Results of the summarizing process for the arXiv paper: 2103.07621v1

This study presents the results of spectroscopic follow-up for 1897 low-metallicity star candidates selected from the Best & Brightest (B&B) Survey. The observations were carried out using the GMOS-N/S and Goodman spectrographs, which provided low-resolution spectra with a resolution of approximately 2000. From these spectra, the authors estimated stellar atmospheric parameters and determined carbon and magnesium abundance ratios, which are representative of alpha elements. The analysis confirmed that 56% of the program stars are metal-poor ([Fe/H] < -1.0), while 30% are classified as very metal-poor (VMP; [Fe/H] < -2.0), and 2% are extremely metal-poor (EMP; [Fe/H] < -3.0). Additionally, the study identified 191 carbon-enhanced metal-poor (CEMP) stars, resulting in CEMP fractions of 19% and 43% for the VMP and EMP regimes, respectively. Among these CEMP stars, 94 belong to Group I ($A({\rm C}) \gtrsim 7.25$) and 97 to Group II ($A({\rm C}) \lesssim 7.25$) in the Yoon-Beers $A$(C)$-$[Fe/H] diagram. To improve target selection criteria for identifying bona fide VMP and EMP stars, the authors combined their data with Gaia EDR3 astrometric information. This approach significantly increased the efficiency compared to random draws from the B&B catalog, more than doubling success rates for different metallicity thresholds: $96\%$, $76\%$, $28\%$, and $4\%$ for [Fe/H] $\leq -1.5$, $\leq -2.0$, $\leq -2.5$, and $\leq -3.0$, respectively. Furthermore, this study investigated the presence of dynamically interesting stars in its sample by associating several VMP/EMP stars with either disk system or halo substructures such as Gaia Sausage/Enceladus and Sequoia with [Fe/H] $\leq -2.5$. The research is partially based on observations obtained under programs at SOAR telescope and Gemini North/South telescopes; SOAR is a joint project between Ministério da Ciência Tecnologia e Inovações do Brasil (MCTI/LNA), US National Science Foundation's NOIRLab (NSF), University of North Carolina at Chapel Hill (UNC), Michigan State University (MSU).

• Spectroscopic follow-up study on 1897 low-metallicity star candidates from the B&B Survey
• Used GMOS-N/S and Goodman spectrographs for observations
• Estimated stellar atmospheric parameters and determined carbon and magnesium abundance ratios
• Confirmed that 56% of program stars are metal-poor, 30% are very metal-poor, and 2% are extremely metal-poor
• Identified 191 carbon-enhanced metal-poor (CEMP) stars, with CEMP fractions of 19% for VMP and 43% for EMP regimes
• Grouped CEMP stars into Group I ($A({\rm C}) \gtrsim 7.25$) and Group II ($A({\rm C}) \lesssim 7.25$)
• Combined data with Gaia EDR3 astrometric information to improve target selection criteria for VMP and EMP stars
• Increased efficiency compared to random draws from B&B catalog, doubling success rates for different metallicity thresholds
• Investigated presence of dynamically interesting stars associated with disk system or halo substructures such as Gaia Sausage/Enceladus and Sequoia with [Fe/H] $\leq -2.5$
• Research based on observations obtained at SOAR telescope and Gemini North/South telescopes

Exploring the Best & Brightest Survey: Spectroscopic Follow-up of Low-Metallicity Star Candidates

The Best & Brightest (B&B) survey is a catalog of low-metallicity star candidates that was recently developed to identify metal-poor stars in our Milky Way galaxy. To further explore these stars, researchers have conducted spectroscopic follow-up observations using the GMOS-N/S and Goodman spectrographs. The results of this study were recently published in a research paper, which provides insight into the metallicity distribution of B&B stars as well as their association with different stellar populations. In this blog post, we will discuss the findings of this research and how it can be used to improve target selection criteria for identifying very metal poor (VMP) and extremely metal poor (EMP) stars.

Spectroscopic Observations

The spectroscopic follow-up observations were carried out on 1897 low-metallicity star candidates from the B&B survey. These observations provided low resolution spectra with a resolution of approximately 2000, from which researchers estimated stellar atmospheric parameters such as carbon and magnesium abundance ratios - representative alpha elements - and determined [Fe/H] values for each star candidate.

From these measurements, 56% of program stars were classified as metal poor ([Fe/H] < -1.0), while 30% were identified as VMP ([Fe/H] < -2.0) and 2% were found to be EMP ([Fe/H] < -3.0). Additionally, 191 carbon enhanced metal poor (CEMP) stars were identified among these targets; 19% belonged to Group I ($A({\rm C}) \gtrsim 7.25$), while 43% belonged to Group II ($A({\rm C}) \lesssim 7.25$).

Improving Target Selection Criteria

In order to improve target selection criteria for identifying bona fide VMP and EMP stars, researchers combined their data with Gaia EDR3 astrometric information; this approach significantly increased success rates for different metallicity thresholds compared to random draws from the B&B catalog: $96\%$, $76\%$, $28\%$, and $4\%$ for [Fe/H] $\leq -1.5$, $\leq -2.0$, $\leq -2.5$, and $\leq -3