Brief Context
Context A recent study by the Indian Institute of Astrophysics (IIA) has accurately estimated the abundance of helium in the Sun’s photosphere. Background Helium is the second most abundant element in the Sun after hydrogen, playing a vital role in its structure and energy dynamics. To accurately measure its abundance in the Sun’s photosphere has been a long-standing challenge due to the lack of helium spectral lines in the visible range.
Source Content
Syllabus: GS3/ Science and Technology
Context
- A recent study by the Indian Institute of Astrophysics (IIA) has accurately estimated the abundance of helium in the Sun’s photosphere.
Background
- Helium is the second most abundant element in the Sun after hydrogen, playing a vital role in its structure and energy dynamics.
- To accurately measure its abundance in the Sun’s photosphere has been a long-standing challenge due to the lack of helium spectral lines in the visible range.
- Traditional methods relied on indirect data from hotter stars, the solar corona and wind, and helioseismology (study of the Sun’s internal oscillations).
The new methodology
- Researchers analyzed high-resolution solar spectra to study both atomic and molecular spectral lines.
- They focused on neutral magnesium (Mg) and magnesium hydride (MgH), as well as neutral carbon (C) and its molecular forms CH and C₂.
How does the method work?
- The spectral lines of both atomic and molecular forms of magnesium and carbon are dependent on the abundance of hydrogen in the Sun’s photosphere.
- Any variation in the helium content directly affects the abundance of hydrogen.
- If the helium abundance increases, the relative abundance of hydrogen decreases.
- This reduction in hydrogen availability impacts the formation of molecules like MgH and CH, and also lowers the opacity of the Sun’s photosphere.
| Internal Structure of Sun – Core: The Sun’s energy originates in its core through nuclear fusion reactions. With extremely high temperatures and pressures, the core fuses hydrogen into helium, releasing energy. – Photosphere: It has no solid surface but appears as a bright disk due to high gas density blocking deeper visibility. – Chromosphere: Located above the photosphere, this layer is less dense and usually visible only during solar eclipses or with special filters. – Corona: The outermost and most extended part of the Sun’s atmosphere. It consists of very hot, low-density plasma and is visible during total solar eclipses. |
Source: PIB