The Chemical Nature of the Young 120-Myr-old Nearby Pisces-Eridanus
  Stellar Stream Flowing through the Galactic Disk
  Recently, a new cylindrical-shaped stream of stars up to 700 pc long was
discovered hiding in the Galactic disk using kinematic data enabled by the Gaia
mission. This stream of stars, dubbed Pisces-Eridanus (Psc-Eri), was initially
thought to be as old as 1 Gyr, yet its stars shared a rotation period
distribution consistent with a population that was 120-Myr-old. Here, we
explore the detailed chemical nature of this stellar stream. We carried out
high-resolution spectroscopic follow-up of 42 Psc-Eri stars using McDonald
Observatory, and combined these data with information for 40 members observed
with the low-resolution LAMOST spectroscopic survey. Together, these data
enabled us to measure the abundance distribution of light/odd-Z (Li, Na, Al,
Sc, V), $\alpha$ (Mg, Si, Ca, Ti), Fe-peak (Cr, Mn, Fe, Co, Ni, Zn), and
neutron capture (Sr, Y, Zr, Ba, La, Nd, Eu) elements along the Psc-Eri stream.
We find that the stream is (1) near solar metallicity with [Fe/H] = -0.03~dex
and (2) has a metallicity spread of 0.07~dex (or 0.04 dex when outliers are
excluded). We also find that (3) the abundance of Li indicates that Psc-Eri is
$\sim$120 Myr old, consistent with its gyrochronology age. Additionally,
Psc-Eri has (4) [X/Fe] abundance spreads which are just larger than the typical
uncertainty in most elements, (5) it is a cylindrical-like system whose outer
edges rotate about the center and, (6) no significant abundance gradients along
its major axis except a potentially weak gradient in [Si/Fe]. These results
show that Psc-Eri is a uniquely close, young, chemically interesting laboratory
for testing our understanding of star and planet formation.
