methyl formate (CH_3_OCHO).2019ApJ...871..251Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/871/251CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJS/156/127 : 350{mu}m molecular line survey of Orion KL (Comito+, 2005)J/ApJS/181/433 : Spectrum of ethyl formate (Medvedev+, 2009)J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)J/ApJ/770/L13 : Detection of CH_3_COOCH_3_ in Orion (Tercero+, 2013)J/ApJ/779/119 : HCOOCH_2_D detection in Orion KL (Coudert+, 2013)J/ApJ/784/L7 : CH_3_CH_2_SH detection in Orion KL (Kolesnikova+, 2014)J/ApJS/215/25 : Methyl formate (HCOOCH_3_) observations (Favre+, 2014)J/A+A/581/A71 : Orion-KL substructure at 1.3mm (Feng+, 2015)J/A+A/581/A48 : 1.3cm line survey toward Orion KL (Gong+, 2015)J/ApJ/803/97 : Transitions of methyl formate toward Orion KL (Sakai+, 2015)J/AJ/154/152 : CARMA 1 cm spectral line survey of Orion-KL (Friedel+, 2017)J/A+A/604/A32 : Orion BN-KL ALMA view (Pagani+, 2017)J/A+A/598/A59 : G31.41+0.31 SMA spectra (Rivilla+, 2017)J/A+A/605/A76 : Spectrum of Orion KL between 41.5 and 50GHz (Rizzo+, 2017)J/A+A/620/A80 : An incipient hot corino in B1b-S (Marcelino+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/871/251https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/871/251http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/871/251https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/871/251https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/871/251http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/871/251GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/ApJ/871/251/table1Selected unblended transitions of the Trans and Gauche conformers of ethyl formate (C_2_H_5_OCHO) observed with the ALMArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintC[GT] Corresponding conformer (G=gauche or T=trans)meta.codecharFreq[213.8/246.2] Rest FrequencyGHzem.freqdoubleQuantTransition quantum numbersphys.mol.qn;phys.atmol.transitioncharSij[0.3/157.2] Strength, S_ij_{mu}^2^; in Debye^2^ unitsD**2phys.atmol.collStrengthfloatEu[152/411] Upper energyKphys.energy;phys.atmol.levelintflag1Detection flag, hot core-SW (G1)meta.code.errorcharvLSR1[3.8/8.1]? Radial velocity, hot core-SW, relative to LSRkm/sspect.dopplerVeloc.opt;pos.lsrfloatnullablee_vLSR1[0.1/0.4]? Uncertainty in vLSR1km/sstat.errorfloatnullabledV1[1.5/4.2]? Linewidth, hot core-SWkm/sspect.line.widthfloatnullablee_dV1[0.1/0.8]? Uncertainty in dV1km/sstat.errorfloatnullableIp1[0.16/1.76]? Line temperature, hot core-SWKspect.line.intensity;spect.linefloatnullablee_Ip1[0.03/0.6]? Uncertainty in Ip1Kstat.errorfloatnullablel_sig1[<= ] Limit flag on {sigma}1meta.code.errorcharsig1[3/37]? Detection level, hot core-SW; in units of {sigma}0stat.likelihood;obsintnullableflag2Detection flag, compact ridge (G1)meta.code.errorcharvLSR2[6.2/8.2]? Radial velocity, compact ridge, relative to LSRkm/sspect.dopplerVeloc;pos.lsrfloatnullablee_vLSR2[0.1/1.3]? Uncertainty in vLSR2km/sstat.errorfloatnullabledV2[1.3/2.8]? Linewidth, compact ridgekm/sspect.line.widthfloatnullablee_dV2[0.1/0.9]? Uncertainty in dV2km/sstat.errorfloatnullableIp2[0.128/1.73]? Line temperature, compact ridgeKspect.line.intensity;spect.linefloatnullablee_Ip2[0.006/0.11]? Uncertainty in Ip2Kstat.errorfloatnullablesig2[4/24]? Detection level, compact ridge; in units of {sigma}0stat.likelihood;obsintnullablesig0[0.007/0.09] 1{sigma} spectrum uncertaintyKstat.errorfloatJ/ApJ/871/251/table2Selected unblended transitions of methyl formate (CH_3_OCHO) observed with the ALMAridgeDetection, ridge (G1)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFreq[214.2/246.7] Rest FrequencyGHzem.freqdoubleQuantTransition quantum numbersphys.mol.qn;phys.atmol.transitioncharSij[0.02/58.17] Strength, S_ij_{mu}^2^ in Debye^2^D**2phys.atmol.collStrengthfloatEu[23/797] Upper energy, KKphys.energy;phys.atmol.levelinthotcoreDetection, hot core-SW (G1)meta.codecharJ/ApJ/871/251/table3Transitions of the Trans and Gauche conformers of ethanol (C_2_H_5_OH) observed with the ALMArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintC[GT] Corresponding conformer (G=gauche or T=trans)meta.codecharFreq[213.7/246.5] Rest FrequencyGHzem.freqdoubleQuantTransition quantum numbersphys.mol.qn;phys.atmol.transitioncharSij[0.32/50.23] Strength, S_ij_{mu}^2^ in Debye^2^D**2phys.atmol.collStrengthfloatEu[24/672] Upper energyKphys.energy;phys.atmol.levelinthotcoreDetection, hot core-SW (G1)meta.codecharridgeDetection, ridge (G1)meta.codechar