KIC 3440495: A Rapidly Rotating δ Scuti-γ Doradus Hybrid Pulsator in a Binary System

In this paper, we study the pulsation properties of KIC 3440495 using Kepler and TESS data. A Fourier analysis of the light curve reveals 24 pulsation modes as well as 29 frequencies associated with rotation. The rotation frequency is derived to be frot = 2.322909(2) day−1, and the rotational modulation is determined to be caused by starspots. A large frequency separation of Δν = 54.5 μHz is found by using a Fourier transform, the autocorrelation function, a histogram of frequency differences, and an échelle diagram. We use the large separation to estimate the refined stellar parameters of the star to be v = [239, 279] km s−1, M= [1.5, 1.65] Me, Requator = [2.03, 2.30] Re, Rpolar = [1.72, 1.78] Re, and ω = [0.61, 0.77]. The phase modulations of the pulsating frequencies show a long-term trend which may be attributed to an orbital effect of a binary system; hence, the star may be a fast rotating pulsator in a binary system. KIC 3440495 has an amplitude spectrum similar to Altair, and is identified as a potential sister of Altair. Based on studies of Altair, KIC 3330495 is presumably a young star at a similar evolutionary stage.National Natural Science Foundation of China (NSFC) 12003060 U2031209Natural Science Foundation of Xinjiang Uygur Autonomous Region 2020D01B59Chinese Academy of Sciences (CAS) "Light of West China" Program 2021-XBQNXZ-029"FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento" by Universidad de Granada E-FQM-041-UGR18"Programas Estatales de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I+D+i y de I+D+i Orientada a los Retos de la Sociedad" from the Spanish Ministry of Science, Innovation and Universities (MCIU) PID2019-107061GB-C63State Agency for Research through the "Center of Excellence Severo Ochoa" award from the Spanish Ministry of Science, Innovation and Universities (MCIU) SEV-2017-070

Asteroseismology of a Double-mode High-amplitude δ Scuti Star TIC 448892817

We thank the anonymous referee for the suggestive comments, which improved the manuscript. We would like to thank the TESS science team for providing such excellent data. J.P.G. acknowledges funding support from Spanish public funds for research from project PID2019-107061GB-C63 from the “Programas Estatales de Generación de Conocimiento y Fortalecimiento Científico y Tecnológico del Sistema de I+D +i y de I+D+i Orientada a los Retos de la Sociedad”, and from the State Agency for Research through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), all from the Spanish Ministry of Science, Innovation and Universities (MCIU). A.G.H. acknowledges support from “FEDER/Junta de Andalucía- Consejería de Economía y Conocimiento” under project E-FQM-041-UGR18 by Universidad de Granada. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences. Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences.We propose that TIC 448892817 is a double-mode high-amplitude δ Scuti star. The radial modes detected in this star provide a unique opportunity to exploit asteroseismic techniques up to their limits. 30 significant frequencies are detected by frequency analysis, while two of them are independent frequencies, i.e., F0 = 13.43538(2) day−1 and F1 = 17.27007(4) day−1. The ratio of f1/f2 is measured to be 0.777957(2), suggesting that this target is a double-mode δ Scuti star. Nearly all the light variation is due to these two modes and their combination frequencies, but several other frequencies of very low amplitude are also present. The stellar evolutionary models were constructed with different mass M and metallicity Z using Modules for Experiments in Stellar Astrophysics (MESA). The frequency ratio f1/f2 obtained by the model is smaller than those obtained by observation. This might be caused by the rotation of the star pointing that rotational effects are more important than previously thought in HADS stars. This is something that deserves to be investigated in future works with models including rotational effects for moderate to intermediate rotators such as FILOU. On the other hand, the parameters obtained from MESA agree well with previous results as well as by observational spectra. The best-fitting model shows that TIC 448892817 is close to entering the first turnoff of the main sequence. In order to accurately determine the effective temperature and metallicities, thus further narrowing the parameter space of this star, we suggest high-resolution spectra is highly desired in the future.Center of Excellence Severo OchoaI+D+i y de I+D+i Orientada a los Retos de la SociedadJunta de Andalucía-Consejería de Economía y Conocimiento E-FQM-041-UGR18State Agency for ResearchMinisterio de Ciencia, Innovación y UniversidadesChinese Academy of SciencesUniversidad de GranadaEuropean Regional Development FundNational Development and Reform CommissionNational Astronomical Observatories, Chinese Academy of SciencesInstituto de Astrofísica de Andalucía SEV-2017-070

Ultra-precise analysis of the light curves of CoRoT and Kepler δ Scuti stars

It is well known that the residuals of the multifrequency analysis of δ Scuti stars are correlated, giving rise to challenging features such as a plateau (HD 50844, HD 50870, HD 49434, . . . ) of non-resolved frequencies with amplitude higher than the expected noise level. Several hypotheses have been advanced to explain these features: effective convection, rotation, non-linear interactions, etc. We have recently demonstrated that in some cases the underlying function describing the light variations of δ Scuti stars has not the property of being analytic. The strong consequence of this result is that the Fourier expansion on which the harmonic analysis is based could be not justified. In order to know the extension of this phenomenon among δ Scuti stars, we have used photometric data from CoRoT seismofield and a set of Kepler stars. The results show that this inconsistency in the application of harmonic analysis is almost ubiquitous to the δ Scuti pulsating stars

Quaternionic Transform: A new Light on the Solar Power Spectrum

Asteroseismology, that is, the use of the frequency content of a time series caused by variations in brightness or radial velocity of a stellar object, is based on the hypothesis that such a series is harmonic and therefore can be described by a sum of sines and cosines. If this were not the case (e.g., the oscillations of an ellipsoid of revolution) it cannot be guaranteed that the Discrete Fourier transform is the least squares approximation to the time series. This report studies the effect of extending the Fourier kernel to a particular quaternion and exploring the impact when it is applied to the best time series that we have (GOLF/SoHO) from the closest star, our Sun. The results are consistent with a notable improvement in the signal-to-noise ratio in the low frequency range. This opens the possibility of detecting the elusive g modes of the Sun in future works.State Agency for Research of the Spanish MCIU through PID2019-107061GB-C63Instituto de Astrofísica de Andalucía (SEV-2017-0709)Spanish Ministry of Science, Innovation and Universities (MCIU)PID2019-110525GB-100 from the State Agency for Research and FEDER.\pa

Observational Δν\Delta\nu-ρˉ\bar\rho relation for δ\delta Sct stars using eclipsing binaries and space photometry

Delta Scuti ($\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\delta$ Sct stars.Comment: 11 pages, including 2 pages of appendix, 2 figures, 2 tables, accepted for publication in ApJ

Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2

We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with periods around 4.7 min, making it the shortest period roAp star known to date. Four out of the five new roAp stars are multiperiodic. Three of these, and the singly-periodic one show the presence of rotational mode splitting. Individual frequencies are provided in all cases. In addition, seven previously known roAp stars are analysed. Additional modes of oscillation are found in some stars, while in others we are able to distinguish the true pulsations from possible aliases present in the ground-based data. We find that the pulsation amplitude in the TESS filter is typically a factor 6 smaller than that in the B filter which is usually used for ground-based observations. For four roAp stars we set constraints on the inclination angle and magnetic obliquity, through the application of the oblique pulsator model. We also confirm the absence of roAp-type pulsations down to amplitude limits of 6 and 13 micromag, respectively, in two of the best characterised non-oscillating Ap (noAp) stars. We announce 27 new rotational variables along with their rotation periods, and provide different rotation periods for seven other stars. Finally, we discuss how these results challenge state-of-the-art pulsation models for roAp stars.We thank the referee for very detailed and useful comments to the original manuscript. This work was supported by FCT - Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017 & POCI-01- 0145-FEDER-030389. MC is supported in the form of work contract funded by national funds through FCT. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement no.: DNRF106). DLH and DWK acknowledge financial support from the Science and Technology Facilities Council (STFC) via grant ST/M000877/1. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. LFM acknowledges support from the UNAM by the way of DGAPA project PAPIIT IN100918. The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement N 670519: MAMSIE) and from the Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO) under the grant agreement G0H5416N (ERC Opvangproject). MS acknowledges the financial support of Postdoc@MUNI project CZ.02.2.69/0.0/0.0/16 027/0008360. EN acknowledges the Polish National Science Center grants no.2014/13/B/ST9/00902. JCS acknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2 and ESP2015- 65712-C5-5-R, and from project RYC-2012-09913 under the ‘Ramón y Cajal’ program of the Spanish Ministry of Science and Education. AGH acknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2 and ESP2015-65712-C5-5-R of the Spanish Ministry of Science and Education. A´ S, ZsB, and RSz acknowledge the financial support of the GINOP-2.3.2-15-2016- 00003, K-115709, K-113117, K-119517 and PD-123910 grants of the Hungarian National Research, Development and Innovation Office (NKFIH), and the Lendület Program of the Hungarian Academy of Sciences, project No. LP2018-7/2018. GH has been supported by the Polish NCN grant 2015/18/A/ST9/00578. MLM acknowledges funding support from Spanish public funds for research under project ESP2015- 65712-C5-3-R. JPG acknowledges funding support from Spanish public funds for research under project ESP2017-87676-C5-5-R. MLM and JPG also acknowledges funding support from the State Agency for Research of the Spanish MCIU through the ”Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). IS acknowledges funding support of NSF under projects DN 08-1/2016 and DN 18/13-12.12.2017. P. Kołaczek-Szymański acknowledges support from the NCN grant no. 2016/21/B/ST9/01126. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program

Study of rotational splittings in δ Scuti stars using pattern finding techniques

ARB, JPG, and RG acknowledge funding support from Spanish public funds for research from project ESP2017-87676-C5-5-R from the `Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion', from project PID2019-107061GB-C63 from the `Programas Estatales de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I+D+i y de I+D + i Orientada a los Retos de la Sociedad', and from the State Agency for Research through the `Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709), all from the Spanish Ministry of Science, Innovation and Universities. ARB also acknowledges funding support from project PRE2018084322 from the `Programa Estatal de Promocion del Talento y su Empleabilidad del Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion 2013-2016' of the Spanish Ministry of Science, Innovation and Universities. AGHacknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2 the SpanishMinistry of Science and Education, and from `European Regional Development Fund/Junta de Andalucia-Consejeria de Economia y Conocimiento' under project E-FQM-041-UGR18 by Universidad de Granada. JCS acknowledges funding support from Spanish public funds for research under projects PID2019-107061GB-C63 and ESP201787676-2-2, and from project RYC-2012-09913 under the `Ramon y Cajal' program of the Spanish Ministry of Science and Education.Detecting and understanding rotation in stellar interiors is nowadays one of the unsolved problems in stellar physics. Asteroseismology has been able to provide insights on rotation for the Sun, solar-like stars, and compact objects like white dwarfs. However, this is still very difficult for intermediate-mass stars. These stars are moderate-to-rapid rotators. Rotation splits and shifts the oscillation modes, which makes the oscillation spectrum more complex and harder to interpret. Here we study the oscillation patterns of a sample of benchmark delta Sct stars belonging to eclipsing binary systems with the objective of finding the frequency spacing related to the rotational splitting (delta r). For this task, we combine three techniques: the Fourier transform, the autocorrelation function, and the histogram of frequency differences. The last two showed a similar behaviour. For most of the stars, it was necessary to determine the large separation (Delta nu) prior to spot delta r. This is the first time we may clearly state that one of the periodicities present in the p modes oscillation spectra of delta Sct stars corresponds to the rotational splitting. This is true independent of the stellar rotation rate. These promising results pave the way to finding a robust methodology to determine rotational splittings from the oscillation spectra of delta Sct stars and, thus, understanding the rotational profile of intermediate-mass pulsating stars.Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion ESP2017-87676-C5-5-RProgramas Estatales de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I+D+i y de I+D + i Orientada a los Retos de la Sociedad PID2019-107061GB-C63State Agency for Research through the `Center of Excellence Severo Ochoa' SEV-2017-0709Spanish Ministry of Science, Innovation and UniversitiesPrograma Estatal de Promocion del Talento y su Empleabilidad del Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion 2013-2016' of the Spanish Ministry of Science, Innovation and Universities PRE2018084322Spanish Government ESP2017-87676-2-2European Regional Development Fund/Junta de Andalucia-Consejeria de Economia y Conocimientoby Universidad de Granada E-FQM-041-UGR18Spanish public funds for research PID2019-107061GB-C63 ESP201787676-2-2Spanish Government RYC-2012-0991

Accurate ρ̄ and log g of δ Sct stars using Asteroseismology

In this work, we present a new method to determine the surface gravity of δ Sct stars. We used a refined Δν=ρ̄ relation and the stellar parallaxes or luminosities to determine their masses and radii. A comparison with the data obtained from the binary analysis, has shown that the values found by both methods are equivalent, within the uncertainties. Moreover, thanks to the refined relation, the uncertainties in log g are of the order of those usually estimated with high-resolution spectroscopy. Because of that, this new method to determine the surface gravity is an important step forward to break the degeneracy problem in the spectroscopic analysis.AGH acknowledges support from Fundação para a Ciência e a Tecnologia (FCT,Portugal) through the fellowship SFRH/BPD/80619/2011 and from grant UID/FIS/04434/2013.AGH, MJPFGM and JCS acknowledge support from the EC Project SPACEINN (FP7-SPACE-2012-312844) .JCSalsoacknowledges funding support from the Spanish “Ministerio de Economía y Competitividad” under“Ramón y Cajal”subprogram. This research made use of the SIMBAD database and the VizieR catalogue access tool operated at CDS, Strasbourg, France, and the SAO/NASA Astrophysics Data System

Asteroseismology of massive stars with the TESS mission: the runaway Beta Cep pulsator PHL 346 = HN Aqr

We report an analysis of the first known Beta Cep pulsator observed by the TESS mission, the runaway star PHL 346 = HN Aqr. The star, previously known as a singly-periodic pulsator, has at least 34 oscillation modes excited, 12 of those in the g-mode domain and 22 p modes. Analysis of archival data implies that the amplitude and frequency of the dominant mode and the stellar radial velocity were variable over time. A binary nature would be inconsistent with the inferred ejection velocity from the Galactic disc of 420 km/s, which is too large to be survivable by a runaway binary system. A kinematic analysis of the star results in an age constraint (23 +- 1 Myr) that can be imposed on asteroseismic modelling and that can be used to remove degeneracies in the modelling process. Our attempts to match the excitation of the observed frequency spectrum resulted in pulsation models that were too young. Hence, asteroseismic studies of runaway pulsators can become vital not only in tracing the evolutionary history of such objects, but to understand the interior structure of massive stars in general. TESS is now opening up these stars for detailed asteroseismic investigation.Comment: accepted for ApJ

Hyperkalemia in Heart Failure Patients in Spain and Its Impact on Guidelines and Recommendations: ESC-EORP-HFA Heart Failure Long-Term Registry

[Abstract] Introduction and objectives: Hyperkalemia is a growing concern in the treatment of patients with heart failure and reduced ejection fraction because it limits the use of effective drugs. We report estimates of the magnitude of this problem in routine clinical practice in Spain, as well as changes in potassium levels during follow-up and associated factors. Methods: This study included patients with acute (n=881) or chronic (n=3587) heart failure recruited in 28 Spanish hospitals of the European heart failure registry of the European Society of Cardiology and followed up for 1 year. Various outcomes were analyzed, including changes in serum potassium levels and their impact on treatment. Results: Hyperkalemia (K+> 5.4 mEq/L) was identified in 4.3% (95%CI, 3.7%-5.0%) and 8.2% (6.5%-10.2%) of patients with chronic and acute heart failure, respectively, and was responsible for 28.9% of all cases of contraindication to mineralocorticoid receptor antagonist use and for 10.8% of all cases of failure to reach the target dose. Serum potassium levels were not recorded in 291 (10.8%) of the 2693 chronic heart failure patients with reduced ejection fraction. During follow-up, potassium levels increased in 179 of 1431 patients (12.5%, 95%CI, 10.8%-14.3%). This increase was directly related to age, diabetes, and history of stroke and was inversely related to history of hyperkalemia. Conclusions: This study highlights the magnitude of the problem of hyperkalemia in patients with heart failure in everyday clinical practice and the need to improve monitoring of this factor in these patients due to its interference with the possibility of receiving optimal treatment.[Resumen] Introducción y objetivos. La hiperpotasemia es una preocupación creciente en el tratamiento de los pacientes con insuficiencia cardiaca y fracción de eyección reducida, pues limita el uso de fármacos eficaces. Este trabajo ofrece estimaciones de la magnitud de este problema en la práctica clínica habitual en España, los cambios en las concentraciones de potasio en el seguimiento y los factores asociados. Métodos. Pacientes con insuficiencia cardiaca aguda (n = 881) y crónica (n = 3.587) seleccionados en 28 hospitales españoles del registro europeo de insuficiencia cardiaca de la European Society of Cardiology y seguidos 1 año para diferentes desenlaces, incluidos cambios en las cifras de potasio y su impacto en el tratamiento. Resultados. La hiperpotasemia (K+ > 5,4 mEq/l) está presente en el 4,3% (IC95%, 3,7-5,0%) y el 8,2% (6,5-10,2%) de los pacientes con insuficiencia cardiaca crónica y aguda; causa el 28,9% de todos los casos en que se contraindica el uso de antagonistas del receptor de mineralocorticoides y el 10,8% de los que no alcanzan la dosis objetivo. Del total de 2.693 pacientes ambulatorios con fracción de eyección reducida, 291 (10,8%) no tenían registrada medición de potasio. Durante el seguimiento, 179 de 1.431 (12,5%, IC95%, 10,8-14,3%) aumentaron su concentración de potasio, aumento relacionado directamente con la edad, la diabetes mellitus y los antecedentes de ictus e inversamente con los antecedentes de hiperpotasemia. Conclusiones. Este trabajo destaca el problema de la hiperpotasemia en pacientes con insuficiencia cardiaca de la práctica clínica habitual y la necesidad de continuar y mejorar la vigilancia de este factor en estos pacientes por su interferencia en el tratamiento óptimo