Julio Chanamé, Jason Curtis, Simon Schuler, Marcel Agüeros, Kevin Covey, Marina Kounkel jeff[email protected] Theia 456: A New Milky Way Stellar Stream Jeff J. Andrews Northwestern University AAS 237, 407. Star Clusters: Galactic & Extragalactic
Julio Chanamé, Jason Curtis, Simon Schuler, Marcel Agüeros, Kevin Covey, Marina Kounkel
Theia 456: A New Milky Way Stellar Stream
Jeff J. Andrews Northwestern University
AAS 237, 407. Star Clusters: Galactic & Extragalactic
Our Evolving Picture of the Milky Way
Credit: Gaia
Our Evolving Picture of the Milky WayPleiades Open Cluster
Omega Cen Globular Cluster
Credit: Gaia
Credit: Gaia
Our Evolving Picture of the Milky WayPleiades Open Cluster
Omega Cen Globular Cluster
Belokurov et al. (2006), Bonaca et al. (2012), and many, many others
Gaia
Structure and Dynamics
“Theia” objects identified by Kounkel & Covey (2019, 2020)
Gaia
• Spans 25 degrees across the sky • Nearly 200 pc long • Distance of 500 pc
Structure and Dynamics
“Theia” objects identified by Kounkel & Covey (2019, 2020)
MoonPleiades
Gaia
• Spans 25 degrees across the sky • Nearly 200 pc long • Distance of 500 pc • Part of the Local Arm
Structure and Dynamics
Gaia
• Spans 25 degrees across the sky • Nearly 200 pc long • Distance of 500 pc • Part of the Local Arm • Orbits within the disk
Structure and Dynamics
Gaia
• Spans 25 degrees across the sky • Nearly 200 pc long • Distance of 500 pc • Part of the Local Arm • Orbits within the disk • The stars appear to have
a common origin
Structure and Dynamics
Gaia
• Spans 25 degrees across the sky • Nearly 200 pc long • Distance of 500 pc • Part of the Local Arm • Orbits within the disk • The stars appear to have
a common origin
Structure and Dynamics
But were they born together?
LAMOST
Metallicity
MoonPleiades
LAMOST
Theia stars have similar iron abundances:
[Fe/H] = -0.08
Metallicity
MoonPleiades
TESS
ZTF
Gyrochronology
Gyrochronology is a way to date stars based on their rotation
Gyrochronology
TESS
ZTF
Gyrochronology
TESS
ZTF
Gyrochronology
TESS
ZTF
Gyrochronology
TESS
ZTF
Gyrochronology
Theia 456 has an age similar to the Pleiades, ~100 Myr
TESS
ZTF
LAMOST
Gaia
NASA
NSF
Chinese Academy Of Sciences
European Space Agency
Science is Collaborative!
TESS
ZTF
Conclusions
•New stellar structure in the Milky Way disk • Spans 200 pc • 25 degrees across the sky
•Most Likely has a common origin • Consistent age • Consistent Metallicity
•Theia 456 is just the beginning • Just one “Theia” object from Kounkel & Covey (2019, 2020)