WWU researchers lead international team to develop 3-D map of Orion

An international team of researchers from Western Washington University, Universidad Nacional Autónoma de Mexico (UNAM) and various other institutions in Chile, Spain and the U.S. have teamed up to create a very detailed model of the Orion Star Forming Complex.

The results of this work are reported in a paper soon to be published in the Astronomical Journal, which describes in detail how the team used data from multiple observatories to understand the makeup of the Orion complex and how objects within it move.

The team was led by WWU’s Marina Kounkel, a postdoctoral research associate, and Kevin Covey, an assistant professor of Physics and Astronomy. 

“The Orion star-forming region is quite exciting since it is an excellent laboratory of star formation in terms of proximity, mass, size, age, and so forth. This is among the best regions to study giant molecular cloud evolution,” said Kounkel.

The Orion Complex is a massive population of thousands of young stars. Some of them are as 1-2 million years, and are still closely associated with the molecular gas from which they formed. The conditions in which many of them are found most closely resemble the environment our own Sun might have been in when it was born. Other stars in the Complex are older, some up to 12 million years and usually no longer associated with the dense gas. While they are still loosely connected to the Orion Complex by gravity, they are starting to disperse.

Understanding how and why these stars form and evolve until they emerge from their nurseries into the Milky Way disk provides researchers with a better understanding about how stars around the universe were formed.

“This work will inspire to make similar studies in other regions," said Genaro Suárez, a graduate student at UNAM.

Understanding how and why these stars form and evolve until they emerge from their nurseries into the Milky Way disk provides researchers with a better understanding about how stars around the universe were formed.

The project is a part of the Sloan Digital Sky Survey (SDSS), a large-scale project aimed to study the story of the stars and galaxies across large areas of the sky. The researchers used the advanced spectrographs of the Apache Point Observatory Galactic Evolution Experiment (APOGEE), capable of observing hundreds of stars in a single exposure, to complete a survey of the Orion Complex. The stellar spectra provide individual physical characteristics of the young stars, like temperatures and surface gravities, along with their radial velocities and ages. The team also used recently published data from the Gaia satellite, a space observatory that provides very precise information about distances and motions of the stars on the sky plane.

“Combining data from APOGE and Gaia allows us to identify groups with distinct spatial and kinematic characteristics," said UNAM's Jesus Hernández.

All these parameters provide the best estimates of the 3D structure and the 3D kinematics of stars in the Orion Complex to date. The result is like a coordinated ballet of stellar motion that shows the dynamical evolution of the young stars across many different ages.

Kounkel said getting access to the broad spectrum of data from so many different sources brought the project to reality.

“The combination of Gaia releasing this data, and APOGEE obtaining so many spectra across the Orion has made putting it all together finally possible, we all have wanted to do it for quite a long time,” said Kounkel. 

For more information on the group's Orion project, contact Kounkel at marina.kounkel@wwu.edu; the 3-D model can be seen at http://mkounkel.com/ori3d/ and the paper can be read at https://arxiv.org/pdf/1805.04649.pdf.