J/MNRAS/514/4781ivo://CDS.VizieR/J/MNRAS/514/4781doi:10.26093/cds/vizier.75144781CDSXiang Y.Gu S.Cao D.2024-08-22T20:15:50Z2022-07-25T13:36:09ZCDS support team

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

cds-question@unistra.frlate-type-starsvariable-starsline-intensitiesWe apply the variational autoencoder (VAE) to the LAMOST-K2 low-resolution spectra to detect the magnetic activity of the stars in the K2 field. After the training on the spectra of the selected inactive stars, the VAE model can efficiently generate the synthetic reference templates needed by the spectral subtraction procedure, without knowing any stellar parameters. Then, we detect the peculiar spectral features, such as chromospheric emissions, strong nebular emissions, and lithium absorptions, in our sample. We measure the emissions of the chromospheric activity indicators, H{alpha} and CaII infrared triplet (IRT) lines, to quantify the stellar magnetic activity. The excess emissions of H{alpha} and CaII IRT lines of the active stars are correlated well to the rotational periods and the amplitudes of light curves derived from the K2 photometry. We degrade the LAMOST spectra to simulate the slitless spectra of the China Space Station Telescope (CSST) and apply the VAE to the simulated data. For cool active stars, we reveal a good agreement between the equivalent widths of H{alpha} line derived from the spectra with two resolutions. The result indicates the ability of identifying the magnetically active stars in the future CSST survey, which will deliver an unprecedented large data base of low-resolution spectra as well as simultaneous multiband photometry of stars.2022MNRAS.514.4781Xhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/514/4781CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/514/4781https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/514/4781http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/514/4781https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/514/4781https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/514/4781http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/514/4781GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/514/4781/table1 (Stellar parameters and chromospheric emissions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/514/4781/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/514/4781/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/514/4781/table1?GETtext/xml+votable180.050000true101.7616915.623060.0055555555555555565/75 92 113 115-116 118 1130 1174 6/261 267 270-273 279-282 285-287 294 313-314 316 319 328 331 337 339-340 343 346-347 353 358-359 361 363 366 377-378 391 401-402 404-405 410 412 439 450 458 471 476 478 480-482 484-485 496 1066 4247 4251-4254 4262 4273-4274 4278 4280 4286 4296 4298 4300-4301 4303 4312 4314 4330-4331 4335 4344 4346-4347 4349 4515 4526 4623 4630-4632 4635 4639 4645 4656-4657 4659-4661 4663 4665 4669 4671 4673-4674 4678-4679 4682 4684-4685 4687-4689 4691 4693 4695 4702-4703 4709-4712 4715-4716 4718 4720-4721 4725-4726 4728 4731-4732 4757 4800 4805 4864 4866 4873-4875 4898 18014-18015 18034 18036 18038-18040 18116 18119 18123-18125 18128-18130 18133-18134 18137 18141-18143 18161 18187 18222-18224 18227 18304 18307-18308 18314 18330 18337 18341 18360 18668 18795 18799 18837-18838 23470 23483-23484 23529 23531-23532 23534 23547 23550 23857 23863 23908 23911 23916 23949 23956 23958 23960-23961 23967-23968 23977 23983 23986 23997-23999 24002 24006 24009-24012 24025 24027 24032 24039 24041 24043 24047 24051 24054 24059-24060 24062 24326-24327 24333 24336 24338 24342 24344 24349 24391 24394 25460 25465 25580 25590 25594 25597 25805 25807-25808 26145 26165 26241 26250 26256 26264 26270 26281 26284 26286 26292 26297 26300 26901 26903 26932 26946 26953 26966 26975 26978 26984 26988 26994 26996 26998 27001-27002 27007 27028-27029 27072 27075 27077-27080 27087-27089 27091-27093 27096-27097 27102-27103 27109 27120 27122-27123 27649 27659 27661 27680-27681 27684-27685 27690 27695 27704 27777 27779 27781 27783 27785-27786 27788 27792https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/514/4781?format=asciidefaultJ/MNRAS/514/4781/table1Stellar parameters and chromospheric emissionsSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsidLAMOST obsidmeta.idlongEPICK2 Ecliptic Plane Input Catalog numbermeta.id;meta.mainlongTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]Metallicityphys.abund.ZfloatEWHaResidual equivalent width of H{alpha}0.1nmstat.fit.residual;spect.line.eqWidthfloatEW8498Residual equivalent width of Ca 84980.1nmstat.fit.residual;spect.line.eqWidthfloatEW8542Residual equivalent width of Ca II 85420.1nmstat.fit.residual;spect.line.eqWidthfloatEW8662Residual equivalent width of Ca II 86620.1nmstat.fit.residual;spect.line.eqWidthfloatlogFHaH{alpha} line surface fluxlog(mW.m**-2)phot.flux;spect.linefloatlogFCaCa II IRT line surface fluxlog(mW.m**-2)phot.flux;spect.linefloatlogR'HaRatio of H{alpha} emission to the bolometric luminosityphot.flux;arith.ratiofloatlogR'CaRatio of Ca II IRT emission to the bolometric luminosityphot.flux;arith.ratiofloat_RAfrom K2 EPIC (Cat. IV/34) (right ascension part)degpos.eq.ra;meta.main_DEfrom K2 EPIC (Cat. IV/34) (declination part)degpos.eq.dec;meta.main