The $\textit{Gaia}$ view of the Cepheus flare

TL;DR

This paper uses Gaia EDR3 data to identify and analyze pre-main-sequence stars in the Cepheus flare, revealing the 3D structure, kinematics, and ages of stellar groups, and discovering new members and a young moving group.

Contribution

It provides a new census of young stars in Cepheus flare using Gaia data, identifying new members, structures, and a previously unknown young moving group.

Findings

Young stellar groups are between 330 and 368 pc away.

The groups divide into three kinematic subgroups.

A new 15-20 million-year-old moving group at 178 pc was discovered.

Abstract

We present a new census of candidate pre-main-sequence stars in the Cepheus flare star-forming region, based on $\textit{Gaia}$ EDR3 parallaxes, proper motions, and colour$-$magnitude diagrams. We identified new candidate members of the previously known young stellar groups associated with NGC$\,$7023, L1177, L1217/L1219, L1228, L1235, and L1251. We studied the 3D structure of the star-forming complex and the distribution of tangential velocities of the young stars. The young stellar groups are located between 330 and 368$\,$pc from the Sun, divide into three kinematic subgroups, and have ages between 1$-$5 million years. The results confirm the scenario of propagating star formation, suggested by previous studies. In addition to the bulk pre-main-sequence star population between 330 and 370$~$pc, there is a scattered and more evolved pre-main-sequence population around 150$-$180$\,$pc. We found new candidate members of the nearby Cepheus Association, and identified a new moving group of 46, 15$-$20 million years old pre-main-sequence stars located at a distance of 178$\,$pc, around the A0-type star HD$\,$190833. A few pre-main-sequence stars are located at 800$-$900$\,$pc, indicative of star-forming regions associated with the Galactic local arm above the Galactic latitude of +10$^{\circ}$.