Rotational Modulation of Spectroscopic Zeeman Signatures in Low-mass Stars
AffiliationSteward Observatory, University of Arizona
MetadataShow full item record
PublisherAmerican Astronomical Society
CitationTerrien, R. C., Keen, A., Oda, K., Partsthey/them, W., Stefánsson, G., Mahadevan, S., Robertson, P., Ninan, J. P., Beard, C., Bender, C. F., Cochran, W. D., Cunha, K., Diddams, S. A., Fredrick, C., Halverson, S., Hearty, F., Ickler, A., Kanodia, S., Libby-Roberts, J. E., … Turner, B. (2022). Rotational Modulation of Spectroscopic Zeeman Signatures in Low-mass Stars. Astrophysical Journal Letters.
JournalAstrophysical Journal Letters
RightsCopyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractAccurate tracers of the stellar magnetic field and rotation are cornerstones for the study of M dwarfs and for reliable detection and characterization of their exoplanetary companions. Such measurements are particularly challenging for old, slowly rotating, fully convective M dwarfs. To explore the use of new activity and rotation tracers, we examined multiyear near-infrared (NIR) spectroscopic monitoring of two such stars-GJ 699 (Barnard's Star) and Teegarden's Star-carried out with the Habitable-zone Planet Finder spectrograph. We detected periodic variations in absorption line widths across the stellar spectrum, with higher amplitudes toward longer wavelengths. We also detected similar variations in the strength and width of the 12435.67 Å neutral potassium (K i) line, a known tracer of the photospheric magnetic field. Attributing these variations to rotational modulation, we confirm the known 145 ± 15 day rotation period of GJ 699, and measure the rotation period of Teegarden's Star to be 99.6 ± 1.4 days. Based on simulations of the K i line and the wavelength dependence of the line-width signal, we argue that the observed signals are consistent with varying photospheric magnetic fields and the associated Zeeman effect. These results highlight the value of detailed line profile measurements in the NIR for diagnosing stellar magnetic field variability. Such measurements may be pivotal for disentangling activity and exoplanet-related signals in spectroscopic monitoring of old, low-mass stars. © 2022. The Author(s). Published by the American Astronomical Society.
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Except where otherwise noted, this item's license is described as Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.