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Register a new userCatalog of averaged magnetic phase curves of stars: the second edition
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Magnetized stars exhibit periodic variations of their longitudinal global magnetic fields, $B_e$, owing to rotation. Here, we present the second catalog of averaged stellar magnetic rotational phase curves and their parameters derived from a compilation of the published observational data and personal communications for 350 stars of various spectral types, which were published up to the end of December 2019. Magnetic Ap and Bp stars constitute the most numerous subset in the catalog (215 objects). Phase curves were obtained by fitting either a sinusoid or a double sine wave to series of the observed $B_e$ measurements using the least squares method. For some stars, we present magnetic phase curves derived from time series of the surface magnetic field, $B_s$, or obtained improved values of the rotational period, $P_{rm rot}$. We have also identified eight stars in our catalog that host planets or planetary systems.
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The second version of the catalog contains information about 275 stars of different types. During the time that has elapsed since the creation of the first catalog, situation fundamentally changed primarily due to the significant increase of accuracy of magnetic fields (MF) measurements. Up to now global magnetic field were discoverd and measured in stars of many types and their behavior partially was studied. Magnetic behavior of Ap Bp stars is the most thoroughly studied. The catalog contains information about 182 such objects. The main goals for the construction of the catalog are: 1. Review and summarize our kowledge about magnetic behavior of different types of stars. 2. The whole data are uniformly presented and processed which will allow one to perform statistical analysis of the variability of the (longitudinal) magnetic fields of stars. 3. The informations are presented in the most convenient form for testing different theoretical models of different kind. 4. The catalog will be useful for the development of observational programs.
We present a cross-calibration of Hipparcos and Gaia EDR3 intended to identify astrometrically accelerating stars and to fit orbits to stars with faint, massive companions. The resulting catalog, the EDR3 edition of the Hipparcos-Gaia Catalog of Accelerations (HGCA), provides three proper motions with calibrated uncertainties on the EDR3 reference frame: the Hipparcos proper motion, the Gaia EDR3 proper motion, and the long-term proper motion given by the difference in position between Hipparcos and Gaia EDR3. Our approach is similar to that for the Gaia DR2 edition of the HGCA, but offers a factor of ~3 improvement in precision thanks to the longer time baseline and improved data processing of Gaia EDR3. We again find that a 60/40 mixture of the two Hipparcos reductions outperforms either reduction individually, and we find strong evidence for locally variable frame rotations between all pairs of proper motion measurements. The substantial global frame rotation seen in DR2 proper motions has been removed in EDR3. We also correct for color- and magnitude-dependent frame rotations at a level of up to ~50 $mu$as/yr in Gaia EDR3. We calibrate the Gaia EDR3 uncertainties using a sample of radial velocity standard stars without binary companions; we find an error inflation factor (a ratio of total to formal uncertainty) of 1.37. This is substantially lower than the position dependent factor of ~1.7 found for Gaia DR2 and reflects the improved data processing in EDR3. While the catalog should be used with caution, its proper motion residuals provide a powerful tool to measure the masses and orbits of faint, massive companions to nearby stars.
The number of known variable stars has increased by several magnitudes over the last decade, and automated classification routines are becoming increasingly important to cope with this development. Here we show that the upside-down CBH variables, which were proposed as a potentially new class of variable stars by Heinze et al. (2018) in the ATLAS First Catalogue of Variable Stars, are, at least to a high percentage, made up of alpha2 Canum Venaticorum (ACV) variables - that is, photometrically variable magnetic chemically peculiar (CP2/He-peculiar) stars - with distinct double-wave light curves. Using suitable selection criteria, we identified 264 candidate ACV variables in the ATLAS variable star catalogue. 62 of these objects were spectroscopically confirmed with spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (all new discoveries except for nine stars) and classified on the MK system. The other 202 stars are here presented as ACV star candidates that require spectroscopic confirmation. The vast majority of our sample of stars are main-sequence objects. Derived masses range from 1.4M(Sun) to 5M(Sun), with half our sample stars being situated in the range from 2 M(Sun) to 2.4 M(Sun), in good agreement with the spectral classifications. Most stars belong to the thin or thick disk; four objects, however, classify as members of the halo population. With a peak magnitude distribution at around 14th magnitude, the here presented stars are situated at the faint end of the known Galactic mCP star population. Our study highlights the need to consider rare variability classes, like ACV variables, in automated classification routines.
We present a catalog of stellar properties for a large sample of 6676 evolved stars with APOGEE spectroscopic parameters and textit{Kepler} asteroseismic data analyzed using five independent techniques. Our data includes evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed by accounting for differences in their solar reference values. We include theoretically motivated corrections to the large frequency spacing ($Delta u$) scaling relation, and we calibrate the zero point of the frequency of maximum power ($ u_{rm max}$) relation to be consistent with masses and radii for members of star clusters. For most targets, the parameters returned by different pipelines are in much better agreement than would be expected from the pipeline-predicted random errors, but 22% of them had at least one method not return a result and a much larger measurement dispersion. This supports the usage of multiple analysis techniques for asteroseismic stellar population studies. The measured dispersion in mass estimates for fundamental calibrators is consistent with our error model, which yields median random and systematic mass uncertainties for RGB stars of order 4%. Median random and systematic mass uncertainties are at the 9% and 8% level respectively for RC stars.
We have recently announced that the General Catalogue of Variable Stars enters the stage of its fifth, purely electronic edition (GCVS 5.1). Recently, we have incorporated a new, completely revised version for 1408 variable stars in the constellation of Centaurus into the GCVS 5.1. Working on this revision, we used current possibilities of data mining, suggested new variability types for many variable stars, found new light elements for a large number of periodic variables. This paper describes the work fulfilled during the preparation of the GCVS 5.1 version for Centaurus, discusses in detail a number of cases most significant astrophysically.
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