Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux
The Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation that may cause changes in their atmospheric dynamics...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acbe38 |
| _version_ | 1797695821975650304 |
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| author | Kosuke Namekata Shin Toriumi Vladimir S. Airapetian Munehito Shoda Kyoko Watanabe Yuta Notsu |
| author_facet | Kosuke Namekata Shin Toriumi Vladimir S. Airapetian Munehito Shoda Kyoko Watanabe Yuta Notsu |
| author_sort | Kosuke Namekata |
| collection | DOAJ |
| description | The Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation that may cause changes in their atmospheric dynamics and chemistry. While X-ray fluxes can be observed directly, EUV fluxes cannot be observed because of severe interstellar medium absorption. Here we present a new empirical method to estimate the whole stellar X-ray plus EUV (XUV) and far-UV (FUV) spectra as a function of total unsigned magnetic fluxes of stars. The response of the solar XUV and FUV spectrum (0.1–180 nm) to the solar total unsigned magnetic flux is investigated by using the long-term Sun-as-a-star data set over 10 yr, and the power-law relation is obtained for each wavelength with a spectral resolution of 0.1–1 nm. We applied the scaling relations to active young Sun-like stars (G dwarfs), EK Dra (G1.5V), π ^1 Uma (G1.5V), and κ ^1 Ceti (G5V) and found that the observed spectra (except for the unobservable longward EUV wavelength) are roughly consistent with the extension of the derived power-law relations with errors of an order of magnitude. This suggests that our model is a valuable method to derive the XUV/FUV fluxes of Sun-like stars, including the EUV band mostly absorbed at wavelengths longward of 36 nm. We also discuss differences between the solar extensions and stellar observations at wavelengths in the 2–30 nm band and conclude that simultaneous observations of magnetic and XUV/FUV fluxes are necessary for further validations. |
| first_indexed | 2024-03-12T03:16:45Z |
| format | Article |
| id | doaj.art-294c58d6ba604fd6a1332330599340b7 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:16:45Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-294c58d6ba604fd6a1332330599340b72023-09-03T14:08:23ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01945214710.3847/1538-4357/acbe38Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic FluxKosuke Namekata0https://orcid.org/0000-0002-1297-9485Shin Toriumi1https://orcid.org/0000-0002-1276-2403Vladimir S. Airapetian2https://orcid.org/0000-0003-4452-0588Munehito Shoda3https://orcid.org/0000-0002-7136-8190Kyoko Watanabe4https://orcid.org/0000-0003-0321-7881Yuta Notsu5https://orcid.org/0000-0002-0412-0849ALMA Project, National Astronomical Observatory of Japan , NINS, Osawa, Mitaka, Tokyo, 181-8588, Japan ; kosuke.namekata@astro.nao.ac.jp, namekata@kusastro.kyoto-u.ac.jpInstitute of Space and Astronautical Science , Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, JapanSellers Exoplanetary Environments Collaboration, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Physics, American University , Washington, DC 20016, USADepartment of Earth and Planetary Science, School of Science, The University of Tokyo , 7-3-1, Hongo, Bunkyo, Tokyo, 113-0033, JapanNational Defense Academy of Japan , 1-10-20 Hashirimizu, Yokosuka 239-8686, JapanLaboratory for Atmospheric and Space Physics, University of Colorado Boulder , 3665 Discovery Drive, Boulder, CO 80303, USA; National Solar Observatory , 3665 Discovery Drive, Boulder, CO 80303, USA; Department of Earth and Planetary Sciences, Tokyo Institute of Technology , 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, JapanThe Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation that may cause changes in their atmospheric dynamics and chemistry. While X-ray fluxes can be observed directly, EUV fluxes cannot be observed because of severe interstellar medium absorption. Here we present a new empirical method to estimate the whole stellar X-ray plus EUV (XUV) and far-UV (FUV) spectra as a function of total unsigned magnetic fluxes of stars. The response of the solar XUV and FUV spectrum (0.1–180 nm) to the solar total unsigned magnetic flux is investigated by using the long-term Sun-as-a-star data set over 10 yr, and the power-law relation is obtained for each wavelength with a spectral resolution of 0.1–1 nm. We applied the scaling relations to active young Sun-like stars (G dwarfs), EK Dra (G1.5V), π ^1 Uma (G1.5V), and κ ^1 Ceti (G5V) and found that the observed spectra (except for the unobservable longward EUV wavelength) are roughly consistent with the extension of the derived power-law relations with errors of an order of magnitude. This suggests that our model is a valuable method to derive the XUV/FUV fluxes of Sun-like stars, including the EUV band mostly absorbed at wavelengths longward of 36 nm. We also discuss differences between the solar extensions and stellar observations at wavelengths in the 2–30 nm band and conclude that simultaneous observations of magnetic and XUV/FUV fluxes are necessary for further validations.https://doi.org/10.3847/1538-4357/acbe38Solar x-ray emissionExtreme ultraviolet astronomySolar extreme ultraviolet emissionSolar coronal heatingStellar x-ray flaresStellar coronae |
| spellingShingle | Kosuke Namekata Shin Toriumi Vladimir S. Airapetian Munehito Shoda Kyoko Watanabe Yuta Notsu Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux The Astrophysical Journal Solar x-ray emission Extreme ultraviolet astronomy Solar extreme ultraviolet emission Solar coronal heating Stellar x-ray flares Stellar coronae |
| title | Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux |
| title_full | Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux |
| title_fullStr | Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux |
| title_full_unstemmed | Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux |
| title_short | Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux |
| title_sort | reconstructing the xuv spectra of active sun like stars using solar scaling relations with magnetic flux |
| topic | Solar x-ray emission Extreme ultraviolet astronomy Solar extreme ultraviolet emission Solar coronal heating Stellar x-ray flares Stellar coronae |
| url | https://doi.org/10.3847/1538-4357/acbe38 |
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