Space Weather & Heliophysics

Revisiting e Eridani with NEID: Identifying New Activity-Sensitive Lines in a Young K Dwarf Star

By Keith Cowing
Status Report
November 20, 2023
Filed under ,
Revisiting e Eridani with NEID: Identifying New Activity-Sensitive Lines in a Young K Dwarf Star
Ranges of each of our seven line lists over the full NEID wavelength range (3800-9300Å). The wavelengths of the lines in each line list are generally uniformly distributed blueward of ∼6500Å, with a notable gap between 6500-9000Å populated by only a couple of lines. — astro-ph.EP

Recent improvements in the sensitivity and precision of the radial velocity (RV) method for exoplanets has brought it close, but not quite to, the threshold (∼10 cm/s) required to detect Earth-mass and other potentially habitable planets around Sun-like stars. Stellar activity-driven noise in RV measurements remains a significant hurdle to achieving this goal.

While various efforts have been made to disentangle this noise from real planetary signals, a greater understanding of the relationship between spectra and stellar activity is crucial to informing stellar activity mitigation. We use a partially automated method to analyze spectral lines in a set of observations of the young, active star ϵ Eridani from the high-precision spectrograph NEID, correlate their features (depth, full width at half maximum, and integrated flux) with known activity indicators, and filter and curate for well-behaved lines whose shape changes are sensitive to certain types of stellar activity.

We then present a list of 9 lines correlated with the S-index in all three line features, including 4 newly-identified activity-sensitive lines; as well additional lines correlated with S-index in at least one feature, and discuss the possible implications of the behavior observed in these lines. Our line lists represent a step forward in the empirical understanding of the complex relationships between stellar activity and spectra, and illustrate the importance of studying the time evolution of line morphologies with stabilized spectrographs, in the overall effort to mitigate activity in the search for small, potentially Earth-like exoplanets.

Sarah Jiang, Arpita Roy, Samuel Halverson, Chad F. Bender, Carlos Selgas, O. Justin Otor, Suvrath Mahadevan, Guðmundur Stefánsson, Ryan C. Terrien, Christian Schwab

Comments: 21 pages, 9 figures. For associated data cube, see this https URL . To be published in The Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2311.10677 [astro-ph.EP] (or arXiv:2311.10677v1 [astro-ph.EP] for this version)
Submission history
From: Sarah Jiang
[v1] Fri, 17 Nov 2023 17:52:23 UTC (2,086 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻