- 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.
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- 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/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.
- ID:
- ivo://CDS.VizieR/J/PASP/116/1012
- Title:
- A star catalog for the open cluster NGC 188
- Short Name:
- J/PASP/116/1012
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new BVRI broadband photometry for the old open cluster NGC 188, based on an analysis of 299 CCD images either obtained by us, donated by colleagues, or retrieved from public archives.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A27
- Title:
- AX Per UBVRI photometry
- Short Name:
- J/A+A/536/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AX Per is an eclipsing symbiotic binary. During active phases, deep narrow minima are observed in its light curve, and the ionization structure in the binary changes significantly. From ~2007.5, AX Per entered a new active phase. We aim to derive the ionization structure in the binary and its changes during the recent active phase. We used optical high- and low-resolution spectroscopy and UBVRcIc photometry. We modeled the SED in the optical and broad wings of the H alpha line profile during the 2007-10 higher level of the AX Per activity. After 10 orbital cycles (~18.6 years), we again measured the eclipse of the hot component by its giant companion in the light curve. We derived a radius of 27+/-2R_{sun}_ for the eclipsed object and 115+/-2R_{sun}_ for the eclipsing cool giant. The new active phase was connected with a significant enhancement of the hot star wind. From quiescence to activity, the mass-loss rate increased from ~9E-8 to ~3E-6M_{sun}_/yr, respectively. The wind causes the emission of the He++ zone, located in the vicinity of the hot star, and also is the reason for the fraction of the [OIII] zone at farther distances. Simultaneously, we identified a variable optically thick warm (T_eff_~6000K) source that contributes markedly to the composite spectrum. The source was located at the hot star's equator and has the form of a flared disk, whose outer rim simulates the warm photosphere. The formation of the neutral disk-like zone around the accretor during the active phase was connected with its enhanced wind. It is probable that this connection represents a common origin of the warm pseudophotospheres that are indicated during the active phases of symbiotic stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/299/834
- Title:
- Berkeley 21 BVI photometry
- Short Name:
- J/MNRAS/299/834
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD BVI photometry of the old open cluster Berkeley 21, one of the most distant clusters in the Galactic anticentre direction, and possibly the lowest metallicity object in the open clusters sample. Its position and metal abundance make it very important for the study of the Galactic disc. Using the synthetic colour-magnitude diagram method, we estimate values for the distance modulus (m-M)_0_=13.4-13.6, reddening E(B-V)=0.74-0.78 (with possible differential absorption), and age= 2.2-2.5Gyr.
- ID:
- ivo://CDS.VizieR/J/AJ/136/594
- Title:
- BS Cas BVR light curves
- Short Name:
- J/AJ/136/594
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolor charge-coupled device (CCD) photometry for the eclipsing binary BS Cassiopeiae, observed on four nights between 2007 December and 2008 January. Using the Wilson-Devinney program, the photometric solution was derived from our BVR observations. Photometric results indicated that BS Cas is a W-subtype binary, whose mass ratio and overcontact degree are q=0.2834(+/-0.0010) and f=31.6%(+/-1.1%), respectively. Light curves of BS Cas present a typical O'Connell effect, which may be attributed to dark spot activity of the primary component.
- ID:
- ivo://CDS.VizieR/J/A+A/463/981
- Title:
- BV CCD photometry in Westerlund 2
- Short Name:
- J/A+A/463/981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The properties of the early-type stars in the core of the Westerlund 2 cluster are examined in order to establish a link between the cluster and the very massive Wolf-Rayet binary WR20a as well as the H II complex RCW 49. Photometric monitoring as well as spectroscopic observations of Westerlund 2 are used to search for light variability and to establish the spectral types of the early-type stars in the cluster core. The first light curves of the eclipsing binary WR 20a in B and V filters are analysed and a distance of 8kpc is inferred. Three additional eclipsing binaries, which are probable late O or early B-type cluster members, are discovered, but none of the known early O-type stars in the cluster displays significant photometric variability above 1% at the 1-sigma level. The twelve brightest O-type stars are found to have spectral types between O3 and O6.5, significantly earlier than previously thought. The distance of the early-type stars in Westerlund 2 is established to be in excellent agreement with the distance of WR20a, indicating that WR20a actually belongs to the cluster. Our best estimate of the cluster distance thus amounts to 8.0+/-1.4kpc. Despite the earlier spectral types, the currently known population of early-type stars in Westerlund 2 does not provide enough ionizing photons to account for the radio emission of the RCW 49 complex. This suggests that there might still exist a number of embedded early O-stars in RCW49.
- ID:
- ivo://CDS.VizieR/J/other/Obs/131.386
- Title:
- BVIc light curves of 8 RR Lyr-type stars
- Short Name:
- J/other/Obs/131.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We took a total of 1175 B, V, and Ic-band CCD frames for 11 GCVS RR Lyr-type variables, for which only the coordinates were known. Observations were made with the 76-crn telescope of the South African Astronomical Observatory. We confirm the variability types, determine the periods, and build the light curves for five objects: BL Aps (P=0.598d), GR Pav (P=0.583d), HI Pav (P=0.643d), HZ Pav (P=0.803d), and IR Pav (P=0.561d). The objects SY Aps (P=0.279d) and IV Pav (P=0.408d) proved to be W UMa-type eclipsing variables; TW Aps (P=0.149d), an SX Phe-type variable; TT Aps (P=482d), an SRD-type semiregular variable, and SW Aps and GI Pav, constant stars.
- ID:
- ivo://CDS.VizieR/J/other/NewA/11.262
- Title:
- BVIc photometry in Lynga 11
- Short Name:
- J/other/NewA/11.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained CCD BVI_KC_ photometry down to V~21.5 for the open cluster Lynga 11 and its surrounding field. This previously unstudied object appears to be rich and highly absorbed. A cluster angular radius of 4.5+/-0.5, equivalent to (3.0+/-0.3)pc, is estimated from star counts in 100-pixel a side boxes distributed throughout the whole observed field. Our analysis suggests that Lynga 11 is moderately young and probably of solar metallicity.
