X-Ray Observation of the Lynds 1157 Dark Cloud Region with ASCA

[摘要] AnASCAobservationofaregioncontainingaClass0protostarIRAS20386+6751intheLynds1157darkcloud,hasbeencarriedout.Theprotostarwasnotdetected,andthe95%upperlimittotheluminositydependsontheassumedNH:LX(0.5–10keV)lt;1.1×1031ergs−1forNH=1×1023cm−2.AClassIprotostarinLynds1152,IRAS20353+6742,inthesamefieldwasalsoundetectedwithanupperlimitaboutthree-timesasmuchastheLynds1157level.Besidesthesenondetections,ninenewX-raysourcesweredetectedandaspectralanalysiswasperformedfor4sources.Oneobject(AXJ2038+6801)showsahardspectrumwithatemperatureofkT∼8keVorapower-lawphotonindexof∼2.0andabsorbedwithNH∼2×1022cm−2.Anotherfainterone(AXJ2036+6800)hasasoftspectrumwithmostoftheemissionfallingbelow2keV.WeexaminethepossiblenatureofthesenewX-raysourcesbasedontheirspectralproperties.

[学科分类] 天文学(综合)

[关键词] "ISM: individual (Lynds 1157)";"stars: pre-main-sequence";"stars: X-rays";"X-rays: sources";"X-rays: spectra"