Suchergebnisse

We report the detection of three RR Lyrae (RRL) stars (two RRc and one RRab) in the ultra-faint dwarf (UFD) galaxy Centaurus I (Cen I) and two Milky Way (MW) δ Scuti/SX Phoenicis stars based on multi-epoch giz DECam observations. The two RRc stars are located within two times the half-light radius (rh) of Cen I, while the RRab star (CenI-V3) is at ∼6 rh. The presence of three distant RRL stars clustered this tightly in space represents a 4.7σ excess relative to the smooth distribution of RRL in the Galactic halo. Using the newly detected RRL stars, we obtain a distance modulus to Cen I of μ0 = 20.354 ± 0.002 mag (σ = 0.03 mag), a heliocentric distance of De = 117.7 ± 0.1 kpc (σ = 1.6 kpc), with systematic errors of 0.07 mag and 4 kpc. The location of the Cen I RRL stars in the Bailey diagram is in agreement with other UFD galaxies (mainly Oosterhoff II). Finally, we study the relative rate of RRc+RRd (RRcd) stars (fcd) in UFD and classical dwarf galaxies. The full sample of MW dwarf galaxies gives a mean of fcd = 0.28. While several UFD galaxies, such as Cen I, present higher RRcd ratios, if we combine the RRL populations of all UFD galaxies, the RRcd ratio is similar to the one obtained for the classical dwarfs (fcd ∼ 0.3). Therefore, there is no evidence for a different fraction of RRcd stars in UFD and classical dwarf galaxies. ; Fermilab LDRD project L2019-011 NASA Fermi Guest Investigator Program Cycle 9 91201 United States Department of Energy (DOE) National Science Foundation (NSF) Spanish Government UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) UK Research & Innovation (UKRI) Higher Education Funding Council for England (HEFCE) National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign University of Chicago Ohio State University Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University Financiadora de Inovacao e Pesquisa (Finep) Fundaco Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) Spanish Government German Research Foundation (DFG) Dark Energy Survey United States Department of Energy (DOE) University of California at Santa Cruz University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid University of Chicago, University College London DES-Brazil Consortium University of Edinburgh ETH Zurich United States Department of Energy (DOE) University of Chicago University of Illinois at Urbana-Champaign Institut de Ciencies de l'Espai (IEEC/CSIC) Institut de Fisica d'Altes Energies, Lawrence Berkeley National Laboratory Ludwig-Maximilians Universitat Munchen associated Excellence Cluster Universe University of Michigan, NSF's NOIRLab University of Nottingham Ohio State University OzDES Membership Consortium University of Pennsylvania University of Portsmouth Stanford University United States Department of Energy (DOE) Stanford University University of Sussex Texas AM University United States Department of Energy (DOE) DE-AC02-07CH11359 ; Versión publicada - versión final del editor

Context. It is known that the observed distribution of frequencies in CoRoT and Kepler δ Scuti stars has no parallelism with any theoretical model. Pre-whitening is a widespread technique in the analysis of time series with gaps from pulsating stars located in the classical instability strip, such as δ Scuti stars. However, some studies have pointed out that this technique might introduce biases in the results of the frequency analysis. Aims. This work aims at studying the biases that can result from pre-whitening in asteroseismology. The results will depend on the intrinsic range and distribution of frequencies of the stars. The periodic nature of the gaps in CoRoT observations, only in the range of the pulsational frequency content of the δ Scuti stars, is shown to be crucial to determining their oscillation frequencies, the first step in performing asteroseismology of these objects. Hence, here we focus on the impact of pre-whitening on the asteroseismic characterization of δ Scuti stars. Methods. We select a sample of 15 δ Scuti stars observed by the CoRoT satellite, for which ultra-high-quality photometric data have been obtained by its seismic channel. In order to study the impact on the asteroseismic characterization of δ Scuti stars we perform the pre-whitening procedure on three datasets: gapped data, linearly interpolated data, and data with gaps interpolated using Autoregressive and Moving Average models (ARMA). Results. The different results obtained show that at least in some cases pre-whitening is not an efficient procedure for the deconvolution of the spectral window. Therefore, in order to reduce the effect of the spectral window to a minimum, in addition to performing a pre-whitening of the data, it is necessary to interpolate with an algorithm that is aimed to preserve the original frequency content.© ESO 2018. ; JPG acknowledge support from the "Junta de Andalucía" local government under project 2012-P12-TIC-2469. JCS and AGH acknowledge funding support from Spanish public funds for research under project ESP2015-65712-C5-5-R (MINECO/FEDER), and from project RYC-2012-09913 under the "Ramón y Cajal" programme of the Spanish MINECO. JCS also acknowledge support by the European FP7 project "SPACEINN" (FP7-SPACE-2011-1). AM acknowledges support by the Spanish MINECO National Space Program through project ESP2015-65712-C5-1-R and "Ramon y Cajal" program RYC-2012-09913. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 749962. ; Peer Reviewed

We present observations of a new phenomenon in pulsating white dwarf stars: large-amplitude outbursts at timescales much longer than the pulsation periods. The cool (T-eff = 11,060 K), hydrogen-atmosphere pulsating white dwarf PG 1149+057 was observed nearly continuously for more than 78.8 day by the extended Kepler mission in K2 Campaign 1. The target showed 10 outburst events, recurring roughly every 8 day and lasting roughly 15 hr, with maximum flux excursions up to 45% in the Kepler bandpass. We demonstrate that the outbursts affect the pulsations and therefore must come from the white dwarf. Additionally, we argue that these events are not magnetic reconnection flares, and are most likely connected to the stellar pulsations and the relatively deep surface convection zone. PG 1149+057 is now the second cool pulsating white dwarf to show this outburst phenomenon, after the first variable white dwarf observed in the Kepler mission, KIC 4552982. Both stars have the same effective temperature, within the uncertainties, and are among the coolest known pulsating white dwarfs of typical mass. These outbursts provide fresh observational insight into the red edge of the DAV instability strip and the eventual cessation of pulsations in cool white dwarfs. ; European Research Council under the European Union's Seventh Framework Programme (FP) / ERC Grant 320964 ; NSF AST-1312983 ; NASA NNX12AC96G ; NASA Science Mission Directorate ; Astronomy

We present a preliminary analysis of the cool pulsating white dwarf (WD) GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two-reaction-wheel-controlled Kepler spacecraft. We detect at least 19 independent pulsation modes, ranging from 828.2-1220.8 s, and at least 17 nonlinear combination frequencies of those independent pulsations. Our longest uninterrupted light curve, 9.0 days in length, evidences coherent difference frequencies at periods inaccessible from the ground, up to 14.5 hr, the longest-period signals ever detected in a pulsating WD. These results mark some of the first science to come from a two-wheel-controlled Kepler spacecraft, proving the capability for unprecedented discoveries afforded by extending Kepler observations to the ecliptic. ; European Research Council under the European Union 320964 ; NSF AST-0909107, AST-1312678 ; Norman Hackerman Advanced Research Program 003658-0252-2009 ; NASA NNX12AC96G, NNX13AC23G, NNX14AB92G ; Foundation for Fundamental Research on Matter (FOM), Netherlands Organisation for Scientific Research (NWO) ; McDonald Observatory

Fractal behaviour, i.e. scale invariance in spatio-temporal dynamics, has been found to describe and model many systems in nature, in particular fluid mechanics and geophysical related geometrical objects, like the convective boundary layer of cumulus cloud fields, topographic landscapes, solar granulation patterns, and observational astrophysical time series, like light curves of pulsating stars. The main interest in the study of fractal properties in such physical phenomena lies in the close relationships they have with chaotic and turbulent dynamic. In this work we introduce some statistical tools for fractal analysis of light curves: Rescaled Range Analysis (R/S), Multifractal Spectra Analysis, and Coarse Graining Spectral Analysis (CGSA), an FFT based algorithm, which can discriminate in a time series the stochastic fractal power spectra from the harmonic one. An interesting application of fractal analysis in asteroseismology concerns the joint use of all these tools in order to develop classification criteria and algorithms for ¿ Scuti pulsating stars. In fact from the fractal and multifractal fingerprints in the background noise of the light curves we could infer properties of different mechanisms of stellar dynamic, among them rotation, modes excitation and magnetic activity. © 2018 The Author(s). ; SdF, JPG and RG acknowledge funding support from Spanish public funds for research under projects ESP2015-65712-C5-3-R. 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 'Ramon y Cajal' program of the Spanish MINECO. SdF, JPG and RG acknowledge support from the 'Junta de Andalucia' regional government under project 2012-P12-TIC-2469. ; Peer Reviewed

Artículo escrito por un elevado número de autores, solo se referencia el que aparece en primer lugar, el nombre del grupo, si lo hubiere, y los autores pertenecientes a la UAM ; We present a search for RR Lyrae stars using the full six-year data set from the Dark Energy Survey covering ∼5000 deg2 of the southern sky. Using a multistage multivariate classification and light-curve template-fitting scheme, we identify RR Lyrae candidates with a median of 35 observations per candidate. We detect 6971 RR Lyrae candidates out to ∼335 kpc, and we estimate that our sample is >70% complete at ∼150 kpc. We find excellent agreement with other wide-area RR Lyrae catalogs and RR Lyrae studies targeting the Magellanic Clouds and other Milky Way satellite galaxies. We fit the smooth stellar halo density profile using a broken-power-law model with fixed halo flattening (q = 0.7), and we find strong evidence for a break at = R0 32.1 +1.1 -0.9 kpc with an inner slope of n1 = 2.54 +0.09 -0.09 and an outer slope of n2 = -5.42 +0.13 -0.14. We use our catalog to perform a search for Milky Way satellite galaxies with large sizes and low luminosities. Using a set of simulated satellite galaxies, we find that our RR Lyrae-based search is more sensitive than those using resolved stellar populations in the regime of large (rh ≥ 500 pc), low-surface-brightness dwarf galaxies. A blind search for large, diffuse satellites yields three candidate substructures. The first can be confidently associated with the dwarf galaxy Eridanus II. The second has a distance and proper motion similar to the ultrafaint dwarf galaxy Tucana II but is separated by ∼5 deg. The third is close in projection to the globular cluster NGC 1851 but is ∼10 kpc more distant and appears to differ in proper motion ; This work is based in part on observations at Cerro Tololo Inter-American Observatory at NSF's NOIRLab (NOIRLab Prop. ID 2012B-0001; PI: J. Frieman), National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under grant Nos. AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP7/2007- 2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and the Brazilian Instituto Nacional de Ciência e Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2)

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-R ; 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 PID2019-107061GB-C63 ; State Agency for Research through the `Center of Excellence Severo Ochoa' SEV-2017-0709 ; Spanish Ministry of Science, Innovation and Universities ; 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 PRE2018084322 ; Spanish Government ESP2017-87676-2-2 ; European Regional Development Fund/Junta de Andalucia-Consejeria de Economia y Conocimientoby Universidad de Granada E-FQM-041-UGR18 ; Spanish public funds for research PID2019-107061GB-C63 ESP201787676-2-2 ; Spanish Government RYC-2012-09913

Fractal fingerprints have been found recently in the light curves of several 5 Scuti stars observed by Convection Rotation and planetary Transits (CoRoT) satellite. This sole fact might pose a problem for the detection of pulsation frequencies using classical pre-whitening techniques, but it is also a potentially rich source for information about physical mechanisms associated with stellar variability. Assuming that a light curve is composed of a superposition of oscillation modes with a fractal background noise, in this work we applied the Coarse Graining Spectral Analysis (CGSA), a fast Fourier transform (FFT)-based algorithm, which can discriminate in a time series the stochastic fractal power spectra from the harmonic one. We have found that the fractal background component is determining the frequency content extracted using classical pre-whitening techniques in the light curves of 5 Scuti stars. This might be crucial to understand the amount of frequencies excited in these kinds of pulsating stars. Additionally, CGSA resulted to be relevant in order to extract the oscillation modes, this points to a new criterion to stop the pre-whitening cascade based on the percentage of fractal component in the residuals.© 2019 The Author(s). ; SdF, JP-G, JRR, ML-M, and RG acknowledge financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severn Ochoa' award for the Institute de Astrofisica de Andalucia (SEV-2017-0709). SdE, JP-G, JRR, ML-M, and RG acknowledge funding support from Spanish public funds for research under projects ESP2015-65712-C5-3-R. JCS and AGH acknowledge funding support from Spanish public funds for research under projects ESP2017-87676-2-2 and ESP2015-65712-C5-5-R. SdF, JP-G, and RG acknowledges support from the 'Junta de Andalucia' regional government under project 2012-P12-TIC-2469. JCS also acknowledges funding support from project RYC-2012-09913 under the 'Ramon y Cajal' program of the Spanish MINECO. ; Peer Reviewed

We present a reference study of the long-term optical variability of young stars using data from the WASP project. Our primary sample is a group of well-studied classical T Tauri stars (CTTSs), mostly in Taurus–Auriga. WASP light curves cover time-scales of up to 7 yr and typically contain 10 000–30 000 data points. We quantify the variability as a function of time-scale using the time-dependent standard deviation 'pooled sigma'. We find that the overwhelming majority of CTTSs have a low-level variability with σ 0.3 mag) is 21 per cent in our sample and 21 per cent in an unbiased control sample. An even smaller fraction (13 per cent in our sample, 6 per cent in the control) show evidence for an increase in variability amplitude as a function of time-scale from weeks to months or years. The presence of long-term variability correlates with the spectral slope at 3–5 μm, which is an indicator of inner disc geometry, and with the U–B band slope, which is an accretion diagnostics. This shows that the long-term variations in CTTSs are predominantly driven by processes in the inner disc and in the accretion zone. Four of the stars with long-term variations show periods of 20–60 d, significantly longer than the rotation periods and stable over months to years. One possible explanation is cyclic changes in the interaction between the disc and the stellar magnetic field. ; The research leading to these results has received funding from the European Union Seventh Framework Programme FP7-2011 under grant agreement no 284405. WASP-South is hosted by the South African Astronomical Observatory, and Super-WASP-North by the Isaac Newton Group and the Instituto de Astrofisica de Canarias; we are grateful for their ongoing support and assistance. Funding for WASP comes from consortium universities and from the UK's Science and Technology Facilities Council. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MICINN through grant AyA2008-02156. ; Peer-reviewed ; Publisher Version

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. © 2019 The Author(s) ; We thank the referee for useful comments and discussions. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program. Funding for the TESS Asteroseismic Science Operations Centre is provided by the Danish National Re-search Foundation (Grant agreement no.: DNRF106), ESA PRODEX (PEA 4000119301), and Stellar Astrophysics Centre (SAC) at Aarhus University. We thank the TESS and TASC/TASOC teams for their support of this work. This research has made use of the SIMBAD data base, operated at CDS, Strasbourg, France. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-2655. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement no.: DNRF106). MC was supported by FCT -Fundacao para a Ciencia e a Tecnologia through national funds and by FEDER through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao by these grants: UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017, and POCI-01-0145-FEDER-030389. MC is supported in the form of work contract funded by national funds through FCT (CEECIND/02619/2017). JDD acknowledges support from the Polish National Science Center (NCN), grant no. 2018/29/B/ST9/02803. AGH acknowledges funding support from Spanish public funds for research under projects ESP201787676-2-2 and ESP2015-65712-C5-5-R of the Spanish Ministry of Science and Education. FKA gratefully acknowledges funding through grant 2015/18/A/ST9/00578 of the Polish National Science Centre (NCN). JPe acknowledges funding support from the NSF REU program under grant number PHY-1359195. APi and KK acknowledge support provided by the Polish National Science Center (NCN) grant No. 2016/21/B/ST9/01126. This project has been supported by the Lendulet Program of the Hungarian Academy of Sciences, project No. LP2018-7/2018, and by the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the K16 funding scheme, project No. 115709. 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 RYC2012-09913 under the 'Ramon y Cajal' program of the Spanish Ministry of Science and Education. The research leading to these results has (partially) received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement N.670519: MAMSIE), from the KULeuven Research Council (grant C16/18/005: PARADISE), from the Research Foundation Flanders (FWO) under grant agreement G0H5416N (ERC Runner Up Project), as well as from the BELgian federal Science Policy Office (BELSPO) through PRODEX grant PLATO. SBF acknowledges support by the Spanish State Research Agency (AEI) through project No. 'ESP2017-87676-C5-1-R' and No MDM-2017-0737 Unidad de Excelencia `Maria de Maeztu'-Centro de Astrobiolog ' ia (CSICINTA). ZsB acknowledges the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the PD1717 funding scheme, project no. PD-123910. DLB acknowledges support from the Whitaker Foundation. SC gratefully acknowledges funding through grant 2015/18/A/ST9/00578 of the Polish National Science Centre (NCN). CCL gratefully acknowledges support from the Natural Sciences and Engineering Research Council of Canada. GMM acknowledges funding by the STFC consolidated grant ST/R000603/1. RMO, SC, and DR were supported in this work by the 'Programme National de Physique Stellaire' (PNPS) of CNRS/INSU co-funded by CEA and CNES. IS acknowledges the partial support of projects DN 08-1/2016 and DN 18/13-12.12.2017. PS acknowledges financial support by the Polish NCN grant 2015/18/A/ST9/00578. MS acknowledges the Postdoc@MUNI project CZ.02.2.69/0.0/0.0/16-027/0008360. JPG, JRR, and MLM acknowledge funding support from Spanish public funds for research under project ESP2017-87676-C5-5-R and from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). JAE acknowledges STFC for funding support (reference ST/N504348/1). LFM acknowledges the financial support from the DGAPA-UNAM under grant PAPIIT IN100918. DMk acknowledges his work as part of the research activity of the National Astronomical Research Institute of Thailand (NARIT), which is supported by the Ministry of Science and Technology of Thailand. MR acknowledges the support of the French Agence Nationale de la Recherche (ANR), under grant ESRR (ANR-16-CE31-0007-01). We acknowledge the International Space Science Institute (ISSI) for supporting the SoFAR international team http://www.issi.unibe.ch/teams/sofar/.TW acknowledges the NSFC of China (Grant Nos. 11873084 and 11521303) and YunnanApplied Basic Research Projects (GrantNo. 2017B008). IS acknowledges for a partial support of DN 08-1/2016 funded by the Bulgarian NSF. This work hasmade 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, ht tps://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. 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 No. 670519: MAMSIE) and from the Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO) under the grant agreement G0H5416N (ERC Opvangproject). This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France (DOI:10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

Context. As primary anchors of the distance scale, Cepheid stars play a crucial role in our understanding of the distance scale of the Universe because of their period-luminosity relation. Determining precise and consistent parameters (radius, temperature, color excess, and projection factor) of Cepheid pulsating stars is therefore very important. Aims. With the high-precision parallaxes delivered by the early third Gaia data release (EDR3), we aim to derive various parameters of Cepheid stars in order to calibrate the period-luminosity and period-radius relations and to investigate the relation of period to p-factor. Methods. We applied an implementation of the parallax-of-pulsation method through the algorithm called spectro-photointerferometry of pulsating stars (SPIPS), which combines all types of available data for a variable star (multiband and multicolor photometry, radial velocity, effective temperature, and interferometry measurements) in a global modeling of its pulsation. Results. We present the SPIPS modeling of a sample of 63 Galactic Cepheids. Adopting Gaia EDR3 parallaxes as an input associated with the best available dataset, we derive consistent values of parameters for these stars such as the radius, multiband apparent magnitudes, effective temperatures, color excesses, period changes, Fourier parameters, and the projection factor. Conclusions. Using the best set of data and the most precise distances for Milky Way Cepheids, we derive new calibrations of the period-luminosity and period-radius relations: MKS = −5.529±0.015 − 3.141±0.050(log P − 0.9) and log R = 1.763±0.003 + 0.653±0.012(log P − 0.9). After investigating the dependences of the projection factor on the parameters of the stars, we find a high dispersion of its values and no evidence of its correlation with the period or with any other parameters such as radial velocity, temperature, or metallicity. Statistically, the p-factor has an average value of p = 1.26±0.07, but with an unsatisfactory agreement (σ = 0.15). In absence of any clear correlation between the p-factor and other quantities, the best agreement is obtained under the assumption that the p-factor can take any value in a band with a width of 0.15. This result highlights the need for a further examination of the physics behind the p-factor. ; European Research Council (ERC) 695099 French National Research Agency (ANR) ANR-15-CE31-0012-01 Spanish Government AYA2017-84089 ; Versión publicada - versión final del editor

I performed photometric observations of the cataclysmic variable candidate ZTF17aaaeefu and discovered very deep eclipses. The observations were obtained over 8 nights covering 7 months. The eclipse profile is similar to the eclipse profiles observed in other cataclysmic variables. During the observations, ZTF17aaaeefu showed brightness changes resembling dwarf nova outbursts and quiescent states. When ZTF17aaaeefu was bright (16.0–16.2 mag), the average eclipse depth was 2.50 ± 0.18 mag. When ZTF17aaaeefu was faint (17.2–17.4 mag), the average eclipse depth was 1.45 ± 0.06 mag. However, these differences in the eclipse depth may be mainly caused by the contaminating effect of three faint stars around ZTF17aaaeefu. In both cases, the average width of the prominent parts of the eclipses was the same and was about 30 min. Due to the large coverage of observations, I measured the orbital period with high precision, Porb=0.18821155±0.00000014 d. I derived the eclipse ephemeris, the validity time of which is 700 years in accordance with the precision of the orbital period. This ephemeris can be used for future studies of the orbital period changes. Because ZTF17aaaeefu has a long orbital period, this cataclysmic variable is of interest for determining the masses of its stellar components. In future radial velocity measurements, my precise eclipse ephemeris may be useful for determining the orbital phases. © 2021, The Author(s), under exclusive licence to Springer Nature B.V. ; This work was supported in part by the Ministry of Science and Higher Education of the Russian Federation, FEUZ-2020-0030, and by the Act no. 211 of the Government of the Russian Federation, agreement no. 02.A03.21.0006. This research has made use of NASA's Astrophysics Data System Bibliographic Services and the International Variable Star Index (VSX) database. The VSX database is operated at AAVSO, Cambridge, Massachusetts, USA. This research has made use of the VizeR catalogue access tool (Ochsenbein et al. ) and the Aladin sky atlas ...

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.