Overview of the Galactic O-Star Spectroscopic Survey (GOSSS) III
The paper presents the third instaLLMent of the Galactic O-Star Spectroscopic Survey (GOSSS), an extensive spectroscopic survey focused on Galactic O-type stars. This release includes 142 new stellar systems, increasing the total count to 590. The paper describes the methodology, results, and implications of this significant expansion of the catalog, contributing to a deeper understanding of the properties and distribution of O-type stars in the Milky Way.
Methodology
The GOSSS employs homogeneous, high signal-to-noise ratio (SNR) digital observations to accurately determine spectral types for over 1000 O stars. The observations were conducted using various telescopes across both hemispheres, including those at the Observatorio de Sierra Nevada, Las Campanas Observatory, Calar Alto Observatory, and Observatorio del Roque de los Muchachos. The spectra were obtained with a resolution of R∼2500 in the blue-violet range, and the paper details updates to the observational setup and classification schemes to enhance the survey's accuracy and comprehensiveness.
Key Findings
- New Stellar Additions: The survey reports 142 new O-type systems, including 20 newly classified O stars. Among these, 11 new double-lined spectroscopic binaries (SB2s) were identified, expanding the census of O+O and O+B type binaries. Additionally, a new triple-lined spectroscopic binary (SB3) of O+O+B type was discovered.
- Revised Classifications: Several previously classified O stars were re-evaluated, resulting in updates to their spectral types. This includes identifying stars that were erroneously classified as O-type in the past and adjusting classifications based on new methodologies.
- Standard Grid Expansion: The paper introduces changes to the standard grid used for spectral classification, including the addition of the luminosity class IV for spectral types O4-O5.5 and adjustments to the criteria for the OVz phenomenon.
Implications and Future Work
The expanded catalog of O stars provides a more robust framework for studying massive stars and their evolutionary paths. The identification of additional binaries advances our understanding of binary formation and evolution dynamics in the galaxy. These findings have implications for theoretical models of stellar evolution and support follow-up studies using high-resolution spectroscopy to further characterize these systems.
Furthermore, the GOSSS has become a valuable dataset for analyzing the interstellar medium (ISM) and extinction patterns across the Milky Way, which could lead to improved models of galactic structure and dynamics.
Conclusion
The third instaLLMent of the GOSSS marks another substantial contribution to the astronomical community's understanding of O-type stars. The use of advanced spectroscopic techniques and comprehensive analysis has led to the identification and correction of previous classification errors, enhancing the accuracy of the Galactic stellar census. This paper sets the stage for continued exploration and paper of massive stars, potentially revealing more about their roles within the galactic ecosystem.
By maintaining a rigorous approach to cataloging and classification, the GOSSS continues to provide essential data for researchers, paving the way for future discoveries in the field of astrophysics. As the survey progresses, it will uncover additional stars and refine the classifications of known systems, making significant strides in both precision and breadth.