Adapting Marchal's test of escape to real triple stars

¹ Department of Astronomy, Nanjing University, 22 Hankou Road, Nanjing 210093, PR China
² Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, PR China e-mail: fyn@pmo.ac.cn

Received: 14 January 2008
Accepted: 11 May 2009

Abstract

Context. For a general N-body system, Marchal constructed an analytical test of escape, which uses only a one-dimensional projected motion state of the system at any given instant. This test is well adapted to identifying real, disintegrating small stellar systems, of which the full motion states are generally unavailable. However, to our knowledge, there has been no practical application of this test until the present-day.

Aims. In this paper, we aim at adapting the above test to visual triple stars with estimable component masses and known kinematic data on the plane perpendicular to the line-of-sight. As illustrating examples, our goal is to identify disintegrating Hipparcos linear triple systems.

Methods. The fundamental techniques of analytical geometry were used to adapt the test of escape to practical applications, and the Monte Carlo method used to cope with the unavoidable observational errors, so that the confidence probability of a real triple star disintegrating could be obtained.

Results. A practical algorithm was designed to make full use of the two-dimensional kinematic data in testing usual visual triple stars. This algorithm is then applied to 24 Hipparcos linear triple systems with estimable component masses and the disintegration probability given.