APA 7: TWs Editor & ChatGPT. (2023, November 2). GHOST Unearths Rare Star with Remarkably Low Metal Content! PerEXP Teamworks. [News Link]
Metal-poor stars are a scarce find, with just a few thousand stars boasting iron abundances [Fe/H] below -2.0 discovered so far. The addition of new metal-poor stars to this limited list is of great significance to astronomers because these celestial objects hold the potential to enhance our understanding of the chemical evolution of the universe.
Situated at a distance of roughly 25,500 light years from Earth, this star, known as SPLUS J142445.34−254247.1 or simply SPLUS J1424−2542, came into astronomers’ view in 2019 as a part of the Southern Photometric Local Universe Survey (S-PLUS). This celestial body boasts a mass of around 0.84 times that of our Sun, carries an estimated age of 10 billion years, and exhibits an effective temperature of approximately 4,750 K.
Prior research on SPLUS J1424−2542 indicated a metallicity level of -3.25, classifying it as an extremely metal-poor star.
Recently, a team of astronomers led by Vinicius M. Placco from the University of São Paulo in Brazil used GHOST observations of SPLUS J1424−2542 to conduct a chemical analysis of the star, providing confirmation of its extremely metal-poor status.
The researchers used GHOST at Gemini South to collect high-resolution spectroscopy, enabling them to determine the chemical abundances of 36 elements, ranging from carbon to thorium.
Analysis of the GHOST spectrum of SPLUS J1424−2542 unveiled 308 absorption features corresponding to 36 different elements. This detailed examination revealed that the star has a metallicity of approximately -3.39, thus confirming its classification as an extremely metal-poor star.
The research unveiled distinctive characteristics of SPLUS J1424−2542, including an enrichment in heavy elements. This particular pattern, coupled with its low metallicity and a carbon-to-iron ratio of 0.06, suggests that the star’s formation involved a gas cloud contaminated by the remnants of two precursor populations. These populations likely include the explosion of a metal-free star (With an estimated mass between 11.3 and 13.4 times that of our Sun) and the consequences of a binary neutron star merger, involving masses around 1.66 and 1.27 times that of the Sun.
The findings indicate that SPLUS J1424−2542 maintains a consistent effective temperature of 4,762 K, in line with previous research. Moreover, the star exhibits a total space velocity estimated at around 108 km/s.
In summary, the researchers concluded that SPLUS J1424−2542 is not only extremely metal-poor but also a low-mass, aged star, and it is part of the in-situ Galactic halo population.
Resources
- NEWSPAPER Nowakowski, T. (2023, October 31). GHOST finds an extremely metal-poor star. Phys.org. [Phys.org]
- JOURNAL Placco, V. M., Almeida-Fernandes, F., Holmbeck, E. M., Roederer, I. U., Mardini, M. K., Hayes, C. R., Venn, K., Chiboucas, K., Deibert, E., Gamen, R., Heo, J., Jeong, M., Kalari, V., Martioli, E., Xu, S., Díaz, R., Gomez-Jimenez, M., Henderson, D. K., Prado, P., . . . Thomas-Osip, J. E. (2023). SPLUS J142445.34-254247.1: An R-Process Enhanced, Actinide-Boost, Extremely Metal-Poor star observed with GHOST. arXiv (Cornell University). [arXiv.org]
