J/MNRAS/500/3926ivo://CDS.VizieR/J/MNRAS/500/3926CDSBanerjee G.Mathew B.Paul K.T.Subramaniam A.Bhattacharyya S.,Anusha R.2023-11-13T08:44:11Z2023-11-13T09:35:24ZCDS support team

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

cds-question@unistra.frbe-starsemission-line-starsstellar-spectral-typesextinctionline-intensitiesvisible-astronomyspectroscopyIn this study, we analyse the emission lines of different species present in 118 Galactic field classical Be stars in the wavelength range of 3800-9000{AA}. We re-estimated the extinction parameter (A_V_) for our sample stars using the newly available data from Gaia DR2 and suggest that it is important to consider A_V_ while measuring the Balmer decrement (i.e. D_34_ and D_54_) values in classical Be stars. Subsequently, we estimated the Balmer decrement values for 105 program stars and found that ~20 per cent of them show D_34_>=2.7, implying that their circumstellar disc are generally optically thick in nature. One program star, HD 60855 shows H{alpha} in absorption - indicative of disc-less phase. From our analysis, we found that in classical Be stars, H{alpha} emission equivalent width values are mostly lower than 40{AA}, which agrees with that present in literature. Moreover, we noticed that a threshold value of ~10{AA} of H{alpha} emission equivalent width is necessary for Fe II emission to become visible. We also observed that emission line equivalent widths of H{alpha}, P14, Fe II 5169, and O I 8446{AA} for our program stars tend to be more intense in earlier spectral types, peaking mostly near B1-B2. Furthermore, we explored various formation regions of Ca II emission lines around the circumstellar disc of classical Be stars. We suggest the possibility that Ca II triplet emission can originate either in the circumbinary disc or from the cooler outer regions of the disc, which might not be isothermal in nature.2021MNRAS.500.3926Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/500/3926CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/67 : Catalogue of Be stars (Jaschek+, 1982)I/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/500/3926https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/500/3926http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/500/3926https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/500/3926https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/500/3926http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/500/3926GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/500/3926/table1 (List of our program CBe stars and the log of observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/500/3926/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/500/3926/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/500/3926/table1?GETtext/xml+votable180.050000true2.695506763.17294060.005555555555555556Cone search capability for table J/MNRAS/500/3926/table2 (Our adopted distance for 83 of our stars whose parallax values are available in Gaia DR2 and their re-estimated A_V_ values)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/500/3926/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/500/3926/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/500/3926/table2?GETtext/xml+votable180.050000true2.695506763.17294060.005555555555555556Cone search capability for table J/MNRAS/500/3926/table3 (List of 35 of our program stars for which A_V_ values are adopted from the literature)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/500/3926/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/500/3926/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/500/3926/table3?GETtext/xml+votable180.050000true25.915158150.68873140.005555555555555556Cone search capability for table J/MNRAS/500/3926/table4 (Estimated Balmer decrements, D_34_ and D_54_ for our program stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/500/3926/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/500/3926/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/500/3926/table4?GETtext/xml+votable180.050000true2.695506763.17294060.0055555555555555566/463 472 474 1011 1163 1301 1305 1342 1348 1392 1429 1441 1586 1725 1748 1768 1784 2775 2884 2996 3004 3030 3036 3050 3058 3060 3063-3064 3066-3067 3100 3243-3244 3247 3258 3270 3277 3283 3286 3290 3306 3308 3316 3464 3491 3588-3589 3602 3608 3610 3615 3634-3635 3638 3662 3723 3751 6780 11959 14152 20869 21365 21439 21447 21515 21529 21556-21558 21646 21656 21665 21718 21943 22044 22059 22087 22089 22112 22121 22135 22197 22209 22236 22246 22254 22503 22615 22854 22906 23394 23632 23644 23716 23829 23905 23963 23976 24142 24183 24363 24457 24467 24469 27545 36282 39924 40285 40865https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/500/3926?format=asciiOpticaldefaultJ/MNRAS/500/3926/table1List of our program CBe stars and the log of observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharONameAlternative namemeta.idcharVmagV-band magnitudemagphot.mag;em.opt.VfloatSpTypeSpectral typesrc.spTypecharDateObservation datetime.epoch;obsExpTimeExposure timestime.duration;obs.exposurefloatSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/500/3926/table2Our adopted distance for 83 of our stars whose parallax values are available in Gaia DR2 and their re-estimated A_V_ valuesAvlitExtinction from literaturemagphys.absorptionfloatr_AvlitReference for Avlit (1)meta.ref;pos.framecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharDistStar distancepcpos.distanceintSimbadSimbad column added by the CDSmeta.ref.urlcharE_DistUpper error on Distpcstat.error;stat.maxinte_DistLower error on Distpcstat.errorintAvRe-estimated extinctionmagphys.absorptionfloate_AvError on Avmagstat.errorfloat_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/500/3926/table3List of 35 of our program stars for which A_V_ values are adopted from the literatureSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharf_Name[*] Flag on Name (1)meta.codecharAvExtinction from literaturemagphys.absorptionfloatr_AvReference for Av (2)meta.ref;pos.framechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/500/3926/table4Estimated Balmer decrements, D_34_ and D_54_ for our program starse_D34c? Error on D34cstat.errorfloatnullableD54c? Estimated Balmer decrement (D_54_)c (2)meta.notefloatnullablee_D54c? Error on D54cstat.errorfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharf_NameFlag on Name (1)meta.codecharEWHaEquivalent width of H{alpha}0.1nmspect.line.eqWidthfloatEWHb? Equivalent width of H{beta}0.1nmspect.line.eqWidthfloatnullableEWHg? Equivalent width of H{gamma}0.1nmspect.line.eqWidthfloatnullableEWcHa? Absorption corrected equivalent width of H{alpha}0.1nmspect.line.eqWidthfloatnullableEWcHb? Absorption corrected equivalent width of H{beta}0.1nmspect.line.eqWidthfloatnullableEWcHg? Absorption corrected equivalent width of H{gamma}0.1nmspect.line.eqWidthfloatnullableD34c? Estimated Balmer decrement (D_34_)c (2)meta.notefloatnullable