
Figure 39: Distribution of short period AM CVn-type systems detectable in soft X-ray and as
optical sources as a function of the orbital period and distance. Top panel: systems detectable in
X-ray only (blue pluses), direct impact systems observable in X-ray and
-band (red filled circles),
systems detectable in X-ray with an optically visible donor (green squares), and systems detectable in
X-ray and with an optically visible disc (large filled triangles). Bottom panel: direct impact systems
(red open circles), systems with a visible donor (green squares), and systems with a visible accretion
disc (small open triangles). The sample is limited by
. Image reproduced with permission
from Figure 1 of [519], copyright by the authors.

