Untangling the Galaxy III: Photometric Search for Pre-main Sequence Stars with Deep Learning

Abstract

A reliable census of of pre-main sequence stars with known ages is critical to our understanding of early stellar evolution, but historically there has been difficulty in separating such stars from the field. We present a trained neural network model, Sagitta, that relies on Gaia DR2 and 2MASS photometry to identify pre-main sequence stars and to derive their age estimates. Our model successfully recovers populations and stellar properties associated with known star forming regions up to five kpc. Furthermore, it allows for a detailed look at the star-forming history of the solar neighborhood, particularly at age ranges to which we were not previously sensitive. In particular, we observe several bubbles in the distribution of stars, the most notable of which is a ring of stars associated with the Local Bubble, which may have common origins with the Gould's Belt.

A gravitational and dynamical framework of star formation: The Orion Nebula

“…To examine the effect the Orion Complex has on its surroundings we use the Gaia EDR3 sample from McBride et al (2020) of low mass young stars. Unlike the older field stars, pre-main sequence stars are dynamically cold with a relatively small velocity dispersion not only within each individual complex, but also as a collective within the Galactic reference frame.…”

“…We added star test particles, up to 250 pc away from Orion in X and Y , with Z randomized between −50-−120 pc, i.e, below the plane but somewhat closer to the plane than Orion. Initial velocity of the test particles was set similar to Orion (U, V = 0 km s −1 , W = −1.5 km s −1 ), as all star forming regions in the solar neighborhood are expanding away from the center of the Local Bubble (McBride et al 2020).…”

Gaia EDR3 Reveals the Substructure and Complicated Star Formation History of the Greater Taurus-Auriga Star Forming Complex

“…In particular, conclusions about the older and distributed populations are biased by incompleteness, and a more thorough search for members of those groups is needed. Recent work performing all-sky searches for young stars will be crucial in this effort, and to identify more related young populations in the Taurus galactic neighborhood (Zari et al 2018;McBride et al 2020;Kerr et al 2021). Moving forward in the Gaia era, we will be able to place the story of specific regions like Taurus into the broader context of star formation in our galaxy at large.…”

“…Large-scale, consistent searches for young (τ 50 Myr) stars without any initial phase space preference (e.g. Zari et al 2018;McBride et al 2020;Kerr et al 2021) are key in unraveling the picture of the greater Taurus region, and any as of yet unknown related populations around it. On-sky distribution of our census of the greater Taurus-Auriga region.…”