J/AJ/170/315ivo://CDS.VizieR/J/AJ/170/315CDSSithajan S.Kaewbiang L.Jones H.R.A.Rittipruk P.Meethong S.2025-12-31T07:45:54Z2025-12-31T08:42:42ZCDS support team

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

cds-question@unistra.frsolar-systemsolar-system-planetsvisible-astronomyspectroscopyThe optical spectra of Titan reveal a rich set of absorption features, most of which are likely associated with methane (CH_4_). Methane is a key molecule in planetary and exoplanetary atmospheres, yet a comprehensive high-resolution linelist at optical wavelengths remains incomplete. This study identified and characterized potential CH_4_ absorption features in high-resolution optical spectra of Titan, providing essential data for linelist development and improving CH_4_ detection and characterization. We analyzed Titan spectra from the ESPRESSO spectrograph (R~190000), identifying intrinsic features and measuring their relative strengths. A conservative detection approach was employed, slightly overestimating solar and telluric contributions to distinguish them from Titan's intrinsic features. To assess the impact of spectral resolution, we compared the ESPRESSO data with Titan UVES data (R~110000). We identified 6195 absorption features in the ESPRESSO spectra potentially associated with CH_4_, of which 5436 are newly reported. ESPRESSO detected twice as many features as UVES in overlapping regions, highlighting the advantage of higher-resolution data. Most detected lines remained unresolved, so our reported features are primarily blended absorption structures. We estimated the detection limit for feature identification to correspond to a CH_4_ absorption coefficient of approximately 0.02km/am. Comparison of our results with a previous analysis of Titan UVES spectra and with experimental CH_4_ data at a similar temperature showed good agreement, while some discrepancies were observed when compared with data acquired at a different temperature. We provide a comprehensive list of Titan absorption features with key reliability metrics, along with Titan's intrinsic spectra, to support future studies.2025AJ....170..315Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/315CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/315https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/315http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/315https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/315https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/315http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/315GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/170/315/table2Identified CH4 absorption features from the ESPRESSO data, with wavelengths provided in vacuumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaEESPRESSO Wavelength0.1nmem.wldoublee_lambdaEESPRESSO Wavelength error0.1nmstat.errorfloatrdepthEESPRESSO relative strengthspect.line.intensityfloate_rdepthEESPRESSO relative strength errorstat.errorfloatSNREESPRESSO SNRstat.snrintlambdaU? UVES Wavelength0.1nmem.wldoublenullablerdepthU? UVES relative strengthspect.line.intensityfloatnullableRS24[N/Y] Matches with Rianco-Silva et al. (2024, Planetary and Space Science, 240, 105836) datameta.codecharSO95[N/Y] Matches with Singh & O'Brien (1995, Journal of Quantitative Spectroscopy and Radiative Transfer, 54, 6071996 and 1996, Ap&SS, 236, 97) datameta.codecharCP23-KP[N/Y] Matches with Campargue et al. (2023, Phys Chem Chem Phys, 25, 32778) Kitt Peak (KP) datameta.codecharCP23-CRDS[N/Y] Matches with Campargue et al. (2023, Phys Chem Chem Phys, 25, 32778) CRDS datameta.codecharSTmask[N/Y] Proximity to strong stellar or telluric linesmeta.codecharJ/AJ/170/315/tablea1ESPRESSO Titan spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength in vacuum0.1nmem.wldoubleRFluxRelative flux (normalized Titan spectrum with the best-fit background removed)phot.flux;arith.ratiodoublee_RFluxRelative flux errorstat.errorfloatMask[0/1] Binary mask indicating whether the corresponding wavelength is in the vicinity of strong solar or telluric lines (0 = yes, 1 = no)meta.codeintJ/AJ/170/315/tablea2UVES Titan spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaVacuum wavelength0.1nmem.wldoubleRFluxRelative flux (normalized Titan spectrum with the best-fit background removed)phot.flux;arith.ratiofloate_RFluxRelative flux errorstat.errorfloat