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<ri:Resource created="2025-05-05T09:38:08Z" status="active" updated="2026-02-10T20:02:48Z" version="1.2" xmlns:cs="http://www.ivoa.net/xml/ConeSearch/v1.0" xmlns:ri="http://www.ivoa.net/xml/RegistryInterface/v1.0" xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0" xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ivoa.net/xml/ConeSearch/v1.0 http://vo.ari.uni-heidelberg.de/docs/schemata/ConeSearch.xsd http://www.ivoa.net/xml/VOResource/v1.0 http://vo.ari.uni-heidelberg.de/docs/schemata/VOResource.xsd http://www.ivoa.net/xml/VODataService/v1.1 http://vo.ari.uni-heidelberg.de/docs/schemata/VODataService.xsd" xsi:type="vs:CatalogService"><title>Spectral classification of young stars using cINN</title><shortName>J/A+A/697/A39</shortName><identifier>ivo://CDS.VizieR/J/A+A/697/A39</identifier><altIdentifier>doi:10.26093/cds/vizier/bc-ns/ldj</altIdentifier><curation><publisher ivo-id="ivo://CDS">CDS</publisher><creator><name>Kang D.E.</name></creator><creator><name>Itrich D.</name></creator><creator><name>Ksoll V.F.</name></creator><creator><name>Testi L.</name></creator><creator><name>Klessen R.S.</name></creator><creator><name>Molinari S.</name></creator><date role="Updated">2026-02-10T20:02:48Z</date><date role="Created">2025-05-05T09:38:08Z</date><contact><name>CDS support team</name><address>CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France</address><email>cds-question@unistra.fr</email></contact></curation><content><subject>open-star-clusters</subject><subject>pre-main-sequence-stars</subject><subject>spectroscopy</subject><subject>effective-temperature</subject><subject>stellar-spectral-types</subject><subject>stellar-ages</subject><description>We introduce an updated version of our deep learning tool that predicts effective temperature, surface gravity, extinction, and veiling from the optical spectra of young low-mass stars with intermediate spectral resolution. We determine the stellar parameters of 2051 stars in Trumpler 14 (Tr14) in the Carina Nebula Complex, observed with VLT/MUSE. We adopt a conditional invertible neural network (cINN) architecture to infer the posterior distribution of stellar parameters and train our cINN on two Phoenix stellar atmosphere model libraries (Settl and Dusty). Compared to the cINNs presented in our first study, the updated cINN considers the influence of the relative flux error on the parameter estimation and predicts an additional fourth parameter, veiling. We test the prediction performance of cINN on synthetic test models to quantify the intrinsic error of the cINN as a function of relative flux error and on 36 class III template stars to validate the performance on real spectra. We provide Teff, logg, Av, and veiling values of 2051 stars in Tr14 measured by our cINN as well as stellar ages and masses derived from the Hertzsprung-Russell diagram based on the measured parameters. Our parameter estimates generally agree well with those measured by template fitting. However, for K- and G-type stars, the Teff derived from template fitting is, on average, 2-3 subclasses hotter than the cINN estimates, while the corresponding veiling values from template fitting appear to be underestimated compared to the cINN predictions. We obtain an average age of 0.7_-0.6_^+3.2^Myr for the Tr14 stars. By examining the impact of veiling on the equivalent width-based classification, we demonstrate that the main cause of temperature overestimation for K- and G-type stars in the previous study is that veiling and effective temperature are not considered simultaneously in their process. Our cINN performs comparably to the multi-dimensional template fitting method while being significantly faster and capable of consistently analysing stars across a wide temperature range (2600-7000K).</description><source format="bibcode">2025A&amp;A...697A..39K</source><referenceURL>https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/697/A39</referenceURL><type>Catalog</type><contentLevel>Research</contentLevel><relationship><relationshipType>IsServedBy</relationshipType><relatedResource ivo-id="ivo://CDS.VizieR/TAP">TAP VizieR generic service</relatedResource></relationship><relationship><relationshipType>IsServedBy</relationshipType><relatedResource>Conesearch service</relatedResource></relationship><relationship><relationshipType>related-to</relationshipType><relatedResource ivo-id="ivo://CDS.VizieR/J/ApJS/194/10">J/ApJS/194/10 : NIR properties of YSO in the CCCP (Preibisch+, 2011)</relatedResource><relatedResource ivo-id="ivo://CDS.VizieR/J/A+A/603/A81">J/A+A/603/A81 : Trumpler 14 and 16 in the Carina nebula (Damiani+, 2017)</relatedResource><relatedResource ivo-id="ivo://CDS.VizieR/J/A+A/658/A198">J/A+A/658/A198 : CHIPS II. 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Should Not be used for identification.</description><ucd>meta.record</ucd><dataType xsi:type="vs:VOTableType">int</dataType></column><column><name>ID</name><description>Star's identification number</description><ucd>meta.id;meta.main</ucd><dataType xsi:type="vs:VOTableType" arraysize="7*">char</dataType></column><column><name>RAJ2000</name><description>Right ascension (J2000)</description><ucd>pos.eq.ra;meta.main</ucd></column><column><name>DEJ2000</name><description>Declination (J2000)</description><ucd>pos.eq.dec;meta.main</ucd></column><column><name>Sample</name><description>[Clean Uncertain] Name of sample group</description><ucd>meta.id;src.sample;pos.lg</ucd><dataType xsi:type="vs:VOTableType" arraysize="10*">char</dataType></column><column><name>SigMed</name><description>Median of relative flux error</description><unit>%</unit><ucd>stat.error</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>Teff</name><description>Effective temperature</description><unit>K</unit><ucd>phys.temperature.effective</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>e_Teff</name><description>Error of Teff</description><unit>K</unit><ucd>stat.error;phys.temperature.effective</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>logg</name><description>Logarithm of surface gravity</description><unit>log(cm.s**-2)</unit><ucd>phys.gravity</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>e_logg</name><description>Error of logG</description><unit>log(cm.s**-2)</unit><ucd>stat.error</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>Av</name><description>Visual extinction</description><unit>mag</unit><ucd>phys.absorption</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>e_Av</name><description>Error of Av</description><unit>mag</unit><ucd>stat.error</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>veilr</name><description>Veiling at 7500{AA}</description><ucd>phys.absorption</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>e_veilr</name><description>Error of veilr</description><ucd>stat.error</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>Library</name><description>[Settl Dusty] Phoenix library origin</description><ucd>meta.note</ucd><dataType xsi:type="vs:VOTableType" arraysize="7*">char</dataType></column><column><name>SpType</name><description>Spectral type</description><ucd>src.spType</ucd><dataType xsi:type="vs:VOTableType" arraysize="5*">char</dataType></column><column><name>e_SpType</name><description>[] Left-hand side error of SpType</description><ucd>stat.error;src.spType</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>E_SpType</name><description>[] Right-hand side error of SpType</description><ucd>stat.error;stat.max</ucd><dataType xsi:type="vs:VOTableType">float</dataType></column><column><name>LbolJ</name><description>? 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