HD 4915: A Maunder Minimum Candidate

Shivani P. Shah; Jason T. Wright; Howard Isaacson; Andrew W. Howard; Jason L. Curtis

doi:10.3847/2041-8213/aad40c

HD 4915: A Maunder Minimum Candidate

Shivani P. Shah, Jason T. Wright, Howard Isaacson, Andrew W. Howard, Jason L. Curtis

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16 Scopus citations

Abstract

We study the magnetic activity cycle of HD 4915 using the Ca ii HK emission line strengths measured by Keck I/High Resolution Echelle Spectrometer (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 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 HK emission lines, and ground- or space-based photometric observations to estimate the sunspot coverage.

Original language	English (US)
Article number	L26
Journal	Astrophysical Journal Letters
Volume	863
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/aad40c
State	Published - Aug 20 2018

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/2041-8213/aad40c

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@article{1b7a784e851f499d804aa50af93ce27e,

title = "HD 4915: A Maunder Minimum Candidate",

abstract = "We study the magnetic activity cycle of HD 4915 using the Ca ii HK emission line strengths measured by Keck I/High Resolution Echelle Spectrometer (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 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 HK emission lines, and ground- or space-based photometric observations to estimate the sunspot coverage.",

author = "Shah, {Shivani P.} and Wright, {Jason T.} and Howard Isaacson and Howard, {Andrew W.} and Curtis, {Jason L.}",

note = "Funding Information: This material is based upon work supported by the NSF Postdoctoral Research Fellowship in Biology under grant No. AST-1602662. Facility: Keck:I (HIRES). Funding Information: The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. Funding Information: The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved.",

year = "2018",

month = aug,

day = "20",

doi = "10.3847/2041-8213/aad40c",

language = "English (US)",

volume = "863",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

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TY - JOUR

T1 - HD 4915

T2 - A Maunder Minimum Candidate

AU - Shah, Shivani P.

AU - Wright, Jason T.

AU - Isaacson, Howard

AU - Howard, Andrew W.

AU - Curtis, Jason L.

N1 - Funding Information: This material is based upon work supported by the NSF Postdoctoral Research Fellowship in Biology under grant No. AST-1602662. Facility: Keck:I (HIRES). Funding Information: The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. Funding Information: The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Publisher Copyright: © 2018. The American Astronomical Society. All rights reserved.

PY - 2018/8/20

Y1 - 2018/8/20

N2 - We study the magnetic activity cycle of HD 4915 using the Ca ii HK emission line strengths measured by Keck I/High Resolution Echelle Spectrometer (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 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 HK emission lines, and ground- or space-based photometric observations to estimate the sunspot coverage.

AB - We study the magnetic activity cycle of HD 4915 using the Ca ii HK emission line strengths measured by Keck I/High Resolution Echelle Spectrometer (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 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 HK emission lines, and ground- or space-based photometric observations to estimate the sunspot coverage.

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JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

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HD 4915: A Maunder Minimum Candidate

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