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.

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.

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.

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 Effects of Heavy-Element Abundance on Classification of G-Type Giants

1976 ◽  
Vol 72 ◽  
pp. 147-147
Author(s):  
P. C. Keenan
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Heavy Element ◽  
Mean Value ◽  
Element Abundance ◽  
Class Iii ◽  
The Mean ◽  
Absolute Magnitudes

Five stars, including ζ Cyg, which had been classified as G6 II to G8 II bright giants, were found by O. C. Wilson to have K-line luminosities close to those of class III giants. These stars show enhancement of the lines of Ba II and other heavy-metal ions also. To eliminate the serious effect of this abundance anomaly on the spectroscopic luminosities new luminosity criteria involving only intercomparisons of lines of elements of the fourth period (Ti, Fe, etc.) were applied on 9 Å mm−1 Coudé spectrograms taken by O. C. Wilson. This Coudé classification gave luminosity classes near IIIa for these stars, implying absolute magnitudes considerably below those of bright giants but somewhat above Wilson's MK values.Another advantage of Coudé classification is the possibility of estimating luminosities for individual barium stars. From Wilson's plate of HD 205011 a luminosity class of III-IIIa is derived. This is consistent with the mean value of Mv = −0.4 derived from statistical parallaxes by MacConnell, Frye and Upgren (Astron. J. 77, (1972), 384) for the barium stars.The detailed account of this investigation will be published elsewhere.

scholarly journals Observed Relations Between Physical Properties and MK Classification as Functions of Metal Abundance for F5-K4 Stars

1976 ◽  
Vol 72 ◽  
pp. 75-78
Author(s):  
M. Grenon
Keyword(s):  
Physical Properties ◽  
Spectral Range ◽  
Spectral Type ◽  
Photometric System ◽  
Luminosity Class ◽  
Empirical Relations ◽  
Metal Abundance ◽  
Systematic Effects ◽  
The Absolute ◽  
Absolute Magnitudes

The Geneva photometric system has been calibrated in terms of [M/H], θeff, Mv in the spectral range F5 to K4. As the spectral type is a datum generally available, we derive empirical relations showing the coupling of θeff and [M/H] at given spectral type and luminosity class. Similar relations are offered for the absolute magnitudes and provide a more accurate means for deriving spectroscopic parallaxes. Systematic effects on the estimation of the luminosity class are also shown.

Split spinal cord malformations in children

1998 ◽  
Vol 88 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Yusuf Ersşahin ◽  
Saffet Mutluer ◽  
Sevgül Kocaman ◽  
Eren Demirtasş
Keyword(s):  
Spinal Cord ◽  
Neurological Deficits ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Content Type ◽  
Spinal Lesion ◽  
The Mean ◽  
Fine Print

Object. The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Methods. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. Conclusions. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients. The risk of neurological deficits resulting from SSCMs increases with the age of the patient; therefore, all patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations.

Role of laparoscopic in diagnosis and treatment of undescended testis in children at Viet Duc Hospital

2018 ◽  
Vol 8 (4) ◽  
Author(s):  
Viet Hoa Nguyen
Keyword(s):  
Laparoscopic Surgery ◽  
Undescended Testis ◽  
Correct Diagnosis ◽  
Diagnosis And Treatment ◽  
Highly Sensitive ◽  
The Mean ◽  
The Right ◽  
Time Of Operation

Abstract Introduction: Evaluating the role of laparoscopic for diagnosis and treatment of undescended testis in children. Material and Methods: Restrospective study, between 6/ 2014 and 6/2017. All the patients are aged from 1 to 16 years with undescended testis underwent laparoscopic surgery for diagnosis and treatment in Deparment of pediatric surgery – Viet Duc hospital enrolled. Results: Of 95 patiens in total had 106 undescended testis diagnosed and treated by laparoscopy. The mean age of patients was 7,5 ± 3,8 years. 44,2% undescended were on the left side, 44,2% were on the right and 11,6% were undescended bilateral. The correct diagnosis by ultrasound accounted in 79,4%. The locations of testis diagnosed by laparoscopic are : intra abdomen in 45,3%, deep inguinal orifice in 16,9%, extra inguinal orifice in 26,4%, no testicle found in 11,4%. The mean time of operation were 67,33± 28,01 pht. Scrotal positions were achieved 74,5%, remove atrophic testis accounted in 7,6%. Stephen- Flowler technique including step I were in 4,7%, step II in 1,9%. The outcome evaluated by testicular positions following 3 months after operation are : good in 79,2%, moderate 13,2%, poor in 7,6%; By classification of Aubert are : good in 81,1%, moderate in 11,3% and poor in 7,6 %. Conclusion: Laparoscopic surgery is not only a highly sensitive diagnostic method to find accurately the location and size of the testes, but also the most effective method to treat impalpable undescended testes.

TRAFFIC FLOWS FORECASTING BASED ON MACHINE LEARNING

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Machine Learning ◽  
Traffic Flows ◽  
Random Forest Regression ◽  
Machine Learning Methods ◽  
Packet Arrival ◽  
Entire Flow ◽  
The Mean ◽  
Active Flow

The article aims to develop a model for forecasting the characteristics of traffic flows in real-time based on the classification of applications using machine learning methods to ensure the quality of service. It is shown that the model can forecast the mean rate and frequency of packet arrival for the entire flow of each class separately. The prediction is based on information about the previous flows of this class and the first 15 packets of the active flow. Thus, the Random Forest Regression method reduces the prediction error by approximately 1.5 times compared to the standard mean estimate for transmitted packets issued at the switch interface.

A multiscale topography analysis of ground stainless steel and titanium alloys

2007 ◽  
Vol 221 (9) ◽  
pp. 1407-1420 ◽  
Author(s):  
S Giljean ◽  
M Bigerelle ◽  
K Anselme
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Titanium Alloys ◽  
Roughness Parameter ◽  
Roughness Parameters ◽  
Observation Scale ◽  
316L Austenitic Stainless Steel ◽  
The Mean ◽  
Best Parameter

This study aims to perform a multiscale analysis of abraded surfaces of 316L austenitic stainless steel and titanium alloys (TiAl6V4) grinded at different paper grades. The authors propose to answer the following question: For a given distribution of silicon carbide grains of the paper, what is the best roughness parameter and at which scale must it be evaluated better to discriminate the effect of the mechanical properties of the materials? Paper grades from 80 to 4000 were used under identical pressure and erosion time. It can be concluded that the values of the amplitude roughness parameters depend on the observation scale. It is outlined that the abrasion process is very reproducible. A statistical analysis is then proposed, first, to define a classification of the relevance of the roughness parameters for each grain size distribution, and second, to determine at which scale the mechanical properties of the bulk are more influenced for all paper grades. Finally, at relevant scales, the Abbott amplitude parameters roughness kernel (RK) is the best parameter to discriminate the paper grade effect. The mean distance between asperities (SM) is the preferred method for determining the wear effect on materials and the linear mean normalizing autocorrelation (AMNLN) is the preferred method for determining the interaction between paper grade and materials.

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