View source for Wind structure of Cyg X-1 (xfig example)

=== Wind structure of Cyg X-1 ===

[[File:sketch.png|450px]]

The clouds included in this sketch are produced by LaTeX using a package providing weather symbols:
<pre>
\documentclass{article}
\usepackage{color}
\usepackage[weather]{ifsym}
\begin{document}
\definecolor{c}{rgb}{.6,.3,0}
\pagestyle{empty}
\strut\hbox to 0pt{\color{c}\FilledCloud}\Cloud
\end{document}
</pre> 
Here, a <code>\Cloud</code> is placed ontop of a <code>\FilledCloud</code> (which was put in a horizontal box of zero width) in order to create a contour around the filled cloud.

Processing the resuting postscript file with <code>ps2eps -B</code> recalculates the bounding box and thus produces an eps image containing the cloud only.
This step is repeated for three colors <code>c</code>, yielding <code>cloud1.eps</code>, <code>cloud2.eps</code>, and <code>cloud0.eps</code>.


You will also need the Roche lobe contours of the companion star HDE226868. See instructions in [[Example:_Chandra_Coverage|Chandra coverage]] to create them.


When done with the preparations, you can compose the figure:
<pre>
require("xfig");

xfig_new_color("direct", 0x000000);
xfig_new_color("abs",    0x0000C0);
xfig_new_color("em",     0xC00000);
xfig_new_color("HDE",    0x60A0FF);

% load the Roche lobe contours:
variable t = fits_read_table("Roche_contours_xz_q0.567.fits+2");
struct_filter(t, [::100]);

variable i = 35*PI/180; % inclination of the system
variable factor = 1.15;
variable l = 10/factor/1.1*sin(i), a = .25,  P = .5;

% simplify the use of xfig_new_photon
define add_photon(xfig, x, y)
{
  variable X1, Y1; (X1, Y1) = xfig.xfig_coords(x[0], y[0]);
  variable X2, Y2; (X2, Y2) = xfig.xfig_coords(x[1], y[1]);
  variable ph = xfig_new_photon(vector(X1-X2, Y1-Y2, 0), a, P);
  ph.translate(vector(X2, Y2, 0));
  ph.set_pen_color(qualifier("color", "black"));
  ph.set_fill_color(qualifier("color", "black"));
  ph.set_thickness(qualifier("width", 1));
  ph.set_line_style(qualifier("line", 0));
  xfig.add_object(ph);
}

% setup the plot with a straightforward coordinate system and no axes
variable xfig = xfig_plot_new(20*.8, 21*.8);
xfig.world(0, 2, -.1, 2);
xfig.axes(; off);

% plot the companion star and the binary axis of the system
xfig.plot(t.x, t.z; color="HDE");
xfig.xylabel(0,0,`\centering\small HDE\\226868`, -.5, 0; color="HDE");
xfig.xylabel(1,0,`\centering\small Cyg\\X-1`);
xfig.plot([.48, 1.67], [0, 0]; line=2, color="#808080", width=2);


% Since there will be lots of lines, 
% a couple of linear equations for the coordinates are needed.
% Never mind the horrible coefficients,
% involving the inclination i and user-chosen radii! ;-)

variable r1=.15, R1=.55, rC1=.65;
% x = t * (1-rC1*s^2) = 1+r4 * s^2
% y = t * (s*c*rC1)   = s*c*r4
% => t = r4/rC1
% => r4/rC1 * (1-rC1*s^2) = 1 + r4*s^2
% => r4 * [ (1-rC1*s^2)/rC1 - s^2 ] = 1
variable rC2 = 1/(1/rC1-2*sin(i)^2);
variable R2 = rC2+R1-rC1;
variable r2 = r1;

% some clouds retreat radially from the star, expanding:
variable x = 1-sin(i)^2*rC1;
variable y = sin(i)*cos(i)*rC1;
variable r = hypot(x, y);
variable alpha = atan2(y,x) - .033;
xfig.plot(r*cos(alpha)*[.54, 2], r*sin(alpha)*[.54, 2]; line=2, color="#D0D0D0");
alpha += 2*.033;
xfig.plot(r*cos(alpha)*[.54, 2], r*sin(alpha)*[.54, 2]; line=2, color="#D0D0D0");

% add the clouds:

% load an exisiting .eps file
variable cl = xfig_new_eps("cloud1.eps"); 

% scale it according to your wishes
cl.scale(1.2); 

% and add it as an object to your figure
xfig.add_object(cl, x, y); 

variable cl = xfig_new_eps("cloud2.eps");
cl.set_depth(200);
cl.scale(1.2*hypot(1+sin(i)^2*rC2, sin(i)*cos(i)*rC2)/r);
xfig.add_object(cl, 1+sin(i)^2*rC2, sin(i)*cos(i)*rC2);

x = .6;  y =  .075;
variable cl = xfig_new_eps("cloud0.eps");
cl.scale(1);
xfig.add_object(cl, x, y);

% Since an xfig plot is basically a struct of function references,
% you can easily add your own functions to it:
xfig = struct { @xfig, add_photon=&add_photon };

% Now call add_photon just like any xfig function you already know:
xfig.add_photon(x+[.02,.18]*sin(i),
                y+[.02,.18]*cos(i); color="em", width=2);
xfig.add_photon(x-[.02,.18]*sin(i),
                y+[.02,.18]*cos(i); color="em", width=2);
xfig.xylabel(x, y-0.04, "emission"; color="em");
xfig.xylabel(x, y-0.09, `($v\approx0$)`; color="em");

variable dx = .04;

variable rr1 = rC1*2-R1;
variable RR1 = rr1 + R2-r2;

variable rr2 = rC2*2-R2;
variable RR2 = rr2 + R1-r1;

xfig.add_photon(1-sin(i)^2*[r1-.05,R1], sin(i)*cos(i)*[r1-.05,R1]; color="direct", width=4);
xfig.add_photon(1+sin(i)^2*[r2, R2], sin(i)*cos(i)*[r2, R2]; color="direct", width=4);

xfig.add_photon(1-sin(i)^2*[rr1,RR1],           sin(i)*cos(i)*[rr1,RR1]; color="abs");
xfig.add_photon(1-sin(i)^2*[rr1,RR1]-dx*cos(i), sin(i)*cos(i)*[rr1,RR1]-dx*sin(i); color="em", width=2);
xfig.add_photon(1-sin(i)^2*[rC1,1.5*rC1-.5*RR1]+dx*cos(i),  sin(i)*cos(i)*[rC1,(RR1+rC1)/2]+dx*sin(i); color="em", width=2);

xfig.add_photon(1+sin(i)^2*[rr2,RR2],           sin(i)*cos(i)*[rr2,RR2]; color="abs", width=3);
xfig.add_photon(1+sin(i)^2*[rr2,RR2]+dx*cos(i), sin(i)*cos(i)*[rr2,RR2]-dx*sin(i); color="em", line=1);
xfig.add_photon(1+sin(i)^2*[rC2,1.5*rC2-.5*RR2]-dx*cos(i),  sin(i)*cos(i)*[rC2,(rC2+RR2)/2]+dx*sin(i); color="em", line=1);

% xfig.plot(1+sin(i)^2*[-rC1,rC2], sin(i)*cos(i)*[rC1,rC2]; line=2);

variable r = (rC1+RR1)/2;
variable x = 1-sin(i)^2*r;
variable y = sin(i)*cos(i)*r;
dx = 0.12;
xfig.xylabel(x-    dx*cos(i), y-    dx*sin(i), `strong absorption,`; color="abs", rotate=-55);
xfig.xylabel(x-1.5*dx*cos(i), y-1.5*dx*sin(i), `stronger than`; rotate=-55);
xfig.xylabel(x-2  *dx*cos(i), y-2  *dx*sin(i), `any emission`; color="em", rotate=-55);
xfig.xylabel(x-2.5*dx*cos(i), y-2.5*dx*sin(i), `at $v\approx0$`; rotate=-55);

variable x = 1-sin(i)^2*(1.375*rC1-.375*RR2);
variable y = sin(i)*cos(i)*(rC1+(-.375*rC1+.375*RR1));
variable x = 1-sin(i)^2*(1.375*rC1-.375*RR2);
variable y = sin(i)*cos(i)*(rC1+(-.375*rC1+.375*RR1));
dx /= 1.5;
xfig.xylabel(x+  dx*cos(i), y-  dx*sin(i), `emission`; color="em", rotate=55);
xfig.xylabel(x+1.5*dx*cos(i), y-1.5*dx*sin(i), `($v\approx0$)`; color="em", rotate=55);

variable r = (rC2+2*RR2)/3;
variable x = 1+sin(i)^2*r;
variable y = sin(i)*cos(i)*r;
dx /= 1.25;
xfig.xylabel(x-2  *dx*cos(i), y+2  *dx*sin(i), `($v\ll0$)`; color="abs", rotate=55);
xfig.xylabel(x-    dx*cos(i), y+    dx*sin(i), `absorption`; color="abs", rotate=55);
xfig.xylabel(x+1.5*dx*cos(i), y-1.5*dx*sin(i), `\small weak emission`; color="em", rotate=55);

dx *= 1.25;
xfig.xylabel(1+sin(i)^2*(1.5*rC2-.5*RR2)-dx*sin(i),  sin(i)*cos(i)*(rC2+RR2)/2-dx*cos(i),
             `\small weak em.`; color="em", rotate=-55, depth=10);

xfig.render("sketch.eps");
</pre>

[[Category:SLxfig]]