supernovae, millisecond pulsars, or low-mass x-ray binaries, then a significant fraction of
accreting white dwarf binaries should have high-mass primaries. If cataclysmic variables are the
progenitors, then more than 10% of them should have white dwarfs in the mass range 1.2-1.4
solar masses. What is the distribution of black hole masses? POINTS could furnish definitive
black hole masses and the beginnings of a black hole mass distribution. This would provide a
critical test for black hole formation models. How is accretion driven? (Secondary evolution?
Magnetic braking? Mass loss? Angular momentum loss?) What is the evolutionary state of the
secondary in a particular accreting system? POINTS has the potential to provide unique insights
into these questions.
J. Selected Exotic Objects
The strongest case for the existence of black holes would be to determine
dynamical masses of
binary systems containing BHCs. Table 5 contains a list of BHCs, based mainly on a table from
Cowley, from which we see that up to nine objects are within potential observing range of
POINTS. Included in this list is the exotic SS 433 (~5
kpc, V=14.2).
[63]
K. Solar System Studies
POINTS has potential to make significant contributions to our knowledge of the solar system.
Current determinations of asteroid masses are as sparse and inaccurate as 20 years ago.
[64]
The
astrometric method, where accurate asteroid positions are determined pre- and post- encounter
with another passing asteroid, is the best one for determining single-asteroid masses. The
observed perturbations are used to determine the mass of the
perturber. POINTS could be used
with this technique to determine asteroid masses much more accurately than is currently possible.
At m
14, there are 464 numbered asteroids when at opposition. For a magnitude cutoff of 18.0,
there are 2914 numbered asteroids available. This is far more than could be studied as part of a
reasonable observation schedule.
[65]
In addition, observations of suitably small planetary
satellites
[66]
could be used to determine planetary masses and low-order
zonal gravitational har-
monic coefficients. Also, the positional accuracies of occultation stars could be greatly
improved. Finally, POINTS could place the solar system in the
extragalactic reference frame.
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POINTS Science
16:29 Wednesday, January 03, 1996
page 17 of 20
[66]
There are 14 with visual magnitude brighter than 18, and 4 brighter than 14.
[65]
Reasenberg, R.D., 1984, BAAS 16, 758, "Microarcsecond Astrometric Interferometry," arrives at a similar result.
[64]
Hoffman, M. (1989). "Asteroid Mass Determination: Present Situation and Perspectives", in
Asteroids II, eds.
Binzel, R.P., Gehrels, T., and Matthews, M.S., U. Arizona Press, Tucson
[63]
Margon, B., and Anderson, S.F., 1989, Astrophys J 347, 448, "Ten Years of SS 433 Kinematics"; Margon, B.,
1984, Ann Rev Astron Astrophys 22, 507, "Observations of SS 433"
