Digital Universe Guide - Hayden Planetarium

70 3. THE MILKY WAY ATLAS
Selection Expressions for the Stars
Alias Partiview Command Description
blue thresh BVcolor -1 0 Select those stars with a (B − V ) color
between −1 and 0, the “bluer” stars
red thresh BVcolor 0 1 See those stars with (B − V ) color
between 0–1, the “redder” stars
eye thresh appmag -30 6.5 See stars that have an apparent
magnitude brighter than 6.5
m75 thresh appmag < 7.5 Show all stars with an apparent
magnitude brighter than 7.5
trig only= dcalc 1 See those stars with pure trig
parallax distances
weighted only= dcalc 2 Show those stars that have
weighted mean distances
bright thresh absmag -10 -3 Show the intrinsically bright stars
faint thresh absmag 0 10 Show the intrinsically faint stars
100ly thresh distly < 100 Display all stars within 100 light-years
500ly thresh distly < 500 Display all stars within 500 light-years
Boxes In addition to the selection statements, we have defined a few boxes in the stars group.
Boxes are useful for highlighting a subset of data within the group (using the boxes command) or
separating data from the group (using the clipbox command). The table shows predefined boxes in the
mw.cf file.
Boxes in the Stars Data Group
Box Dimensions (parsecs)
Number (xcen,ycen,zcen xlen,ylen,zlen) Description
1 –400, –200, –200 400, 200, 100 Box around the Gould Belt
2 –42.35, –0.26, –17.12 3.5, 3.5, 3.5 Box around the Hyades star cluster
3 –100.93, 24.83, –45.95 6, 3, 3 Box around the Pleiades star cluster
clipbox –400, –200, –200 400, 200, 100 Clip box around the Gould Belt
Pressing the Box Toggle Button in Partiview will produce two boxes around the Hyades and Pleiades;
however, the box around the Gould Belt will be invisible. Use the showbox and hidebox commands to
alter which boxes are displayed. showbox 1 will turn on the Gould Belt box, for example. (The Gould
Belt is a grouping of bright stars inclined to the Galactic plane that demonstrate recent star formation.)