| Name: manjunath hegde |
| Affiliation: indian institute of astrophysics |
| Conference ID: ASI2026_472 |
| Title: A Declining Trend in Sunspot Group Tilt Angles Over Three and half solar cycles: 21-24 |
| Abstract Type: Oral |
| Abstract Category: Sun, Solar System, Exoplanets, and Astrobiology |
| Author(s) and Co-Author(s) with Affiliation: Manjunath Hegde(IIAP), Ravindra B(IIAP), Hiremath K M(IIAP) |
| Abstract: The tilt angle, defined as the angle between the line connecting the two polarities of a sunspot group and the solar equator, plays a critical role in linking the Sun’s global magnetic field and is a key parameter in dynamo models. This study examines the long-term characteristics of sunspot group tilt angles using data from the Debrecen Photoheliographic Database (DPD), covering three and a half solar cycles (1974–2013). Using tilt angles provided in the DPD catalog, we compute annual averages and apply weighted linear regression to assess long-term trends, along with wavelet transform analysis to identify short-term periodicities. Our analysis reveals a significant, consistent decrease in the magnitude of sunspot tilt angles, with an average yearly decline of approximately \(0.06 \pm 0.01\) degrees. Additionally, a wavelet analysis indicates a short-term 4--6 year periodicity. |
