The First Extensive Spectroscopic Study of Young Stars in the North America and Pelican Nebulae Region

TL;DR

This study provides the first extensive spectroscopic analysis of young stars in the North America and Pelican Nebulae, identifying 580 likely members and deriving their ages, spectral types, and properties to understand star formation history.

Contribution

It introduces a large-scale spectroscopic survey of young stars in the NAP region, employing multiple instruments and advanced spectral fitting techniques to determine stellar parameters and ages.

Findings

Identified 580 young star members in NAP region.

Median stellar age approximately 1 million years.

Evidence for sequential star formation history.

Abstract

We present a spectroscopic survey of over 3400 potential members in the North America and Pelican nebulae (NAP) using several low-resolution ($R\approx$ 1300-2000) spectrographs: Palomar/Norris, WIYN/HYDRA, Keck/DEIMOS, and MMT/Hectospec. We identify 580 young stars as likely members of the NAP region based on criteria involving infrared excess, Li I 6708 absorption, X-ray emission, parallax, and proper motions. The spectral types of individual spectra are derived by fitting them with templates that are either empirical spectra of pre-main sequence stars, or model atmospheres. The templates are artificially veiled, and a best-fit combination of spectral type and veiling parameter is derived for each star. We use the spectral types with archival photometry to derive $V$-band extinction and stellar luminosity. From the H-R diagram, the median age of the young stars is about 1 Myr, with a luminosity dispersion of $\sim$0.3--0.4 dex. We investigate the photometric variability of the spectroscopic member sample using ZTF data, and conclude that photometric variability, while present, does not significantly contribute to the luminosity dispersion. While larger than the formal errors, the luminosity dispersion is smaller than if veiling were not taken into account in our spectral typing process. The measured ages of stellar kinematic groups, combined with inferred ages for embedded stellar populations revealed by Spitzer, suggests a sequential history of star formation in the NAP region.