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| Auteurs principaux: | , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Accès en ligne: | https://arxiv.org/abs/2507.15953 |
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| _version_ | 1866916855346626560 |
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| author | France, Kevin Duvvuri, Girish Froning, Cynthia Brown, Alexander Schneider, P. Christian Pineda, J. Sebastian Wilson, David Youngblood, Allison Airapetian, Vladimir Namekata, Kosuke Notsu, Yuta Sextro, Tristen |
| author_facet | France, Kevin Duvvuri, Girish Froning, Cynthia Brown, Alexander Schneider, P. Christian Pineda, J. Sebastian Wilson, David Youngblood, Allison Airapetian, Vladimir Namekata, Kosuke Notsu, Yuta Sextro, Tristen |
| contents | The extreme-ultraviolet (EUV; 100 -- 911 Å) spectra of F, G, K, and M stars provide diagnostics of the stellar chromosphere through the corona, with line and continuum formation temperatures spanning roughly 10$^{4}$ - 10$^{7}$ K. The EUV stellar spectrum in turn drives atmospheric photochemistry and numerous escape processes on orbiting planets. We present a new study of the EUV history of solar-type stars, using new and archival {\it Hubble Space Telescope} observations of solar analogs (T$_{\odot}$ $\pm$ 150 K for stars older than 100 Myr) and ``Young Suns" (age $<$ 100 Myr) that will evolve into main sequence early G-type stars to predict the 90 -- 360 Å EUV flux from a sample of 23 stars. We find that the EUV activity evolution for solar-type stars follows a two-component behavior: a saturated L(EUV)/L$_{bol}$ plateau (at a level of about 10$^{-4}$) followed by a power law decay ($α$ $\approx$ $-$1.1) after ages of $\approx$ 50 -- 100 Myr. Consequently, the EUV flux incident at 1 AU around solar analogs varies over the lifetime of the Sun, ranging from 100 $\times$ the present day UV irradiance at 10 Myr to 0.3 $\times$ the present-day level at 10 Gyr. We find that the EUV luminosity is approximately the same as the soft X-ray luminosity up to approximately 1 Gyr, after which the EUV luminosity of the stars dominate. In comparison to Sun-like stars, the EUV saturation level of early/mid M dwarfs is several times higher and lasts $\sim$10 -- 20 times longer. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_15953 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Semi-Empirical Estimate of Solar EUV Evolution from 10 Myr to 10 Gyr France, Kevin Duvvuri, Girish Froning, Cynthia Brown, Alexander Schneider, P. Christian Pineda, J. Sebastian Wilson, David Youngblood, Allison Airapetian, Vladimir Namekata, Kosuke Notsu, Yuta Sextro, Tristen Solar and Stellar Astrophysics Earth and Planetary Astrophysics The extreme-ultraviolet (EUV; 100 -- 911 Å) spectra of F, G, K, and M stars provide diagnostics of the stellar chromosphere through the corona, with line and continuum formation temperatures spanning roughly 10$^{4}$ - 10$^{7}$ K. The EUV stellar spectrum in turn drives atmospheric photochemistry and numerous escape processes on orbiting planets. We present a new study of the EUV history of solar-type stars, using new and archival {\it Hubble Space Telescope} observations of solar analogs (T$_{\odot}$ $\pm$ 150 K for stars older than 100 Myr) and ``Young Suns" (age $<$ 100 Myr) that will evolve into main sequence early G-type stars to predict the 90 -- 360 Å EUV flux from a sample of 23 stars. We find that the EUV activity evolution for solar-type stars follows a two-component behavior: a saturated L(EUV)/L$_{bol}$ plateau (at a level of about 10$^{-4}$) followed by a power law decay ($α$ $\approx$ $-$1.1) after ages of $\approx$ 50 -- 100 Myr. Consequently, the EUV flux incident at 1 AU around solar analogs varies over the lifetime of the Sun, ranging from 100 $\times$ the present day UV irradiance at 10 Myr to 0.3 $\times$ the present-day level at 10 Gyr. We find that the EUV luminosity is approximately the same as the soft X-ray luminosity up to approximately 1 Gyr, after which the EUV luminosity of the stars dominate. In comparison to Sun-like stars, the EUV saturation level of early/mid M dwarfs is several times higher and lasts $\sim$10 -- 20 times longer. |
| title | A Semi-Empirical Estimate of Solar EUV Evolution from 10 Myr to 10 Gyr |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2507.15953 |