Relationship Between Low And High Frequencies In Delta Scuti Stars: Photometric Kepler And Spectroscopic Analyses Of The Rapid Rotator KIC 8054146

dc.contributor.utaustinauthorBreger, Michelen_US
dc.contributor.utaustinauthorP. Robertsonen_US
dc.creatorBreger, Michelen_US
dc.creatorFossati, L.en_US
dc.creatorBalona, L.en_US
dc.creatorKurtz, D. W.en_US
dc.creatorRobertson, Paulen_US
dc.creatorBohlender, D.en_US
dc.creatorLenz, P.en_US
dc.creatorMueller, I.en_US
dc.creatorLueftinger, T.en_US
dc.creatorClarke, B. D.en_US
dc.creatorHall, Jennifer R.en_US
dc.creatorIbrahim, Khadeejah A.en_US
dc.description.abstractTwo years of Kepler data of KIC 8054146 (delta Sct/gamma Dor hybrid) revealed 349 statistically significant frequencies between 0.54 and 191.36 cycles day(-1) (6.3 mu Hz to 2.21 mHz). The 117 low frequencies cluster in specific frequency bands, but do not show the equidistant period spacings predicted for gravity modes of successive radial order, n, and reported for at least one other hybrid pulsator. The four dominant low frequencies in the 2.8-3.0 cycles day(-1) (32-35 mu Hz) range show strong amplitude variability with timescales of months and years. These four low frequencies also determine the spacing of the higher frequencies in and beyond the delta Sct pressure-mode frequency domain. In fact, most of the higher frequencies belong to one of three families with spacings linked to a specific dominant low frequency. In the Fourier spectrum, these family regularities show up as triplets, high-frequency sequences with absolutely equidistant frequency spacings, side lobes (amplitude modulations), and other regularities in frequency spacings. Furthermore, within two families the amplitude variations between the low and high frequencies are related. We conclude that the low frequencies (gravity modes, rotation) and observed high frequencies (mostly pressure modes) are physically connected. This unusual behavior may be related to the very rapid rotation of the star: from a combination of high-and low-resolution spectroscopy we determined that KIC 8054146 is a very fast rotator (upsilon sin i = 300 +/- 20 km s(-1)) with an effective temperature of 7600 +/- 200 K and a surface gravity log g of 3.9 +/- 0.3. Several astrophysical ideas explaining the origin of the relationship between the low and high frequencies are explored.en_US
dc.description.sponsorshipAustrian Fonds zur Forderung der wissenschaftlichen Forschung P 21830-N16en_US
dc.description.sponsorshipNASA's Science Mission Directorateen_US
dc.identifier.citationBreger, Michel, L. Fossati, L. Balona, D. W. Kurtz, P. Robertson, D. Bohlender, P. Lenz et al. "Relationship between Low and High Frequencies in ? Scuti Stars: Photometric Kepler and Spectroscopic Analyses of the Rapid Rotator KIC 8054146." The Astrophysical Journal, Vol. 759, No. 1 (Nov., 2012): 62.en_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectstars: abundancesen_US
dc.subjectstars: individual (kic 8054146)en_US
dc.subjectstars: oscillationsen_US
dc.subjectstars: rotationen_US
dc.subjectstars: variables: delta scutien_US
dc.subjecta-type starsen_US
dc.subjectpraesepe clusteren_US
dc.subjectturbulent convectionen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleRelationship Between Low And High Frequencies In Delta Scuti Stars: Photometric Kepler And Spectroscopic Analyses Of The Rapid Rotator KIC 8054146en_US

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