- ID:
- ivo://CDS.VizieR/J/A+A/521/A36
- Title:
- BV differential photometry of V711 Tau
- Short Name:
- J/A+A/521/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We attempt to establish the real nature of the orbital period variation and its relation to the spot activity of V711 Tau, and determine why the (B-V) colour of the star appears to be nearly independent of its V magnitude. We wish to verify whether existing predictions in the literature for the long-term spot activity of the star are true or not by making extended photometric observations, and whether the broad component of H{alpha} emission originates in more localised active regions, as suggested by some chromospheric models, by searching for any correlation between the base-line width of the emission and the light modulation.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/465/943
- Title:
- BVI and RV curves of 5 eclipsing binaries
- Short Name:
- J/A+A/465/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters. We carried out new photometric and spectroscopic observations of five bright close eclipsing binaries, predominantly in the southern skies. We obtained full Johnson BV light curves, which were modelled with the Wilson-Devinney code. Radial velocities were measured with the cross-correlation method using IAU radial velocity standards as spectral templates. Period changes were studied with the O-C method, utilising published epochs of minimum light (XY Leo) and ASAS photometry (VZ Lib). For three objects (DX Tuc, QY Hya, V870 Ara), absolute parameters have been determined for the first time. We spectroscopically detected the tertiary components in XY Leo and VZ Lib and discovered one in QY Hya. For XY Leo we updated the light-time effect parameters and detected a secondary periodicity of about 5100d in the O-C diagram that may hint at the existence of short-period magnetic cycles. A combination of recent photometric data shows that the orbital period of the tertiary star in VZ Lib is likely to be over 1500d. QY Hya is a semi-detached X-ray active binary in a triple system with K and M-type components, while V870 Ara is a contact binary with the third smallest spectroscopic mass ratio for a W UMa star to date. Being close to the theoretical minimum for contact binaries, this small mass ratio suggests that V870 Ara has the potential of constraining evolutionary scenarios of binary mergers. The inferred distances to these systems are compatible with the Hipparcos parallaxes.
- ID:
- ivo://CDS.VizieR/J/A+A/478/865
- Title:
- BVIc differential photometry of GSC 0762-110
- Short Name:
- J/A+A/478/865
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry of the triple-mode radially pulsating variable GSC 0762-0110 has been performed. The star has a fundamental period of 0.1945d and period ratios of 0.7641 and 0.8012. In addition two non-radial modes were found, for which the amplitude diminished considerably over the last few years. The data presented here are the B, V and Ic differential instrumental magnitudes of GSC 0762-0110 with respect to GSC 0766-2426. The V data are from four different observatories, the B and Ic data from a single observatory. Instrumental details are given in the paper.
- 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/A+A/539/A139
- Title:
- BVIc light curves of SZ Cam
- Short Name:
- J/A+A/539/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P=2.7-days in a long orbit (~55yrs) around a non-eclipsing SB1 pair of orbital period P=2.8-days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BV IC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a beta Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is 0.33265+/-0.00005-days and the observed total amplitude in the B band is 0.0105+/-0.0005mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2300
- Title:
- BVIc light curves of 3 type II Cepheids
- Short Name:
- J/AJ/139/2300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Light curves in the B, V, and Ic passbands have been obtained for the type II Cepheids V154 in M3 and V42 and V84 in M5. Alternating cycle behavior, similar to that seen among RV Tauri variables, is confirmed for V84. Old and new observations, spanning more than a century, show that V154 has increased in period while V42 has decreased in period. V84, on the other hand, has shown large, erratic changes in period that do not appear to reflect the long-term evolution of V84 through the Hertzsprung-Russel diagram.
- ID:
- ivo://CDS.VizieR/J/ApJS/137/209
- Title:
- BVIc photoelectric obs. of southern Cepheids
- Short Name:
- J/ApJS/137/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 2097 photometric observations in the BVI_C_ system are presented for 117 Cepheids located in the southern hemisphere. The main purpose of the photometry is to provide new epochs of maximum brightness for studying Cepheid period changes, as well as to establish current light elements for the Cepheids.
- 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.
- ID:
- ivo://CDS.VizieR/J/AZh/88/886
- Title:
- BVIc photometry of Cepheids from ASAS-3 catalog
- Short Name:
- J/AZh/88/886
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2008-2010, we obtained 6095 CCD frames in the BVIc photometric system for 49 classical Cepheids discovered in the ASAS-3 project. The observations were obtained on the 76-cm telescope of the South African Astronomical Observatory (SAAO, RSA) and the 40-cm telescope of the Cerro Armazones Observatory of the Catholic University of the North (OCA, Chile), with a SBIGCCD ST-10XME camera. We present tabulated observations, light curves, and revised elements for the brightness variations.
- ID:
- ivo://CDS.VizieR/J/AJ/140/677
- Title:
- BVIc photometry of IC 4665
- Short Name:
- J/AJ/140/677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, BVIc photometric survey of the young open cluster IC 4665, which improves on previous studies of this young cluster by incorporating a rigorous standardization procedure, thus providing high-fidelity colors and magnitudes for cluster members. We use this new photometric dataset to reevaluate the properties (age and distance) of IC 4665.
