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Abstract Stellar positions and velocities from Gaia are yielding a new view of open cluster dispersal. Here we present an analysis of a group of stars spanning Cepheus (l= 100°) to Hercules (l= 40°), hereafter the Cep-Her complex. The group includes four Kepler objects of interest: Kepler-1643 b (R_p= 2.32 ± 0.13R_⊕,P= 5.3 days), KOI-7368 b (R_p= 2.22 ± 0.12R_⊕,P= 6.8 days), KOI-7913 Ab (R_p= 2.34 ± 0.18R_⊕,P= 24.2 days), and Kepler-1627 Ab (R_p= 3.85 ± 0.11R_⊕,P= 7.2 days). The latter Neptune-sized planet is in part of the Cep-Her complex called theδLyr cluster. Here we focus on the former three systems, which are in other regions of the association. Based on kinematic evidence from Gaia, stellar rotation periods from TESS, and spectroscopy, these three objects are also ≈40 million years (Myr) old. More specifically, we find that Kepler-1643 is ${46}_{-7}^{+9}$Myr old, based on its membership in a dense subcluster of the complex called RSG-5. KOI-7368 and KOI-7913 are ${36}_{-8}^{+10}$Myr old, and are in a diffuse region that we call CH-2. Based on the transit shapes and high-resolution imaging, all three objects are most likely planets, with false-positive probabilities of 6 × 10⁻⁹, 4 × 10⁻³, and 1 × 10⁻⁴for Kepler-1643, KOI-7368, and KOI-7913, respectively. These planets demonstrate that mini-Neptunes with sizes of ≈2 Earth radii exist at ages of 40 Myr. 

Context. In spiral galaxies, star formation tends to trace features of the spiral pattern, including arms, spurs, feathers, and branches. However, in our own Milky Way, it has been challenging to connect individual star-forming regions to their larger Galactic environment owing to our perspective from within the disk. One feature in nearly all modern models of the Milky Way is the Sagittarius Arm, located inward of the Sun with a pitch angle of ∼12°. Aims. We map the 3D locations and velocities of star-forming regions in a segment of the Sagittarius Arm using young stellar objects (YSOs) from the Spitzer /IRAC Candidate YSO (SPICY) catalog to compare their distribution to models of the arm. Methods. Distances and velocities for these objects are derived from Gaia EDR3 astrometry and molecular line surveys. We infer parallaxes and proper motions for spatially clustered groups of YSOs and estimate their radial velocities from the velocities of spatially associated molecular clouds. Results. We identify 25 star-forming regions in the Galactic longitude range ℓ  ∼ 4.​ ° 0–18.​ ° 5 arranged in a narrow, ∼1 kpc long linear structure with a high pitch angle of ψ  = 56° and a high aspect ratio of ∼7:1. This structure includes massive star-forming regions such as M8, M16, M17, and M20. The motions in the structure are remarkably coherent, with velocities in the direction of Galactic rotation of | V φ |≈240 ± 3 km s −1 (slightly higher than average) and slight drifts inward ( V R  ≈ −4.3 km s −1 ) and in the negative Z direction ( V Z  ≈ −2.9 km s −1 ). The rotational shear experienced by the structure is ΔΩ = 4.6 km s −1 kpc −1 . Conclusions. The observed 56° pitch angle is remarkably high for a segment of the Sagittarius Arm. We discuss possible interpretations of this feature as a substructure within the lower pitch angle Sagittarius Arm, as a spur, or as an isolated structure.