The solar atmosphere is composed of various layers interconnected through magnetic fields. The magnetic field acts as a conduit to transfer energy and mass from the inner layers to the outer layers, commonly known as the coronal heating problem and is also the prime driver of solar wind.
| Photo Credit: file photo
Astronomers at the Indian Institute of Astrophysics (IIA) have found a new way to probe deeper into the sun’s secrets by studying the magnetic field at different layers of the solar atmosphere. The astronomers have done this using data from IIA’s Kodaikanal Tower Tunnel Telescope.
According to the Department of Science and Technology, the solar atmosphere is composed of various layers interconnected through magnetic fields. The magnetic field acts as a conduit to transfer energy and mass from the inner layers to the outer layers, commonly known as the coronal heating problem and is also the prime driver of solar wind. To understand the physical mechanisms behind these processes, measurements of magnetic fields at different heights of the solar atmosphere are important.
IIA astronomers have examined an active region (sunspot) with complex features, including multiple umbrae and a penumbra, through simultaneous observations in the Hydrogen-alpha and Calcium II 8662 Å lines from the Kodaikanal Tower Tunnel telescope.
The study used data from multiple spectral lines acquired simultaneously, especially the Hydrogen-alpha line, at 6562.8 Angstroms (Å), to infer the magnetic field’s stratification at various heights of the solar atmosphere, taken from the Tunnel Telescope at the Kodaikanal Solar Observatory, which IIA operates.
The primary mirror (M1) of the 3-mirror setup at the Tunnel Telescope tracks the sun, the secondary mirror (M2) redirects sunlight downwards, and the tertiary mirror (M3) makes the beam horizontal. This kind of setup, where the primary mirror is rotated to track a moving object in the sky, in this case, the sun, is called a Coelostat. An achromatic doublet (38 cm aperture, f/96) focuses the sun’s image at a distance of 36 m with an image scale of 5.5 arcsec per mm.
The chromospheric magnetic field in the spectral lines is typically inferred using the Calcium II 8542 Å and Helium I 10830 Å line. However, these diagnostic probes have certain limitations which limit their applicability across diverse solar features.
