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

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 = 31500 and 11930, respectively) to find the best solar twin candidates and then observed at McDonald Observatory with higher resolving power (TS23, R = 60000) 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 analogs and 13 solar-type stars. In addition, we identified 9 close solar twins whose stellar parameters are the most similar to those of the Sun.

Galactic chemical evolution of the solar neighborhood, solar twins and exoplanet indicators

“…The latter reference is of interest because it lists all but one of the BD18 stars in a solar twin search. Additional references may be found in the exhaustive study of the solar twin problem by Yana Galarza et al (2021).…”

“…Numerous workers have sought an optimum sample of representative stars for the solar neighborhood. The topic was reviewed in detail by Yana Galarza et al (2021), who discuss new criteria based on Gaia data, geochronology, and magnetic activity.…”

Rocky planet engulfment in the binary system HIP 71726-37

“…( √ ) Stellar parameters for HIP 71737 and the Sun, both relative to the primary component HIP 71726. ( †) Trigonometric surface gravity (Yana Galarza et al 2021, see their equation 3). traction, order extraction, etc.…”

“…The radial/barycentric velocity correction and normalization of the TS23 spectra were carried out using our own semi-automatic Python scripts described in Yana Galarza et al (2021). The Equivalent Widths (EWs) were measured manually through Gaussian fits to the line profile using the KAPTEYN kmpfit Package (Terlouw & Vogelaar 2015), which is also implemented in our scripts.…”

“…Additionally, we estimated the activity indices (S HK,TS23 ) measuring the flux in the Ca II H&K lines following the prescription given in Wright et al (2004). The S HK,TS23 was converted to the Mount Wilson system (S MW ) using the equation (4) of Yana Galarza et al (2021). Then, we determined the chromospheric indices (log R HK ) following the procedure of Noyes et al (1984).…”