- Context. HD 93129A was classified as the earliest O-type star in the Galaxy (O2 If*) and is considered as the prototype of its spectral class. However, interferometry shows that this object is a binary system, while recent observations even suggest a triple configuration. None of the previous spectral analyses of this object accounted for its multiplicity. With new high-resolution UV and optical spectra, we have the possibility to reanalyze this key object, taking its binary nature into account for the first time. Aims. We aim to derive the fundamental parameters and the evolutionary status of HD 93129A, identifying the contributions of both components to the composite spectrum Results. Despite the similar spectral types of the two components, we are able to find signatures from each of the components in the combined spectrum, which allows us to estimate the parameters of both stars. We derive log(L/L-circle dot) = 6.15, T-eff = 52 kK, and log (M)over dot = -4.7[M-circle dot yr(-1)] for the primary Aa, and log(L/L-circle dot) = 5.58,Context. HD 93129A was classified as the earliest O-type star in the Galaxy (O2 If*) and is considered as the prototype of its spectral class. However, interferometry shows that this object is a binary system, while recent observations even suggest a triple configuration. None of the previous spectral analyses of this object accounted for its multiplicity. With new high-resolution UV and optical spectra, we have the possibility to reanalyze this key object, taking its binary nature into account for the first time. Aims. We aim to derive the fundamental parameters and the evolutionary status of HD 93129A, identifying the contributions of both components to the composite spectrum Results. Despite the similar spectral types of the two components, we are able to find signatures from each of the components in the combined spectrum, which allows us to estimate the parameters of both stars. We derive log(L/L-circle dot) = 6.15, T-eff = 52 kK, and log (M)over dot = -4.7[M-circle dot yr(-1)] for the primary Aa, and log(L/L-circle dot) = 5.58, T-eff = 45 kK, and log (M)over dot = -5.8 [M(circle dot)yr(-1)] for the secondary Ab. Conclusions. Even when accounting for the binary nature, the primary of HD 93129A is found to be one of the hottest and most luminous O stars in our Galaxy. Based on the theoretical decomposition of the spectra, we assign spectral types O2 If* and O3 III(f*) to components Aa and Ab, respectively. While we achieve a good fit for a wide spectral range, specific spectral features are not fully reproduced. The data are not sufficient to identify contributions from a hypothetical third component in the system.…
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MetadatenAuthor details: | David GrunerORCiDGND, Rainer HainichGND, Andreas Alexander Christoph SanderORCiDGND, Tomer ShenarORCiDGND, Helge Tobias TodtORCiD, Lidia M. OskinovaORCiDGND, Varsha RamachandranORCiDGND, T. Ayres, Wolf-Rainer HamannORCiDGND |
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DOI: | https://doi.org/10.1051/0004-6361/201833178 |
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ISSN: | 1432-0746 |
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Title of parent work (English): | Astronomy and astrophysics : an international weekly journal |
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Publisher: | EDP Sciences |
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Place of publishing: | Les Ulis |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2018/11/08 |
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Publication year: | 2018 |
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Release date: | 2021/04/21 |
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Tag: | stars: atmospheres; stars: early-typeP; stars: fundamental parameters; stars: individual: HD 93129A |
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Volume: | 621 |
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Number of pages: | 16 |
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Funding institution: | NASANational Aeronautics & Space Administration (NASA) [NAS 5-26555, NAS5-26555]; ESO telescopes at the La Silla Paranal Observatory [095.D-0234(A)]; National Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA); National Science FoundationNational Science Foundation (NSF); Deutsche Forschungsgemeinschaft (DFG)German Research Foundation (DFG) [HA 1455/26]; STFCScience & Technology Facilities Council (STFC) [ST/R000565/1]; German "Verbundforschung" (DLR) grant [50 OR 1612]; DLR grantHelmholtz AssociationGerman Aerospace Centre (DLR) [50 OR 1508]; NASA Office of Space ScienceNational Aeronautics & Space Administration (NASA) [NNX09AF08G]; STScISpace Telescope Science Institute [HST-GO-12278.01-A, HST-GO-13346.01-A] |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 52 Astronomie / 520 Astronomie und zugeordnete Wissenschaften |
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| 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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Publishing method: | Open Access / Bronze Open-Access |
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