Hd 140283: A Star in the Solar Neighborhood That Formed Shortly After the Big Bang

Abstract

HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 ± 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 ± 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = −1.67 and [Fe/H] = −2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about ±0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 ± 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang.

Benchmark stars forGaiaFundamental properties of the Population II star HD 140283 from interferometric, spectroscopic, and photometric data

“…These ages are slightly larger than the adopted age of the Universe (13.77 Gyr, Bennett et al 2013) but within their quoted error bars. The new better precision in the parallax from Bond et al (2013) reduces the derived uncertainty in the radius (this work) by a factor of 30% and leaves the radius uncertainty dominated almost entirely by its angular diameter.…”

“…Charbonnel & Primas 2005) and to study neutron-capture elements to understand better heavy element nucleosynthesis (Siqueira Mello et al 2012;Gallagher et al 2010;Collet et al 2009). Concerning the fundamental properties of this star, Bond et al (2013) published a refined parallax π = 17.15 + −0.14 mas, an uncertainty one fifth of that determined by the Hipparcos satellite (van Leeuwen 2007, 17.16 ± 0.68 mas), and assuming zero reddening determined an age of 14.5 Gyr. More recently, VandenBerg et al (2014) determined an age for HD 140283 of 14.27 Gyr.…”

A Possible Alternative to the Accelerating Universe III

“…However a rough estimate indicates that a correction for this effect would be less than 0.5 percent, and in view of the sizes of the other uncertainties, it can be ignored at this stage of the study. An interesting hint of possible support for the alternative model comes from the fairly recent study of the star HD 140283 by Bond et al [12], who describe it as a subgiant with low metallicity in the solar neighborhood, at approximately 100 lyr from earth. They found that when all uncertainties are included the star's age is 14.46 ± 0.8 Gyr.…”

Early Formed Astrophysical Objects and Cosmological Antimatter

“…The metal deficient high velocity subgiant in the solar neighborhood HD 140283 has the age 14.46 ± 0.31 Gyr [26] The central value exceeds the universe age by two standard deviations, if H = 67.3 and t U = 13.8, while for H = 74, and thusA possible explanation of this discrepancy could be an unusual initial chemical content of such stars. Normally a pre-stellar cloud consists of 25% of He 4 and 75% of hydrogen.…”