Spectroscopic and photometric confirmation of chromospheric activity in four stars
Articles > Article · 2018
Authors: Orkun ÖZDARCAN, Hasan Ali DAL
Astronomische Nachrichten, Journal Indexed in SCI Expanded, International, WoS, 2018, vol 339, pp 277-287
Summary
We present an analysis of medium‐resolution optical spectra and long‐term V band photometry of four cool stars, BD+13 5000, BD+11 3024, TYC 3557‐919‐1, and TYC 5163‐1764‐1. Our spectroscopic analysis demonstrates that the stars are giant or subgiant from K0 or K1 spectral type, and all of them exhibit emission features in their Ca ii H& K lines. These features appear to be modulated with the rotation of the stars. Except for BD+11 3024, we observe that the radial velocities of the target stars are not stable, which suggests that each of them might be a member of a binary system. Global analysis of photometric data indicates a clear cyclic variation for BD+13 5000 and TYC 5163‐1764‐1, with a period of 8.0 ± 0.3 and 5.04 ± 0.04 year, respectively. Besides that, we observe a dramatic increase (∼0 7) in the mean brightness of BD+11 3024, accompanied with a 2.87 ± 0.12 cyclic variation, embedded into the global brightening trend, which indicates possible multiple cycles on this star.