SPYGLASS. II. The Multi-Generational and Multi-Origin Star Formation History of Cepheus Far North

TL;DR

This study reconstructs the detailed, multi-generational star formation history of the Cepheus Far North association using Gaia data, revealing complex internal structures and distinct formation nodes over the past 10 million years.

Contribution

It provides a comprehensive, multi-method analysis of CFN's star formation history, identifying subgroups and their ages, and uncovering the association's internal complexity and formation nodes.

Findings

Identified over 500 CFN members across 7 subgroups.

Revealed a largely continuous 10 Myr star formation history.

Discovered two distinct star formation nodes associated with different stars.

Abstract

Young stellar populations provide a record of past star formation, and by establishing their members' dynamics and ages, it is possible to reconstruct the full history of star formation events. Gaia has greatly expanded the number of accessible stellar populations, with one of the most notable recently-discovered associations being Cepheus Far North (CFN), a population containing hundreds of members spanning over 100 pc. With its proximity (d $\lesssim$ 200 pc), apparent substructure, and relatively small population, CFN represents a manageable population to study in depth, with enough evidence of internal complexity to produce a compelling star formation story. Using Gaia astrometry and photometry combined with additional spectroscopic observations, we identify over 500 candidate CFN members spread across 7 subgroups. Combining ages from isochrones, asteroseismology, dynamics, and lithium depletion, we produce well-constrained ages for all seven subgroups, revealing a largely continuous 10 Myr star formation history in the association. By tracing back the present-day populations to the time of their formation, we identify two spatially and dynamically distinct nodes in which stars form, one associated with $\beta$ Cephei which shows mostly co-spatial formation, and one associated with EE Draconis with a more dispersed star formation history. This detailed view of star formation demonstrates the complexity of the star formation process, even in the smallest of regions.