- ID:
- ivo://CDS.VizieR/J/other/RMxAA/39.89
- Title:
- UBVRI and polarisation in Lynga 1
- Short Name:
- J/other/RMxAA/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD UBVRI (Cousins system) photometric observations complemented with spectroscopy and polarimetric observations that were carried out in the open cluster Lynga 1. Our data indicate that the cluster reddening is E_B-V_=0.45+/-0.03, the ratio A_v_/E_B-V_=R suggests that the extinction law may be slightly anomalous (R~3.5) and that the cluster distance modulus is V_0_-M_v=11.40+/-0.2. The age of Lynga 1 is between 100 and 125Myr according to a fitting of theoretical isochrones, and the slope of its mass spectrum is x~1.7. The brightest red star in the field is a cluster member of spectral type K2 II-Ib.
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- ID:
- ivo://CDS.VizieR/J/AJ/123/1528
- Title:
- UBV(RI)_C_ and JHK photometry in NGC 2264
- Short Name:
- J/AJ/123/1528
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical and near-infrared study of a 45'x45' field in NGC 2264, which includes both S Mon and the Cone Nebula. We report photometry at optical (UBVR_C_I_C_) and near-infrared (JHK) wavelengths for ~600 stars and spectroscopic classifications for ~400 of these stars. We identify circumstellar disk candidates using three techniques: excess ultraviolet (U-V) emission, excess near-IR (I-K and H-K) emission, and H{alpha} emission-line equivalent widths for those stars with spectra. We find generally good correlation between disk indicators thought to originate from different physical processes. We find little if any evolution of disk fraction with stellar age or mass. However, when we derive mass accretion rates (dM/dt) from the excess emission at U, we find that dM/dt decreases with age over the age range spanned by our data, ~0.15 Myr, and increases with mass over the range ~0.25-1M_{sun}_. These findings are comparable to results found previously by us in the Orion Nebula cluster flanking fields.
- ID:
- ivo://CDS.VizieR/J/AJ/118/2894
- Title:
- UBVRI CCD photometry in NGC 188
- Short Name:
- J/AJ/118/2894
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision UBVRI CCD photometry of the old open cluster NGC 188. Our color-magnitude diagram extends from near the red giant branch tip to as faint as ~5mag below the main-sequence turnoff. From an analysis of these data along with published photometry for M67, we draw the following conclusions: (1) From the UBV two-color diagram, we find a reddening of E(B-V)=0.04+/-0.02 for M67 and E(B-V)=0.09+/-0.02 for NGC 188. (2) Based on main-sequence fitting to solar abundance isochrones, the distance moduli turn out to be (m-M)v=9.69+/-0.11 for M67 and (m-M)v=11.44+/-0.08 for NGC 188. (3) The comparison of the CMDs to theoretical isochrones indicates that an amount of core convective overshoot equivalent to 0.10 of a pressure scale height is appropriate for M67, while no overshoot is required to fit the CMD of NGC 188. These isochrones suggest that NGC 188 is 3.0+/-0.7 Gyr older than M67. (4) There is a clear indication of mass segregation in both M67 and NGC 188, with the most massive stars (M/M_{sun}_>1.1) being more centrally concentrated than those that are the least massive (0.8>=M/M_{sun}_>0.65).
- ID:
- ivo://CDS.VizieR/J/A+AS/114/489
- Title:
- UBVRI CCD photometry of Cepheus OB3
- Short Name:
- J/A+AS/114/489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Johnson CCD photometry was performed in the two subgroups of the association Cepheus OB3, for selected fields each containing at least one star with previous UBV photoelectric photometry. Photometry for about 1000 stars down to visual magnitude 21 is provided, although the completeness tests show that the sample is complete down to V=19mag. Individual errors were assigned to the magnitude and colours for each star. Colour-colour and colour-magnitude diagrams are shown. Astrometric positions of the stars are also given. Description of the reduction procedure is fully detailed.
- ID:
- ivo://CDS.VizieR/J/A+AS/111/75
- Title:
- UBVRI CCD photometry of NGC 4755
- Short Name:
- J/A+AS/111/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations in U, B, V, R and I passbands have been used to generate (U-B), (B-V) colour-colour and deep V, (B-V); V, (U-B) and V, (V-I) colour-magnitude diagrams for the young open cluster NGC 4755. The sample consists of 813 stars reaching down to V about 20mag.
- ID:
- ivo://CDS.VizieR/J/AJ/147/139
- Title:
- UBVRI CCD photometry of open clusters. II. NGC 6866
- Short Name:
- J/AJ/147/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a maximum-likelihood procedure to fit theoretical isochrones to the observed cluster color-magnitude diagrams of NGC6866, an open cluster in the Kepler spacecraft field of view. The Markov chain Monte Carlo algorithm permits exploration of the entire parameter space of a set of isochrones to find both the best solution and the statistical uncertainties. For clusters in the age range of NGC6866 with few, if any, red giant members, a purely photometric determination of the cluster properties is not well-constrained. Nevertheless, based on our UBVRI photometry alone, we have derived the distance, reddening, age, and metallicity of the cluster and established estimates for the binary nature and membership probability of individual stars. We derive the following values for the cluster properties: (m-M)_V_=10.98+/-0.24, E(B-V)=0.16+/-0.04 (so the distance=1250pc), age=705+/-170Myr, and Z=0.014+/-0.005.
- ID:
- ivo://CDS.VizieR/J/AJ/145/7
- Title:
- UBVRI CCD photometry of the open cluster NGC 6811
- Short Name:
- J/AJ/145/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6811 is one of the four open clusters located in the Kepler spacecraft field of view. We obtained UBVRI photometry of the cluster on six nights (four of them photometric) with the 1.08m Hall and 1.83m Perkins telescopes at Lowell Observatory. The mean photometric precision ranges from better than 0.01mag in the V, B-V, V-R, and V-I indices among stars brighter than magnitude 15 to about 0.05mag for U-B at magnitude 18. We followed a Bayesian statistical approach using the Markov Chain Monte Carlo algorithm to determine the cluster reddening, distance, age, and iron content from a maximum-likelihood fit to stellar isochrones. Using the Yale-Yonsei isochrones, we derived E(B-V)=0.066+/-0.025, (m-M)_V_=10.13+/-0.19, age=1.06+/-0.19Gyr, and Z=0.012+/-0.004 ([Fe/H]=-0.18); with the Padova isochrones, we found E(B-V)=0.081+/-0.015, (m-M)_V_=10.31+/-0.11, age=0.94+/-0.08Gyr, and Z=0.012+/-0.002 ([Fe/H]=-0.20). The uncertainties include possible errors in the photometric zero points of +/-0.01mag, but do not include uncertainties in the models. Taking into account the differences between the two sets of models, we find the best estimate for the cluster parameters to be E(B-V)=0.074+/-0.024, (m-M)_V_=10.22+/-0.18, age=1.00+/-0.17Gyr, and Z=0.012+/-0.004 ([Fe/H]=-0.19).
- ID:
- ivo://CDS.VizieR/J/MNRAS/276/33
- Title:
- UBVRI CCD sequences for wide-field surveys. I.
- Short Name:
- J/MNRAS/276/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a campaign to secure deep UBVRI CCD photometric calibration in all UK Schmidt equatorial fields with galactic latitudes |b|<~50{deg}. In this paper we provide information on deep BVRI sequences (B<22mag) in 14 UK Schmidt survey fields centred at declination=0{deg}. Deep U sequences have been obtained for 11 of these fields.
- ID:
- ivo://CDS.VizieR/J/AJ/149/146
- Title:
- UBV(RI)c differential light curves of HR Boo
- Short Name:
- J/AJ/149/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HR Bootis is a neglected binary that is found to be a solar-type (G2V) extreme mass ratio binary (EMRB). It was discovered by Hanley & Shapley in 1940. Surprisingly, little has been published in the intervening years. In 1999 it was characterized by a 0.31587day orbital period. Since that time it has been observed by various observers who have determined ~20 timings of minimum light over the past ~15000 orbits. Our observations in 2012 represent the first precision curves in the BVR_c_I_c_Johnson-Cousins wavelength bands. The light curves have rather low amplitudes, averaging some 0.5 magnitudes, yet they exhibit total eclipses, which is typical of the rare group of solar-type EMRBs. An improved linear ephemeris was computed along with a quadratic ephemeris showing a decaying orbit, which indicates magnetic breaking may be occurring. The light curve solution reveals that HR Boo is a contact system with a somewhat low 21% Roche-lobe fill-out but a mass ratio of q=4.09 (0.2444), which defines it as an EMRB. Two spots, both hot, were allowed to iterate to fit the light curve asymmetries. Their radii are 32{deg} and 16{deg}. Both are high-latitude polar spots indicative of strong magnetic activity. The shallow contact yet nearly equal component temperatures makes it an unusual addition to this group.
- ID:
- ivo://CDS.VizieR/J/A+A/493/959
- Title:
- UBV(RI)cHalpha photometry in omega Cen
- Short Name:
- J/A+A/493/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- omega Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions in the color-magnitude diagram promises to clarify some of these peculiarities. To be able to target cluster members reliably during spectroscopic surveys and both spatial and radial distributions in the cluster outskirts without including field stars, a high quality proper-motion catalog of omega Cen and membership probability determination are required. The only available wide field proper-motion catalog of omega Cen is derived from photographic plates, and only for stars brighter than B~16. Using ESO archive data, we create a new, CCD-based, proper-motion catalog for this cluster, extending to B~20. We used high precision astrometric software developed specifically for data acquired by WFI@2.2m telescope and presented in the first paper of this series.
