Gaia Net: Toward Robust Spectroscopic Parameters of Stars of all Evolutionary Stages

Abstract We present a new processing of XP spectra for 220 million stars released in Gaia DR3. The new data model is capable of handling objects with T eff between 2000 and 50,000 K and with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> </mml:math> between 0 and 10, including objects of multitude of masses and evolutionary stages. This includes for the first time ever robust processing of spectroscopic parameters for pre-main-sequence stars, with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> </mml:math> sensitivity toward their age. Through this analysis we examine the distribution of young low-mass stars with ages of up to 20 Myr in the solar neighborhood, and we identify a new massive (&gt;1000 stars) population, Ophion, which is found east of Sco–Cen. This population appears to be fully disrupted, with negligible kinematic coherence. Nonetheless, due its young age it appears to still persist as a spatial overdensity. Through improved determination of ages of the nearby stars, it may be possible to better recover the star-forming history of the solar neighborhood outside of the moving groups.