pro show_sk
  name='snap_010'
  readnew,name,h,'HEAD'
  readnew,name,x,'POS',part=0
  readnew,name,m,'MASS',part=0
  readnew,name,sfr,'SFR',part=0

  rr=SQRT(x[0,*]^2+x[1,*]^2)
  NN=20
  rtab=20.0*10.0d0^(findgen(NN)/(NN-1)*3-3)
  rho_tab=fltarr(NN-1)
  sfr_tab=fltarr(NN-1)

  FOR i=0,NN-2 DO BEGIN
     jj=WHERE(rr GT rtab[i] AND rr LE rtab[i+1],nfound)
     IF nfound GT 0 THEN BEGIN
        area=!Pi*(rtab[i+1]^2-rtab[i]^2)
        rho_tab[i]=TOTAL(m[jj]*1e10)/area/1e6
        sfr_tab[i]=TOTAL(sfr[jj])/area
     END
  END
  plot,rho_tab,alog10(sfr_tab),xtit='rho_gas [Msol/pc^2]',ytit='rho_sfr [Msol/year/kpc^2]',xr=[3,3000],xst=1,yr=[-4,1.7],yst=1,xth=2,yth=2,psym=4,thick=2,symsize=2,chars=2,charth=2,/xlog

  save_screen,'sk'
  
end