scholarly journals Young open cluster IC 4996 and its vicinity: multicolor photometry and Gaia DR2 astrometry

2019 ◽  
Vol 623 ◽  
pp. A22 ◽  
Author(s):  
V. Straižys ◽  
R. P. Boyle ◽  
K. Milašius ◽  
K. Černis ◽  
M. Macijauskas ◽  
...  
Keyword(s):  
Open Cluster ◽  
Interstellar Extinction ◽  
Mean Value ◽  
Photometric System ◽  
B Stars ◽  
Dust Clouds ◽  
Wide Range ◽  
Cluster Distance ◽  
Young Open Cluster ◽  
Similar Distance

The open cluster IC 4996 in Cygnus and its vicinity are investigated by applying a two-dimensional photometric classification of stars measured in the Vilnius seven-color photometric system. Cluster members are identified by applying distances based on the Gaia DR2 parallaxes and the point vector diagram of the Gaia DR2 proper motions. For some B-type stars, spectroscopic MK types are also obtained from the Asiago spectra and collected from the literature. New parameters of the cluster are derived. The interstellar extinction AV covers a wide range of values, from 1.3 to 2.4 mag; the mean value in the central part of the cluster is 1.8 mag. The cluster distance is 1915 ± 110 pc, and its age is within 8–10 Myr. The cluster exhibits a long sequence from early-B to G stars, where stars cooler than B8 are in the pre-main-sequence stage. The plot of extinction versus distance shows a steep rise of AV up to 1.6 mag at 700–800 pc, which is probably related to dust clouds at the edge of the Great Cygnus Rift. The next increase in extinction by an additional 0.8 mag at d ≥ 1.7 kpc is probably related to the associations Cyg OB1 and Cyg OB3. The cluster IC 4996 does not belong to the Cyg OB1 association, which is located closer to the Sun, at 1682 ± 116 pc. It seems likely that the cluster and the surrounding O-B stars have a common origin with the nearby association Cyg OB3 since Gaia data show that these stellar groups are located at a similar distance.

scholarly journals Photometric, kinematic, and variability study in the young open cluster NGC 1960

2020 ◽  
Vol 492 (3) ◽  
pp. 3602-3621 ◽  
Author(s):  
Y C Joshi ◽  
J Maurya ◽  
A A John ◽  
A Panchal ◽  
S Joshi ◽  
...  
Keyword(s):  
Open Cluster ◽  
Mass Range ◽  
Mass Function ◽  
Variable Stars ◽  
B Stars ◽  
V Band ◽  
Short Period ◽  
Young Open Cluster ◽  
Mass Segregation ◽  
Variability Study

ABSTRACT We present a comprehensive photometric analysis of a young open cluster NGC 1960 (= M36) along with the long-term variability study of this cluster. Based on the kinematic data of Gaia DR2, the membership probabilities of 3871 stars are ascertained in the cluster field among which 262 stars are found to be cluster members. Considering the kinematic and trigonometric measurements of the cluster members, we estimate a mean cluster parallax of 0.86 ± 0.05 mas and mean proper motions of μRA = −0.143 ± 0.008 mas yr−1 and μDec. = −3.395 ± 0.008 mas yr−1. We obtain basic parameters of the cluster such as E(B − V) = 0.24 ± 0.02 mag, log(Age/yr) = 7.44 ± 0.02, and d = 1.17 ± 0.06 kpc. The mass function slope in the cluster for the stars in the mass range of 0.72–7.32 M⊙ is found to be γ = −1.26 ± 0.19. We find that mass segregation is still taking place in the cluster which is yet to be dynamically relaxed. This work also presents first high-precision variability survey in the central 13 arcmin × 13 arcmin region of the cluster. The V-band photometric data accumulated on 43 nights over a period of more than 3 yr reveals 76 variable stars among which 72 are periodic variables. Among them, 59 are short period (P < 1 d) and 13 are long period (P > 1 d). The variable stars have V magnitudes ranging between 9.1 to 19.4 mag and periods between 41 min and 10.74 d. On the basis of their locations in the H–R diagram, periods, and characteristic light curves, 20 periodic variables belong to the cluster are classified as 2 δ-Scuti, 3 γ-Dor, 2 slowly pulsating B stars, 5 rotational variables, 2 non-pulsating B stars, and 6 as miscellaneous variables.

scholarly journals Investigation of contact binaries in the field of NGC 6811

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Xu-Zhi Li ◽  
Liang Liu ◽  
Xu-Dong Zhang
Keyword(s):  
Binary Systems ◽  
Open Cluster ◽  
Interstellar Extinction ◽  
Cluster Center ◽  
Strong Interactions ◽  
Cluster Distance ◽  
Metal Abundance ◽  
Contact Binaries ◽  
Contact Binary ◽  
Distance Data

Abstract Contact binary systems are very important for studying physical processes such as strong interactions between stars, mass transfer, and stellar merger. Further, the members of an open cluster have the same age, metal abundance, and interstellar extinction conditions. Therefore, we can conduct a comparative study on the different binary systems of the same open cluster. NGC 6811 is an observed intermediate-aged, slightly reddened open cluster in the Kepler field of view; we conducted a corresponding study on the contact binary systems in this cluster. We analyzed six suspected targets and found a total of five EW-type binary systems within a field of 40′ radius of the NGC 6811 cluster center. These targets were analyzed base on the Kepler data, and the corresponding system parameters were obtained by using the latest version of the Wilson–Devinney code. Further, we also used Gaia DR2 data and the cluster distance data to estimate the absolute parameters of these targets to determine whether they are members of the cluster. Finally, we determined that two targets (KIC 9470175 and KIC 9533706) are most likely cluster members; KIC 9957411 and KIC 9776718 are definitely not members of the cluster, just background stars.

scholarly journals Some Observational Limitations of Extinction Measurements in the Rocket Ultraviolet

1965 ◽  
Vol 7 ◽  
pp. 11-16
Author(s):  
Jan Borgman
Keyword(s):  
Energy Distribution ◽  
Wide Band ◽  
Interstellar Extinction ◽  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Spectral Lines ◽  
Photometric System ◽  
B Stars ◽  
The Difference ◽  
The Moment

Even Before any Measurement of stellar fluxes in the ultraviolet had been obtained, predictions were being made on the basis of stellar atmosphere models. At the moment, it seems that such com-putations (for example, see ref. 1) are in reasonable agreement with actual observations from rockets (ref. 2) in the spectral region down to about 2000 Å. At shorter wavelengths it is necessary to take into account the appreciable blanketing by spectral lines which unavoidably is present in the transmission bands of any wide-band photometric system, even in the case of early B stars, as has been shown in reference 3.It must be anticipated that the reduction of extinction measurements in the UV from spaceborne instruments will follow the same procedure that has been used so far: stars with the same intrinsic energy distribution but with different amounts of reddening material in the line of sight are compared, the difference in energy distribution being attributed to the wavelength dependence of interstellar extinction.

scholarly journals IC 361, a distant intermediate-age cluster in Camelopardalis

2009 ◽  
Vol 5 (S266) ◽  
pp. 557-560
Author(s):  
Justas Zdanavičius ◽  
Richard P. Boyle ◽  
Frederick J. Vrba ◽  
Kazimieras Zdanavičius ◽  
Stanislava Bartašiūtė
Keyword(s):  
Open Cluster ◽  
Interstellar Extinction ◽  
Distance Modulus ◽  
Ccd Photometry ◽  
True Distance ◽  
Individual Stars ◽  
Cluster Distance ◽  
Spiral Arm

AbstractWe have undertaken CCD photometry in the eight-color Vilnius + I system for the open cluster IC 361 (l = 147.5°, b = 5.7°) located in the constellation of Camelopardalis. Based on multicolor data, estimates of distance moduli, foreground reddening and metallicity have been obtained for individual stars measured in the field of the cluster. This allowed us to eliminate most of the field stars and to identify the probable cluster members, from which we derived the true distance modulus (m − M)0 = 12.7 mag and metallicity [Fe/H] = −0.3 dex. The interstellar extinction is found to be nonuniform across the field, with values of AV ranging from 1.9 to 2.6 mag. A comparison of the color–magnitude diagrams with Padova isochrones yields (m − M)0 = 12.6 mag, or a cluster distance of 3.3 kpc, and an age of 1.0 Gyr. Therefore, IC 361 appears to be a mildly metal-deficient cluster of intermediate age, located as far as, or just beyond, the Perseus spiral arm.

scholarly journals New slowly pulsating B stars in the field of the young open cluster NGC 2244 discovered by the MOST photometric satellite★

2011 ◽  
Vol 420 (1) ◽  
pp. 291-298 ◽  
Author(s):  
D. Gruber ◽  
H. Saio ◽  
R. Kuschnig ◽  
L. Fossati ◽  
G. Handler ◽  
...  
Keyword(s):  
Open Cluster ◽  
B Stars ◽  
Young Open Cluster

scholarly journals ​Estimation of Genetic Variability and Genetic Divergence in Dolichos Bean [Lablab purpureus (L.) Sweet.] Genotypes

2021 ◽  
Author(s):  
Udit Kumar ◽  
Pramila . ◽  
K. Prasad ◽  
R.K. Tiwari ◽  
Saipayan Ghosh ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Coefficient Of Variation ◽  
Genetic Divergence ◽  
Mean Value ◽  
Yellow Mosaic Virus ◽  
Lablab Purpureus ◽  
Wide Range ◽  
Cluster Distance ◽  
Maturity Period

Background: Dolichos bean is an important leguminous vegetable having a wide range of variation in different quantitative characters. Assessing genetic diversity among dolichos bean accessions can ensure development of suitable high-yielding and adapted varieties with suitable maturity period. Methods: Fifteen genotypes were evaluated for different characters in Dolichos bean at two locations of Dr. Rajendra Prasad Central Agricultural University viz. Vegetable Research Farm, Pusa and Krishi Vigyan Kendra, Birauli, Samastipur, Bihar during the year 2018-19 and pooled data was analyzed. The genotypes were evaluated for genetic variability and genetic divergence for 14 characters. For the assessment of genetic diversity among the fifteen genotypes of dolichos bean, Mahalanobis (D2) statistic (Mahalanobis, 1936) was used, following the procedure given by Rao, 1952. Grouping of genotypes into clusters was done using Tocher’s method as described by Rao, 1952. Result: Phenotypic Coefficient of Variation (PCV) was slightly higher than Genotypic Coefficient of Variation (GCV) for all the characters indicated that the characters were less influenced by environment. The characters having high heritability and high genetic advance include harvesting duration, number of pods per plant, pod length, pod diameter, individual pod weight, weight of seeds per pod, 100 fresh green seed weight, pod yield and percent incidence of yellow mosaic virus. Therefore, selection for above characters is highly effective. Genetic diversity analysis evaluated that all genotypes could be placed into 6 clusters. Genotypes grouped in Cluster III and I have highest mean value for all characters as well as highest inter-cluster distance.

scholarly journals Stellar population astrophysics (SPA) with the TNG

2020 ◽  
Vol 633 ◽  
pp. A38 ◽  
Author(s):  
V. D’Orazi ◽  
E. Oliva ◽  
A. Bragaglia ◽  
A. Frasca ◽  
N. Sanna ◽  
...  
Keyword(s):  
Open Cluster ◽  
Solar Spectrum ◽  
Chemical Properties ◽  
Mean Value ◽  
Open Clusters ◽  
Hyades Cluster ◽  
Chemical Content ◽  
Young Open Cluster ◽  
Solar Type ◽  
Young Counterpart

Context. Open clusters exquisitely track the Galactic disc chemical properties and its time evolution; a substantial number of studies and large spectroscopic surveys focus mostly on the chemical content of relatively old clusters (age ≳ 1 Gyr). Interestingly, the less studied young counterpart populating the solar surrounding has been found to be solar (at most), with a notable surprising lack of young metal-rich objects. While there is wide consensus about the moderately above-solar composition of the Hyades cluster, the metallicity of Praesepe is still controversial. Recent studies suggest that these two clusters share identical chemical composition and age, but this conclusion is disputed. Aims. With the aim of reassessing the metallicity of Praesepe, and its difference (if any) with the Hyades cluster, we present in this paper a spectroscopic investigation of ten solar-type dwarf members. Methods. We exploited GIARPS at the TNG to acquire high-resolution, high-quality optical and near-IR spectra and derived stellar parameters, metallicity ([Fe/H]), light elements, α- and iron-peak elements, by using a strictly differential (line-by-line) approach. We also analysed in the very same way the solar spectrum and the Hyades solar analogue HD 28099. Results. Our findings suggest that Praesepe is more metal-rich than the Hyades, at the level of Δ[Fe/H] = +0.05 ± 0.01 dex, with a mean value of [Fe/H] = +0.21 ± 0.01 dex. All the other elements scale with iron, as expected. This result seems to reject the hypothesis of a common origin for these two open clusters. Most importantly, Praesepe is currently the most metal-rich, young open cluster living in the solar neighbourhood.

Interstellar Extinction in the Direction of The Barnard 1 Dark Cloud in Perseus

2003 ◽  
Vol 12 (3) ◽  
Author(s):  
K. Černis ◽  
V. Straižys
Keyword(s):  
Open Cluster ◽  
Interstellar Extinction ◽  
Photometric System ◽  
Dark Cloud ◽  
Photoelectric Photometry ◽  
Reflection Nebula ◽  
Absolute Magnitudes ◽  
Cloud Complex

AbstractSpectral and luminosity classes, absolute magnitudes, color excesses, interstellar extinctions and distances are determined for 98 stars down to 18 mag in the Barnard 1 dark cloud belonging to the Per OB2 association. The classification of stars is based on their photoelectric photometry in the Vilnius seven-color photometric system. The extinction vs. distance diagram exhibits the presence of two dust layers at 150 and 230 pc distances. The distance of the first cloud, which gives an extinction Ay of 0.3 mag, coincides with the distance of the Taurus dark cloud complex. The second cloud with much larger extinction is about at the same distance as the clouds in the direction of the nearby objects: reflection nebula NGC 1333 and open cluster IG 348.

scholarly journals The young open cluster NGC 7067 using Strömgren photometry

2016 ◽  
Vol 466 (3) ◽  
pp. 3636-3647 ◽  
Author(s):  
M Monguió ◽  
I Negueruela ◽  
A Marco ◽  
C González-Fernández ◽  
J Alonso-Santiago ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Milky Way ◽  
Open Cluster ◽  
Physical Parameters ◽  
Wide Field ◽  
Isaac Newton ◽  
Cluster Distance ◽  
Young Open Cluster ◽  
Isaac Newton Telescope ◽  
Spiral Arm

Abstract NGC 7067 is a young open cluster located in the direction between the first and the second Galactic quadrants and close to the Perseus spiral arm. This makes it useful for studies of the nature of the Milky Way spiral arms. Strömgren photometry taken with the Wide Field Camera at the Isaac Newton Telescope allowed us to compute individual physical parameters for the observed stars and hence to derive the cluster's physical parameters. Spectra from the 1.93-m telescope at the Observatoire de Haute-Provence helped to check and improve the results. We obtained photometry for 1233 stars, individual physical parameters for 515 and spectra for 9 of them. The 139 selected cluster members lead to a cluster distance of 4.4 ± 0.4 kpc, with an age below log10(t(yr)) = 7.3 and a present mass of 1260 ± 160 M⊙. The morphology of the data reveals that the centre of the cluster is at (α, δ) = (21: 24: 13.69, +48: 00: 39.2) J2000, with a radius of 6.1 arcmin. Strömgren and spectroscopic data allowed us to improve the previous parameters available for the cluster in the literature.

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