scholarly journals Photometric Classification of Carbon-Rich Stars

1989 ◽  
Vol 106 ◽  
pp. 62-62
Author(s):  
V. Straizys
Keyword(s):  
Photometric Determination ◽  
Abundance Ratio ◽  
Photometric System ◽  
The Mean ◽  
Absolute Magnitudes

The Vilnius seven-color photometric system with the mean wavelengths of bandpasses at 345, 374, 405, 466, 516, 544, and 656 nm is intended for photometric determination of spectral classes, absolute magnitudes, and metallicities of stars and the amount of interstellar reddening. At the same time, different reddening-free diagrams of the system make it possible to recognize stars with different peculiarities. Carbon-rich stars are among these types of objects. For separation of carbon, barium, and CH stars from normal stars, the diagram Q (345, 374, 466, 544), Q (405, 516, 656) is the best. Its merit is based on sensitivity of the 405 magnitude to the violet depression and of the 374 magnitude to the absorption of the C3, SiC, and CN bands, This diagram can be used to estimate the C/0 abundance ratio with corresponding calibration at hand.

Application of the Strömvil Photometric System for a Search of Solar-Type Stars

1997 ◽  
Vol 161 ◽  
pp. 375-380
Author(s):  
Vytautas Straižys
Keyword(s):  
Planetary Systems ◽  
Photometric System ◽  
Color System ◽  
Solar Type ◽  
The Mean ◽  
Absolute Magnitudes ◽  
20 Nm

AbstractThe seven-color photometric system, introduced by Vilnius astronomers in 1963-1967, makes possible a completely photometric determining of spectral classes (and temperatures), absolute magnitudes (and surface gravities), interstellar reddenings and distances of stars of all normal spectral types. Recently it was suggested to join this system with the Stromgren four-color system. The new seven-color system, called the Stromvil system, has the mean wavelengths of the passbands at 350, 375, 411, 467, 516, 547 and 656 nm and half-widths of the order of 20 nm. The system can be effectively used for detection and classification of solar-type stars which are expected to be the best sites for existence of planetary systems and life.

New calibration of the Vilnius photometric system

2018 ◽  
Vol 14 (A30) ◽  
pp. 486-486
Author(s):  
M. Maskoliunas ◽  
J. Zdanavičius ◽  
V. Čepas ◽  
A. Kazlauskas ◽  
R. P. Boyle ◽  
...  
Keyword(s):  
Photometric Determination ◽  
High Dispersion ◽  
Physical Parameters ◽  
Photometric System ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Temperatures ◽  
Absolute Magnitudes ◽  
Gaia Dr2

AbstractThe medium-band Vilnius photometric system with the mean wavelengths at 345 (U), 374 (P), 405 (X), 466 (Y), 516 (Z), 544 (V), and 656 (S) nm for many years was an important tool to determine interstellar reddenings and distances of single stars due to its ability to classify stars of all temperatures in spectral classes and luminosity classes in the presence of different interstellar reddenings. At present, Gaia DR2 presents distances to stars with an unprecedented accuracy at least up to 3 kpc. However, multicolor photometry, which allows the classification of stars as well as the preliminary determination of stellar temperatures, gravities, metallicities and interstellar reddenings, remains an important method for distant stars. Here we present an empirical calibration of the intrinsic color indices of the Vilnius system in terms of physical parameters of stars for dwarf and giant stars of spectral classes F-G-K-M. In any attempted photometric determination of physical parameters of stars it is important to have an extensive and homogeneous sample of spectroscopically determined parameters for stars for which there are also accurate photometric data. As a source catalogue for the Vilnius photometry the latest updated version of the Catalogue of Photoelectric Observations in the Vilnius System was used, which contains compilations from the published photometry for about 11 000 stars. The stars which had both the Gaia DR2 parallaxes and the determinations of stellar parameters from high-dispersion spectra were extracted from this catalogue. The final sample contains more than 1500 stars of spectral classes F-M. The majority of these stars (ca 70%) are not reddened, for others the values of interstellar reddening AV were determined using the regular techniques of photometric classification in the Vilnius system. The absolute magnitudes MV and consequently the luminosity classes were determined using Gaia DR2 parallaxes. We present the analytical expressions for the effective temperature Teff and surface gravity logg and evaluate the errors of solutions for dwarf and giant stars. To test the accuracy of the proposed method, we have compared our results with the stars observed by Gaia and with the stellar parameters available from the large spectroscopic surveys: APOGEE, Gaia-ESO, GALAH, LAMOST, RAVE and SEGUE. The results of comparison contain 5-6 % outliers.The proposed method allows the fast and straightforward evaluation of stellar physical parameters for the stars observed in the Vilnius photometric system. Despite the fact, that the accuracy of determination is significantly lower than in the case of spectroscopic methods, the method described may be useful for distant faint stars, which are still inaccessible for spectroscopic observations.

scholarly journals Studies of Large-Amplitude δ Scuti Variables

1993 ◽  
Vol 139 ◽  
pp. 104-104
Author(s):  
W. J. F. Wilson ◽  
E. F. Milone ◽  
D. J. I. Fry
Keyword(s):  
Radial Velocity ◽  
Large Amplitude ◽  
Light Curves ◽  
Pulsating Stars ◽  
Modest Contribution ◽  
The Mean ◽  
Absolute Magnitudes ◽  
Scuti Stars ◽  
Radial Velocity Data

The determination of Baade-Wesselink radii and luminosities for pulsating stars are long-standing and highly desired goals since they provide the promise of being standard candles. In a modest contribution towards these goals, we have undertaken a programme to determine the radii and luminosities of the large-amplitude δ Scuti stars DY Herculis, EH Librae and DY Pegasi from optical and infrared photometry and cross-correlated radial velocity data. We use Fourier representations for V, I and J light curves and for the radial velocity curves in Baade-Wesselink analyses to derive minimum radii over the pulsation cycles. These radii and their errors and the mean bolometric luminosities and absolute magnitudes will be discussed here and in papers to follow. As a check, we also apply our method to the data and results of other groups.

EVALUATION OF FLAME PHOTOMETRIC DETERMINATION OF MAGNESIUM IN PLANT MATERIAL

1964 ◽  
Vol 44 (6) ◽  
pp. 520-524
Author(s):  
A. A. MacLean
Keyword(s):  
Standard Error ◽  
Plant Material ◽  
Photometric Determination ◽  
Flame Photometry ◽  
Mean Values ◽  
Edta Titration ◽  
The Mean ◽  
Flame Method ◽  
Oxyhydrogen Flame

Flame methods for the determination of magnesium in plant material were compared with EDTA titration and a thiazole yellow procedure. Mean values for quadruplicate determinations on 24 samples were 0.544, 0.543, 0.532, and 0.514% for EDTA, flame photometry with an oxyhydrogen flame, thiazole yellow, and flame photometry with an oxyacetylene flame respectively.The degree of precision, as indicated by the standard error of the mean, was highest for the oxyhydrogen flame method and lowest when the oxyacetylene flame was used.Silica repressed magnesium emission with either flame source but degree of interference was greater with the oxyhydrogen flame.

scholarly journals Globular Clusters in the Vilnius Photometric System

1988 ◽  
Vol 126 ◽  
pp. 515-516
Author(s):  
K. Zdanavičius
Keyword(s):  
Globular Clusters ◽  
Photometric System ◽  
Two Dimensional ◽  
Halo Stars ◽  
Dimensional Classification

The Vilnius photometric system was developed for photometric two-dimensional classification of stars and for the determination of interstellar reddening. The system consists of seven magnitudes U, P, X, Y, Z, V and S with mean wavelengths of 345, 375, 405, 466, 516, 544 and 655 nm and half-widths of the order 20 – 30 nm (Straižys 1977). Later on the system was successfully used for the determination of temperatures and the metallicities of halo stars (Bartkevičius and Sperauskas 1983).

scholarly journals The Integrated Photometry of Globular Clusters in the Vilnius Photometric System

1980 ◽  
Vol 85 ◽  
pp. 483-484
Author(s):  
K. Zdanavičius ◽  
V. Straižys
Keyword(s):  
Globular Clusters ◽  
Color Index ◽  
Photometric System ◽  
Intrinsic Values ◽  
Average Color ◽  
Color Excess ◽  
Free Parameters ◽  
Range Of Variation

Thirty-three globular clusters of our Galaxy were observed with the filters of the Vilnius photometric system UPXYZVS with 3450, 3740, 4050, 4660, 5160, 5440, 6550 å filters (Straižys 1977). For the classification of clusters in metallicities the reddening-free parameters QUYV QPYV and QXYV can be used. In Figure 1 these Q parameters, having a range of variation of the order of 0.4, are plotted against metallicity values from Kukarkin (1974). The parameter QPYZ has an even larger range of variation (of the order of 0.6). For determination of color excesses of clusters every color index can be used if its intrinsic values for a given metallicity defined by quantities Q are known (Figure 2). Average color excesses determined from the diagrams QUYV, (Y-V)o; QPYV, (Y-V)o and QXYV (Y-V)o and transformed to EB-V in Figure 3 are compared with color excesses from Kukarkin (1974). To summarize, the Vilnius system presents a number of metallicity sensitive, reddening-free parameters which can be used for [Fe/H] and color-excess determinations of globular clusters.

scholarly journals Results from Three Dimensional Spectral Classification of Population II Stars Using the DDO Photometric System

1973 ◽  
Vol 50 ◽  
pp. 176-182
Author(s):  
W. Osborn
Keyword(s):  
Globular Clusters ◽  
Three Dimensional ◽  
Photometric System ◽  
Horizontal Branch ◽  
Intermediate Band ◽  
Theoretical Predictions ◽  
The Mean ◽  
Red Giant ◽  
The Masses

The David Dunlap Observatory (DDO) intermediate-band photometric system described in the previous paper has been used to observe a number of red giant branch, horizontal branch, and asymptotic branch members in each of the five globular clusters M3, M5, M10, M13, and M92. A calibration of the DDO system is described by which it was possible to determine the effective temperatures, surface gravities, [Fe/H] values, and masses of the observed stars. The mean [Fe/H] values for the clusters were found to be −1.01 for M3, −0.68 for M5, −1.44 for M10, −1.69 for M13, and −1.96 for M92. Evidence was found that the masses of the horizontal branch and asymptotic branch stars are systematically smaller than those of red giant branch members. Two stars were discovered to have CN bands that are anomalously strong for Population II objects. The observational results have been compared with the theoretical predictions of two detailed Population II evolutionary tracks and in general the agreement is good.

Classification of Metal-Deficient Dwarfs in the Vilnius Photometric System

2003 ◽  
Vol 12 (4) ◽  
Author(s):  
R. Lazauskaitė ◽  
A. Bartkevičius ◽  
S. Bartašiūtė
Keyword(s):  
Classification Scheme ◽  
Photometric System ◽  
New Classification ◽  
Quantitative Classification ◽  
Absolute Magnitudes ◽  
Visual Binaries

AbstractMethods used for the quantitative classification of metal-deficient stars in the Vilnius photometric system are reviewed. We present a new calibration of absolute magnitudes for dwarfs and subdwarfs, based on Hipparcos parallaxes. The new classification scheme is applied to a sample of Population II visual binaries.

scholarly journals OSTEOMETRIC ANALYSIS OF SUPRAORBITAL FORAMEN AND NOTCH IN MALAYSIAN CRANIA

2019 ◽  
pp. 347
Author(s):  
ABDELNASSER IBRAHIM ◽  
SOHAYLA M ATTALLA ◽  
ASPALILAH ALIAS ◽  
MOHAMED SWARHIB ◽  
SITI NOORAIN ABU BAKAR ◽  
...  
Keyword(s):  
Anatomical Variations ◽  
Precise Determination ◽  
Reference Points ◽  
Transverse Diameter ◽  
Horizontal Diameter ◽  
Anatomical Classification ◽  
The Mean ◽  
Supraorbital Foramen

Objective: A clear knowledge of the location of supraorbital foramen (SOF) is vital for the surgeons, particularly in endoscopic surgery and regional block in crania. The aim of this study was to analyze SOF and notch in skulls of various ancestries. Methods: The anatomical variations of SOF and notch were examined in 100 adults skulls (55 males and 45 females) of the Malay, Chinese, and Indian ancestries by traditional measurement made with the Osirix software. The parameters included distance between supraorbital structure and nasal midline, shape, and transverse diameter of the SOF. Results: It was manifested that bilateral supraorbital notch (SON) was the most prevalent combination in both sexes and ancestries (61%), while combined SON and foramen (11%) were the least prevalent characteristic. The mean distances of supraorbital structure from nasal midline bilaterally in males were slightly greater than females. The horizontal diameter of SOF, notch and their distances from the nasal midline showed no difference between ancestries. Conclusion: This study would serve as a guide for the surgeons when surgery is performed on the scalp. It can help in the precise determination of reference points for supraorbital nerve blockade for the Malaysians. In addition, the variations exhibited in supraorbital measurements inevitably revealed that sex and ancestry should be taken into consideration when choosing samples for anatomical classification of crania.

scholarly journals OSTEOMETRIC ANALYSIS OF SUPRAORBITAL FORAMEN AND NOTCH IN MALAYSIAN CRANIA

2018 ◽  
Vol 11 (10) ◽  
pp. 509 ◽  
Author(s):  
Abdelnasser Ibrahim ◽  
Sohayla M Attalla ◽  
Aspalilah Alias ◽  
Mohamed Swarhib ◽  
Siti Noorain Abu Bakar ◽  
...  
Keyword(s):  
Anatomical Variations ◽  
Precise Determination ◽  
Reference Points ◽  
Transverse Diameter ◽  
Horizontal Diameter ◽  
Anatomical Classification ◽  
The Mean ◽  
Supraorbital Foramen

Objective: A clear knowledge of the location of supraorbital foramen (SOF) is vital for the surgeons, particularly in endoscopic surgery and regional block in crania. The aim of this study was to analyze SOF and notch in skulls of various ancestries.Methods: The anatomical variations of SOF and notch were examined in 100 adults skulls (55 males and 45 females) of the Malay, Chinese, and Indian ancestries by traditional measurement made with the Osirix software. The parameters included distance between supraorbital structure and nasal midline, shape, and transverse diameter of the SOF.Results: It was manifested that bilateral supraorbital notch (SON) was the most prevalent combination in both sexes and ancestries (61%), while combined SON and foramen (11%) were the least prevalent characteristic. The mean distances of supraorbital structure from nasal midline bilaterally in males were slightly greater than females. The horizontal diameter of SOF, notch and their distances from the nasal midline showed no difference between ancestries.Conclusion: This study would serve as a guide for the surgeons when surgery is performed on the scalp. It can help in the precise determination of reference points for supraorbital nerve blockade for the Malaysians. In addition, the variations exhibited in supraorbital measurements inevitably revealed that sex and ancestry should be taken into consideration when choosing samples for anatomical classification of crania.

Sign in / Sign up

Export Citation Format

Share Document