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341. M67 variable stars photometry
ID:
ivo://CDS.VizieR/J/MNRAS/455/2337
Title:
M67 variable stars photometry
Short Name:
J/MNRAS/455/2337
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we continue the release of high-level data products from the multiyear photometric survey collected at the 67/92cm Schmidt Telescope in Asiago. The primary goal of the survey is to discover and to characterize variable objects and exoplanetary transits in four fields containing five nearby open clusters spanning a broad range of ages. This second paper releases a photometric catalogue, in five photometric bands, of the solar-age, solar-metallicity open cluster M 67 (NGC 2682). Proper motions are derived comparing the positions observed in 2013 at the Asiago's Schmidt Telescope with those extracted from Wide Field Imager@2.2m Max-Planck-Gesellschaft/European Southern Obseratory images in 2000. We also analyse the variable sources within M 67. We detected 68 variables, 43 of which are new detection. Variable periods and proper-motion memberships of a large majority of sources in our catalogue are improved with respect to previous releases. The entire catalogue will be available in electronic format. Besides the general interest on an improved catalogue, this work will be particularly useful because of: (1) the imminent release of Kepler/K2 Campaign-5 data of this clusters, for which our catalogue will provide an excellent, high spatial resolution input list, and (2) characterization of the M 67 stars which are targets of intense High Accuracy Radial velocity Planet Searcher and High Accuracy Radial velocity Planet Searcher for the Northern hemisphere radial-velocity surveys for planet search.
342. M53 variable stars V light curves
ID:
ivo://CDS.VizieR/J/A+A/358/547
Title:
M53 variable stars V light curves
Short Name:
J/A+A/358/547
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of the application of the Image Subtraction Method (ISM) to the CCD observations of the central region of globular cluster M53. We have obtained good quality light curves of the 23 previously known RR Lyrae stars in this cluster. We have also confirmed the variability of ten RR Lyrae candidates discovered by Kravtsov. Moreover, we have found four new variables of this type in the core of the cluster. Altogether, the light curves have been obtained for 37 RR Lyrae stars. We also report the discovery of variations in six cluster bright giants.
343. MWC 349A Halpha lines with 14<n<24 spectra
ID:
ivo://CDS.VizieR/J/A+A/571/L4
Title:
MWC 349A Halpha lines with 14<n<24 spectra
Short Name:
J/A+A/571/L4
Date:
21 Oct 2021
Publisher:
CDS
Description:
The UC-HII region of MWC 349A is the prototype of an ionized wind driven by a massive star surrounded by a disk. Recent high angular resolution observations of the millimeter recombination lines have shown that the disk rotates with a Keplerian law in its outer parts. However, the kinematics of innermost regions in the UC-HII region of MWC 349A is still unknown, in particular the radius where the wind is launched from the disk. We performed hydrogen recombination line observations with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory to study the kinematics of its innermost regions by studying their spectral features. In addition to the two laser peaks, we report the first detection of two new components that are blueshifted with respect to the laser peaks for all the recombination lines with principal quantum number n<22. These new spectral features originate from the region where the wind is ejected from the disk. We used our 3D non-LTE radiative transfer model for recombination lines (MORELI) to show that these features are consistent with the wind being ejected at a radius of about 24 AU from the star, which supports magnetohydrodynamic wind models.
344. Nearby visual double stars UBVRI photometry
ID:
ivo://CDS.VizieR/J/A+A/422/1023
Title:
Nearby visual double stars UBVRI photometry
Short Name:
J/A+A/422/1023
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present accurate CCD astrometric and photometric data for 31 nearby visual double stars in the standard filters BVRI. The observations were collected with a 1.3-m telescope in 2001-2002. The results consist of relative astrometric positions (epoch, angular separation and position angle) and differential BVRI photometry of the components. Mean errors are: 0.01" for the separation; 0.06{deg} for the position angle; and 0.015mag for the photometric data. Comparing the relative positions at different epochs, we evaluate the physical association of the systems. We additionally derive fractional masses and true separations for the most probable binary systems and, whenever orbits are available, also total and component masses.
345. New {beta} Cep stars in NGC 637
ID:
ivo://CDS.VizieR/J/A+A/533/A70
Title:
New {beta} Cep stars in NGC 637
Short Name:
J/A+A/533/A70
Date:
21 Oct 2021
Publisher:
CDS
Description:
Studying stellar pulsations in open clusters offers the possibility of performing ensemble asteroseismology. The reasonable assumption that the cluster members have the same age, distance, and overall metallicity aids in the seismic modelling process and tightly constrains it. Therefore it is important to identify open clusters with many pulsators. New pulsating stars of the beta Cephei type were searched for among the members of the open cluster NGC 637. Thirty-one hours of time-resolved V filter CCD photometry were obtained. The measurements confirmed two previously known variables, and revealed three new beta Cephei stars and one more candidate. All four pulsators have sufficiently large amplitudes for easy mode identification and are multiperiodic. With four certain pulsating members, NGC 637 is now among the open clusters that are richest in beta Cephei stars. It is thus an excellent target for ensemble asteroseismology, and to examine the differences between pulsating and apparently constant stars in the beta Cephei domain.
346. New times of maximum of CY Aqr
ID:
ivo://CDS.VizieR/J/other/JAD/16.2
Title:
New times of maximum of CY Aqr
Short Name:
J/other/JAD/16.2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a collection of 102 new times of maximum of the SX Phoenicis star CY Aquarii. These times, together with 20 times of maximum taken from the literature, lead to a new local linear ephemeris for 2003-2009 with a formally slightly shorter period than the one for 1996-2002. It will require at least another half decade of additional monitoring before any significant update to any model can be considered. Such monitoring should preferably occur at regular intervals, be done in a consistent photometric band, and at high time resolution. A set of 114 new times of maximum obtained since 2002 leads to a new local linear ephemeris for 2003-2009: Tmax=2426159.512(+/-0.001)+0.061038349E(+/-0.000000002).
347. New variable stars in NGC 6366
ID:
ivo://CDS.VizieR/J/other/RMxAA/44.365
Title:
New variable stars in NGC 6366
Short Name:
J/other/RMxAA/44
Date:
21 Oct 2021
Publisher:
CDS
Description:
New CCD photometry of NGC 6366 has lead to the discovery of some variable stars. Two possible Anomalous Cepheids (or Pop II Cepheids), three long period variables, one SX Phe and one eclipsing binary have been found. Also a list of 10 candidate variables is reported. The light curve of the RRab star, V1, has been decomposed into its Fourier harmonics, and the Fourier parameters were used to estimate the star's metallicity and distance; [Fe/H]=-0.87+/-0.14 and d=3.2+/-0.1kpc. It is argued that V1 may not be a member of the cluster but rather a more distant object. If this is so, an upper limit for the distance to the cluster of 2.8+/-0.1kpc can be estimated. The P-L relationship for SX Phe stars and the identified modes in the newly discovered SX Phe variable, V6, allow yet another independent determination of the distance to the cluster of d=2.7+/-0.1kpc. The M_V_-[Fe/H] relationship for RR Lyrae stars is addressed and the case of V1 is discussed.
348. New variable stars towards Galactic Bulge
ID:
ivo://CDS.VizieR/J/MNRAS/482/3058
Title:
New variable stars towards Galactic Bulge
Short Name:
J/MNRAS/482/3058
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of 3714 variable stars towards the Galactic bulge, including 2521 previously uncatalogued variables, using time-series photometry extracted from data obtained with the VIMOS imager at the Very Large Telescope. Observations of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field in the Galactic Bulge were taken over 2yr between March and October at a cadence of ~4d, enabling the detection of variables with periods up to ~100d. Many of these were already known, but we detected a significant number of new variables, including 11 Cepheids, a further 88 potential Cepheid candidates, and many contact binaries. Here we publish the catalogue of the new variables, containing coordinates, mean magnitudes as well as periods and classification; full light curves for these variables are also made available electronically.
349. New white dwarf pulsators for TESS
ID:
ivo://CDS.VizieR/J/MNRAS/478/2676
Title:
New white dwarf pulsators for TESS
Short Name:
J/MNRAS/478/2676
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of our survey searching for new white dwarf pulsators for observations by the TESS space telescope. We collected photometric time-series data on 14 white dwarf variable candidates at Konkoly Observatory, and found two new bright ZZ Ceti stars, namely EGGR 120 and WD 1310+583. We performed a Fourier analysis of the datasets. In the case of EGGR 120, which was observed on one night only, we found one significant frequency at 1332uHz with 2.3mmag amplitude. We successfully observed WD 1310+583 on eight nights, and determined 17 significant frequencies in the whole dataset. Seven of them seem to be independent pulsation modes between 634 and 2740uHz, and we performed preliminary asteroseismic investigations of the star utilizing six of these periods. We also identified three new light variables on the fields of white dwarf candidates: an eclipsing binary, a candidate delta Scuti/beta Cephei and a candidate W UMa-type star.
350. NGC 2004
ID:
ivo://CDS.VizieR/J/AJ/102/137
Title:
NGC 2004
Short Name:
J/AJ/102/137
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a new CCD photometric investigation of stars in the field of the LMC cluster NGC 2004 are reported and discussed. B, V photometry is given for more than 1500 objects, the large majority to be ascribed to the cluster. A new color-magnitude diagram is presented. It shows a well-defined blue sequence (BS) of H-burning stars, running from V~=21mag up to V~=13mag, together with a group of cluster He-burning red supergiants with V~=13mag and a clump of field red giants at about V~=19 mag. Theoretical evolutionary computations are reported covering the range of massive stars evolving in the cluster. These evolutionary tracks can match the observed CM diagram provided that a low efficiency of the surface convection (a low value of the mixing length) is adopted. Comparison of the theoretical luminosity function with the upper portion of the observed BS distribution suggests a cluster age of about 8 million years, in agreement with previous evaluations. The completeness of the sample and the contribution of field stars have been estimated. The CM distribution of cluster stars has been compared with the results of synthetic clusters based on the adopted evolutionary scenario. We find that the observed distribution of cluster stars in the different evolutionary phases appears in good agreement with prediction based on theoretical evolutionary lifetimes. Moreover, the distribution of H-burning stars agrees with a Salpeter distribution in the whole range 2<=M/M_{sun}_<=20. After a short review of the current theoretical scenario concerning massive stars, the CM diagram of field stars is discussed, reaching the conclusion that the observed clump of red giants is the natural consequence of the peculiar large lifetimes in the central He burning phase of stars with M~=3M_{sun}_.

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