AstroGrav Help /Window Types /Star WindowsVersion 5.2.1

Star Windows

Introduction

Star windows let you view the details of background stars in solar system simulations.

A star window can only be opened by double-clicking on one of the background stars in a view window of a solar system simulation. There is no menu item for opening a new star window. A star window is tied to the view window from which it was opened in the sense that some of its data is viewpoint dependent, and so changes as the viewpoint is changed. Some of the data is also time dependent, and so changes as the simulation evolves.

The values that are displayed are calculated relative to the viewpoint, so that the choice of viewpoint is important. If the viewpoint is on the Earth, some quantities (such as speed, motions, and position angles) change rapidly as a result of the Earth's changing velocity. If you want to see the values as they would appear in a star catalogue, you should use the View / View From... command to switch to a Floating viewpoint, so that the viewpoint's velocity is constant.

A star window contains the following eight data areas.

Date/Viewpoint
Names/Catalogues
Physical Elements
Position/Velocity
Ecliptic Coordinates
Equatorial Coordinates
Galactic Coordinates
Horizontal Coordinates

The Names/Catalogues and Physical Elements areas contain data that is constant and does not vary as the time and viewpoint changes. All the other areas contain data that varies as the time and viewpoint changes, although in some cases the rate of change is very small. The Horizontal Coordinates data will be blanked out if the viewpoint is not somewhere on the Earth.

Date/Viewpoint

The Date/Viewpoint area shows the following data items.

Date is the simulation date and time.
Viewpoint is the viewpoint in the associated view window, which is the view window from which the star window was opened.

Names/Catalogues

The Names/Catalogues area shows the following data items.

Name is the most common form of the star's name - for example, 'Sirius'.
Harvard Revised No is the star's number in the Yale Bright Star Catalogue. This will be blank if the star is not present in the Yale Bright Star Catalogue.
Flamsteed Designation is the star's Flamsteed number and constellation. This will be blank if the star does not have a Flamsteed number.
Bayer Designation is the star's Bayer designation, which takes the form of a greek letter followed by a constellation. This will be blank if the star is not one of the brighter ones, because only the brighter stars have Bayer designations.
Variable Designation is the star's variable designation. This will be blank if the star is not a variable.
Durchmusterung ID is the star's identifier in the Bonner Durchmusterung, Cordoba Durchmusterung, or Cape Photographic Durchmusterung. Entries in the Bonner Durchmusterung start with 'BD', entries in the Cordoba Durchmusterung start with 'CD', and entries in the Cape Photographic Durchmusterung start with 'CP'.
Henry Draper No is the star's number in the Henry Draper Catalogue. This will be blank if the star is not present in the Henry Draper Catalogue.
Hipparcos No (HIP) is the star's number in the Hipparcos Catalogue. This will be blank if the star is not present in the Hipparcos Catalogue.
Tycho Designation (TYC) is the star's designation in the Tycho Catalogue. This will be blank if the star is not present in the Tycho Catalogue.

Physical Elements

The Physical Elements area shows the following data items.

B-V Color is the star's Johnson B-V color index.
Temperature is the star's temperature.
Luminosity is the star's luminosity.
Mass is the star's mass.
Radius is the star's radius.
Absolute Magnitude is the star's absolute magnitude, which is magnitude of the star when viewed from a distance of 10 parsecs.

Position/Velocity

The Position/Velocity area shows the following data items as seen from the viewpoint.

Constellation is the constellation in which the star appears as seen from the viewpoint.
Distance is the distance of the star from the viewpoint.
Radial Speed is the radial component of the velocity of the star relative to the viewpoint, where the radial component is the component parallel to the line between the viewpoint and the star.
Transverse Speed is the transverse component of the velocity of the star relative to the viewpoint, where the transverse component is the component perpendicular to the line between the viewpoint and the star.
Total Speed is the speed of the star relative to the viewpoint.
Angular Diameter is the apparent angular diameter of the star as seen from the viewpoint.
Magnitude is the apparent magnitude of the star as seen from the viewpoint.

Ecliptic Coordinates

The Ecliptic Coordinates area shows the following data items as seen from the viewpoint.

Longitude is the longitude at which the star appears in the ecliptic reference frame.
Latitude is the latitude at which the star appears in the ecliptic reference frame.
Longitude Motion is the longitude component of the star's angular velocity in the ecliptic reference frame.
Latitude Motion is the latitude component of the star's angular velocity in the ecliptic reference frame.
Total Motion is the magnitude of the star's angular velocity in the ecliptic reference frame.
Position Angle is the position angle of the star's angular velocity in the ecliptic reference frame, with the position angle measured anticlockwise from ecliptic north.

Equatorial Coordinates

The Equatorial Coordinates area shows the following data items as seen from the viewpoint.

Right Ascension is the right ascension at which the star appears in the J2000 equatorial reference frame.
Declination is the declination at which the star appears in the J2000 equatorial reference frame.
Right Ascension Motion is the right ascension component of the star's angular velocity in the J2000 equatorial reference frame.
Declination Motion is the declination component of the star's angular velocity in the J2000 equatorial reference frame.
Total Motion is the magnitude of the star's angular velocity in the J2000 equatorial reference frame.
Position Angle is the position angle of the star's angular velocity in the J2000 equatorial reference frame, with the position angle measured anticlockwise from J2000 equatorial north.

Galactic Coordinates

The Galactic Coordinates area shows the following data items as seen from the viewpoint.

Longitude is the longitude at which the star appears in the galactic reference frame.
Latitude is the latitude at which the star appears in the galactic reference frame.
Longitude Motion is the longitude component of the star's angular velocity in the galactic reference frame.
Latitude Motion is the latitude component of the star's angular velocity in the galactic reference frame.
Total Motion is the magnitude of the star's angular velocity in the galactic reference frame.
Position Angle is the position angle of the star's angular velocity in the galactic reference frame, with the position angle measured anticlockwise from galactic north.

Horizontal Coordinates

The Horizontal Coordinates area shows the following data items as seen from the viewpoint.

Azimuth is the azimuth at which the star appears in the horizontal reference frame.
Altitude is the altitude at which the star appears in the horizontal reference frame.
Azimuth Motion is the azimuth component of the star's angular velocity in the horizontal reference frame.
Altitude Motion is the altitude component of the star's angular velocity in the horizontal reference frame.
Total Motion is the magnitude of the star's angular velocity in the horizontal reference frame.
Position Angle is the position angle of the star's angular velocity in the horizontal reference frame, with the position angle measured anticlockwise from the zenith.