Examinando por Autor "Bowman, D. M."

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Acceso Abierto
The first view of δ Scuti and γ Doradus stars with the TESS mission
(Oxford Academics: Oxford University Press, 2019-10-07) Antoci, V.; Cunha, M. S.; Bowman, D. M.; Murphy, S. J.; Kurtz, D. W.; Bedding, T. R.; Borre, C. C.; Christophe, S.; Daszyńska-Daszkiewicz, J.; Fox Machado, L.; García Hernández, A.; Ghasemi, H.; Handberg, R.; Hansen, H.; Hasanzadeh, A.; Houdek, G.; Johnston, C.; Justesen, A. B.; Kahraman Alicavus, F.; Kotysz, K.; Latham, D.; Matthews, J. M.; Monster, J.; Niemczura, E.; Paunzen, E.; Sánchez Arias, J. P.; Pigulski, A.; Pepper, J.; Richey Yowell, T.; Safari, H.; Seager, S.; Smalley, B.; Shutt, T.; Sódor, A.; Suárez, J. C.; Tkachenko, A.; Wu, T.; Zwintz, K.; Barceló Forteza, S.; Brunsden, E.; Bognár, Z.; Buzasi, D. L.; Chowdhury, S.; De Cat, P.; Evans, J. A.; Guo, Z.; Guzik, J. A.; Jetvic, N.; Lampens, P.; Lares Martiz, M.; Lovekin, C.; Li, G.; Mirouh, G. M.; Mkrtichian, D.; Monteiro, M. J. P. F. G.; Nemec, J. M.; Ouazzani, R. M.; Pascual Granado, J.; Reese, D. R.; Rieutord, M.; Rodon, J. R.; Skarka, M.; Sowicka, P.; Stateva, I.; Szabó, R.; Weiss, W. W.; Universidad Nacional Autónoma de México (UNAM); Agence Nationale de la Recherche (ANR); National Natural Science Foundation of China (NSFC); Danish National Research Foundation (DNRF); National Aeronautics and Space Administration (NASA); Fundacao para a Ciencia e a Tecnologia (FCT); National Science Centre, Poland (NCN); Hungarian Academy of Sciences (MTA); European Research Council (ERC); Ministerio de Economía y Competitividad (MINECO); Research Foundation Flanders (FWO); BELgian federal Science Policy Office (BELSPO); Science and Technology Facilities Council (STFC); Johnston, C. [0000-0002-3054-4135]; Granado, J. P. [0000-0003-0139-6951]; Monteiro, M. J. P. F. G. [0000-0003-0513-8116]; Szabo, R. [0000-0002-3258-1909]; Browman, D. [0000-0001-7402-3852]; Safari, H. [0000-0003-2326-3201]; Simon, M. [0000-0002-5648-3107]; Houdek, G. [0000-0003-1819-810X]; Ghasemi, H. [0000-0001-9534-9763]; Handerberg, R. [0000-0001-8725-4502]; Borre, C. C. [0000-0003-1286-8512]; Cunha, M. [0000-0001-8237-7343]; Justensen, A. B. [0000-0002-0174-2466]; Antoci, V. [0000-0002-0865-3650]; Christophe, S. [0000-0002-4153-870X]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 and 2 of the TESS mission. We utilize the 2-min cadence TESS data for a sample of 117 stars to classify their behaviour regarding variability and place them in the Hertzsprung–Russell diagram using Gaia DR2 data. Included within our sample are the eponymous members of two pulsator classes, γ Doradus and SX Phoenicis. Our sample of pulsating intermediate-mass stars observed by TESS also allows us to confront theoretical models of pulsation driving in the classical instability strip for the first time and show that mixing processes in the outer envelope play an important role. We derive an empirical estimate of 74 per cent for the relative amplitude suppression factor as a result of the redder TESS passband compared to the Kepler mission using a pulsating eclipsing binary system. Furthermore, our sample contains many high-frequency pulsators, allowing us to probe the frequency variability of hot young δ Scuti stars, which were lacking in the Kepler mission data set, and identify promising targets for future asteroseismic modelling. The TESS data also allow us to refine the stellar parameters of SX Phoenicis, which is believed to be a blue straggler.
Acceso Abierto
Variability of OB stars from TESS southern Sectors 1–13 and high-resolution IACOB and OWN spectroscopy
(EDP Sciences, 2020-07-13) Burssens, S.; Simón Díaz, S.; Bowman, D. M.; Holgado, G.; Michielsen, M.; De Burgos, A.; Castro, N.; Barbá, R. H.; Aerts, C.; Agencia Estatal de Investigación (AEI); European Research Council (ERC); National Aeronautics and Space Administration (NASA); Holgado, G. [0000-0002-9296-8259]; Bowman, D. [0000-0001-7402-3852]; Burssens, S. [0000-0002-1593-0863]; Aerts, C. [0000-0003-1822-7126]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The lack of high-precision long-term continuous photometric data for large samples of stars has impeded the large-scale exploration of pulsational variability in the OB star regime. As a result, the candidates for in-depth asteroseismic modelling have remained limited to a few dozen dwarfs. The TESS nominal space mission has surveyed the southern sky, including parts of the galactic plane, yielding continuous data across at least 27 d for hundreds of OB stars. Aims. We aim to couple TESS data in the southern sky with ground-based spectroscopy to study the variability in two dimensions, mass and evolution. We focus mainly on the presence of coherent pulsation modes that may or may not be present in the predicted theoretical instability domains and unravel all frequency behaviour in the amplitude spectra of the TESS data. Methods. We compose a sample of 98 OB-type stars observed by TESS in Sectors 1–13 and with available multi-epoch, high-resolution spectroscopy gathered by the IACOB and OWN surveys. We present the short-cadence 2 min light curves of dozens of OB-type stars, which have one or more spectra in the IACOB or OWN database. Based on these light curves and their Lomb–Scargle periodograms, we performed variability classification and frequency analysis. We placed the stars in the spectroscopic Hertzsprung–Russell diagram to interpret the variability in an evolutionary context. Results. We deduce the diverse origins of the mmag-level variability found in all of the 98 OB stars in the TESS data. We find among the sample several new variable stars, including three hybrid pulsators, three eclipsing binaries, high frequency modes in a Be star, and potential heat-driven pulsations in two Oe stars. Conclusions. We identify stars for which future asteroseismic modelling is possible, provided mode identification is achieved. By comparing the position of the variables to theoretical instability strips, we discuss the current shortcomings in non-adiabatic pulsation theory and the distribution of pulsators in the upper Hertzsprung–Russell diagram.