Searching for new solar twins: The Inti survey for the Northern Sky

• Published in: Monthly notices of the Royal Astronomical Society 2021-06, Vol.504 (2), p.1873-1887
• Main Authors: Yana Galarza, Jhon, López-Valdivia, Ricardo, Lorenzo-Oliveira, Diego, Reggiani, Henrique, Meléndez, Jorge, Gamarra-Sánchez, Daniel, Flores, Matias, Portal-Rivera, Jerry, Miquelarena, Paula, Ponte, Geisa, Schlaufman, Kevin C, Vargas Auccalla, Teófilo
• Format: Article
• Language: English
• Subjects: Metallicity; Northern Hemisphere; Northern sky; Parameter estimation; Parameter identification; Resolution; Signal to noise ratio; Sky surveys (astronomy); Spectrographs; Stellar evolution; Sun
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stab987

ABSTRACT Solar twins are key in different areas of astrophysics, however only just over a hundred were identified and well-studied in the last two decades. In this work, we take advantage of the very precise Gaia (DR2/EDR3), Tycho, and 2MASS photometric systems to create the ${{Inti}}$ survey of new solar twins in the Northern Hemisphere. The spectra of our targets were initially obtained with spectrographs of moderate resolution (ARCES and Goodman spectrographs with R  = 31 500 and 11 930, respectively) to find the best solar twin candidates and then observed at McDonald Observatory with higher resolving power (TS23, R  = 60 000) and signal-to-noise ratio (SNR ∼ 300–500). The stellar parameters were estimated through the differential spectroscopic equilibrium relative to the Sun, which allow us to achieve a high internal precision (σ(Teff)  = 15 K, σ(log g)  = 0.03 dex, σ($\rm {[Fe/H]}$)  = 0.01 dex, and σ(vt)  = 0.03 km s−1). We propose a new class of stars with evolution similar to the Sun: solar proxy, which is useful to perform studies related to the evolution of the Sun, such as its rotational and magnetic evolution. Its definition is based on metallicity (−0.15 dex ≤ $\rm {[Fe/H]}$ ≤  + 0.15 dex) and mass (0.95 M⊙ ≤ M ≤ 1.05 M⊙) constraints, thus assuring that the star follows a similar evolutionary path as the Sun along the main sequence. Based on this new definition, we report 70 newly identified solar proxies, 46 solar analogues, and 13 solar-type stars. In addition, we identified nine close solar twins whose stellar parameters are the most similar to those of the Sun.