Visual Basic Program "VB MASS GAL.BAS":
Mass of a Galaxy calculation based on rotation curve

Introduction and Purpose

The reason of this program is the following question: How much dark matter ? The program is identical in performance as the QBASIC program:MASS_GAL.BAS

This program calculates:

Operation - part 1
When the program starts you get the following display:

The Mass Galaxy Control Form shows the following 11 parameters.
  1. # r Defines the number of segments in the r direction. Standard value is 5.
  2. # z Defines the number of segments in the z direction. Standard value is 3.
  3. delta alpha Defines the delta angle alpha. Standard value is 10 degrees.
  4. Radius BulgeDefines the radius of the bulge. Standard value = 7500 light years
  5. Radius Visible galaxyDefines the radius of visible galaxy. Standard value = 60000 light years
  6. Radius Total galaxyDefines the radius of total galaxy. Standard value = 70000 light years
  7. height disk Defines the height of the disk at centre of Galaxy. Standard value is 2000 light years.
  8. shape disk Defines the height of the disk at distance of Radius Total galaxy. Shape = 1 means that the distance is equal height disk. Standard value = 0.1
  9. sp velocity Defines velocity setpoint for calibration at a distance of 25000 lightyears. Standard value is 250 km/sec.
  10. disk type Defines the disk type.
    There are 4 disk types:
    1 = straight line. 2 = cosinus (0 - 90). 3 = cosinus (90 - 180). 4 = cosinus (0 - 180)
    The standard value is 3.
  11. disk Dens CorrectionDefines Disk Density Correction relative to bulge. Standard value is 0.6
  12. calibration Defines calibration condition. 1 = yes. 0 = No. Standard value is 1.
The form has two commands START and END a special parameter called Test and there is a second Form called Display

Operation - part 2 START and END command
Just press START in order to start the simulation.

When the simulation is finished modify the parameters and press START again or press END to finish.

Operation - part 3 TEST parameter
There are 9 standard tests included which have the values from 1 to 9.

There is a special test with the value -1.

In order to select a test change the parameter Test to the requested value and select START

VB Program: VB MASS GAL.BAS source

In order to get the Visual Basic source and the executable program use the following zip file:VB MASS GAL.ZIP
This ZIP file contains the following files:
(1)VB Mass gal.vbw (2)VB Mass gal.vbp (3) VB Mass gal.exe (4) VB Mass gal.bas (5) VB Mass gal.frm and (6) VB Mass gal.pict.frm
The Visual Basic Executable program requires MSVDVM50.DLL:

In order to retrieve the QBASIC source select:MASS_GAL.BAS
To see the QBASIC listing select:MASS_GAL.HTM
For the QBASIC Execution file select: MASS_GAL.EXE and: brun45.exe

For similar programs in Excel select circ11.xls to circ16.xls. The purpose of those programs is to calculate disk density profiles to support (flat) galaxy rotation curves.
For a description of those programs and of "Read me First" select circ11.xls.htm
For a program to calculate galaxy rotation curves use: Grotc.xls.
For a description of this programs and of "Read me First" select grotc.xls.htm

Technical Data

For technical data see program2


The dark matter simulation gives 2 results:
  1. When you compare the calculated rotation curve with a measured one (See the book: UNIVERSE ) page 492, you will see that the two are almost the same. This means that the amount of invisible matter or dark matter for our Galaxy is almost zero.
  2. The real amount of visible mass of our Galaxy (taken the shape into account) is roughly four times as much as when you consider our Galaxy as a point.

Created: 9 September 1996
modified: 4 December 2001
Excel programs added: 1 Sept 2003
Visual Basic Program added: 1 May 2011

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