The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500

TL;DR

This paper introduces a high-quality spectroscopic survey of Galactic O stars, providing a new classification system, an updated atlas, and detailed analysis of 184 northern bright O stars, significantly improving classification accuracy.

Contribution

It presents a new spectral classification system, an updated atlas, and a nearly complete sample of bright northern O stars, enhancing the accuracy and consistency of stellar classifications.

Findings

New spectral classification system and atlas for O stars

High-precision classifications with improved accuracy

Comprehensive sample of 184 northern bright O stars

Abstract

We present the first installment of a massive spectroscopic survey of Galactic O stars, based on new, high signal-to-noise ratio, R~2500 digital observations from both hemispheres selected from the Galactic O-Star Catalog of Ma\'iz Apell\'aniz et al. (2004) and Sota et al. (2008). The spectral classification system is rediscussed and a new atlas is presented, which supersedes previous versions. Extensive sequences of exceptional objects are given, including types Ofc, ON/OC, Onfp, Of?p, Oe, and double-lined spectroscopic binaries. The remaining normal spectra bring this first sample to 184 stars, which is close to complete to B=8 and north of delta = -20 and includes all of the northern objects in Ma\'iz Apell\'aniz et al. (2004) that are still classified as O stars. The systematic and random accuracies of these classifications are substantially higher than previously attainable, because of the quality, quantity, and homogeneity of the data and analysis procedures. These results will enhance subsequent investigations in Galactic astronomy and stellar astrophysics. In the future we will publish the rest of the survey, beginning with a second paper that will include most of the southern stars in Ma\'iz Apell\'aniz et al. (2004).