Kavli Affiliate: Gregory J. Herczeg
| First 5 Authors: Min Fang, Lynne A. Hillenbrand, Jinyoung Serena Kim, Krzysztof Findeisen, Gregory J. Herczeg
| Summary:
We present a spectroscopic survey of over 3400 potential members in the North
America and Pelican nebulae (NAP) using several low-resolution ($Rapprox$
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.
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