To be investigated:

- gyration radii
  especially helium giants
  and        compact objects.

- Zeta for Roche-lobe:
  Mass transfer timescales may flip-flop between boundaries.

- Effective radius variation in case of mass transfer.
  what is the effective radius for different timescales (types) of
  mass transfer. And how does it adjust after mass transfer is
  completed or if the mass transfer timescale changes.
  Also importand in case of mildly perturbed triples.

- Output functions need to be modernized.....

- Function and variable nomenclature.

- How to determine the evolutionary state and age of a merger product?

- Low mass main-sequence stars which lose mass may become brown dwarfs. 

- Thermo nuclear flash is currently implemented for all accreting
  white dwarfs. For some this treatment may be far to violent.

- Dynamical timescale: currently implemented as
  sqrt(t_dyn * t_kh)

- Nuclear timescale for non-main-sequence stars: currently implemented as
  sqrt(t_kh * t_nuc)
  Published timescales for slow mass transfer indicate similar
  timescales. The current implementation, however, is rather un-physical.

- Core-mass determination for Hertzsprung-gap stars. Currently linear.

- Brown dwarfs require update.

- Radii for Wolf-Rayet stars.

- Angular momentum loss for mass transfer onto compact objects.
  Currently implemented in similar fashion as for other accretors.
  No discrimination is made between various types of compact objects.

- Stellar rotation.
  a) Initial rotation
  b) spin-down due to expansion and core-halo discrimination.
  c) spin-up in mass accretion phase

- Exchange of mass in stellar wind should be performed consistently.
  Perform wind mass loss in ::double_star instead of ::single_star.

- What is the strucure of a `ZAMS' helium star.

- Mergers and contact binaries can be the result of a `too big' timestep.

To be solved by experts (wij niet dus):
Peter, GertJan, Lev, Onno, Ed, Frank, Norbert, Alex, Lex, Martijn, Chris, Lit
SE/BE    SE     BE    BE   BE   Obs    HMS      HMS  Obs   CV       BE

  - Peter
? New EFT equations: stellar evolution fits.
  SeBa version 4.0

  - ? Lit
? How much mass is lost in stellar wind by low-mass stars.
  What is the time dependence of this wind?

  - Lit?
? Zeta adiabatic and Zeta Thermal.
  Values are not avaiable for many stellar types and the range in mass 
  is extremley limited.

- Habets lezen...
? How far can one strip a helium star?
- Mario, Lev, Nomoto
? How do ONeMg stars evolve?
- Mario, Lev, Nomoto
? How do helium stars with an ONeMg core (the cores of stripped helium
  stars) form?  

Stellar evolution
  - Peter, Onno
? What happens to a helium star which accretes hydrogen.
? What happens to a star with a hydrogen envelope which accretes helium.

- Key:  Peter, GertJan, Norbert, Alex
? Naked core helium stars:
  a) What is the difference between helium stars (with the same mass) 
     formed from stripping 
     a sub-giant (hydrogen shell burning star) and from stripping
     a super-giant (double shell burning star).

  b) Currently we assume that hertzsprung-gap and sub_giants form `ZAMS' 
     helium stars, where horizontal branch and super giants form
     `evolved' helium stars.
     -We assume the following parametrization:
      1) the `age' of the helium star is zero for hg and gs stars.
      2) the `age' of the helium star is proportional to the time
         spent on the hb.
      3) the `age' of the helium star is 0.9 of the total lifetime of
	 a helium star with the same mass if the he star was formed
	 from a Sg.

  c) How massive is the CO core for a helium star which ascends the
     helium giant branch.

  d) How much mass loses a helium star in stellar wind.

  e) What is the radius of the helium core of a giant?




Binary evolution
  - Onno, Peter
? To which published binary evolution tracks should the results of
  SeBa be compared/calibrated.

- De Kool
? a) Reaction of low-mass main-sequence stars to mass loss on a nuclear
     and thermal timescale.
- Norbert
  b) And what about high mass main-sequence stars.
     Is it possible to strip a massive (M>~25Msun) main-sequence star to
     less than ~1Msun? 

- Key: Onno, Chris, Peter 
? Is it possibile that mass transfer on a dynamical
  timescale stabilizes and becomes thermal or even nuclear (for
  convective stars)?
  Can a star go from Dynamic -> Thermal or
                from Dynamic -> Nuclear.

- Onno, Peter, GertJan
? How does the radius of the donor react on mass loss.
  Is this reaction mass-transfer timescale dependent, and how.

