- ID:
- ivo://CDS.VizieR/J/A+A/542/A89
- Title:
- Hvar survey for roAp stars. I.
- Short Name:
- J/A+A/542/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rapidly oscillating Ap (roAp) stars exhibit short time scale photometric and/or radial velocity variations, which are most important to test current pulsation models as well as our assumptions of the atmospheric structure characteristics. In addition, their chemical peculiarity makes them very interesting for probing stellar formation and evolution in the presence of a global magnetic field. To date, only a limited number of about 45 roAp stars are known. In order to increase the sample, we obtained photometric time series of 20 good roAp candidates to search for pulsations. We present the time series analysis of about 60 hours of CCD photometry taken at the 1 meter Austrian-Croatian Telescope (Hvar Observatory) and derive effective temperatures for the programme objects. The upper amplitude limits of the Fourier spectra are typically below 2mmag in Bessell B with one good candidate for follow-up observations to find possible pulsation. In addition, we present a list of further roAp candidates, worth to be (re)investigated.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/137/3181
- Title:
- HW Vir differential VR light curves
- Short Name:
- J/AJ/137/3181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the very short period subdwarf B eclipsing binary HW Vir, we present new CCD photometry made from 2000 through 2008. In order to obtain consistency of the binary parameters, our new light curves, showing sharp eclipses and a striking reflection effect, were analyzed simultaneously with previously published radial velocity data. The secondary star parameters of M_2_=0.14M_{sun}_, R_2_=0.18R_{sun}_, and T_2_=3084K are consistent with those of an M6-7 main-sequence star. A credibility issue regarding bolometric corrections is emphasized. More than 250 times of minimum light, including our 41 timings and spanning more than 24yr, were used for a period study. From a detailed analysis of the O-C diagram, it emerged that the orbital period of HW Vir has varied as a combination of a downward-opening parabola and two sinusoidal variations, with cycle lengths of P_3_=15.8yr and P_4_=9.1yr and semiamplitudes of K_3_=77s and K_4_=23s, respectively. The continuous period decrease with a rate of -8.28x10^-9^d/yr may be produced by angular momentum loss due to magnetic stellar wind braking but not by gravitational radiation.
283. IC 348 membership
- ID:
- ivo://CDS.VizieR/J/ApJ/593/1093
- Title:
- IC 348 membership
- Short Name:
- J/ApJ/593/1093
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new census of the stellar and substellar members of the young cluster IC 348. We have obtained images at I and Z for a 42'x28' field encompassing the cluster and have combined these measurements with previous optical and near-infrared photometry. From spectroscopy of candidate cluster members appearing in these data, we have identified 122 new members, 15 of which have spectral types of M6.5M9, corresponding to masses of ~0.08-0.015M_{sun}_ by recent evolutionary models. The latest census for IC 348 now contains a total of 288 members, 23 of which are later than M6 and thus are likely to be brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/361/929
- Title:
- IC 4651 uvby photometry
- Short Name:
- J/A+A/361/929
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New accurate CCD photometry in the u, v, b and y bands of the Stroemgren system filters has been obtained for 17640 stars to approximately. V=20mag in a approximately 21' x 21' field centered on the intermediate-age open cluster IC 4651. The observations was obtained with the Danish 1.5-m telescope at the European Southern Observatory, La Silla, Chile. Table 1 contains information about the Date, Night, Filter, Exposure time, Airmass, CCD rotation angle, and RA- , DE-offsets for all 89 frames. Table 2 gives cross-references between the MEI-system (this paper) and the Lindoff (1972A&AS....7..231L, IC 4651 NNN), Eggen (1971ApJ...166...87E, Cl* IC 4651 Egg NN), Anthony-Twarog & Twarog (1987AJ.....94.1222A, Cl* IC 4651 AT 1-NNN, Cl* IC 4651 AT 2-NN), and Anthony-Twarog et al. (1988AJ.....95.1453A, Cl* IC 4651 AMC I-NNN, Cl* IC 4651 AMC NNNN) identification numbers. Table 3 is the final catalogue of the new Stroemgren uvby photometry, ordered by MEI identification number. For each star, it gives the MEI number, Global CCD x- and y-coordinates, J2000 coordinates , the new y, b, v, and u magnitudes on the standard system, number of detections of the individual stars, and their mean errors.
- ID:
- ivo://CDS.VizieR/J/A+AS/126/81
- Title:
- IC 2602 VRI photometry
- Short Name:
- J/A+AS/126/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of VRI photometry of the young open cluster IC 2602. Two 15x15arcmin^2^ fields were observed in February and May 1991 using the 1-m Swope telescope at Las Campanas. Using theoretical isochrones obtained from D'Antona & Mazzitelli (1994ApJS...90..467D), and allowing for observational and other uncertainties, we identify 78 primary candidate members with 12<V<18.5 from their positions on colour-magnitude diagrams. We compare the cluster field with an offset field of similar galactic latitude and estimate the contamination due to background stars to be large, >=50%, as might be expected given its low galactic latitude. We also compare our photometry with that given for the X-ray detected stars of Randich et al. (1995A&A...300..134R) present complimentary narrow band H{alpha} photometry for a subset of the stars.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A89
- Title:
- i light curve ans spectra of Hen2-11 central star
- Short Name:
- J/A+A/562/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type I nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.
- ID:
- ivo://CDS.VizieR/J/AJ/116/2728
- Title:
- I photometry of early-type galaxies
- Short Name:
- J/AJ/116/2728
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a project to compare the fundamental plane and Tully-Fisher distance scales, we present here I-band CCD photometry for 636 early-type galaxies in eight clusters and groups of galaxies. These are the A262, A1367, Coma (A1656), A2634, Cancer and Pegasus Clusters, and the NGC 383 and NGC 507 Groups. Sample selection, cluster properties, and cluster membership assignment criteria are discussed. We present photometric parameters that are used in the fundamental plane relation, the effective radius r_e_, and the effective surface brightness {mu}_e_, as derived from a r^1/4^ fit to the observed radial photometric profile of each galaxy. A comparison with similar data found in the literature for the Coma Cluster shows that large systematic uncertainties can be introduced in the measurement of r_e_ and {mu}_e_ by the particular method used to derive those parameters. However, the particular combination of these two parameters that enters in the fundamental plane relation is a quantity that can be measured with high accuracy.
- ID:
- ivo://CDS.VizieR/J/A+A/436/853
- Title:
- IR photometry of Alpha Per low-mass members
- Short Name:
- J/A+A/436/853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared (K'-band) survey of 0.7 square degree area in the {alpha} Persei open cluster (age=90Myr, distance=182pc) carried out with the Omega-Prime camera on the Calar Alto 3.5-m telescope. Combining optical data (Rc and Ic) obtained with the KPNO/MOSA detector and presented in Stauffer et al. (1999ApJ...527..219S; S99) with the K' observations, a sample of new candidate members has been extracted from the optical-infrared colour-magnitude diagram. The location of these candidates in the colour-colour diagram suggests that two-thirds of them are actually reddened background giants. About 20 new candidate members with masses between 0.3 and 0.04M_{sun}_ are added to the ~400 known Alpha Per cluster members. If they are indeed Alpha Per members, four of the new candidates would be brown dwarfs. We discuss the advantages and drawbacks of the near-infrared survey as compared to the optical selection method. We also describe the outcome of optical spectroscopy obtained with the Twin spectrograph on the Calar Alto 3.5-m telescope for about 30 candidates, including selected members from the optical sample presented in Barrado y Navascues et al. (2002, Cat. <J/A+A/395/813>) and from our joint optical/infrared catalogue. These results argue in favour of the optical selection method for this particular cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/101/1561
- Title:
- Isophotometry of ellipticals in Abell clusters
- Short Name:
- J/AJ/101/1561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/450/147
- Title:
- IzJHKs photometry of Collinder 359
- Short Name:
- J/A+A/450/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first deep, optical, wide-field imaging survey of the young open cluster Collinder 359, complemented by near-infrared follow-up observations. This study is part of a large programme aimed at examining the dependence of the mass function on environment and time. We have surveyed 1.6 square degrees in the cluster, in the I and z filters, with the CFH12K camera on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection limits in both filters of 22.0 and 24.0mag, respectively. Based on their location in the optical (I-z,I) colour-magnitude diagram, we have extracted new cluster member candidates in Collinder 359 spanning 1.3-0.03M_{sun}_, assuming an age of 60Myr and a distance of 450pc for the cluster. We have used the 2MASS database as well as our own near-infrared photometry to examine the membership status of the optically-selected cluster candidates. Comparison of the location of the most massive members in Collinder 359 in a (B-V,V) diagram with theoretical isochrones suggests that Collinder 359 is older than Alpha Per but younger than the Pleiades. We discuss the possible relationship between Collinder 359 and IC 4665 as both clusters harbour similar parameters, including proper motion, distance, and age.
