- ID:
- ivo://CDS.VizieR/J/MNRAS/211/637
- Title:
- Abell 85 CCD observations
- Short Name:
- J/MNRAS/211/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A CCD camera survey has been conducted of the X-ray emitting regions of a sample of clusters of galaxies. This sample includes at least one cluster from each of the classes in the new Forman-Jones classification scheme (Forman & Jones 1982ARA&A..20..547F). In this paper, the techniques used to obtain, reduce and analyse the data are presented, along with results for the cluster Abell 85. For the central X-ray emitting region of this cluster, a core radius of between 1.2 and 1.6Mpc is estimated from the galaxy radial number density distribution. The properties of the galaxies in the core of this cluster are significantly different from those of the galaxies in the outer regions of the area covered in the survey, in terms of luminosity function and colour distribution.
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- ID:
- ivo://CDS.VizieR/J/A+AS/140/155
- Title:
- Abell 496 gri photometry
- Short Name:
- J/A+AS/140/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We initiated a large project aimed to estimate the Luminosity Function of galaxies in clusters and to evaluate its relation to cluster morphology. With this paper we deem necessary to outline the general procedures of the data reduction and details of the data analysis. The cluster sample includes the brightest southern ROSAT all-sky survey clusters with z<0.1 . These have been observed in three colours g, r, i, and mapped up to a few core radii using a mosaic of CCD frames. E/S0 galaxies in the cluster core are singled out both by morphology (for the brightest galaxies), and by colour. The details of the data reduction procedure are illustrated via the analysis of the cluster Abell 496, which has been used as a pilot cluster for the whole program. The related photometric catalogue consists of 2355 objects. The limiting magnitudes (the reference Surface Brightness is given in parenthesis) in the various colours are respectively g(25.5)=24.14, r(25.5)=24.46, i(25.0)=23.75. These correspond to the limiting absolute magnitudes -12.28, -11.96 and -12.67 (H_0_=50km/s/Mpc).
- ID:
- ivo://CDS.VizieR/J/A+AS/139/525
- Title:
- Abell 496 heliocentric velocities
- Short Name:
- J/A+AS/139/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Catalogue of velocities for 466 galaxies in the direction of the cluster Abell 496, in a region covering about 160'x160' including previously published redshifts and redshifts from the CfA redshift survey.
4. AH Cam
- ID:
- ivo://CDS.VizieR/J/AJ/107/679
- Title:
- AH Cam
- Short Name:
- J/AJ/107/679
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989-1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686d and an apparent secondary period of 0.2628d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with {DELTA}S<=2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental mode vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.
- ID:
- ivo://CDS.VizieR/J/AJ/147/145
- Title:
- Algol-type binaries. VIII. DI Peg & AF Gem
- Short Name:
- J/AJ/147/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New extensive photometry for two triple binary stars, DI Peg and AF Gem, was performed from 2012 October to 2013 January, with two small telescopes at Xinglong station (XLs) of NAOC. From new multi-color observations and previously published ones in literature, the photometric models were (re)deduced using the updated Wilson-Devinney code. The results indicated that the low third lights exist in two classic Algol-type binaries, whose fill-out factors for the more massive components are f_p_=78.2(+/-0.4)% for DI Peg, and f_p_=69.0(+/-0.3)% for AF Gem, respectively. Through analyzing the O-C curves, the orbital periods for two binaries change in the complicated mode. The period of DI Peg possibly appears to show two light-time orbits, whose modulated periods are P_3_=54.6(+/-0.5)yr and P_4_=23.0(+/-0.6)yr, respectively. The inferred minimum masses for the inner and outer sub-stellar companions are M_in_=0.095M_{sun}_ and M_out_=0.170M_{sun}_, respectively. Therefore, DI Peg may be a quadruple star. The orbital period of AF Gem appears to show a continuous period decrease or a cyclic variation; the latter may be preferable. The cyclic oscillation, with a period of 120.3(+/-2.5)yr, may be attributed to the light-time effect due to the third body. This kind of additional companion may extract angular momentum from the central system, which may play a key role in the evolution of the binary.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1242
- Title:
- ALHAMBRA photometric system
- Short Name:
- J/AJ/139/1242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the characterization of the optical range of the ALHAMBRA photometric system, a 20 contiguous, equal-width, medium-band CCD system with wavelength coverage from 3500{AA} to 9700{AA}. The photometric description of the system is done by presenting the full response curve as a product of the filters, CCD, and atmospheric transmission curves, and using some first- and second-order moments of this response function. We also introduce the set of standard stars that defines the system, formed by 31 classic spectrophotometric standard stars which have been used in the calibration of other known photometric systems, and 288 stars, flux calibrated homogeneously, from the Next Generation Spectral Library (NGSL). Based on the NGSL, we determine the transformation equations between Sloan Digital Sky Survey ugriz photometry and the ALHAMBRA photometric system, in order to establish some relations between both systems. Finally, we develop and discuss a strategy to calculate the photometric zero points of the different pointings in the ALHAMBRA project.
- ID:
- ivo://CDS.VizieR/J/other/NewA/48.42
- Title:
- AQ Boo VRI differential light curves
- Short Name:
- J/other/NewA/48.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained the first VRI CCD light curves of the short-period contact eclipsing binary AQ Boo, which was observed on March 22 and April 19 in 2014 at Xinglong station of National Astronomical Observatories, and on January 20, 21 and February 28 in 2015 at Kunming station of Yunnan Observatories of Chinese Academy of Sciences, China. Using our six newly obtained minima and the minima that other authors obtained previously, we revised the ephemeris of AQ Boo. By fitting the O-C (observed minus calculated) values of the minima, the orbital period of AQ Boo shows a decreasing tendency dP/dt=-1.47(0.17)x10^-17^day/year. We interpret the phenomenon by mass transfer from the secondary (more massive) component to the primary (less massive) one. By using the updated Wilson & Devinney (1971ApJ...166..605W) program, we also derived the photometric orbital parameters of AQ Boo for the first time. We conclude that AQ Boo is a near contact binary with a low contact factor of 14.43%, and will become an over-contact system as the mass transfer continues.
- ID:
- ivo://CDS.VizieR/J/A+A/450/873
- Title:
- Araucaria: NGC 6822 bright variables VI phot.
- Short Name:
- J/A+A/450/873
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a search for variable stars in the dwarf irregular galaxy NGC 6822 using wide-field multi-epoch VI photometry down to a limiting magnitude of ~22. A part from the Cepheid variables in this galaxy already reported in an earlier paper by Pietrzynski et al. (2004AJ....128.2815P), we have found 1019 "non-periodic" variable stars, 50 periodically variable stars with periods ranging from 0.12 to 66 days and 146 probably periodic variables. Twelve of these stars are eclipsing binaries and fifteen are likely new, low-amplitude Cepheids.
- ID:
- ivo://CDS.VizieR/J/AJ/138/478
- Title:
- AR Boo differential BVR photometry
- Short Name:
- J/AJ/138/478
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD photometric observations of the eclipsing system AR Boo were obtained from 2006 February to 2008 April. The star's photometric properties are derived from detailed studies of the period variability and of all available light curves.
10. Arp 2
- ID:
- ivo://CDS.VizieR/J/AJ/109/650
- Title:
- Arp 2
- Short Name:
- J/AJ/109/650
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained the first B,V CCD color-magnitude diagram (CMD) of the galactic globular cluster Arp 2. About 1600 stars have been measured between the tip of the red giant branch at V ~ 15.5 and V ~ 23.5, about two magnitudes below the main sequence turnoff. A centrally concentrated population of blue stragglers has been detected. The slope of the red giant branch and the overall CMD morphology are consistent with that of a metal-poor cluster, with [Fe/H] = 18.4+/-0.25. A preliminary spectroscopic measurement based on the Ca II triplet yields [Fe/H] = -1.73+/-0.05. The comparison of the CMD of Arp 2 with that of other clusters favors a value more metal-poor than that indicated by the Ca II triplet. In this respect, Arp 2 is similar to Ruprecht 106 [Buonanno et al. =1990AJ....100.1811B and =1993AJ....105..184B]. Differential ages between Arp 2 and a number of reference clusters are obtained from the vertical age parameter Delta V^TO_HB, and the horizontal age parameter, {Delta}(B-V)^TO_RGB. By requiring both age estimators to give consistent results, we find that Arp 2 is ~ 3 Gyr younger than the group of the metal-poor clusters and slightly older than Ruprecht 106. The detection of young metal-poor clusters ([Fe/H] <= -1.8) implies a complex scenario for the origin of the galactic halo, possibly involving interactions with satellite galaxies and their cluster systems.
