Selections from 2017: The Age of a 4-Star System

Artist's impression of a quadruple star system in which two binaries orbit each other. [Institute for Astronomy, U of Hawaii]

January 11, 2018- Dr. James MacDonald and Dr. Dermott Mullan recently derived the age of the quadruple star system KIC 7177553. The system appears to be younger than originally thought — it’s best modeled as being 32–36 million years old. 

Based on stellar models and the observed radii of the stars, their ages are likely between 32 and 36 million years. The KIC 7177553 system is intriguing because of its complex structure: it consists of two binaries (one of which is eclipsing) orbiting each other in a hierarchical structure. Observations of KIC 7177553 can teach us how hierarchical systems like this one form and evolve, but first we need to determine how old the system is so we know what stage of its evolution we’re seeing. The authors’ estimate of 32–36 million years is relatively young for stars; this age places them in the pre-main-sequence phase.
Dr. MacDonald and Dr. Mullan have had this work recently featured in AAS Nova (, a feature of the AAS journals. You can find the AAS article here:
The full text of Dr. MacDonald and Dr. Mullan's work is here: