tides2.f

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      SUBROUTINE tides2(QPERI,M1,M2,S1,S2,KSTAR,ECC,KG,WS,QS,DE2,DE3)
*
*
*       Tidal energy loss for interacting bodies.
*       -----------------------------------------
*
      IMPLICIT REAL*8 (a-h,o-z)
      REAL*8  size(2),ratio(2),zeta(2),psi2(2),psi3(2),de2(2),de3(2),
     &        efac2,efac3,ws(2),qs(2),m1,m2,body(2)
      INTEGER kstar(2),ip(2),kg(2)
*
*
*       Copy masses & radii to local arrays.
      body(1) = m1
      body(2) = m2
      SIZE(1) = s1
      SIZE(2) = s2
      efac = 2.0/(1.0 + ecc)
*
*       Assign the appropriate polytropic reference index (n = 3, 2 or 3/2).
      DO 5 k = 1,2
          ii = 3
          IF (kstar(k).EQ.0) ii = 1
          IF (kstar(k).GE.10) ii = 2
          ip(k) = ii
    5 CONTINUE
*
*       Form dimensionless ratios & tidal efficiency factors for each star.
      DO 10 k = 1,2
          l = 3 - k
          ratio(k) = SIZE(k)/qperi
          IF (ratio(k).GT.0.1) THEN
              icase = ip(k)
              zeta(k) = sqrt((body(k)/(body(k) + body(l)))/ratio(k)**3)
              IF (zeta(k).GT.2.0) THEN
                  alpha = 0.5 + 0.25*(0.5*(zeta(k) - 2.0))**1.5
              ELSE
                  alpha = 0.5
              END IF
              zeta(k) = zeta(k)*efac**alpha
              IF (kg(k).EQ.0) THEN
                  psi2(k) = efac2(zeta(k),icase)
                  psi3(k) = efac3(zeta(k),icase)
              ELSE
                  psi2(k) = qs(1)*efac2(ws(1)*zeta(k),icase)
                  psi3(k) = qs(2)*efac3(ws(2)*zeta(k),icase)
              END IF
          END IF
   10 CONTINUE
*
*       Obtain energy loss due to second & third order modes.
      DO 20 k = 1,2
          l = 3 - k
*         IF (RATIO(K).GT.0.1) THEN
          IF (ratio(k).GT.0.5) THEN    ! awaiting bug fix (too large values)
              r2 = ratio(k)**2
              r6 = r2*r2*r2*body(l)**2/SIZE(k)
              de2(k) = r6*psi2(k)
              de3(k) = r6*r2*psi3(k)
          ELSE
              de2(k) = 0.0
              de3(k) = 0.0
          END IF
   20 CONTINUE
*
      RETURN
*
      END