HD 196390: A Tight Correlation of Differential Abundances with Condensation Temperature

Abstract

Bedell et al. (2018) give precision differential abundances for 79 mostly G-dwarf stars. We correct these abundances for Galactic chemical evolution in a manner similar to that used by these authors but with parameters derived from linear fits to plots of [El/H] vs. age in lieu of [El/Fe]. We examine the resulting abundances for correlations with the 50% condensation temperature using values from both Lodders (2003) and Wood et al. (2019), and compare with the results of Bedell et al. HD 196390 is distinct in having the most significant correlation of the 79-star sample. We report statistics for a subset of stars with lower significance, but of some interest.

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

“…Only elements from carbon to zinc were used. We excluded the neutron-addition (nA) elements from consideration in the search for 𝑇 c correlations for reasons noted by Meléndez et al (2014), and adopted by Cowley et al (2020) in their survey of the BD18 sample. Many examples may be seen in the plots of the BD18 abundances vs. 𝑇 c , where the nA abundances scatter sometimes above (HIP 8507) and sometimes below (HIP 9349) the trends for the lighter elements (see TccorGIF1 in the zenodo archive).…”

Modeling stellar abundance patterns resulting from the addition of earthlike planetary material

“…It is necessary to subtract the effects of GCE prior to examining the differential abundances for possible effects of addition or subtraction of planetary material. This was done by Cowley, Bord & Yüce (2020a) 2 in their study of T c correlations among the 79 stars of Bedell, et al (2018, henceforth, BD18) which included the first three examples below. BD18 give precision differential abundances for the following 30 elements: C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy.…”

“…Among the stars of BD18 noted by Cowley, Bord & Yüce (2020a), HD 42618 was unusual because of its negative slope, and because it has a known planet containing some 14.4 earth masses. The formal probability that an unweighted linear fit of [El/H] with T c occurs by chance was 2.1 • 10 −5 , but the two-parameter linear regression fit is only of marginal significance.…”

“…HD 140538 (ψ Ser, Fig. 2, Right) is among the stars of Cowley, Bord & Yüce (2020a) which have a significant [El/H] vs. T c plot. Although classified as G2.5 V, it is not considered a solar twin possibly because it is thought to be in a triple system, with two dwarf M companions (Mahdi, et al 2016).…”