HD 4915: A Maunder Minimum Candidate

TL;DR

This paper investigates the magnetic activity cycle of HD 4915, suggesting it may be entering a grand minimum state similar to the Sun's Maunder Minimum, based on long-term spectroscopic observations.

Contribution

It presents evidence of a decreasing amplitude in HD 4915's magnetic cycle, indicating a potential grand minimum, and recommends further multi-method monitoring.

Findings

Decreasing amplitude in magnetic activity cycle.

Potential entry into a grand minimum state.

Need for continued multi-method observations.

Abstract

We study the magnetic activity cycle of HD 4915 using the \ion{Ca}{2} H \& K emission line strengths measured by Keck I/HIRES spectrograph. The star has been observed as a part of California Planet Search Program from 2006 to present. We note decreasing amplitude in the magnetic activity cycle, a pattern suggesting the star's entry into a Magnetic Grand Minimum (MGM) state, reminiscent of the Sun's Maunder and Dalton Minima. We recommend further monitoring of the star to confirm the grand minimum nature of the dynamo, which would provide insight into the state of the Sun's chromosphere and the global magnetic field during its grand minima. We also recommend continued observations of H \& K emission lines, and ground or space based photometric observations to estimate the sunspot coverage.