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Active Research: the SPYGLASS Program

My recent work has been focussed on the SPYGLASS (Stars with Photometrically Young Gaia Luminosities Around the Solar System) program, an ambitious project to identify young stars and map young stellar associations in the solar neighborhood. These associations hold a star formation record that persists for tens of millions of years, allowing for the progression of star formation across the entire formation process to be studied. The SPYGLASS program has two primary components: first, the large-scale view of local star formation, which includes the detection of new associations and subsequence assessments of demographics and large-scale structure, and second the study of individual populations, which reveals star formation patterns at the population level. Three studies from this survey have already been published, with a fourth now up on ArXiv. Expect more to be released soon!

Large Scale Star Formation

The SPYGLASS program enables the widespread identification of young stars and the associations that they exist in, enabling insights into both population demographics and large-scale patterns. Work so far has been focussed on the identification and discovery of stellar populations, which provides numerous readily-accessible young populations for studying the progression of star formation within individual events. As our methodology develops, we will be expanding this work to cover statistics of our populations and formation patterns at large scales. The flagship paper identifying young populations and providing an overview of the discoveries is available in SPYGLASS-I. The figure at right provides an overview of the populations we identified. An expansion of this work to 1 kpc is underway, which contains about 5 times as many associations, including nearly twice as many within the radius searched in SPYGLASS-I.  While not published, new membership assessments for all populations are complete! Please contact me if you're interested in studying any specific region or using my lists for new projects!

Regional Studies

Studies of individual associations and star-forming regions allow us to uncover star formation patterns and learn about the processes that guide the evolution of a star-forming region. These studies rely on the dynamical traceback of young associations, which uses high-quality position and velocity measurements from both the Gaia spacecraft and independent spectroscopic measurements to compute past stellar positions. The results show not just the positions of subgroups relative to each other, but also show the dispersal of stars after formation, with the moment of closest configuration indicating subgroup age. We refine these ages using other methods, providing a comprehensive view of the locations of stars at the times of formation, and how one formation event leads to the next. Papers have already been released detailing this analysis for the relatively new association of Cepheus Far North, as well as Fornax-Horologium and the remainder of the Austral Complex, which includes Tuc-Hor, Carina, and Columba.

Cepheus Far North is one of the largest associations from SPYGLASS-I without previous widespread coverage. We made extensive new radial velocity measurements, and our traceback of members reveals:

  • Subgroups form in two distinct nodes – maybe from a fragmenting filament?

  • Star formation across both nodes takes place over a 10 Myr time period, or ~8 Myr in each node.

  • Distribution of ages is consistent with continuous formation

  • EE Dra, a new gravitationally bound open cluster that is ~10 solar mass and ~27 Myr old.

See the figure at right for the complete history of CFN's formation. Stars appear at their moment of formation, and their evolution is shown from 32 Myr ago to the present day. ​

Fornax-Horologium (FH) is centered on the χ1 Fornacis Cluster, and is the nearest SPYGLASS-I association to the Sun. Our study includes Tuc-Hor, Carina, and Columba, which form an extensive and interconnected "Austral Complex". We find:

  • Co-spatial formation for Carina, Columba, and FH, while Tuc-Hor forms in a distinct note, similar to the formation nodes in CFN.

  • Platais 8, a Sco-Cen subgroup in SPYGLASS-I, stays nearby throughout the complex's formation, suggesting that viewing the complex in isolation may miss large-scale patterns and connections. 

These regional studies have so far revealed a pattern in which associations are composed of multiple discrete star formation nodes which are not obvious in dynamical or spatial coordinates. These nodes of common formation may represent the clearest discrete unit of star formation, and resolving more of them as well as calculating their positions during formation may be critical to the demystification of large-scale star formation patterns

Our recent SPYGLASS-IV publication expanded our survey of young stellar populations to 1 kpc, revealing 116 young associations, 10 of which are completely new, and an additional 20 of which substantially different from any existing group definition. This survey provides both a new sample of small and high-velocity young associations which are unique from previously-known populations, while also revealing larger connecting structures that suggest links between groups like Perseus OB2 and Orion. Our expanded search radius and sensitivity to larger structures also reveal features which connect to the scale of spiral arms, outlining the recently-formed Radcliffe wave as well as a pair of perpendicular structures at older ages. These older structures may suggest a transition from perpendicular, spur-oriented star formation to formation aligned with the spiral arms in the last 30 Myr. The figures below display the structures identified in galactic XYZ, l/b sky coordinates, and transverse velocity space.

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