- ID:
- ivo://CDS.VizieR/J/A+A/461/509
- Title:
- Membership and spectroscopy of IC 2391
- Short Name:
- J/A+A/461/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution. The young and nearby open cluster IC 2391 is well-suited to studies of these two evolutionary phases. We establish a bona fide set of cluster members and then analyze this set in terms of binary frequency, projected rotational velocities, [Fe/H], and lithium abundance. In the wake of the Hipparcos distance controversy for the Pleiades, we compare the main-sequence fitting distance modulus to the Hipparcos mean parallax for IC 2391.
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192. Members of IC 2391
- ID:
- ivo://CDS.VizieR/J/A+AS/126/357
- Title:
- Members of IC 2391
- Short Name:
- J/A+AS/126/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New 4-colour BV(RI)_KC_ CCD photometry to a limiting magnitude of V=~19 is presented for 1428 objects observed towards the direction of the young, open cluster IC 2391. We observed 36 (2'x3') fields within 17arcmin of the nominal cluster core. By fitting the theoretical isochrones of D'Antona & Mazzitelli (1994ApJS...90..467D) to a combination of colour-magnitude and colour-colour diagrams, we have identified 17 stars as probable cluster members with a further 85 stars as possible members. The brightness distribution of low-mass members is compared with the luminosity function observed for the Pleiades and we estimate that the contamination due to background giants should be small.
- ID:
- ivo://CDS.VizieR/J/AJ/147/130
- Title:
- Minimum times of 7 eclipsing systems
- Short Name:
- J/AJ/147/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The minimum timings of eclipsing binaries V418 Aql, SU Boo, RV CVn, CR Cas, GV Cyg, V432 Per, and BD+42 2782 were collected and analyzed. Their long-term behavior was studied via period analysis, revealing a periodic term in eclipse times. We derived 576 new times of minimum. Hence, to describe the periodic variation, a third-body hypothesis was proposed and the resulting orbital periods are as follows: 70, 7.4, 53, 37, 27, 53, and 18 yr, respectively. For the system V432 Per an additional 9.5 yr variation was also found. The predicted minimum masses of these distant bodies were calculated and their detectability discussed. The light curves of SU Boo and RV CVn were analyzed using the PHOEBE program, resulting in physical parameters of the components. New variable stars in the field of V418 Aql were discovered.
- ID:
- ivo://CDS.VizieR/J/AJ/118/453
- Title:
- M9 RR Lyrae CCD observations
- Short Name:
- J/AJ/118/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations have been used to study 16 of the previously known variables in the Oosterhoff type II globular cluster M9. The properties of the RR Lyrae variables in M9 are compared with those in the Oosterhoff type I cluster M3. Methods devised by Simon, Jurcsik, & Kovacs have been used to derive physical parameters for the stars from Fourier analysis. The mean metal abundance so derived for M9, [Fe/H]=-1.77, is in good agreement with the metal abundance derived from spectroscopic observations. All methods for calculating the absolute magnitudes of RR Lyrae variables from Fourier coefficients indicate that the RR Lyrae variables in M9 are more luminous than those in M3. However, there are three RR Lyrae stars in M3 that may be as bright as the M9 stars. These three are thought to be in a more advanced evolutionary state than the other M3 RR Lyrae stars. Absolute magnitudes have also been derived for the RR Lyrae stars in M68 and M107. The different methods predict that RR Lyrae stars in metal-poor clusters are more luminous than those in more metal-rich clusters, but there are inconsistencies in the relative luminosities derived by the different methods.
- ID:
- ivo://CDS.VizieR/J/AJ/107/622
- Title:
- M68 variable star light curves
- Short Name:
- J/AJ/107/622
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 20 CCD images of the globular cluster M68, taken during 14th - 17th April 1989 with the 1.5m Danish telescope in La Silla, have been the subject of a photometric investigation.
- 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.
- 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.
- 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.
- 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.
- 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.
