For 10 points, name this property of a system, which is also used todescribe an equilibrium that is not resistant to perturbation.
Long, thin elliptical galaxies suffer from the "firehose" type of this phenomenon. Stars that appear ona feature of the H-R diagram with this in the name contain doubly-ionized helium in their atmospheres.Orbits near fixed points in systems of linear differential equations have this property the eigenvalues of theassociated matrix have real parts greater than zero. This word names a (*) "strip" in the HR diagram thatcontains variable stars. This condition also occurs when the second derivative of the potential energy is less thanzero for a system with no net forces or torques. For 10 points, name this property of a system, which is also used todescribe an equilibrium that is not resistant to perturbation.
Long, thin elliptical galaxies suffer from the "firehose" type of this phenomenon.
instability [accept anything saying that the system is unstable]