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671. Oxygen abundances in chromospherically active stars
ID:
ivo://CDS.VizieR/J/A+A/423/677
Title:
Oxygen abundances in chromospherically active stars
Short Name:
J/A+A/423/677
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss oxygen abundances derived from [O I] 6300 and the O I triplet in stars spanning a wide range in chromospheric activity level, and show that these two indicators yield increasingly discrepant results with higher chromospheric/coronal activity measures. While the forbidden and permitted lines give fairly consistent results for solar-type disk dwarfs, spuriously high O I triplet abundances are observed in young Hyades and Pleiades stars, as well as in individual components of RS CVn binaries (up to 1.8dex). The distinct behaviour of the [O I]-based abundances which consistently remain near-solar suggests that this phenomenon mostly results from large departures from LTE affecting the O I triplet at high activity level that are currently unaccounted for, but also possibly from a failure to adequately model the atmospheres of K-type stars. These results suggest that some caution should be exercised when interpreting oxygen abundances in active binaries or young open cluster stars.
672. Parameters of RR Lyrae Type Variables
ID:
ivo://CDS.VizieR/J/PAZh/27/132
Title:
Parameters of RR Lyrae Type Variables
Short Name:
J/PAZh/27/132
Date:
21 Oct 2021
Publisher:
CDS
Description:
The method of statistical parallaxes is applied to a sample of 262 Rrab RR Lyr type variables with published photoelectric photometry, radial velocities, abundances and with known absolute proper motions. The proper motions are adopted from the Hipparcos, PPM, NPM1, and the Four-Million Catalog (Volchkov et al. 1992, Ed. by A.P.Gulyaev and V.V. Nesterov, Mosk. Gos. Univ., Moscow, p. 67) and in the case the last three catalogs are reduced to the Hipparcos system. The parameters of the velocity distribution of halo (U0, V0, W0) = ( -9+/-12, -214+/-10, -16+/-7) km/s and thick-disk (U0, V0, W0) = (-16+/-8, -41+/-7, -18+/-5) km/s RR Lyrae subsamples are inferred as well as the intensity-averaged absolute magnitudes of the corresponding populations: <MV> = 0.77+/-0.10 and <MV> = +1.11+/-0.28 for halo and thickdisk objects, respectively.
673. Parenago Catalog of Stars in Orion Nebula
ID:
ivo://CDS.VizieR/II/171
Title:
Parenago Catalog of Stars in Orion Nebula
Short Name:
II/171
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present catalogue is a machine-readable version of the catalogue of stars in the area of the Orion nebula, published by P.P. Parenago (1954). The sky area between 5h 24m and 5h 36m in right ascension (1900.0) and between -4 and -7 degrees in declination (1900.0), containing the Orion nebula, has been investigated in that work. Ten of variable stars in original Parenago (1954) catalogue had CSV numbers (Kukarkin et al., 1951) but since that time all of them were confirmed as variables and included in GCVS (Kholopov et al., 1985a&b, 1987). We superseded CSV-numbers by GCVS-names in the machine-readable version for the following stars: ------------------------------------------------ Number in CSV-number GCVS-name the catalogue ------------------------------------------------ 1605 606 V372 ORI 1613 607 V373 ORI 1635 608 V374 ORI 1713 609 V375 ORI 1748 610 V387 ORI 1762 100569 V376 ORI 1974 617 V377 ORI 2183 625 V388 ORI 2393 630 V380 ORI 2478 634 V381 ORI ------------------------------------------------
674. Par-Lup3-4 CO ALMA images
ID:
ivo://CDS.VizieR/J/A+A/640/A13
Title:
Par-Lup3-4 CO ALMA images
Short Name:
J/A+A/640/A13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12M_{sun}_ object known to power an optical jet. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2-1), CO(3-2), and ^13^CO(3-2). Our observations reveal for the first time the base of a bipolar molecular outflow in a very low-mass star, as well as a stream of material moving perpendicular to the primary outflow of this source. The primary outflow morphology is consistent with the previously determined jet orientation and disk inclination. The outflow mass is 9.5x10^-7^M_{sun}_, with an outflow rate of 4.3x10^-9^M_{sun}_/yr. A new fitting to the spectral energy distribution suggests that Par-Lup3-4 may be a binary system. We have characterized Par-Lup3-4 in detail, and its properties are consistent with those reported in other very low-mass sources. This source provides further evidence that very low-mass sources form as a scaled-down version of low-mass stars.
675. Patterns of color variations in close binaries
ID:
ivo://CDS.VizieR/J/A+A/480/495
Title:
Patterns of color variations in close binaries
Short Name:
J/A+A/480/495
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the first of a series of papers in which we present the results of a long-term photometric monitoring project carried out at Catania Astrophysical Observatory aimed at studying magnetic activity in late-type components of close binary systems, its dependence on global stellar parameters, and its evolution on different time scales from days to years. In this first paper, we present the complete observation dataset and new results of an investigation into the origin of brightness and color variations observed in the well-known magnetically active close binary stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra . About 38000 high-precision photoelectric nightly observations in the U, B and V filters are analysed. Correlation and regression analyses of the V magnitude vs. U-B and B-V color variations are carried out and a comparison with model variations for a grid of active region temperature and filling factor values is also performed. We find the existence of two different patterns of color variation. Eight stars in our sample: BY Dr, VY Ari, V775 Her, II Peg, V1149 Ori, HU Vir, EI Eri and DH Leo become redder when they become fainter, as is expected from the presence of active regions consisting of cool spots. The other six stars show the opposite behaviour, i.e. they become bluer when they become fainter. For V711 Tau this behaviour could be explained by the increased relative U- and B- flux contribution by the earlier-type component of the binary system when the cooler component becomes fainter. On the other hand, for AR Psc, UX Ari, RS CVn, SZ Psc and AR Lac the existence of hot photospheric faculae must be invoked. We also found that in single-lined and double-lined binary stars in which the fainter component is inactive or much less active the V magnitude is correlated to B-V and U-B color variations in more than 60% of observation seasons. The correlation is found in less than 40% of observation seasons when the fainter component has a non-negligible level of activity and/or hot faculae are present but they are either spatially or temporally uncorrelated to spots.
676. Period analysis of 7 field RRab stars
ID:
ivo://CDS.VizieR/J/ApJ/863/151
Title:
Period analysis of 7 field RRab stars
Short Name:
J/ApJ/863/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the times of light maximum collected from the GEOS RR Lyrae database and determined from sky surveys, we utilize the O-C method to study the period variations of seven field ab-type RR Lyrae stars. The time coverage of data for most stars is more than 100 years, allowing us to investigate period changes over a large time span. We find that the O-C diagrams for most stars can be described by a combination of cyclic variations and long-term period changes. Assuming the former were caused by the light-travel-time effect, the pulsation and orbital parameters are obtained by the nonlinear fitting. We find that the orbital periods in our sample range from 33 to 78 years, and the eccentricities are relatively higher than the results for other candidates (e>0.6). The minimal masses of the potential companions of XX And, BK Dra, and RY Psc are less than one solar mass, and those of SV Eri, AR Her, and RU Scl are 3.3, 2.1, and 3.4M_{sun}_, respectively. Moreover, we suggest that the companion of AR Her may be a blue straggler that experienced mass transfer or a merger of two stars. The O-C diagram for ST Vir also shows distinct long- term period decrease, and in the O-C residuals, additional quasi-periodic variations that can be described by damped oscillation are found. Combining the data from the literature and our analysis, we plot the log P-AO-C diagram. The distribution of our binary candidates suggests that their period variations are not caused by the Blazhko effect.
677. Period change for 143 SuperWASP eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/549/A86
Title:
Period change for 143 SuperWASP eclipsing binaries
Short Name:
J/A+A/549/A86
Date:
21 Oct 2021
Publisher:
CDS
Description:
Building on previous work, a new search of the SuperWASP archive was carried out to identify eclipsing binary systems near the short-period limit. 143 candidate objects were detected with orbital periods between 16000 and 20000s, of which 97 are new discoveries. Period changes significant at 1{sigma} or more were detected in 74 of these objects, and in 38 the changes were significant at 3{sigma} or more. The significant period changes observed followed an approximately normal distribution with a half-width at half-maximum of ~0.1s/yr. There was no apparent relationship between period length and magnitude or direction of period change. Amongst several interesting individual objects studied, 1SWASP J093010.78+533859.5 is presented as a new doubly eclipsing quadruple system, consisting of a contact binary with a 19674.575s period and an Algol-type binary with a 112799.109s period, separated by 66.1AU, being the sixth known system of this type.
678. Period changes in SuperWASP eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/578/A136
Title:
Period changes in SuperWASP eclipsing binaries
Short Name:
J/A+A/578/A136
Date:
21 Oct 2021
Publisher:
CDS
Description:
Orbital period changes of binary stars may be caused by the presence of a third massive body in the system. Here we have searched the archive of the Wide Angle Search for Planets (SuperWASP) project for evidence of period variations in 13927 eclipsing binary candidates. Sinusoidal period changes, strongly suggestive of third bodies, were detected in 2% of cases; however, linear period changes were observed in a further 22% of systems. We argue on distributional grounds that the majority of these apparently linear changes are likely to reflect longer-term sinusoidal period variations caused by third bodies, and thus estimate a higher-order multiplicity fraction of 24% for SuperWASP binaries, in good agreement with other recent figures for the fraction of triple systems amongst binary stars in general.
679. Period changes of 148 Galactic Cepheids
ID:
ivo://CDS.VizieR/J/MNRAS/511/2125
Title:
Period changes of 148 Galactic Cepheids
Short Name:
J/MNRAS/511/2125
Date:
14 Feb 2022 13:42:07
Publisher:
CDS
Description:
Investigating period changes of classical Cepheids through the framework of O-C diagrams provides a unique insight to the evolution and nature of these variable stars. In this catalogue, we present the O-C diagrams and period change rates derived for 148 Galactic Classical Cepheids variables, along with the exact period values of these stars for a given date as determined by the O-C diagrams. The catalogue also contains photometric data adopted from Gaia EDR3 and the David Dunlap Observatory Cepheid Database, which were used for the study, and the results obtained from the statistical modelling of the individual O-C diagrams. We find that a significant fraction of the Cepheids show period fluctuations, which appear on the O-C diagrams as quasi-periodic waves, which could be modelled and described through the statistical framework. For completeness, we also included all photometric data collected from various previous publications and survey that were used for the research.
680. Periodic variables in Catalina and LINEAR
ID:
ivo://CDS.VizieR/J/other/Ap/64.27
Title:
Periodic variables in Catalina and LINEAR
Short Name:
J/other/Ap/64.27
Date:
22 Feb 2022
Publisher:
CDS
Description:
In this study we continue spectral class determinations for large number of optically faint periodic variables taken from the Catalina Surveys Data Release 1 (CSDR1)and LINEAR data sets. Spectral classes and physical parameters are presented for 1184 periodic variables with periods P>=10 days, taken from modern large sky area spectroscopic and photometric databases, including LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope), SDSS(Sloan Digital Sky Survey), the Hamburg Quasar Survey(HQS)m the Hamburg /ESO Survey (HES), and Gaia Data Release 2 (DR2). In Gaia DR2 catalogue, luminosities are presented for 276 objects and radial velocities (RV) for 108. Spectral classes were confirmed for more than 650 objects. The majority of the variables are found to be F, G, K, M dwarfs and giants, a few dozen carbon (C) stars (N-type Asymptotic Giant Branch (AGB) stars), and a few S stars. Some periodic variables are blue objects, such as B and A stars. The periods are in the range 10<=P<=1504 days and Catalina magnitudes in range 11.5<=V<=20.0mag. Finding new and faint evolved AGB stars in the halo of our Galaxy is the first priority. A catalogue containing multi-parameter data for 1184 periodic variables from modern astronomical databases has been generated.