Fast Integrated Spectra Analyzer: A New Computational Tool for Age and Reddening Determination of Small Angular Diameter Open Clusters

The radial mass distribution (obtained by counting stars in strips) of the real cluster is compared successively to the distribution functions of a simulated cluster of 100 stars, each of which corresponds to a certain dynamical age, Tdyn, The value of Tdyn, belonging to the function most similar to the observed one is taken to be the dynamical age of the cluster. The radius is given in units of R1/2 (sphere containing half of the total mass); this unit is nearly time-independent. The difference between the distribution functions is measured by the maximum Δmax of the Kolmogorov-Smirnov test which is free from assumptions on the form of the distributions. The minimum in the plot Δmax vs Tdyn, indicates the age of the cluster. It is then converted into an absolute age, Tabs (in years), by The error due to the dynamical theory (limited number of distribution functions, etc.) is estimated at 12%, the error due to the uncertainty of diameter and mass of the cluster is about 30%. Unreliable results were obtained in case of strongly inhomogeneous reddening of the cluster. As an example, the plot of the test values for NGC 457 is given in Figure 1.

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Maximum-Likelihood method for determination of membership in open clusters

The Astronomical Journal ◽

10.1086/112132 ◽

1977 ◽

Vol 82 ◽

pp. 818 ◽

Cited By ~ 16

Author(s):

Mark H. Slovak

Keyword(s):

Maximum Likelihood ◽

Maximum Likelihood Method ◽

Open Clusters ◽

Likelihood Method

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Numerical Simulation of Offshore Pipeline Installation by Lateral Deflection Procedure

Volume 3: Pipeline and Riser Technology; CFD and VIV ◽

10.1115/omae2007-29703 ◽

2007 ◽

Author(s):

Danilo Machado Lawinscky da Silva ◽

Rodrigo Almeida Bahiense ◽

Breno Pinheriro Jacob ◽

Fernando Gomes da Silva Torres ◽

Antonio Roberto Medeiros ◽

...

Keyword(s):

Numerical Simulation ◽

Numerical Simulations ◽

Computational Tool ◽

Lateral Deflection ◽

Correct Definition ◽

Offshore Pipeline ◽

Definition Of

Conventional offshore pipeline installation operations in Brazil have been performed in an S-Lay procedure employing the BGL-1 barge, owned by Petrobras. However, this procedure has some limits, and may not be feasible in some particular scenarios. Therefore, the objective of this work is to present the numerical simulation of an alternative pipeline installation procedure. This procedure basically consists of performing the pipeline assembly on shore, and deflecting it to the sea using a tug boat. The numerical simulations employ the SITUA-Prosim computational tool, which is able to incorporate the correct definition of the seabed and shore from bathymetric curves. An actual pipeline installation by this lateral deflection procedure is analyzed and discussed. The characterization of the procedure passes through the determination of the better velocity and direction of the tug boat in order to minimize the efforts on the pipeline (especially due to the curvatures).

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A Determination of Secular Parallaxes of Reference Stars from Relative Proper Motions of Open Clusters

International Astronomical Union Colloquium ◽

10.1017/s0252921100027949 ◽

1970 ◽

Vol 7 ◽

pp. 74-76

Author(s):

A. N. Deutsch

Keyword(s):

Systematic Errors ◽

Open Clusters ◽

Radial Velocities ◽

Proper Motions ◽

The Mean

The determination of secular parallaxes of stars is usually based on meridian observations of proper motions of bright stars, this introducing known systematic errors. The mean parallaxes of stars can be obtained by means of radial velocities which are known for the bright stars. The more perspective method, the reference of stars to galaxies, is not applicable at low galactic latitudes.

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