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22481. UBVRI and CT1T2 photometry of 15 open clusters
ID:
ivo://CDS.VizieR/J/MNRAS/466/4960
Title:
UBVRI and CT1T2 photometry of 15 open clusters
Short Name:
J/MNRAS/466/4960
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBVRI and CT_1_T_2_ photometry for 15 catalogued open clusters of relative high brightness and compact appearance. From these unprecedented photometric data sets, covering wavelengths from the blue up to the near-infrared, we performed a thorough assessment of their reality as stellar aggregates. We statistically assigned to each observed star within the object region a probability of being a fiducial feature of that field in terms of its local luminosity function, colour distribution and stellar density. Likewise, we used accurate parallaxes and proper motions measured by the Gaia satellite to help our decision on the open cluster reality. 10 catalogued aggregates did not show any hint of being real physical systems; three of them had been assumed to be open clusters in previous studies, though. On the other hand, we estimated reliable fundamental parameters for the remaining five studied objects, which were confirmed as real open clusters. They resulted to be clusters distributed in a wide age range, 8.0<=log(t yr^-1^)<=9.4, of solar metal content and placed between 2.0 and 5.5kpc from the Sun. Their ages and metallicities are in agreement with the presently known picture of the spatial distribution of open clusters in the Galactic disc.
22482. UBVRI and H{alpha} in NGC 6530
ID:
ivo://CDS.VizieR/J/AJ/120/333
Title:
UBVRI and H{alpha} in NGC 6530
Short Name:
J/AJ/120/333
Date:
21 Oct 2021
Publisher:
CDS
Description:
New UBVRI and H{alpha} photometry has been obtained for the young open cluster NGC 6530 located 10' east of the Lagoon Nebula (M8). We found 37 pre-main-sequence (PMS) stars with H{alpha} emission and nine PMS candidates using the R-H{alpha} color, a measure of H{alpha} emission. From this new photometry we derived the cluster parameters (V_0_-M_V_=11.25+/-0.1mag and E(B-V)=0.35mag), typical age (1.5Myr), and an age spread of about 5Myr. We confirmed the presence of a small amount of differential reddening across the cluster. We also verified the abnormal reddening law for the cluster, especially for a heavily embedded O7 V star, Herschel 36. Comparisons were made for several PMS evolution models with regard to the resulting age distribution and the initial mass function.
22483. UBVRI and H-beta observations of 3C 390.3
ID:
ivo://CDS.VizieR/J/A+A/376/775
Title:
UBVRI and H-beta observations of 3C 390.3
Short Name:
J/A+A/376/775
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-band light curve dating back to 1966 shows a large increase in brightness during 1970-1971, followed by a gradual decrease down to a minimum in 1982. During the 1995-2000 lapse the broad H{beta} emission and the continuum flux varied by a factor of ~3. Two large amplitude outbursts, of different duration, in continuum and light were observed i.e.: in October 1994 a brighter flare that lasted ~1000 days and in July 1997 another one that lasted ~700 days were detected. The response time lag of the emission lines relative to flux changes of the continuum has been found to vary with time i.e. during 1995-1997 a lag of about 100 days is evident, while during 1998-1999 a double valued lag of ~100 days and ~35 days is present in our data. The flux in the H{beta} wings and line core vary simultaneously, a behavior indicative of predominantly circular motions in the broad line region. Important changes of the H{beta} emission profiles were detected: at times, we found profiles with prominent asymmetric wings, like those normaly seen in Sy1s, while at other times, we observe profiles with weak, almost symmetrical wings, similar to those of Sy1.8s.
22484. UBVRI and infrared photometry of NGC 2215
ID:
ivo://CDS.VizieR/J/AJ/149/190
Title:
UBVRI and infrared photometry of NGC 2215
Short Name:
J/AJ/149/190
Date:
21 Oct 2021
Publisher:
CDS
Description:
Optical UBVRI photometric measurements using the Faulkes Telescope North were taken in early 2011 and combined with 2MASS JHK_s_ and WISE infrared photometry as well as UCAC4 proper motion data in order to estimate the main parameters of the galactic open cluster NGC 2215 of which large uncertainty exists in the current literature. Fitting a King model we estimate a core radius of 1.12'+/-0.04'(0.24+/-0.01pc) and a limiting radius of 4.3'+/-0.5'(0.94+/-0.11pc) for the cluster. The results of isochrone fits indicates an age of log(t)=8.85+/-0.10 with a distance of d=790+/-90pc, a metallicity of [Fe/H]=-0.40+/-0.10dex, and a reddening of E(B-V)=0.26+/-0.04. A proportion of the work in this study was undertaken by Australian and Canadian upper secondary school students involved in the Space to Grow astronomy education project, and is the first scientific publication to have utilized our star cluster photometry curriculum materials.
22485. UBVRI and polarisation in Lynga 1
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.
22486. UBV(RI)_C_ and JHK photometry in NGC 2264
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.
22487. UBVRI CCD photometry in NGC 188
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).
22488. UBVRI CCD photometry of Cepheus OB3
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.
22489. UBVRI CCD photometry of NGC 4755
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.
22490. UBVRI CCD photometry of open clusters. II. NGC 6866
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.

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