The Study of [Th/Eu] as a Cosmic Chronometer

Azhari, Ainun (2023) The Study of [Th/Eu] as a Cosmic Chronometer. Master's Thesis / Essay, Astronomy.

Preview	Text Master's Thesis Ainun Azhari.pdf Download (16MB) | Preview
	Text toestemming.pdf Restricted to Registered users only Download (129kB)

Abstract

Stellar age is a fundamental parameter in astronomy, and most age-determination methods are model-dependent. This currently has been alleviated by asteroseismology, allowing more precise age determination through seismic masses. However, this method is rather expensive to perform for a large number of stars, and so it is desirable to have some alternative methods to derive stellar age precisely and less expensively. In this thesis, I investigate the use of [Th/Eu] as a chronometer. I derive [Eu/Fe] and [Th/Fe] abundances to study the reliability of [Th/Eu] abundance ratio to determine stellar age. I also explore the use of the Th II line at 5989 A˚ to derive reliable Th abundance. I determine the abundance ratios of [Eu/Fe], [Th/Fe], and [Th/Eu] using high-resolution spectra and spectral synthesis code Turbospectrum. For this purpose, I use the Eu II line at 6645 A˚ which is commonly used and widely studied to obtain reliable Eu abundance. For Th abundance determination, I use the Th II line at 5989 A˚. This line is less troubled by blending compared to the more commonly used line the more commonly used Th II line at 4019 A˚, which is not available in the spectra. This approach could be useful to determine stellar age for a large number of stars in the Milky Way, as an alternative to asteroseismology which requires long and continuous photometric observations.

Item Type:	Thesis (Master's Thesis / Essay)
Supervisor name:	Tolstoy, E. and Matsuno, T.
Degree programme:	Astronomy
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	17 Jul 2023 07:21
Last Modified:	17 Jul 2023 07:21
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/30664

Actions (login required)

View Item