New Method to Estimate Helium Abundance in the Sun

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Why in news?

Recent Study conducted by researchers from the Indian Institute of Astrophysics (IIA), reliably estimate Helium abundance in the Sun.

Helium – It is the 2^nd most abundant element in the Sun after Hydrogen.
But the accurate measurement of helium abundance in the Sun's photosphere has been a longstanding challenge.
Traditional estimates relied on indirect methods, such as:
- Extrapolation from hotter stars.
- Measurements from the solar corona and solar wind.
- Seismology studies of the Sun's interior.
Reason - Helium does not produce observable spectral lines from the Sun's visible surface (photosphere).

New Methodology

They analyzed high-resolution solar spectrum data from
- Neutral magnesium (Mg) atomic lines and magnesium hydride (MgH) molecular lines.
- Neutral carbon (C) atomic lines and hydrocarbon (CH and C₂) molecular lines.
Relative consistency - The technique is based on the principle of elemental abundance consistency between atomic and molecular forms of the same element.

Key Findings

The research confirmed a helium-to-hydrogen ratio of approximately 0.1.
It also confirmed that for every 10 hydrogen atoms in the Sun, there is about 1 helium atom.

Significance

This could be a major step in assessing the opacity of the Sun’s photosphere.
Validates previously assumed helium abundance values with direct evidence.
Estimating accurate models of solar structure and evolution, as helium content significantly influences a star's lifetime, energy production, and evolutionary path.
Solar helium measurements help constrain theories about Big Bang nucleosynthesis and the early universe's elemental production.

Reference