We introduce and analyse a new family of multiple orthogonal polynomials of hypergeometric type with respect to two measures supported on the positive real line which can be described in terms of confluent hypergeometric functions of the second kind. These two measures form a Nikishin system. Our focus is on the multiple orthogonal polynomials for indices on the step line. The sequences of the derivatives of both type I and type II polynomials with respect to these indices are again multiple orthogonal and they correspond to the original sequences with shifted parameters. For the type I polynomials, we provide a Rodrigues-type formula. We characterise the type II polynomials on the step line, also known as $d$-orthogonal polynomials (where $d$ is the number of measures involved so that here $d=2$), via their explicit expression as a terminating generalised hypergeometric series, as solutions to a third-order differential equation and via their recurrence relation. The latter involves recurrence coefficients which are unbounded and asymptotically periodic. Based on this information we deduce the asymptotic behaviour of the largest zeros of the type II polynomials. We also discuss limiting relations between these polynomials and the multiple orthogonal polynomials with respect to the modified Bessel weights. Particular choices on the parameters for the 2-orthogonal polynomials under discussion correspond to the cubic components of the already known threefold symmetric Hahn-classical multiple orthogonal polynomials on star-like sets.

针对正实线上支持的两个量度，我们介绍并分析了一个新的超几何类型的正交正交多项式族，这可以用第二种融合的超几何函数来描述。这两种措施构成了Nikishin系统。我们的重点是针对步骤线上的索引的多个正交多项式。I型和II型多项式的导数相对于这些索引的序列再次是多重正交的，并且它们对应于具有移位参数的原始序列。对于I型多项式，我们提供了Rodrigues型公式。我们在步骤线上刻画了II型多项式的特征，也称为$d$-正交多项式（其中 $d$ 是涉及的措施数量，所以这里 $d=2$），通过将它们的显式表示为终止的广义超几何级数，作为三阶微分方程的解以及通过其递归关系。后者涉及无界且渐近周期性的递归系数。根据此信息，我们推断出II型多项式的最大零点的渐近行为。我们还讨论了相对于修改后的Bessel权重，这些多项式与多个正交多项式之间的限制关系。所讨论的2个正交多项式的参数上的特定选择对应于星形集合上已知的三重对称Hahn-经典多重正交多项式的三次分量。