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41. All Sky Automated Survey variable stars
ID:
ivo://CDS.VizieR/J/AcA/48/35
Title:
All Sky Automated Survey variable stars
Short Name:
J/AcA/48/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results of the first two months of observations using the All Sky Survey prototype camera are presented. More than 45000 stars in 24 Selected Fields covering 140 square degrees were monitored a few times per night resulting in the I-band catalog containing 10^7^ individual measurements. Period search revealed 126 variable stars brighter than 13mag with periods less than 20d. Only 30 of them are known variable stars included in the General Catalogue of Variable Stars (<II/214>). The other 90 objects are newly detected variable stars - mainly eclipsing binaries (75%) and pulsating stars (17%). We estimate that completeness of the current catalogs of variable stars is smaller than 50% already for the stars brighter than 9mag. The catalog is accessible over the WWW: http://www.astrouw.edu.pl/~gp/asas/asas.html
42. All-Sky Compiled Catalogue of 2.5 million stars
ID:
ivo://CDS.VizieR/I/280B
Title:
All-Sky Compiled Catalogue of 2.5 million stars
Short Name:
I/280B
Date:
21 Oct 2021
Publisher:
CDS
Description:
The All-Sky Compiled Catalogue of 2501313 stars (ASCC-2.5) with the limiting magnitude V=12-14 is a result of a merging of star lists from present day large high-precision catalogues from space (Hipparcos- Tycho family catalogues: Hipparcos main catalogue including Multiple System Annex [I/239], Tycho-1 [I/239], Tycho-2 [I/259], ACT-RC [I/246], TRC [I/250]) and ground-based (PPM-N [I/146], PPM-S [I/193], PPM-add [I/208], CMC11 [I/256]) observations and reduction to standard systems of corresponding stellar data. The data from the Tycho-2 Spectral Type Catalog [III/231], and the 2MASS All-Sky Catalog of Point Sources [II/246] are added. The basic stellar data presented in the ASCC-2.5 are the equatorial coordinates (J2000, epoch 1991.25), proper motions in the Hipparcos system, B and/or V stellar magnitudes in the Johnson system. Additionally, for some stars we give trigonometric parallaxes, spectral classes in the MK or HD system, multiplicity and variability flags, Hipparcos, Tycho-2, HD, DM designations. Equatorial coordinates and their standard errors were taken from the source catalogues in accordance with the priority: Hipparcos [I/239/hip_main], Tycho-2 [I/259], Tycho-1 [I/239/tyc_main], CMC11 [I/256], PPM [I/146,I/193,I/208]. Proper motions from the source catalogues were compared with Hipparcos data.The compiled proper motions in the Hipparcos system and their standard errors were computed as the weighted means. The weights were set in accordance with the proper motion errors listed for individual stars in the source catalogues. Trigonometric parallaxes are taken from the Hipparcos and Tycho-1 catalogues. Stellar B, V magnitudes were determined on the basis of the ground- based photometric data taken from CMC11, Hipparcos, as well as space BT, VT from Tycho-1, Tycho-2. Magnitudes from the PPM catalogue were used if no other photometric data were available. Tycho data were transformed to the Johnson system via: V = VT - 0.09 (B-V)T + dV, (B-V) = 0.850 (B-V)T + d(B-V), i.e. using the recommendations from the Introduction to the Tycho catalogue and including additional corrections dV and d(B-V). These additional corrections were determined by comparison with ground-based data in the Johnson system. These corrections depend non-linearly on colour and reach 0.02 and 0.04 mag, respectively. Infrared stellar magnitudes J, H, K_s_ and their errors were copied from the 2MASS catalogue. Spectral classes in the MK or HD systems were taken from Hipparcos, CMC11, PPM, and Tycho-2 Spectral Type catalogues. Multiplicity and variability flags were taken from Tycho-1, Tycho-2, Hipparcos, CMC11, and PPM catalogues. The 1st version of the ASCC-2.5 contained some errors in the zones -1 to +1 degree which have been corrected (see details in the "History" section below). The 2nd version included a new file (ccadd.dat) containing the previously missing stars (including components of multiple systems). Note that the ASCC numbers did not change between the two versions, but additional numbers (2600001 to 2603318) were assigned. In the present 3rd version of the ASCC-2.5 the stars from file ccadd.dat are inserted in the basic files in accordance with their coordinates. Stars in the ASCC-2.5 are divided into 30 files ordered by declination (North and South polar caps and 28 bands of 5 degrees width), then sorted in order of right ascension within each file.
43. {alpha}-element abundances of Cepheid stars
ID:
ivo://CDS.VizieR/J/A+A/580/A17
Title:
{alpha}-element abundances of Cepheid stars
Short Name:
J/A+A/580/A17
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new homogeneous measurements of Na, Al, and three alpha-elements (Mg, Si, Ca) for 75 Galactic Cepheids, complemented with Cepheid abundances available in the literature, for a total of 439 stars. The abundances are based on high spectral resolution (R~38000) and high signal-to-noise ratio (S/N~50-300) spectra collected with UVES at ESO VLT. Special attention was given to providing a homogeneous abundance scale for these five elements plus iron. In addition, accurate Galactocentric distances (RG) based on near-infrared photometry are also available for all the Cepheids in the sample. We found that these five elements display well-defined linear radial gradients and modest standard deviations over the entire range of RG. The [element/Fe] abundance ratios are constant across the entire thin disk and over the entire period range; only the Ca radial distribution shows marginal evidence of slopes. These results indicate that the chemical enrichment history of iron and of the quoted elements has been quite similar across the four quadrants of the Galactic thin disk, and very homogenous within the range in age covered by the Cepheids (~10-300Myr). Finally, we also find that Cepheid abundances agree with similar abundances for thin and thick disk dwarf stars, and they follow the typical Mg-Al and Na-O correlations.
44. alpha Leo spectro-interferometric observation
ID:
ivo://CDS.VizieR/J/MNRAS/511/4724
Title:
alpha Leo spectro-interferometric observation
Short Name:
J/MNRAS/511/4724
Date:
15 Mar 2022 08:32:16
Publisher:
CDS
Description:
Differential Interferometry allows to obtain the differential visibility and phase, in addition to the spectrum. The differential phase contains important information about the structure and motion of stellar photosphere such as stellar spots and non-radial pulsations, and particularly the rotation. Thus, this interferometric observable strongly helps to constrain the stellar fundamental parameters of fast rotators. The spectroastrometry mainly uses the photocentre displacements, which is a first approximation of the differential phase, and is applicable only for unresolved or marginally objects. We study here the sensitivity of relevant stellar parameters to the simulated photocentres using the scirocco code: a semi-analytical algorithm dedicated to fast rotators, applied to two theoretical modelling stars based on Achernar and Regulus, in order to classify the importance of these parameters and their impact on the modelling. We compare our simulations with published VLTI/AMBER data. This work sets the limits of application of photocentre displacements to fast rotators, and under which conditions we can use the photocentres and/or the differential phase, through a pre-established physical criterion. To validate our theoretical study, we apply our method of analysis on observed data of the edge-on fast rotator Regulus. For unresolved targets, with a visibility V~1, the photocentre can constrain the main stellar fundamental parameters of fast rotators, whereas from marginally resolved objects (0.8<=V<1), mainly the rotation axis position angle (PA_rot_) can be directly deduced from the vectorial photocentre displacement, which is very important for young cluster studies.
45. alpha Persei and Praesepe Clusters
ID:
ivo://CDS.VizieR/J/AJ/123/1570
Title:
alpha Persei and Praesepe Clusters
Short Name:
J/AJ/123/1570
Date:
21 Oct 2021
Publisher:
CDS
Description:
Two hundred forty-two members of the Praesepe and alpha Persei clusters have been surveyed with high angular resolution 2.2{mu}m speckle imaging on the 3m Infrared Telescope Facility, the 5m Hale, and the 10m Keck telescopes, along with direct imaging using the near-infrared camera (NICMOS) aboard the Hubble Space Telescope. The observed stars range in spectral type from B (~5M_{sun}_) to early M (~0.5M_{sun}_), with the majority of the targets more massive than ~0.8M_{sun}_. The one quadruple and 39 binary systems detected encompass separations from 0.053" to 7.28"; 28 of the systems are new detections, and there are nine candidate substellar companions.
46. Amplitudes of single-mode Cepheids
ID:
ivo://CDS.VizieR/J/A+A/504/959
Title:
Amplitudes of single-mode Cepheids
Short Name:
J/A+A/504/959
Date:
21 Oct 2021
Publisher:
CDS
Description:
The dependence of amplitude on the pulsation period differs from other Cepheid-related relationships. We attempt to revise the period-amplitude (P-A) relationship of Galactic Cepheids based on multi-colour photometric and radial velocity data. Reliable P-A graphs for Galactic Cepheids constructed for the U, B, V, Rc, and Ic photometric bands and pulsational radial velocity variations facilitate investigations of previously poorly studied interrelations between observable amplitudes. The effects of both binarity and metallicity on the observed amplitude, and the dichotomy between short- and long-period Cepheids can both be studied. A homogeneous data set was created that contains basic physical and phenomenological properties of 369 Galactic Cepheids. Pulsation periods were revised and amplitudes were determined by the Fourier method. P-A graphs were constructed and an upper envelope to the data points was determined in each graph. Correlations between various amplitudes and amplitude-related parameters were searched for, using Cepheids without known companions.
47. Analysis of the B3IV star HD 43317
ID:
ivo://CDS.VizieR/J/A+A/542/A55
Title:
Analysis of the B3IV star HD 43317
Short Name:
J/A+A/542/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
OB stars are important building blocks of the Universe, but we have only a limited sample of them well understood enough from an asteroseismological point of view to provide feedback on the current evolutionary models. Our study adds one special case to this sample, with more observational constraints than for most of these stars. Our goal is to analyse and interpret the pulsational behaviour of the B3 IV star HD 43317 using the CoRoT light curve along with the ground-based spectroscopy gathered by the Harps instrument. This way we continue our efforts to map the Beta Cep and SPB instability strips. We used different techniques to reveal the abundances and fundamental stellar parameters from the newly-obtained high-resolution spectra. We used various time-series analysis tools to explore the nature of variations present in the light curve. We calculated the moments and used the pixel-by-pixel method to look for line profile variations in the high- resolution spectra. We find that HD 43317 is a single fast rotator (v_rot_~50%v_crit_) and hybrid SPB/Beta Cep-type pulsator with Solar metal abundances. We interpret the variations in photometry and spectroscopy as a result of rotational modulation connected to surface inhomogeneities, combined with the presence of both g and p mode pulsations. We detect a series of ten consecutive frequencies with an almost constant period spacing of 6339s as well as a second shorter sequence consisting of seven frequencies with a spacing of 6380s. The dominant frequencies fall in the regime of gravito- inertial modes.
48. AN Lyn light maxima
ID:
ivo://CDS.VizieR/J/A+A/328/235
Title:
AN Lyn light maxima
Short Name:
J/A+A/328/235
Date:
21 Oct 2021
Publisher:
CDS
Description:
New uvby data collected of AN Lyn together with the reanalysis of old data establish that this star is a multiperiodic pulsator. Three independent frequencies ({nu}_1_=10.1756, {nu}_2_=18.1309 and {nu}_3_=9.5598c/d) and some interactions between them are found to be present in the light curve. Changes in amplitude with a large time scale are confirmed for the main frequency. Moreover, changes in amplitude are also present for the secondary frequencies, especially for {nu}_3_. After subtraction of the secondary frequencies from the light curves, the classical O-C method has been used to analyse the behaviour of the main period. A comparison is made between AN Lyn and the other two known {delta} Sct stars with atypical light curves, i.e., V1719 Cyg and V798 Cyg. New uvby data have been also collected for V1719 Cyg and the O-C method has been used to analyse the behaviour of the main period. It is found that the main pulsation of this star can be well described by means of a linear ephemeris with a period of P=0.26729700d over the last eighteen years. Finally, analysis of the different data sets available in the literature do not reveal significative changes in the amplitude of the main frequency of V1719 Cyg.
49. Anomalous RRd stars in Magellanic Clouds
ID:
ivo://CDS.VizieR/J/MNRAS/463/1332
Title:
Anomalous RRd stars in Magellanic Clouds
Short Name:
J/MNRAS/463/1332
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars has been extracted from the latest edition of the Optical Gravitational Lensing Experiment collection of RR Lyrae variables in the Magellanic System. The stars pulsating simultaneously in the fundamental (F) and first-overtone (1O) modes have distinctly different properties than regular double-mode RR Lyrae variables (RRd stars). The P_1O_/P_F_ period ratios of our anomalous RRd stars are within a range of 0.725-0.738, while 'classical' double-mode RR Lyrae variables have period ratios in the range of 0.742-0.748. In contrast to the typical RRd stars, in the majority of the anomalous pulsators, the F-mode amplitudes are higher than the 1O-mode amplitudes. The light curves associated with the F-mode in the anomalous RRd stars show different morphology than the light curves of, both, regular RRd stars and single-mode RRab stars. Most of the anomalous double-mode stars show long-term modulations of the amplitudes (Blazhko-like effect). Translating the period ratios into the abundance parameter, Z, we find for our stars Z{in}(0.002, 0.005) - an order of magnitude higher values than typical for RR Lyrae stars. The mass range of the RRd stars inferred from the W_I_ versus P_F_ diagram is (0.55-0.75)M_{sun}_. These parameters cannot be accounted for with single star evolution assuming a Reimers-like mass-loss. Much greater mass-loss caused by interaction with other stars is postulated. We blame the peculiar pulsation properties of our stars to the parametric resonance instability of the 1O-mode to excitation of the F- and 2O-modes as with the inferred parameters of the stars 2{omega}_1O_~={omega}_F_+{omega}_2O_.
50. An SX Phoenicis Variable light curve
ID:
ivo://CDS.VizieR/J/AZh/84/695
Title:
An SX Phoenicis Variable light curve
Short Name:
J/AZh/84/695
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present investigation of V=17mag star, which appears to be SX Phe type variable. Observations at 1.8 and 1.0 meter telescopes of Boyhunsan and Mount Lemon observatories permit us to improve the light elements and to investigate the power spectrum. We applied a Fourier decomposition to the data in order to determine the component frequencies of the synthetic light curve, and five components including a pair of closely separated components of f_1_=24.6539 and f_2_=24.8173 c/d were identified. We proposed that one of these two components corresponds to a non-radial oscillation mode. Other observed frequencies are the combinations of the first two. Metallicity of the star was estimated to be [Fe/H]<-2. We also found that one of the faint variable stars, No. 14, in the field is RRc type pulsator.