- ID:
- ivo://CDS.VizieR/J/AJ/149/62
- Title:
- BVR light curves of V508 Oph
- Short Name:
- J/AJ/149/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, new CCD photometric observations of V508 Oph obtained in 2009 and 2010 at the Xinglong Observatory are presented. From the new observations, six new times of minimum light were derived. The light curves were analyzed by using the 2003 version of the Wilson-Devinney program. It is found that the asymmetric light curves can be modeled by a hot spot on the secondary component. The degree of overcontact is 15.4%, implying that the system is a shallow-contact binary. Combining the new times of minimum light with the photoelectric and CCD data compiled from the database, we investigate its orbital period. The results show that the orbital period may be undergoing multiple changes: a long-term decrease at a rate of dP/dt=-(1.502+/-0.063)x10^-7^days/year, and a small periodic variation with a period of 24.27(+/-0.34) years. Since V508 Oph is an overcontact system and both components are late-type stars, we discuss the possible connection between the mass transfer, magnetic activity, the third body, and the orbital period changes.
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- ID:
- ivo://CDS.VizieR/J/A+A/454/179
- Title:
- BVR phot. of Basel 11b, King 14, Czernik 43
- Short Name:
- J/A+A/454/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To progress in galactic studies based on open clusters, e.g. cluster formation rate or kinematical properties, one needs to improve the number of open clusters observed. However, only half of the 1700 known galactic open clusters have been properly observed so far, making any statistical investigation insignificant, especially at larger distances from the Sun. We study marginally investigated or neglected open clusters with Bessell CCD BVR photometry, whose data were used to fit isochrones to the individual color-magnitude diagrams. We examined the galactic clusters Basel 11b, King 14 and Czernik 43, the last being observed for the first time to this extent. As well as a careful comparison to available photometry, their parameters such as age, interstellar reddening, distance and apparent diameter were determined. The obtained cluster properties were verified by near infrared 2MASS data. The three investigated intermediate age clusters are all located in the galactic disk with distances between 1.8 and 3.0kpc from the Sun.
- ID:
- ivo://CDS.VizieR/J/other/AISAO/32.31
- Title:
- BVr photometry in SA68, SA 5 and M 82
- Short Name:
- J/other/AISAO/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A description of the photometry and spectroscopy of the objects of the fields SA 68 (00h14m51.03s +15deg36'19.1"), M 82 (9h53m28.33s +69deg52'12.7") and SA 57 (13h06m03.69s +29deg36'31.8") is given. Photometric samples of the objects are complete to B=21.75m for the field SA 68, to B=22.25m for the field M 82. and to B=23m for the field SA 57. Spectroscopy is completed up to 64 % for the field SA 68, to 63% for the field M 82, and to 56% for the field SA 57. Photometric and spectroscopic data are gathered into catalogues.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1032
- Title:
- BVR photometry of BO CVn and SS Com
- Short Name:
- J/AJ/131/1032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BO CVn and SS Com are two short-period W UMa-type binary stars with spectral types earlier than F5. In the present paper new CCD photometric light curves in B, V, and R bands of BO CVn and the first complete light curve in V band of SS Com are presented.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/71
- Title:
- BVR photometry of 10 ESO/SERC fields
- Short Name:
- J/A+AS/125/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For calibration of ESO/SERC survey plates, photometric CCD sequences have been obtained for 10 ESO/SERC fields in the area 10h00m<R.A.<15h30m and -34deg<Decl.<-18deg. In Tables 2 to 20, the catalogue of the CCD sequences is given. It contains B, V and R magnitudes for 117 galaxies and 162 stars with 12.7<V<21.0. Column 2 gives the object type, S for star, G for galaxy. The positions were measured from scans of Schmidt plates with one of the PDS machines at the Astronomisches Institut, Muenster, Germany. Their accuracy is between 0.5 and 1.0arcsec.
- ID:
- ivo://CDS.VizieR/J/AJ/151/124
- Title:
- BVR photometry of IZ Mon and AR Dra
- Short Name:
- J/AJ/151/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-color photometric observations for two neglected near-contact binaries, IZ Mon (P=0.77980^d^) and AR Dra (P=0.67584^d^). By the aid of the updated W-D analysis code, the photometric solutions were deduced from the multi-color light curves (LCs). IZ Mon is a semi-detached binary with a mass ratio of q=0.388(+/-0.002) , while AR Dra is a detached star with a mass ratio of q=0.652(+/-0.002). The asymmetric LCs of IZ Mon were modeled by a hot spot on the secondary's surface, which may be attributed to mass transfer from the primary. Based on all collected eclipse times for two systems, we constructed their timing residual curves. The orbital period for IZ Mon may be continuously decreasing at a rate of dP/dt=-2.06(+/-0.04)days/yr, which may result from mass and angular momentum loss from the central system. For AR Dra, there exists a cyclic variation with a period of P_3_=104.9(+/-2.9)yr due to light-time orbit effect via the presence of the third body, whose mass is more than 0.28(+/-0.02)M_{Sun}_. Finally, two near-contact binaries, IZ Mon and AR Dra, will evolve into contact binaries.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/596
- Title:
- BVR photometry of NGC 6584
- Short Name:
- J/PAZh/21/596
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Automatic stellar photographic BVR photometry reaching 1mag below the horizontal branch of NGC 6584, located at V~16.5mag, has been performed for this poorly studied globular cluster. One of the photoelectric standard stars used in our reductions appears to be variable. We also determined accurate coordinates of 52 variable stars in the cluster and around it.
- ID:
- ivo://CDS.VizieR/J/AJ/109/173
- Title:
- BVR photometry of NGC 6822
- Short Name:
- J/AJ/109/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our proposed method to study the star-formation histories in nearby irregulars is here applied to NGC 6822. To this purpose we have obtained accurate CCD photometry of three regions in the galaxy, reaching V=23.5 with the required accuracy of {sigma}_BVR_<=0.1mag. Major information on the stellar populations, star-formation rates, and initial mass functions of these regions in the last 1Gyr are derived from the comparison of the observational color-magnitude diagrams and luminosity functions with the corresponding synthetic diagrams and luminosity functions generated by a numerical simulation code based on stellar evolutionary tracks. We find that in the last 1Gyr the star-formation activity has been rather continuous, possibly occurring in long episodes of moderate activity separated by short quiescent periods, and that the initial mass function exponent a is in the vicinity of Salpeter's value, i.e., slightly flatter than in the solar neighborhood. The studied regions of NGC 6822 appear to contain different stellar populations. The preferred star formation regime for region A is a continuous activity coupled with a moderately flat {alpha}. For region C, instead, our best models suggest a discontinuous star formation and a moderately steep {alpha}. NGC 6822 is the last object of our original sample of five nearby irregulars. We can then draw the scenario resulting from this sample: most of the observed fields appear to have experienced a gasping regime of star formation, with average exponent {alpha}=2.35 for the initial mass function. Despite their small sizes, the majority of the sample galaxies contain different stellar populations in different regions.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1599
- Title:
- B'V'R' photometry of S5 0716+714
- Short Name:
- J/AJ/133/1599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We first introduce a novel photometric system that consists of a Schmidt telescope, an objective prism, a CCD camera, and, in particular, a multipeak interference filter. The multipeak interference filter enables light in multiple passbands to pass through it simultaneously. The light in different passbands is differentially refracted by the objective prism and is focused on the CCD in separate regions, so we have multiple "images" for each object on the CCD frames. This system enables us to monitor blazars exactly simultaneously in multiple wave bands on a single telescope and to accurately trace the color change during the variation. We used this novel system to monitor the BL Lacertae object S5 0716+714 during 2006 January and February and achieved a very high temporal resolution. The object was very bright and very active during this period. Two strong flares were observed, with variation amplitudes of about 0.8 and 0.6mag in the V' band, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/110/212
- Title:
- BVR photometry of stars in NGC 2366
- Short Name:
- J/AJ/110/212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar content of the Im galaxy NGC 2366 is discussed on the basis of CCD BVR photometry. The three brightest blue and red stars have been used to estimate its distance, obtaining a value of 2.9pc. The spatial distribution of the young stellar population is discussed in the light of the integrated color indices and the color-magnitude diagrams of different zones of the galaxy. A generalized star formation burst seems to have taken place about 50Myr ago. The youngest stars are preferentially formed in the South-West part of the bar, where the giant H II complex NGC 2363 is located, being younger and bluer. The bar seems to play a role favoring star formation in one of its extremes. Self-propagation however, does not seem to be triggering star formation at large scale. A small region, populated by very young stars has also been found at the East of the galaxy.
