galaxy_rotation.tex

\documentclass{standalone}
%\pagenumbering{gobble}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% two layer infall model
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\usepackage{tikz,xcolor}
\usetikzlibrary{arrows,snakes}
\usetikzlibrary{shapes.geometric}
\usetikzlibrary{backgrounds}
\usetikzlibrary{arrows.meta}

\tikzset{partial ellipse/.style args={#1:#2:#3}{insert path={+ (#1:#3) arc (#1:#2:#3)}}}
\tikzset{photon/.style={->, snake=snake, line after snake=1mm}}

\begin{document}

%\tikzstyle{background grid}=[draw, black!30,step=.5cm]
%\begin{tikzpicture}[scale=1.0, font=\sffamily, show background grid]
\begin{tikzpicture}[scale=1.0, font=\sffamily]

	% Sun
	\draw[line width=0.2mm, solid] (0,0) circle (10);
	\draw[fill] (0,10) circle (0.15);
	\draw[fill, color=white] (0,10) circle (0.08);
	\draw[thick, arrows={-Triangle[angle=60:7pt]}] (0,10) -- (1.5,10);
		\node[align=center] at (2,10.2) {\huge{$V_{\rm S}$}};

	% source
	\draw[line width=0.2mm, solid] (0,0) circle (7);
	\draw[fill] (3,6.325) circle (0.1);
		\node[align=center] at (3.2,6.7) {\Large{$A$}};
	\draw[thick, arrows={-Triangle[angle=60:7pt]}] (3,6.325) -- (4.8,5.4715);
		\node[align=center] at (5.7,5.7) {\huge{$V(R)$}};
	\draw[line width=0.3mm] (6.8,1.65) circle (0.1);
		\node[align=center] at (7.1,2.0) {\Large{$B$}};

	% triangle
	\draw[line width=0.4mm, solid] (0,10) -- (3,6.325);
	%\draw[line width=0.3mm, dotted] (3,6.325) -- (11,-3.475);
	\draw[line width=0.3mm, dotted] (3,6.325) -- (9.5,-1.635);
	\node[align=right] at (0.3,9.1) {\Large{$\l$}};
	\draw[thick, arrows={-Triangle[angle=60:7pt]}] (3,6.325) -- (4,5.1);
		\node[align=center] at (4.2,4.5) {\huge{$V_{rad}$}};
	\node[align=right] at (3.8,5.65) {\Large{$\theta$}};

	% Galaxy center
	\draw[fill] (0,0) circle (0.1);

	% annotation
	\draw[line width=0.4mm] (0,0) -- (0,10);
		\node[align=center] at (-0.65,5.5) {\huge{$R_{\rm S}$}};
	\draw[line width=0.4mm] (0,0) -- (3,6.325);
		\node[align=center] at (2.1,3.5) {\huge{$R$}};
	\node[align=right] at (-0.8,10.4) {\huge{Sun}};
	\node[align=right] at (-0.65,-0.35) {\huge{GC}};

	\node[align=center] at (0,-3) {\Huge{$\frac{R}{\sin l} = \frac{R_{\rm S}}{\cos\theta}$}};


\end{tikzpicture}

\end{document}